Human Physiology Flashcards
(125 cards)
1
Q
What are the three main functions of the digestive system?
A
- Break down nutrients (physical/chemical breakdown)
- Absorption of nutrients (taken into the body from digestive tract)
- Assimilation (basic macromolecules used as energy, or to build larger + more complex structures)
2
Q
What is the path that food takes as it travels through the digestive system?
A
Oral cavity –> pharynx –> esophagus –> stomach –> small intestine –> large intestine –> rectum –> anus
3
Q
Wild carrrrrrd! See how well you can label the structures of the digestive system. If not, look at slide 8 of the slide pictured on the answer.
A
https://docs.google.com/presentation/d/1PEhG_FD1Me5Emw5nfJYbiEn-9c_yxpRUCGB6v8aOflQ/edit#slide=id.p8 and
4
Q
Define and describe peristalsis.
A
The rhythmic and sequential contraction of muscles surrounding the digestive tract.
It pushes food through the digestive system. It involves longitudinal and circular muscle; their contractions mix the food with enzymes and move it along the gut.
- Contraction of smooth muscles behind bolus forces it forward
- Waves of muscle contractions move bolus toward stomach.
5
Q
What are the two types of digestion?
A
Mechanical - the physical breakdown of food into smaller pieces through chewing, grinding etc
Chemical - breakdown of food into its basic components, using enzymes to enact a chemical change
6
Q
Define absorption with regards to the body and nutrients.
A
The movement of nutrients from the digestive system into the circulatory system.
7
Q
Name one enzyme used to break down carbohydrates, proteins, and fats respectively, and what they get broken down into.
A
Carbohydrates –>
- Amylase
- Sucrase-isomaltase
- Maltase
- Lactase
–> Glucose
Proteins –>
- Pepsin
- Protease trypsin
- Peptidase
–> Amino acids
Fats –>
- Lipase
–> Fatty acids and glycerol
8
Q
Describe how starch is digested.
A
Pancreatic amylase –> comes from the pancreas, location of digestion is small intestine (lumen) + optimal pH of 7.5-7.8
Salivary amylase –> comes from the salivary glands, location of digestion is mouth and esophagus (optimal pH of 6-7)
End product: maltose.
9
Q
Describe how protein is digested.
A
Pepsin –> comes from stomach lining, location of digestion is stomach (optimal pH of 2)
Trypsin –> comes from pancreas, location of digestion is small intestine (optimal pH of 7.8-8.7)
End product: small polypeptides and single amino acids
10
Q
Describe how lipids (triglycerides) are digested. (extrapolate just a bit more about location of digestion)
A
Pancreatic lipase –> comes from pancreas, location of digestion is small intestine (lumen), which requires liver bile to emulsify fats and pancreatic bile to neutralize pH (optimal pH of 7.2)
End product: glycerol, fatty acids, monoglycerides
11
Q
Describe how lactose is digested.
A
Lactase –> comes from gland cells of intestine wall, location of digestion is in small intestine (optimal pH of 6.5)
End products: glucose, galactose
12
Q
Describe how nucleic acids are digested.
A
Nuclease –> comes from the pancreas, location of digestion is small intestine (optimal pH of 8.0 - 9.0)
End product: nucleosides
13
Q
How does pH affect enzyme activity in the digestive system?
A
It results in certain enzymes being active at specific locations of the digestive tract.
14
Q
What is dialysis tubing?
A
–> Partially permeable cellulose tubing that contains microscopic pores
–> Allows water, small molecules, and ions to pass through freely, but restricts movement of large molecules
15
Q
How is dialysis tubing used as a model of the small intestine?
A
–> Medium outside (water) represents the blood into which digested products are absorbed
–> Tubing represents epithelium of the small intestine
–> The high concentration of glucose solution inside tubing is observed after a starch-filled meal has been digested
–> The glucose molecules diffuse from a region of higher concentration in the tubing to lower concentration in the beaker.
–> The starch molecules are too big to pass through the pores of the tubing.
16
Q
What are the two locations of mechanical digestion, and what are the three locations of chemical digestion?
A
Mechanical:
- mouth (teeth/tongue)
- stomach
Chemical:
- mouth
- stomach
- small intestine
17
Q
What are the four locations where chemicals for digestion are created?
