Module 3: Homeostasis Flashcards
1
Q
Digestive Physiology: What is toxoplasma and what does it affect? State an example.
A
Toxoplasma is a parasitic protist that is able to affect any homeotherm. It can be found in mice by reducing gene factors for the hormone vasopressin. Vasopressin controls the amygdala in the brain (registering responses).
2
Q
Digestive Physiology: What are the 4 processes in mechanical digestion?
A
Ingestion, digestion, absorption, and elimination.
3
Q
Digestive Physiology: When would animals use endosymbiotic bacteria?
A
When a lack of digestive tract is present, the endosymbiotic bacteria aids with converting organic chemical energy into usable forms. Or by processing the nutrients directly in a rich environment.
4
Q
Digestive Physiology: 2 examples of animals that use endosymbiotic bacteria in digestion.
A
- Tapeworms lack a gut, hence will move along the individual’s gut and consume their nutrients along the intestine.
- Rifitia (vent worms), have no digestive tract, no anus, and no mouth. They will harbor a bag of bacteria and treat it as a farm through their red gills to help convert organic chemical energy to usable energy (carbon-based nutrients).
5
Q
Digestive Physiology: What is cellulose and why can it not be digested?
A
Cellulose is a glucose polymer that plants use for their structure. Most animals cannot digest glucose due to lacking cellulase, the enzyme that breaks down the glucose polymer.
6
Q
Digestive Physiology: What enzyme is able to break down bacteria into food?
A
Lysozyme
7
Q
Digestive Physiology: How do termites and rotifers interpret cellulase?
A
Termites and rotifers do not have cellulase (an enzyme for breaking down cellulose). The incorporation of a cellulase gene into an organism’s own genes occurs through gene transfer facilitated by endosymbiotic microtubules.
8
Q
Gut Microbiome: What is the role of light junctions in a healthy gut and how are they connected?
A
Light junctions are formed by the epithelial cells which are connected by proteins. Their role is to help prevent leakage in the gut between cells in the extracellular fluid.
9
Q
Gut Microbiome: How is a healthy ecosystem maintained in the gut?
A
There is a protective layer of mucus where the gut balances out the microtubes. This allows the bacteria to use nutrients to be converted into short fatty acids. Therefore the metabolites cross the cell barrier and are responsible for signaling the molecules in the microbiome status.
10
Q
Gut Microbiome: What happens if the gut is imbalanced?
A
A maladatpive method will happen. Occurs by stopping the mucus layer from producing and depriving.
11
Q
Gut Microbiome: In extreme cases of an imbalanced gut, what will happen?
A
Breaking of cell-to-cell connections can lead to cellular damage and allow entry of foreign particles into the body through the epithelium, leading to local inflammation that can impact the immune response.
12
Q
Gut Complexity: Give an example of an animal that consists of a complex gut process.
A
The hydra begins with the food being digested in a central cavity that is surrounded by the tentacles, which also act as the hydra’s mouth. The digestive enzymes are secreted into this cavity and break down the food. The nutrients are then absorbed by the cells lining the cavity, and the waste is expelled through the same opening where the food was ingested. Once the digestion is complete, the hydra will continue to look for its next meal by extending its tentacles and scanning the surrounding water for any potential prey.
13
Q
Fermentation Chambers: What is the oldest known organism with a unidirectional gut, and how does this specialized digestive system allow for different degrees of digestion through regional specialization, starting from the mouth and moving anteriorly through the linear gut to the anus? What is the role of pH?
A
The oldest organism is known as the Cloudina. Digestion will occur through regional specialization beginning at the mouth and going through the linear gut moving anteriorly. At the anterior end, the food breaks down by using teeth, beaks, tongues, and muscles. pH is significant in stomach acid by aiding the process of breaking down macromolecules for the basic gut.
14
Q
Regionalization: What is an example of a specialized compartment and explain how it works.
A
Ruminants, such as cows, have a specialized compartment in their anterior region that helps break down food. The cow chews small amounts of food, which is then sent to chambers where cellulose helps break it down into a mushy pulp. The cow regurgitates and continues to chew and swallow the small pieces of food, which enters an acidic chamber for further digestion.
15
Q
Surface Area: How is carbohydrate digested in the gut?
A
Carbohydrate is digested in a specific location within the gut due to the cells in that region being able to secrete enzymes that can break them down. Some breakdown of carbohydrates occurs in the mouth, which signals the body that glucose is on its way. However, not much happens to carbohydrates in an acidic stomach. Once in the small intestine, hydrolytic enzymes called saccharides break down complex carbohydrates into smaller and smaller units.
16
Q
Cellular Specialization: How does surface area affect nutrient uptake in animals?
A
The surface area in the gut of animals is crucial for the efficient absorption and transportation of nutrients. Most animals have a compressed gut that creates circular folds and villi on the surface, which have many cells, and those involved in absorption have their own cellular extensions called microvilli. Underneath the villi are vessels that collect material from the gut and deliver it to the right part of the body. Nutrients move into the capillary beds or the extracellular fluid of the villi, which gets collected by the lymph vessels
17
Q
Appetite: How do hormones regulate hunger in animals?
A
Various hormones regulate hunger in animals by signaling the brain about the state of the body. Leptin is released by adipose tissue when it’s full, signaling contentment and inhibiting hunger. Peptide YY is released by the gut when the colon is full, sending a satiety message to the brain. Insulin is secreted by the pancreas when glucose levels are high, telling the brain that the animal is content. Ghrelin is released by an empty stomach, stimulating the appetite. All of these signals converge on the hypothalamus, where a decision is made whether to send a signal to the animal’s behavioral centers that it is hungry.
18
Q
Matching Feeding To Energetic Needs: Discuss how animals regulate their hunger and mention examples.
A
Appetite is dependent on feeding strategies and timelines, therefore varying amongst different species. For example, Barnacles, filter-feed all the time and don’t need to think about hunger. Or bears override their hunger centers and put themselves into a metabolic arrest for months without eating.
Note, Large predators go through cycles of feast and famine, where they endure extended periods without food and then consume large amounts during gorging periods.
19
Q
Integrating Tissue Function with Homeostasis: What is an example of how the control of appetite needs to be flexible in animals that migrate?
A
The control of appetite needs to be flexible in migrating animals. For instance, some shorebirds will overeat and become overweight in preparation for their migration. Hummingbirds will double their weight by putting on fat before a long flight without feeding.
20
Q
Osmoregulation: What is osmoregulation?
A
Osmoregulation is the process by which living organisms regulate the concentration of water and dissolved substances, such as salts and minerals, within their bodies. This process helps to maintain the proper balance of fluids and solutes in the body and is crucial for the survival of organisms in different environments.
21
Q
Osmolarity-Related Terminology: What is the correlation between osmosis and molarity? Include examples of conversions.