A
- Salivary glands
- Liver
- Pancreas
- Small intestine
18
Q
Define the jobs of the esophagus and stomach.
A
Esophagus: to carry food from the mouth to the stomach
Stomach: to mix food by churning it in stomach acid, beginning protein digestion
19
Q
Define the jobs of the liver and gallbladder.
A
Liver: Creates bile that helps break down fats and get rid of waste in the body.
- Changes food into energy
- Cleans alcohol, some medicines, and poisons from the blood
Gallbladder: Stores the bile made in the liver, then empties it to help digest fats.
20
Q
Define the job of the pancreas.
A
It makes enzymes for digestion and the hormone insulin (which helps the body turn food into energy).
21
Q
Define the jobs of the small and large intestines.
A
Small intestine: Place where most of the digestion and absorption of nutrients occurs.
Large intestine: (aka colon) Place where water and dissolved minerals are absorbed.
22
Q
Why does food need to be mechanically and chemically broken down in digestion?
A
To convert food into energy for our bodies. Macromolecules must be broken down into monomers, which are smaller and absorbable.
23
Q
What are the functions of the six features lining the villi of the small intestine? (SLIM SR)
A
Smooth muscle - circular and longitudinal muscle contract to mix the food with enzymes, moving it along the gut
Lacteals - absorb lipids from intestine into lymphatic system
Intestinal glands - exocrine pits release digestive juices
Microvilli - ruffling of epithelial membrane further increases surface area
Single layer epithelium - minimises diffusion distance between lumen and blood
Rich blood supply - dense capillary network rapidly transforms absorbed products
24
Q
What are the four methods of membrane transport?
A
- Simple diffusion
–> Small, hydrophobic molecules
–> Products of lipid digestion - Facilitated diffusion
–> Fructose, glucose, hydrophilic monomers
–> Protein channels - Active transport
–> Glucose, amino acids, mineral ions
–> Cells of epithelium synthesize ATP - Pinocytosis
–> Small droplets of liquid surrounded by small section of phospholipid membrane
–> Fat droplets in lumen
25
Wild carrrrrd! Do your best to draw a labelled diagram of the human digestive system. You can check using the picture linked.
https://docs.google.com/document/d/1iNxToWFjp5729743pNrfvjtbaj4shzvfIOuICQjHeBM/edit
26
What is the equation for respiration?
Glucose + Oxygen --> Carbon Dioxide + Water + Energy
C6H12 + 6O2 --> 6CO2 + 6H2O + ATP
27
Where are the two locations of gas exchange?
1. Between the cells and the blood at the capillaries (small blood vessels)
2. Between the blood and the external environment at the alveoli (structures in the lungs)
28
What surfaces do gases exchange across, and what is required for exchange to occur? What is an important feature of exchange surfaces as a result?
They exchange across thin cell membranes. Ventilation is required to maintain a concentration gradient, so exchange can occur between air in alveoli and blood in capillaries. Since this must occur through water, the exchange surface must be moist/wet.
29
What is diffusion driven by with regards to oxygen and the body?
Diffusion is driven by the difference in oxygen concentration between:
--> the cells and blood
--> the lungs and the external environment
30
How is gas exchanged in bacteria?
Using non-specialized tissue, gas exchange occurs through the surface membrane in a moist environment.
31
How does respiration occur in humans? What are some of the features that improve the system?
By gas exchange which occurs through lungs.
- The internal system reduces water loss
- Branching of airways increases surface area
- Specialized alveoli increase efficiency of gas exchange
32
Wild carrrrrd! Can you label the respiratory system? It's pictured on the back.
https://docs.google.com/presentation/d/1gyrs0jNWrXmo9A2jj6V4tcoSgKHtLSI07pp5irJtt3I/edit#slide=id.p21
33
Why is a ventilation system needed for respiration?
- Lungs are not muscular and cannot ventilate themselves
- Ventilation is needed to maintain the concentration gradients in the alveoli.
--> It replaces diffused oxygen to keep the concentration high
--> It removes carbon dioxide to keep the concentration low.
That way, oxygen can diffuse from air --> blood, and carbon dioxide can diffuse from blood --> air.
34
Explain the aspects of the process of breathing in, and the process of breathing out.