A
Molarity: the number of moles of glucose per L solution.
The combination of molarity and osmosis creates osmolarity, which is molarity that lumps all the different solutes together.
1 M glucose has an osmolarity of 1 OsM.
1 M NaCl has an osmolarity of 2 OsM.
There is a difference between the conversions due to not all the NaCl dissociated into the ions.
22
Q
Osmotic Pressure: What is osmotic pressure and how does it affect the movement of water between compartments separated by an osmotic gradient?
A
Osmotic pressure is the force that drives the movement of water from a region of lower solute concentration to a region of higher solute concentration. The movement of water will continue until the osmotic pressure on both sides is equal, which is when the movement will stop.
23
Q
Osmolarity vs. Tonicity: What is the difference between osmolarity and tonicity, and how do they relate to a cell’s volume?
A
The difference between osmolarity and tonicity is that osmolarity is a property of a solution that is defined in units of osmolarity, while tonicity refers to how the solution affects a cell’s volume. A hypotonic solution causes a cell to swell, while a hypertonic solution causes a cell to shrink.
24
Q
Osmolarity vs. Tonicity: What is the importance of osmoregulation?
A
Osmoregulation is important for animals to control ion and water movement in and out of the extracellular fluid (ECF) to maintain the proper osmolarity and ensure the health of its cells. Changes in ECF osmolarity can cause cell damage and loss of integrity.
25
Aquatic Environments: What is the relationship between aquatic animals and osmotic challenges, and how do different animals cope with changes in osmolarity in their environment?
Aquatic animals face diverse osmotic challenges due to varying osmolarity in their habitats. Intertidal animals, such as rock gunnels, maintain a constant internal osmolarity to tolerate rapid changes, which is known as osmoregulation. Blue mussels and little skates change their internal osmolarity to match the external environment, which is called osmoconformity.
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Osmoregulators vs. Osmoconformers: What is the difference between an osmoregulator and an osmoconformer in animals?
Animals that are able to maintain a constant internal osmolarity despite changes in external osmolarity are osmoregulators. Those that permit their internal osmolarity to change are osmoconformers.
27
Tolerance of osmotic Challenges: What do the terms euryhaline and stenohaline mean in the context of animal osmoregulation?
Animals that can tolerate wide ranges in external osmolarity are called euryhaline, while those that live in a narrow range of salts are called stenohaline. These terms describe an animal's ability to tolerate changes in external salt concentrations.
28
Transport Epithelia: 4 Key Factors of transport epithelia.
1. Transport epithelia are tissues that move ions in and out of the body.
2. Examples of transport epithelia include gills, lungs, skin, kidney, and intestine.
3. Transport epithelia have 4 main features: different transporters on the inner and outer membranes, tight connections between cells, diverse cell types, and abundant mitochondria.
4. Ion movement requires energy, so transport epithelial cells usually have abundant mitochondria for the aerobic production of ATP.
29
Specialized Tissues and Organs (Oldest Version): Explain the evolution of osmoregulatory tissue.
Flame cells are the oldest version of dedicated osmoregulatory tissues found in flatworms. The system consists of one cell that makes a tubule and another that creates a current to bring fluids into the tubule, which then gets collected and excreted from the body. Earthworms have a more complex version, with many cells joined together to draw fluids from the interstitial fluid into the tubule and excrete them through a hole in the body wall. Similar to the function of the kidney.
30
Specialized Tissues and Organs (Malpighian Tubules): What are Malpighian tubules in insects, and how do they help retain water in the body? How do mosquitoes use these tubules to compress their blood meal?
Insects, which colonized land early on, use Malpighian tubules to collect ions and excrete them via the gut. They help retain water in the body. Mosquitoes excrete water while feeding on blood to compress the meal into a concentrated protein meal.
31
Vertebrate Kidney - Structure, and Function: What is the structure and function of the nephron in the vertebrate kidney?
The nephron is the functional unit of the vertebrate kidney. It consists of two parts: the tubule and the glomerulus. Blood vessels enter the mouth of the kidney tubule (Bowman’s capsule) at the glomerulus, and low molecular weight solutes and fluid leave the blood through filtration. The fluid then moves through the tubule and is modified by transport epithelia that transport specific molecules in specific regions, reclaiming useful molecules from the urine and releasing them into the interstitial fluid. The urine is collected by the peritubular capillaries, which are responsible for maintaining an osmotic gradient that is essential for making concentrated urine. The fluid is carried through the proximal tubule, loop of Henle, distal tubule, and collecting ducts, which then empty into the ureter and eventually the urinary bladder.
32
Mammalian Kidney: What is the function of the proximal tubule in the nephron?
The proximal tubule modifies the urine by recovering valuable ions and excreting drugs and excess water-soluble vitamins. In the descending limb of the loop of Henle, aquaporins are the only transporters of importance for excretion, which increase the urine's osmolarity. As the tubule returns to the surface, cells no longer make aquaporins and instead make the transporters needed to recover NaCl, decreasing the urine's osmolarity but keeping the volume constant. The distal tubule is where the fine-tuning of the urine occurs, and is the target of various hormones that govern urine production.
33
Loop Henle: Describe the kidney.
The arrangement of multiple tubules in densely packed space within the kidney, beginning in the outer layer or cortex and looping down into the inner medulla and back up to the cortex. The collecting ducts of the tubules empty into a cavity in the kidney, which in turn empties into the ureter that carries urine from the kidney to the urinary bladder. The length of the loop of Henle in mammalian kidneys varies based on the need for water conservation, with longer loops allowing for the formation of concentrated urine.
34
Regulation of Water Balance: What is the role of ADH in the regulation of water balance in the body?
The hypothalamus detects high osmolarity in the blood and secretes the hormone ADH or antidiuretic hormone. ADH travels to the kidney where it increases the ability of the collecting duct to recover water, reducing urine volume. ADH also sends signals to the thirst centers to alter behavior to increase water consumption. This process is turned off by negative feedback when the combination of water recovery and drinking resets osmolarity.
35
ADH and Aquaporin - Localizing in the Collecting Duct: What hormone is secreted by the posterior pituitary in response to osmosensing and how does it signal the recovery of water in the kidneys?
The hormone is called vasopressin or antidiuretic hormone (ADH). Its receptor is on the cell membrane and triggers the activation of cAMP production and protein kinase A activity, leading to the movement of vesicles containing aquaporins to the cell membrane for facilitated diffusion of water.
36
Renin-Angiotensin-Aldosterone System (RAAS): What is the RAAs pathway and how does it respond to reduced blood pressure?
The RAAs pathway is a regulatory pathway that responds to reduced blood pressure caused by dehydration or blood loss. When vessels going into the glomerulus sense low blood pressure or volume, they release the enzyme renin, which activates the hormone angiotensin, produced by the liver. Angiotensin II triggers the release of aldosterone, which targets the kidney to increase the recovery of water and Na, increasing blood volume and pressure.
37
Evolutionary Origins of Cardiorespiratory Systems: What is the significance of having three embryonic cell layers in triploblasts?
The formation of three embryonic cell layers in triploblasts created the opportunity to make more specialized tissues, including those of the cardiorespiratory systems. This allowed for the evolution of more complex organisms with the ability to control the movement of fluids and gases to support their metabolic rates.
38
Vessels and Pumps - Arterial and Venous Vessels: What is the main reason why the outer layer and smooth muscle layer of an artery is thicker compared to a vein?
The outer layer and smooth muscle layer of an artery are thicker due to arteries have to cope with higher blood pressure without stretching too much.
39
Vessels and Pumps - Capillaries: What are sphincters in relation to capillaries?
Sphincters are muscle-like cells that control the diameter of capillaries, which can open and close as needed to control where blood flows.
40
Vessels and Capillaries - Interstitial Fluid: What is the function of the basal lamina layer in the context of the intestinal epithelium and capillary endothelium?
The basal lamina layer serves as a connective tissue that is produced at the base of both the intestinal cells and capillary endothelium, preventing leakage between the cells. It also forms a mesh that allows interstitial fluid to leak between and across it, which is contiguous with the fluid that the blood vessel runs through.
41
Vessels and Pumps - Regulating Flow: What is the role of endothelial cells in capillaries?
The endothelial cells in capillaries form the innermost layer of the vessel wall and are responsible for the exchange of gases, nutrients, and waste products between the blood and the surrounding tissue. These cells are very thin to allow for efficient diffusion, and their permeability can be regulated to control the flow of substances in and out of the bloodstream.
42
Vessels and Pumps - Regulating Flow: What are the two key features of capillaries in terms of their arrangement and relationship to surrounding tissues?
1. The presence of sphincters, which are muscle-like cells that control the diameter of the vessels and can open and close as needed to control blood flow.
2. Their relationship to surrounding tissues, where the capillary bed is perfusing the tissue with cells running through the gaps between the capillaries, and communication between the capillary and tissue cells occurs through the interstitial fluid.
43
Vessels and Pumps - Capillaries and Lymphatics: What are the lymph vessels responsible for?
The lymph vessels collect fluids, debris, and even cells that have leaked out of capillary beds and bring them back to lymph nodes for cleaning up.
44
Vessels and Pumps - Capillaries and Lymphatics: What is the purpose of the second set of vessels that run through the interstitial fluid?
The second set of vessels, which are the lymph vessels, collect materials that have leaked out of capillary beds, such as fluids, debris, and cells, and bring them back to lymph nodes for cleaning up.
45
Vessels and Pumps - Capillaries and Lymphatics: What is the role of lymph nodes in the process of collecting leaked materials?
The lymph nodes are responsible for cleaning up the materials that are collected by the lymph vessels, which include fluids, debris, and cells that have leaked out of the capillary beds.
46
Vessels and Pumps - Heart: What did the muscles in the wall of blood vessels become in the evolution of the cardiovascular system?
Dedicated pumps that formed a heart.
47
Vessels and Pumps - Heart: What was the first step in the evolution of the cardiovascular system?
The muscles in the wall of blood vessels got stronger, enabling them to generate force and pressure within the loop.
48
Vessels and Pumps - Heart: What is the relationship between the vasculature and the pump in the evolution of the cardiovascular system?
Evolution has led to many relationships between the vasculature and the pump
49
Closed Vs. Open Circulatory Systems: What is the difference between the cardiovascular system and the circulatory system in insects?
Insects have a cardiovascular system where blood vessels don't go to capillaries but empty into a cavity called a sinus, making it an inefficient open circulatory system. Their circulatory fluid, called hemolymph, moves nutrients and hormones around the body, and they have a separate tracheal system for respiration.
50
Closed Vs. Open Circulatory Systems: How does an earthworm's circulatory system work?
An earthworm's circulatory system is a closed system, with blood contained within vessels all the time. It has multiple hearts and muscular blood vessels in the anterior segments that generate force and pressure to move fluids around. The animal breathes essentially over its entire body surface, collecting oxygen without the need for capillaries to exchange gases.
51
Closed Vs. Open Circulatory Systems: What key factor to remember when exploring the circulatory system of vertebrates?
The hearts become more complicated in structure with more chambers and more control over which circuits serve which parts of the body.
52
Origins of Multichambered Hearts and Circuits - How is the circulation in reptiles different from that in mammals?
Reptiles have a more complicated circulation, with more heart compartments, and better separation of the pulmonary and systemic circuits. In mammals, there is complete separation of the blood serving the lungs and the blood going to the rest of the body.
53
Origins of Multichambered Hearts and Circuits - Why are the left and right sides of the heart regulated differently?
The left and right sides of the heart are regulated differently because they have different functions and pressures to perform. The left ventricle has to pump blood to the rest of the body, which requires a lot of pressure, while the right ventricle only has to pump blood to the lungs, which have thin, fragile vessels.
54
Origins of Multichambered Hearts and Circuits - What is the role of the left ventricle in the heart?
The left ventricle is responsible for pumping blood to the systemic circulation that serves most of the body. It has to pump blood up to the brain and down to the feet, and have enough pressure to drive it all the way back to the heart. The left ventricle is a super strong pump with thick muscular walls in mammals.
55
Origins of Multichambered Hearts and Circuits - Why is the right ventricle thinner than the left ventricle?
The right ventricle is thinner than the left ventricle because it only has to generate enough force to pump blood through the pulmonary circuit to the lungs, which have thin, fragile vessels. It doesn't need to produce as much pressure as the left ventricle.
56
Origins of Multichambered Hearts and Circuits - What happens to the right ventricle in chronic obstructive pulmonary disease (COPD)?
In chronic obstructive pulmonary disease, the need for oxygen causes the right ventricle to become a bit stronger by thickening the right wall of the heart. However, if the wall becomes too thick, it can impair the filling of the heart and the development of proper pressure and force, making it a poor pump.
57
Pacemaker Cells and Transmission of Signals: How can you make a pacemaker go faster?
By making the sodium channel a little bit leakier or having it stay open for longer, which depolarizes the cell to the threshold faster and starts the contraction faster.
58
Pacemaker Cells and Transmission of Signals: Why is it a problem if the wave of contractions continued from the SA node to the apex of the heart?
If the wave continued from the SA node to the apex of the heart, it would push blood to the bottom of the heart instead of pumping it out through the arteries, causing a problem.
59
Pacemaker Cells and Transmission of Signals: How are the pacemaker cells connected to the rest of the heart cells?