Breathing in:
- external intercostals contract, diaphragm contracts
- chest wall and lungs expand
- expansion of ribs moves sternum upward and outward
Breathing out:
- external intercostals relax, internal intercostals and abdominals contract for active expiration only, diaphragm relaxes
- chest cavity and lungs contract, ribs and sternums repress
35
Explain the regulation of breathing by the medulla.
- Brain sends nerve signals to the rib cage and diaphragm
- Rate of breathing controlled by CO2 levels in blood
- When CO2 is produced by cells in cellular respiration, it dissolves in blood plasma and creates carbonic acid
- Low pH levels are sensed in the blood vessels running through the medulla oblongata, sending signals to increase breathing rate
- This causes the pH to return to normal
36
State everything you know about type I pneumocytes. (Pancake Junction Is Amniotic)
- Involved in the process of gas exchange between the alveoli and capillaries
- Squamous in shape and extremely thin (approx 0.15 micrometers) to minimize diffusion distance for respiratory gases
- Connected by occluding junctions, which prevents leakage of tissue fluid into alveolar air space
- Amniotic, unable to replicate, but type II cells can differentiate into type I cells if needed
37
State everything you know about type II pneumocytes. (Surfactant Cubes Store 5%)
- responsible for secretion of pulmonary surfactant, which reduces surface tension in alveoli
- Cuboidal in shape, possess many granules for storing surfactant components
- Compose approx 5% of the alveolar surface
38
Name some qualities of alveoli.
- Only one cell thick
- Moist surface
- Surrounded by capillaries
- Abundant to increase surface area
39
Explain surface tension with regards to alveoli.
- Alveolar cells have a layer of water, and the top layer interacts only with the layer below due to air in the lungs
- Cohesive forces pull the top layer of water molecules together, resulting in surface tension on the alveolar surface.
- As the alveoli deflate, they become harder to inflate--the force needed to overcome surface tension increases as the diameter of the alveoli decreases.
40
What does surfactant do and why?
It decreases surface tension during exhalation to prevent the alveoli from becoming too difficult to inflate.
41
What is the difference between ventilation and gas exchange?
Ventilation is the flow of air in and out of the alveoli, including inspiration and expiration.
Gas exchange is the diffusion of the gases oxygen and carbon dioxide.
It occurs in:
- the alveoli (oxygen diffuses from alveoli into blood, carbon dioxide diffuses from blood into alveoli)
- the tissues (oxygen diffuses from blood into cells, carbon dioxide diffuses from cells into bloods)
42
What is the pathway that air follows during ventilation?
Mouth / nasal passage --> trachea --> two bronchi --> bronchioles --> alveoli
43
What is emphysema, and what does it do to a person?
The destruction of lung tissue around the bronchioles
- Makes airways unable to hold their functional shape upon exhalation
- Loss of elasticity makes it difficult to exhale
- Easy to inhale, hard to exhale, leads to shortness of breath.
44
Name four symptoms of emphysema.
Can name any of these five:
- Shortness of breath
- Phlegm production
- Increased susceptibility to chest infections
- Cyanosis
- Expansion of the ribcage
45
What causes emphysema?
Long-term exposure to chemical irritants e.g. tobacco smoke, air pollution.
- The irritants cause an inflammatory response in the alveolar cells
- White blood cells (phagocytes) release elastase as part of inflammatory response
- Elastase breaks down walls of alveoli
- Large air cavity lined with carbon deposits forms
46
What is lung cancer? What are some things that arise from it?
The uncontrolled proliferation of lung cells, which leads to tumour growth.
- Cancer cells divide rapidly and are less able to die.
- Abnormal growth can impact normal tissue.
- The tumours can remain in place (benign) or or spread to other regions of the body (malignant)
47
Name four causes of lung cancer.
Can name any of these five:
- Smoking
- Asbestos
- Air pollution
- Certain infections
- Genetic predispositions
48
Why is lung cancer more likely to metastasize?
The lungs possess a rich blood supply, increasing the ability of the cancer to spread.
49
What are the most common symptoms of lung cancer? What are some symptoms caused by the cancer mass compressing adjacent organs?
- Coughing up blood
- Wheezing, respiratory distress
- Weight loss
- Chest pain
- Difficulty swallowing
- Heart complications.
50
What are the six purposes of the circulatory system?