The pacemaker cells are connected to electrical fibers that send the contraction signal to the apex of the heart, triggering a contraction from the tip to the arteries that carry blood away from the heart.
60
Pacemaker Cells and Transmission of Signals: What type of sodium channel do pacemaker cells have?
Pacemaker cells have a type of sodium channel that shows a slow leak. As Na comes into the cell, it slowly depolarizes.
61
Pacemaker Cells and Transmission of Signals: What happens when the membrane potential of a pacemaker cell hits a threshold?
The depolarization causes the pacemaker to fire action potential.
62
Interaction Between Pressure and Flow: How is the capacity of a blood vessel estimated?
The capacity of a blood vessel is estimated by measuring its cross-sectional area.
63
Interaction Between Pressure and Flow: What happens to the cross-sectional area of blood vessels as you move from large arteries to small ones?
As you move from large arteries to small ones, the cross-sectional area is pretty constant, transitioning from a few large vessels to many small ones.
64
Interaction Between Pressure and Flow: What happens to blood velocity as the total cross-sectional area grows?
As the total cross-sectional area grows, blood velocity slows down.
65
Interaction Between Pressure and Flow: What happens to blood pressure as you move through the circuit?
Near the heart, the arteries experience each pulse of pressure from contraction. By the time the blood gets to the capillary bed, there is almost no evidence of a pulse in pressure, and flow is fairly regular.
66
Interaction Between Pressure and Flow: How is blood pressure measured?
Interaction Between Pressure and Flow: Blood pressure is measured in an artery that experiences the pulses of pressure from contraction. The highest pressure is the systolic pressure and the lowest pressure is the diastolic pressure. The mean arterial pressure is a weighted average of these two extremes, with diastolic pressure weighted twice as much as systolic pressure.
67
Interaction Between Pressure and Flow: Why is the slow blood flow in capillaries beneficial?
The slow blood flow in capillaries means more time for the capillaries to complete the exchange of materials with the surrounding tissues.
68
Determinants of Hemodynamics: What is cardiac output and how is calculated?
Cardiac output is a measure of the heart's function expressed as the amount of blood pumped by the heart in one minute. It is calculated by multiplying stroke volume, the amount of blood pumped in one heartbeat, by heart rate, and the number of heartbeats per minute.
69
Determinants of Hemodynamics: How is the cardiovascular system regulated to maintain mean arterial pressure?
The cardiovascular system is regulated by changing the contractile properties of the heart and the nature of the resistance to flow. The body can alter the stroke volume, heart rate, or both, to change cardiac output. Resistance is also determined by the number of vessels in the circuit, the arterial smooth muscle contractions, the number of open capillary beds, and the properties of blood.
70
Determinants of Hemodynamics: How does resistance affect blood flow in the cardiovascular system?
Resistance affects blood flow by determining how difficult it is for blood to move around. Resistance is determined by the number of vessels in the circuit, the arterial smooth muscle contractions, the number of open capillary beds, and the properties of blood, such as how many blood cells are in circulation.
71
Circulatory Fluids: What is the main component of blood?
The main component of blood is plasma, which is a fluid that carries many proteins, metabolites, and hormones in the blood.
72
Circulatory Fluids: What is the function of erythrocytes?
Erythrocytes, also known as red blood cells, are responsible for carrying oxygen from the lungs to the body's tissues and bringing carbon dioxide from the tissues back to the lungs to be exhaled.
73
Circulatory Fluids: How do animals control the levels of erythrocytes in the blood?
Animals control the levels of erythrocytes in the blood through the process of erythropoiesis. When oxygen levels are low, or blood has been lost, stem cells in the bone marrow are triggered to induce erythropoiesis to make new red blood cells.
74
Circulatory Fluids: What is the function of plasma in the blood?
Plasma in the blood carries many proteins, including antibodies, and most of the metabolites and hormones in the blood.
75
Evolved Respiratory System: What is the main reason why animals evolved cardiorespiratory systems?
Animals evolved cardiorespiratory systems to ensure that the enzyme cytochrome oxidase has its substrate, molecular oxygen, delivered and to remove CO2 and distribute metabolic water throughout the body.
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23 Respiratory Gases - Partial Pressures: What is the difference between the pressure and concentration of a gas?
Pressure is the force per unit area exerted by a gas on its container, and it can be measured in units such as mm Hg, atmospheres, or torr. The partial pressure of a gas is the amount of total pressure that is due to that gas. Concentration, on the other hand, is the number of moles of the molecule per volume, and it is measured in molarity. For gases, it refers to the number of moles per liter volume.
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23 Respiratory Gases - Partial Pressures: How does the concentration of oxygen in water compare to its concentration in the air?
Oxygen concentration in air is about 8.7 mM, whereas, at equilibrium, it will only be 0.3 mM in water. This is because oxygen does not dissolve in water easily. In contrast, CO2 dissolves in water as easily as it dissolves in air, and the concentrations of CO2 will be the same in air and water.
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Respiratory Drive - Air Breathers: What happens if your blood starts to accumulate CO2?
If your blood starts to accumulate CO2, it will have an acidification effect on your blood, which will cause the chemosensors in your aorta and carotid arteries to signal your brain to increase respiration.
79
Respiratory Drive - Air Breathers: How does high altitude affect respiration?
At high altitudes, oxygen is lower and this pushes the brain toward sending signals to breathe faster and deeper.
80
Respiratory Drive - Air Breathers: What muscles are involved in respiration?
The intercostal muscles and the diaphragm are involved in respiration.
81
Respiratory Drive - Air Breathers: What are chemosensors and where are they located?
Chemosensors are receptors that detect changes in chemical levels, and they are located in the aorta (which senses blood leaving the heart) and in the carotid bodies of your carotid arteries (which sense blood going to your brain).
82
Respiratory Systems: How does the brain control breathing?
The brain controls breathing how fast and how deeply we breathe affects the muscles of the thorax.
83
Respiratory Systems: How does gas exchange occur in mammals?
Gas exchange in mammals occurs in relatively less efficient lungs, filled with alveoli that are being serviced by capillaries. Oxygen moves from the inhaled air in the lungs, across a moist layer of mucus, across the alveolar wall, into the interstitial fluid, across the capillary wall, and into the blood vessel.
84
Respiratory Systems: What is the counter-current exchange system in fish?
The counter-current exchange system in fish is a respiratory system where water comes into the gills and flows from front to back, while the blood flows from back to front, through the gill filaments. This arrangement is extremely efficient at extracting oxygen.
85
Respiratory Systems: How do birds solve respiratory challenges?
Birds solve their respiratory challenges by inhaling and storing some oxygen in a sack that looks like a lung. As they exhale, the stored oxygen is pushed out to another real lung, and as they inhale again, it is pushed back over to another sack and eventually out of the system. This compartmentalization allows each region of the respiratory tract to be optimized for gas exchange despite declining oxygen in the air as it moves through.
86
Respiratory Systems: What is the respiratory system of insects like?
Insects have a tracheal respiratory system that consists of small tubes that branch off the animal's wall, delivering oxygen to every cell. The insect controls its gas exchange by moving air in and out of these tracheae, pumping its body wall.
87
Respiratory Systems: How is the efficiency of gas exchange impaired in the respiratory system?
The efficiency of gas exchange in the respiratory system can be impaired by a buildup of mucus in the lungs or edema in the lung tissue.
88
Respiratory Systems: What are the two circuits in the circulatory system?
The two circuits in the circulatory system are the pulmonary circuit that goes from the heart to the lungs and back and the systemic circuit that goes from the heart to the rest of the body and back.
89
Respiratory Systems: How do partial pressures of oxygen and CO2 change as blood moves through the body?
As blood moves through the body, the partial pressures of oxygen and CO2 change due to sources and sinks. Oxygen enters the peripheral tissues while CO2 leaves, causing a reduction of oxygen and enrichment of CO2 in the blood.
90
Red Blood Cells and Oxygen Transport: What is hemoglobin and how many subunits does it have?
Hemoglobin is a protein that carries most of the oxygen in the blood. It has four subunits.
91
Red Blood Cells and Oxygen Transport: What is cooperativity in the context of hemoglobin binding to oxygen?
Cooperativity is a phenomenon where the binding of oxygen to one subunit of hemoglobin causes a structural change that increases the oxygen affinity in the neighboring subunits, making it easier for more oxygen to bind.
92
Red Blood Cells and Oxygen Transport: How does the oxygen pressure affect the amount of oxygen that is unloaded from hemoglobin as it moves through the tissues?
The difference in oxygen pressure determines whether oxygen falls off the hemoglobin, and the greater the gradient, the more oxygen is unloaded. During exercise, oxygen pressures in the tissue drop, creating a greater driving force for oxygen to come off hemoglobin.
93
Red Blood Cells and Oxygen Transport: What conditions can cause a shift in the oxygen-hemoglobin binding curve?
Low pH, high temperature, and some metabolites can cause the whole curve to shift right, making it less likely for hemoglobin to hold onto its oxygen at any given oxygen pressure.
94
Immunity: What is a phagocyte?
A phagocyte is a cell that can "eat" or engulf other cells or particles. It is a type of immune cell that plays an important role in defending the body against pathogens and other foreign invaders.
95
Immunity: What is the role of a macrophage in the immune system?
A macrophage is a type of phagocyte that plays a key role in the immune response. It can identify and engulf pathogens, debris from cell and tissue breakdown, and defective cells. Macrophages also play a role in advertising this information to other cells of the immune system to recruit them into the process.
96
Immunity: What is the difference between the innate and adaptive immune systems?
The innate immune system is a collection of physical, chemical, and cellular defenses that work nonspecifically against pathogens. This includes physical barriers like intact skin, as well as cells that can recognize and destroy common molecular structures found in pathogens. The adaptive immune system, on the other hand, has a more specific response to particular molecular structures and can ramp up its response when it finds those pathogens. It is subdivided into the humoral response (involving antibodies) and the cell-mediated response (involving various cells).
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Immunity: What are pathogen-associated molecular patterns (PAMPs)?
Pathogen-associated molecular patterns (PAMPs) are molecular structures commonly found in pathogens, such as viral proteins, membrane molecules, or even RNA. Cells of the innate immune system can recognize these patterns and use them to identify and destroy pathogens.
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Immunity: What is the difference between the humoral and cell-mediated responses in the adaptive immune system?
The humoral response involves the production of antibodies that can bind to and neutralize pathogens in body fluids. The cell-mediated response, on the other hand, involves the activation of various types of cells (such as T cells) that can directly attack and destroy infected cells.
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Specificity: What are PRRs?
PRRs (Pattern Recognition Receptors) are receptors found on cells like macrophages that look for PAMPs in an effort to find foreign material.
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Specificity: What are epitopes?
Epitopes are fine molecular patterns recognized by the receptors of the adaptive immune system.
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Specificity: What is the function of antibodies in the immune system?
Antibodies are soluble receptors that float around looking for their binding partner, an antigen.
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Specificity: What is the function of LPS in gram-negative bacteria?
LPS extends from the membrane of the cell outward, advertising itself as a PAMP to the immune system.
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Specificity: How do LPS molecules differ within and between bacteria?
LPS molecules differ in terms of how many and what types of sugars are connected together.
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Innate Imunninity: What happens when the healthy skin is cut, breaking the first barrier?
Bacteria and other pathogens can then cross that barrier and enter the interstitial or extracellular fluid.
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Innate Imunninity: What are mast cells?
Mast cells are immune cells that recognize the presence of pathogens and respond by emptying themselves of bags of histamine.
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Innate Immunity: What is the function of inflammation in the immune response?
Inflammation is part of the defense and healing process. When there is damage, the changes in the blood vessels bring more blood to the area, causing it to warm the tissue, and permit fluids to leak out of the blood vessels, causing swelling, or edema.
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Defense Strategies in The Intervetrabtes: What are antimicrobial peptides and how do they function as innate defenses?
Antimicrobial peptides are short proteins found in many animals that can bind to pathogens and trigger their death. They act as innate defenses by inserting themselves into the membranes of specific kinds of bacteria and disrupting their function, leading to their destruction.
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Defense Strategies in The Intervetrabtes: What was the purpose of the experiment with drosomycin and defensin in flies?
The purpose of the experiment was to determine the specificity of the antimicrobial peptides drosomycin and defensin in their ability to defend against specific pathogens. Mutant flies with disrupted genes for both peptides were exposed to a fungus and a bacterium, and the results showed that each peptide had some specificity in that it could protect against one type of pathogen but not the other.
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Defense Strategies in The Intervetrabtes: How do innate immune cells like mast cells respond to the presence of pathogens?
Innate immune cells like mast cells recognize the presence of pathogens and respond by emptying themselves of bags of histamine. The histamine signals to cells in the bloodstream that pathogens are attacking and causes the cells of the capillaries to relax their connections, allowing phagocytes to squeeze between the capillary cells and follow the histamine trail to the site of infection.
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Defense Strategies in The Intervetrabtes: What is the role of the adaptive immune system in defending against pathogens?
The adaptive immune system recognizes specific molecular patterns called epitopes on pathogens and produces highly specific responses to defend against them. This system includes cells like B and T cells, as well as proteins like antibodies that can bind to and neutralize specific pathogens.
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Phagocytosis: How does the interaction between a phagocytic cell's receptors and a pathogen lead to the destruction of the pathogen?