1. Transport oxygen to cells
2. Transport waste away from the cells
3. Transport nutrients (minerals, glucose, protein)
4. Transport hormones (chemical messengers)
5. Distribute heat
6. Provide defense - immune system
51
What are the three basic components of the circulatory system?
- Blood
- Heart
- Blood vessels
52
What are the jobs of red blood cells, white blood cells, and platelets, respectively?
Red blood cells
- Carry oxygen and carbon dioxide attached to hemoglobin to working muscles
White blood cells
- Responsible for defense against foreign agents
Platelets (much smaller than red blood cells, smaller parts of larger cells)
- Create blood clots at the site of vessel damage
Plasma (clear liquid protein and salt solution made mainly of water)
53
What are the three subdivisions of the circulatory system?
1. Systemic system - blood --> body cells
2. Pulmonary system - blood --> lungs
3. Cardiac system - blood travels from heart --> tissues of heart
54
What did William Harvey prove about the heart and blood?
- Too much blood flows through the body for the liver to be continuously producing it--it would have to make 540 lbs a day.
- The heart has two circuits (pulmonary & systemic)
- Blood flows in a closed circuit, with arteries carrying blood away from the heart and veins returning to the heart
- Veins have valves.
55
What was the process of William Harvey's discovery regarding arteries/veins? (7 points)
- Tied a ligature around the upper part of a man's arm.
- Flow of blood into the lower portion of the arm was cut off (because arteries are deeper set in the tissue than veins).
- When loosened slightly, blood flowed into the lower part of the arm but was unable to escape back to the upper part.
- Recognized because when the veins became more visible as they were engorged with blood. - Noticed small bumps in the veins -- valves discovered by Fabricius.
- Using a finger to force the blood away from the shoulder and toward the hand was impossible
- Valves in veins prevent the backflow of blood.
56
What did Harvey conclude about the circulatory system?
Arteries, deeper in the body, move blood away from the heart.
Veins, more towards the surface of the body, return blood to the heart.
Capillaries, found in all body tissues, fuse arteries and veins, and are the location of nutrient and gas exchange.
57
What are the alternate terms for red blood cells and white blood cells?
- RBC: erythrocytes
- WBC: leukocytes
58
Where are white blood cells produced?
- Long bones
- Lymph tissue of the body
59
Plasma is __% water and makes up __% the volume of blood.
- 90
- 55
60
What do plasma proteins do?
They help to clot the blood, and with the circulation between cells and tissue.
61
What is fibrinogen?
A plasma protein that is involved the clotting process.
62
How are percentages of the blood divided?
1. 55% plasma
2. Approx 45% red blood cells
3. Less than 1% of platelets and white blood cells
63
Describe the initiation of the heart rate.
- In the right atrium is a structure called the sinoatrial node, or the SAN
- It acts as a pacemaker controlling the rate of contraction (heart rate)
- Stimulation of this node initiates a wave of electrical impulses that spread across the atria, causing atrial systole
- Cardiac muscles are myogenic (they can initiate their own contraction)
64
Describe the propagation of impulse.
- Electrical signal in atria is picked up by a second node, the atrioventricular node
- Passes the signal down to the apex of the heart (bottom of ventricles)
- Passed through specialized conducting cardiac muscle fibres called "bundle of His"
- From apex, electrical activity is spread through ventricles along Purkinje fibres
- Therefore, ventricles contract from bottom up once filled with blood
65
What is fibrillation, and when does it occur?
- Rapid irregular contraction of muscle fibres in heart.
- Occurs when cells are not contracting in a regular fashion
- When it happens in the ventricles, it means that blood is not being forced into blood vessels
66
How does the medulla regulate the heart rate? Describe the systems of regulation in full.
It receives information from different parts of the body, and decides whether to activate the:
1. Parasympathetic system to slow the heart rate down.
--> Force of contraction decreases
--> No effect on blood vessels
--> Bronchoconstriction in lungs
--> Motility of GIT increases
--> Sphincter relaxes
--> Increased secretions in GIT
2. Sympathetic system to increase the heart rate.
--> Force of contraction increases
--> Blood vessels constrict
--> Bronchodilation in lungs
--> Motility of GIT decreases
--> Sphincter contracts
--> Decreased secretions in GIT
67
What are neurotransmitters?