Once the phagocytic cell's receptor binds to the pathogen, the cell engulfs it and breaks it down for food. In some cases, the pathogen might make it inside the cell, and this same interaction might cause the cell to recognize it has been infected and cause the cell to kill itself.
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Phagocytosis: How does a phagocytic cell recognize something it should eat?
Phagocytic cells produce receptors that scan the surrounding fluids looking for ligands. The receptors are called PRRs, or pattern recognition receptors. A common type is called a TLR, for Toll-like receptor, which looks for PAMPs, or pathogen-associated molecular patterns. Once the receptor binds its target, the cell engulfs it, breaking it down for food.
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Phagocytosis: What is the function of Toll-like receptors (TLRs) in phagocytic cells?
Toll-like receptors (TLRs) are a type of PRR (pattern recognition receptor) that phagocytic cells use to identify PAMPs (pathogen-associated molecular patterns). TLRs bind to PAMPs and trigger the engulfment of the pathogen by the cell.
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Innate Immune Cells: What are the two main types of cells in the innate immune system that kill pathogens?
The two main types of cells in the innate immune system that kill pathogens are phagocytes and natural killer (NK) cells.
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Innate Immune Cells: How do infected cells communicate with NK cells to signal that they need to be killed?
When an infected cell produces signals that they export to its cell membrane, this basically advertises a kill signal to NK cells.
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Innate Immune Cells: What are some names for phagocytes in different species?
Phagocytes go by different names based on the species and their developmental origins. Examples include macrophages, neutrophils, and dendritic cells.
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Innate Immune Cells: What is the difference between the mechanisms of phagocytes and NK cells in killing pathogens?
Phagocytes eat pathogens to clean up fluids around cells, while NK cells kill infected cells. The difference between these two assassins is how specific the signal is. Cytotoxic T cells, which will be discussed later, share some similarities with NK cells.
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Innate Immune Cells: What is the role of natural killer (NK) cells in the innate immune system?
Natural killer (NK) cells are the innate immune system's hunters. Their job is to kill cells that have become infected with a virus or that have incurred mutations that might lead to cancers.
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Inflammation: What are the five signs of inflammation?
The five signs of inflammation are heat and redness from the increased blood flow, swelling from the fluid leakage, pain because the swelling squeezes nerves, and loss of function of that tissue region.
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Inflammation: What happens if inflammation extends too far?
If inflammation extends too far, it can result in more systemic effects and the whole body may become hot, resulting in a fever.
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Inflammation: How does local hyperthermia enhance defense strategies?
Local hyperthermia enhances defense strategies because some of the steps that activate the immune response are extremely sensitive to temperature.
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Behavioral Fever: What happens when an ectotherm, like an iguana, gets an infection?
When an ectotherm, like an iguana, gets an infection, it changes its behavior and spends more time in the sun, warming its body temperature.
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Behavioral Fever: How do animals that maintain a high body temperature produce enough metabolic heat to control their body temperature?
Animals that maintain a high body temperature produce enough metabolic heat to control their body temperature through various physiological mechanisms, such as shivering, sweating, or panting.
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Behavioral Fever: What is an ectotherm?
An ectotherm is an animal that cannot generate its own body heat internally and relies on external sources, such as the environment, to regulate its body temperature.
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Cells Adaptive Immunity - Granulocytes: What is the role of granulocytes in the immune system?
Granulocytes are part of the innate immune system and are responsible for dealing with pathogens and allergens.
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Cells Adaptive Immunity - Granulocytes: How are neutrophils, basophils, and eosinophils distinguished from each other?
Neutrophils bind to a neutral dye, basophils a basic dye, and eosinophils an acidic dye.
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Cells Adaptive Immunity - Granulocytes: What are PMN cells?
PMN cells stand for polymorphic nuclei cells and refer to the granulocytes' nuclei, which take on all sorts of weird lobes.
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Cells Adaptive Immunity - Granulocytes: What are granulocytes?
Granulocytes are a type of blood cell that possess granules, which are secretory vesicles filled with enzymes and other secretions.
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Cells Adaptive Immunity - Granulocytes:
The three types of granulocytes are neutrophils, basophils, and eosinophils
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Cells Adaptive Immunity - Monocytes: What is the role of dendritic cells in the immune system and How are the fragments of pathogens displayed?
Dendritic cells eat pathogens and display fragments of them on the cell surface as signals for the adaptive immune system. These fragments of pathogens are used as signals for the adaptive immune system.
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Adaptive Immunity - APC: What is the role of dendritic cells as antigen-presenting cells (APCs)?
Dendritic cells act as antigen presenting cells (APCs) by consuming pathogens and fragmenting them into small pieces that they display on their cell surface using a receptor protein called MHC receptor. This advertises the presence of pathogens to other cells and signals the adaptive immune system to get involved.
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Cells Adaptive Immunity - Lymphocytes:What are the two types of lymphocytes?
B cells and T cells.
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Cells Adaptive Immunity - Lymphocytes: What is the common feature of B and T cells?
B and T cells have a receptor that binds a specific molecular motif called the antigen.
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Receptors - Antigen Recognition: What is the structure of the receptor that binds the antigen?
The receptor has a Y-shape, with two arms that combine to form the complete receptor. The tips of the two arms bind the antigen.
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Receptors - Antigen Recognition: What are the four polypeptide chains that make up the receptor?
The four polypeptide chains are two identical heavy chains and two shorter light chains.
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Receptors - Antigen Recognition: What is the difference between a receptor and an antibody?
When the receptor is attached to a cell, like a B cell or a T cell, it's called a receptor. However, some B cells make the same receptor but secrete it to float freely in the blood. At this point, the receptor is called an antibody.
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Generating Diversity in B and T Cell Receptors: How does the adaptive immune system generate such a large repertoire of different proteins from a small set of genes?
The adaptive immune system generates millions of different proteins from a small set of genes through recombination and mutation events that occur during the differentiation of the lymphoid precursor cells.
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Generating Diversity in B and T Cell Receptors: What is self-tolerance in the adaptive immune system?
Self-tolerance is the process of getting rid of the cells that make a receptor that binds to your own proteins. This process occurs during early development, where B and T cell lines are presented with antigens derived from the organism itself, triggering cell death in the lymphocyte. The only B and T cells that remain have receptors that bind non-self antigens.
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B and T Cell Activation: What is the difference between memory B cells and plasma cells?
Memory B cells sit and wait for the reappearance of the antigen, which allows for a faster and stronger immune response, while plasma cells become factories that secrete antibodies to fight off the infection.
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B and T Cell Activation: What is the function of helper T cells?
Helper T cells are activated T cells that assist in the immune response by releasing cytokines to activate other immune cells such as B cells, cytotoxic T cells, and macrophages.
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B and T Cell Activation: What is the function of cytotoxic T cells?
Cytotoxic T cells are activated T cells that migrate to the site of infection, bind to the pathogen-infected cells, and secrete cytotoxic proteins to kill them.
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Immunological Memory: What is immunological memory?
Immunological memory is the ability of the immune system to remember a pathogen that it has been exposed to previously and to produce a more rapid and effective immune response upon subsequent exposure.
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Immunological Memory: What is the concept behind vaccinations?
The concept behind vaccinations is to create active immunity by exposing the body to an antigen in a controlled manner, which allows the immune system to develop memory B and T cells and be prepared for a future attack.
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Immunological Memory: How do mRNA vaccines work?
mRNA vaccines work by delivering the genetic material that codes for a specific pathogen protein to cells in the body. The cells use this genetic material to produce the pathogen protein and display it on their cell surface, which triggers an immune response and the development of memory B and T cells.
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Immunological Memory: What is passive immunity and how does it arise?
Passive immunity is the transfer of preformed antibodies from one individual to another. It can arise naturally, for example through the transfer of antibodies from a mother to her fetus, or through breastfeeding where antibodies are passed from mother to infant.
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Helper T Cells: How do helper T cells connect the processes of various immune cells?
When a pathogen appears, it gets eaten by phagocytes that function as antigen-presenting cells. These take the antigen and mount it on the surface of the cell membrane. Helper T cells also bind that antigen, and when a Helper T cell finds the APC, this causes an exchange of signaling factors between the cells. This ultimately activates the helper T cell, which then goes off to find cells to help.
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Cytotoxic T Cells: What happens when a cytotoxic T cell binds to a cell displaying a compatible antigen?
When a cytotoxic T cell binds to a cell displaying a compatible antigen, it initiates the process of destroying that cell by secreting perforin, which pokes holes in the cell, and enzymes that break down the cell.
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Allergic Reactions: What are autoimmune disorders?
Autoimmune disorders are diseases where the immune system fails to distinguish between self and non-self and attacks the body's own cells and tissues.
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Allergic Reactions: What are allergies?
Allergies are immune system responses that are out of proportion to the threat. When the immune system encounters an allergen, it triggers the release of histamine, which can cause a variety of symptoms.
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Allergic Reactions: What are Immunoglobulins?
Immunoglobulins are different types of antibodies produced by the body. They play a key role in the immune system's response to pathogens and other foreign substances.
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Allergic Reactions: What is IgE?
IgE is an Immunoglobulin that floats in solution but binds mast cells, extending its antigen-binding domain outward. When it encounters an allergen, it activates the mast cell to release histamine.
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Reproductive Hormones: What are gonadotropins?
Gonadotropins are hormones released by the pituitary gland that act on the gonads (testes or ovaries) to stimulate the production and release of sex hormones. In females, the two main gonadotropins are luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
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Reproductive Hormones: What is the role of gonadotropin-releasing hormone (GnRH)?
Gonadotropin-releasing hormone (GnRH) is released by the hypothalamus and stimulates the pituitary gland to release gonadotropins, which then act on the gonads to regulate the production and release of sex hormones. In females, GnRH is essential for the menstrual cycle and ovulation.
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Reproduction: What are the two modes of reproduction?
Sexual and asexual.
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Reproduction: What is sexual reproduction? What is asexual reproduction?
Sexual reproduction involves a female and males, although they are not necessarily different individuals. In this context, female means an organism that makes big gametes that we call eggs, and male makes small gametes that we call sperm.
Asexual reproduction allows a successful phenotype/genotype to flourish under the right conditions because asexual clones are as well-suited to an environment as their parent.
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Fragmentation: What is a polychaete?
A polychaete is a type of segmented worm distantly related to the familiar earthworm.
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Fragmentation: What is the benefit of segmentation
The benefit of segmentation is that different regions can perform different functions.
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Fragmentation: How is reproductive physiology regulated in polychaetes?
Reproductive physiology in polychaetes is regulated by hormones in response to particular environments. In option B, hormones tell the tail to break off and become another worm. In C, the tail end divides itself up into a whole bunch of different worms. In option E, they become specialized to produce gametes and engage in sexual reproduction.
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Budding: What is budding?
Budding is a way of reproducing yourself in an environment that's relatively stable. In the case of the hydra and sea anemones, it allows them to create identical clones of themselves.
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Parthenogenesis: What is parthenogenesis?
Parthenogenesis is a way of making offspring that are near clones of yourself by using gametogenesis to create the raw material.
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Parthenogenesis: How do aphids reproduce using parthenogenesis?
Aphids are able to take advantage of a good environment by duplicating themselves using the female's reproductive tract to make offspring but bypassing the male.
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Parthenogenesis: Why do animals use parthenogenesis?
Animals use parthenogenesis in stable environments because it allows them to reproduce without the need for males, which can be a disadvantage in some situations.
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Parthenogenesis in Vertebrates: What is the unique variation of parthenogenesis seen in whip-tailed lizards?
Whip-tailed lizards have evolved a unique variation on parthenogenesis in which females fertilize their eggs with the cells they normally kill off, essentially using a polar body as a sperm alternative. This occurred after males were lost in isolated populations.
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Parthenogenesis in Vertebrates: Why do female whip-tailed lizards engage in mating behaviors even though they have no need for a mate?
Female whip-tailed lizards engage in mating behaviors even though they have no need for a mate because it happened so recently that they still have the behavioral and hormonal mechanisms in place for mating. Their position in the copulation is driven by hormones, and if they are on the receiving end, the behavior changes hormones that trigger ovulation.
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Genetic Sex Determination: What is a karyotype?
A karyotype is an image that shows the chromosomal complement of an animal.
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Genetic Sex Determination: How are chromosomes paired in humans?
Each chromosome in humans is paired because humans are diploid. One version comes from the father, and the other version comes from the mother.
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Genetic Sex Determination: How do many mammals determine sex?
Many mammals determine sex in the same way as humans. Individuals with two copies of the same sex chromosome are female, and if the sex chromosomes are different, they become male.
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Environmental Sex Determination: What primarily determines the sex of turtle eggs?
In turtles, the sex of the eggs is primarily determined by the temperature in the nest.
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Environmental Sex Determination: What impact does global warming have on the sex ratios of populations?
If the average temperatures get too hot in critical windows of development, the sex ratios of populations will shift to extremes.
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Hermaphrodites: What is a hermaphrodite, and how is their situation different from animals that have environmental sex determination?
Hermaphrodites are organisms that have both male and female reproductive organs. Their situation is more complicated than animals with environmental sex determination because they can produce both types of gametes
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Hermaphrodites: What is a serial hermaphrodite?