Substances or chemicals that activate nerve cells and allow them to communicate with other nerve cells and muscle cells.
68
What are the neurotransmitters involved in the sympathetic and parasympathetic nervous systems?
1. Norepinephrine and epinephrine activate the sympathetic nervous system and cause the heart rate to speed up, in preparation for vigorous physical activity.
2. Acetylcholine stimulates the parasympathetic nervous system and lowers the heart rate.
69
What occurs to blood pressure as blood travels away from the heart?
Pressure decreases.
70
What do the outer layer (tunica externa) and middle layer (tunica media) of arteries contain? Describe the nature of their lumen and the reason for them.
- Collagen to prevent the artery rupturing due to high pressure blood flow
- Muscle and elastin to help maintain pulse flow by contracting and stretching
- The lumen is small and narrow to maintain high pressure.
71
Describe the nature of the lumen, walls, and valves of veins.
- Wide lumen --> keeps pressure low and allows greater flow of blood
- Thin walls
- Valves --> prevents blood pooling at extremities
- Skeletal muscles --> contract below valves to push blood back into heart
72
What is the nature of the arterial walls, and what are they composed of? How does this help with maintaining blood pressure?
--> They contain elastic fibres formed from elastin, which is stretched at every heartbeat; recoil propels blood forward
--> They have muscular walls to help with propulsion of blood
73
Describe the structure of capillaries.
- Walls made up of a single layer of endothelial cells --> allows for ease of diffusion, as capillaries are involved with material and gas exchange
- Very small diameter, maintaining low blood pressure
- May contain pores --> aids in transport of material
74
What artery is high in carbon dioxide and low in oxygen, and what vein is high in oxygen and low in carbon dioxide?
- Pulmonary artery
- Pulmonary vein
75
What are diastole and systole?
Diastole: phase of heartbeat when heart muscle relaxes and allows chambers to fill with blood -- vasodilation.
Systole: phase of heartbeat when heart muscle contracts and pumps blood from chambers into arteries -- vasoconstriction
76
Detail the six steps leading to occlusions in the coronary arteries?
1. Narrowing of lumen (stenosis) due to fatty deposits developing
2. Restricted flow increases pressure in artery and leads to damage in arterial wall
3. Repair is done with fibrous tissue, reducing elasticity of artery/capillary
4. Smooth lining is progressively degraded, lesions form called "atherosclerotic plaques"
5. If plaque ruptures, blood clotting is triggered, forming a thrombus that restricts blood flow
6. Dislodged thrombus can become an embolus and cause blockage in a smaller arteriole
77
What is the difference between arteriosclerosis and atherosclerosis?
Arteriosclerosis - hardening of arteries
Atherosclerosis - hardening of arteries due to plaque build up
78
How does atherosclerosis lead to an acute myocardial infarction?
Atherosclerosis can lead to blood clots that cause coronary heart disease when occurring in coronary arteries. Myocardial tissue requires oxygen and nutrients from the coronary arteries to function.
79
How does cardiac arrest work?
- The heart stops beating suddenly.
- Treated with a defibrillator
- Different from a heart attack, where blood flow to the heart is interrupted.
80
How are blockages of coronary arteries treated?
- With bypass surgery
- By creating a stent
81
Describe the process of putting in a stent.
1. Balloon catheter inserted into artery
2. Balloon inflated to expand stent
3. Balloon deflated
4. Catheter removed; stent remains to hold artery open.
82
Name four risk factors for heart disease.
- high blood cholesterol levels
- smoking
- high blood pressure (hypertension)
- high blood sugar levels, usually due to diabetes
- genetic factors (thus a family history of the disease)
- diet (rich in saturated fats, salt)
- lack of exercise
- gender (more common in males due to less estrogen)
- age --> blood vessels lose flexibility with age
83
Define an embolism.
- A blocked artery caused by a foreign body.
84
Describe hemostasis.
The prevention of bleeding and maintenance of blood volume.
- The tearing or puncturing of a blood vessel initiates clotting, and the end result is the formation of an insoluble network of fibers.
85
What are the main purposes of clotting?
--> Coagulation prevents blood loss
--> It prevents the entry of pathogens
86
List out the seven steps of blood clotting.