A serial hermaphrodite is an organism that starts life as one sex and later changes to the other. Many fish are serial hermaphrodites.
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Hermaphrodites: What is a simultaneous hermaphrodite?
A simultaneous hermaphrodite is an organism that has both male and female reproductive organs at the same time. Earthworms and nudibranchs are examples of simultaneous hermaphrodites.
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Hermaphrodites: How do wrasses determine their sex?
Wrasses determine their sex by social hierarchy. The largest or most aggressive female in a harem can transform into a reproductive male and take over the harem if the male is removed.
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Gametogenesis and Meiosis: What is meiosis and how does it differ from mitosis?
Meiosis is a type of cell division that occurs in sexually reproducing organisms to produce gametes. It differs from mitosis in several ways, including the fact that meiosis involves two rounds of cell division, resulting in the production of four haploid daughter cells, while mitosis only involves one round of cell division, producing two diploid daughter cells. Additionally, meiosis involves the recombination and crossing over of genetic material between homologous chromosomes, which increases genetic diversity, while mitosis does not.
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Gametogenesis and Meiosis: What is the process called when maternal and paternal chromosomes exchange material during meiosis?
The process is called crossover, or recombination.
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Gametogenesis and Meiosis: What is the impact of random assortment during meiosis?
The impact of random assortment is that the homologous chromosomes are separated into different daughter cells, resulting in random combinations of chromosomes that have been shuffled through recombination.
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Reproductive Strategies: What are the three reproductive strategies and how do they differ from each other?
The three reproductive strategies are ovipary, ovovivipary, and vivipary. In ovipary, the embryo grows externally to the female and is surrounded by a protective shell that allows access to yolk produced by the mother. In ovovivipary, the female retains the embryo within the uterus and provides it access to a yolk sac for nutrients. The embryo is birthed at some point and swims away. In vivipary, the female provides nutrition directly from the uterus to the fertilized eggs, which are retained in the uterus until live birth.
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Maternal Products: What is oophagy?
Oophagy is a reproductive strategy in some species of sharks, where the infant sharks eat unfertilized eggs produced by the mother.
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Maternal Products: What is a placenta?
A placenta is a sac composed of both maternal and embryonic tissues that serves as an interface between mother and infant in utero. It allows for the exchange of nutrients, gases, and waste products between the mother and developing embryo.
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Maternal Products: What is crop milk?
Crop milk is a slimy secretion produced by pigeons and other birds from their digestive tracts, which is fed to their chicks.
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Lactation: What is colostrum and why is it important for newborns?
Colostrum is the first milk produced by mammary glands after birth. It is rich in immunoglobulins which are protective factors that the mother produces to transfer immunity to the offspring. Colostrum is important because it provides passive immunity to the newborn, whose gut is not yet ready to digest food. It contains a concentrated slurry of antibodies which are readily absorbed by the gut and transferred into the circulation to protect the infant from disease.
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Lactation: How does the composition of milk change over time?
The composition of milk changes over time, influenced by the needs of the infant for growth. Initially, the first milk, colostrum, is rich in immunoglobulins for protection against disease. As the infant grows, the milk transitions to a nutritional resource, and the composition changes in nutritional profile. Milk contains fats, sugars, proteins, water, minerals, and vitamins. The fat content is there in part for flavor and offers a feeding incentive for the offspring. Fats are also needed for membrane synthesis in all mammals. Sugars are needed for energy, certainly, but also to make nucleotides for DNA. Mammals make proteins with the main function of delivering amino acid building blocks to the infant.
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Evolution of Lactation: What are monotremes and how do they nurse their young?
Monotremes are a group of mammals that lay eggs, including the platypus and echidna. Monotremes nurse their young by the mother oozing watery milk from many simple mammary gland ducts over the undersurface of her belly. The offspring come by and basically, just lick the mother's belly. The milk is simple in composition and there are no specializations to permit the offspring to latch on.
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Evolution of Lactation: How do placental mammals deliver milk?
Placental mammals have the same arrangements of glands and nipples to deliver milk in short bursts. Mammals match the number of mammary glands to the number of offspring, typically with some reserve capacity.
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Ovarian and Uterine Cycles: What are tropic hormones?
Tropic hormones are hormones whose main job is to tell target tissues to secrete hormones.
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Ovarian and Uterine Cycles: What is the role of steroids in pregnancy?
Steroids prepare the uterus to receive and support a fertilized ovum and are important for sustaining the pregnancy and preparing the mother for childbirth and postpartum care.
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Embryonic Development - Zygote to Blastula: What is the blastula stage?
The blastula stage is a mass of cells with a gap, known as the blastocoel, which is a landmark for later development.
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Gastrulation: What are extraembryonic membranes and where are they found?
Extraembryonic membranes are structures that are not part of the embryo proper and are found in all reptiles, birds, and mammals.
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Gastrulation: What is the trophoblast and what does it become in mammals?
The trophoblast is the outer layer of cells of the blastula that implants into the uterine wall in mammals. In mammals, it becomes the interface between the embryo and the uterine wall.
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Extraembryonic Membranes: What are the extraembryonic membranes in birds and what are their functions?
he extraembryonic membranes in birds are the amnion, allantois, yolk sac, and chorion. The amnion acts as a shock absorber and helps in the development of the embryo within the fluid-filled bag. The allantois collects nitrogenous waste products expelled by the developing embryo and helps with gas exchange. The yolk sac contains the yolk and blood vessels from the embryo run through it, allowing the uptake of nutrient stores. The chorion is the membrane that contains all these structures.
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Extraembryonic Membranes: What is the function of the amnion in mammals?
The function of the amnion in mammals is similar to that in birds. It acts as a shock absorber and helps in the development of the embryo within the fluid-filled amniotic sac.
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Extraembryonic Membranes: What is the function of the allantois in mammals?
The function of the allantois in mammals is similar to that in birds. It collects nitrogenous waste products expelled by the developing embryo and helps with gas exchange.
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Extraembryonic Membranes: What is the function of the chorion in mammals?
The function of the chorion in mammals is similar to that in birds. It is the membrane that contains all the other extraembryonic membranes and helps in the exchange of gases and nutrients between the mother and the developing embryo.
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Extraembryonic Membranes: What is the function of the yolk sac in mammals?
The function of the yolk sac in mammals is not as significant as in birds since mammals receive their nutrients through the placenta. However, the yolk sac still plays a role in the development of the digestive and reproductive systems of the embryo.
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Extraembryonic Membranes: What are the three regions of the embryo distinguished based on the structures they will eventually become?
The three regions of the embryo distinguished based on the structures they will eventually become are the endoderm, mesoderm, and ectoderm.
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What hormones are involved in preparing the uterus for birth?
Estradiol strengthens the muscle in the uterus, but progesterone prevents it from contracting.