1. Injury exposes collagen fibers to blood
2. Platelets in blood stick to collagen fibers
3. Platelets and damaged cells release clotting factors
4. Platelets release chemicals that make surrounding platelets sticky
5. Platelets clump together and form a platelet plug.
6. Fibrin clots form to reinforce the seal
7. Clot traps red blood cells and dries to form a scab
87
What are the three stages of inflammation?
- Increased diameter and permeability of blood vessels
--> Increases blood flow to area
--> Moves material into tissue spaces
- Phagocyte migration
--> Phagocytic cells arrive in area to destroy microbes
- Tissue repair
--> New tissue created to replace dead or damaged cells
88
What is produced in adaptive immunity, and what is this a response to?
Antibodies, in a response to exposure to a pathogen. The antigens present on a pathogen stimulate an immune response.
89
What are antibodies produced by?
B lymphocytes, which are activated by T lymphocytes. The B cells multiply to form clones of plasma cells, which secrete antibodies
90
What are four ways that antibodies inactivate agents by binding to them?
--> Neutralization: blocks viral binding sites and coats bacteria
--> Agglutination of microbes
--> Precipitation of dissolved antigens
--> Activation of complement system
91
Detail the non-specific immune response.
--> No memory or lasting protective immunity
--> Limited repertoire of recognition molecules
--> Phylogenetically ancient (primitive) responses
--> Involves action of phagocytes (consume pathogens by phagocytosis) and natural killer cells (destroy infected cells)
92
Detail the specific immune response.
--> Antigen specificity generates responses tailored to specific pathogens or infected cells
--> Has a memory to "remember" pathogens, acts faster second time
--> No limit to recognition repertoire
--> Involves phagocytes, T cells, B cells (memory cells survive to initiate secondary response to future exposure)
93
How does the secondary immune response differ from the primary immune response?
No antigen presentation or activation of helper T/B cells is needed for the secondary response, so it's significantly faster.
The memory cells divide by mitosis to form clones of plasma cells and memory cells
--> Plasma cells produce antibodies to give a fast response to the invading pathogen
--> Memory cells stay in the body to defend against future attack.
94
Where are B cells and T cells produced, and where do they mature?
They are produced in bone marrow. B cells mature in the bone marrow, T cells mature in the thymus. Both enter the lymph nodes and spleen after maturation.
95
What are antigens?
Foreign substances that stimulate the production of antibodies e.g. molecules on the surface of viruses and bacteria.
96
What is the non-specific reaction to pathogens?
- Macrophages engulf pathogens non-selectively and break them down internally
- Proportion of macrophages (dendritic cells) will present antigenic fragments of pathogen to Helper T cells
97
What is the job of Helper T cells in clonal selection?
--> Release cytokines when activated
--> Cytokines stimulate a specific B cell that produces antibodies to antigen to divide and form clones
98
List details of plasma B cells and memory B cells
Plasma
--> Majority
--> Short lived
--> Produce large quantities of specific antibody
Memory
--> Smaller proportion
--> Long-lived
--> Provide long-term immunity
99
Explain polyclonal activation.
Pathogens typically contain multiple distinct antigenic fragments. A single pathogen can stimulate several different T and B lymphocytes to produce a variety of specific antibodies.
100
Explain adaptive immunity.
Immune system relies on clonal selection of plasma cells to produce large numbers of antibodies
--> Delay between primary immune response during initial exposure and production of antibodies
Memory cells (B and T) prevent delay in antibody production in subsequent exposures. Pathogen exposure can no longer cause the disease, so individual is "immune".
101
Define a pathogen.
A disease causing agent that disrupts the normal physiology of the infected organism.
102
What are the methods of entry of a pathogen?
Direct:
1. Person to person - touching or exchanging bodily fluids
2. Droplet spread
Indirect:
1. Airborne - some infectious agents travel far and remain suspended in air
2. Contaminated objects
3. Food and drinking water
4. Animal-to-person contact
5. Animal reservoirs
6. Insect bites
7. Environmental reservoirs
103
What are the three levels of defense against pathogens?
1. Protective layers
- Skin
- Mucous
2. Non-specific response
- Macrophages
- Inflammation response
3. Specific response
- Antibodies
- Lymphocytes
- Memory cells
104
How does sweat fight off pathogens?
It contains lysozyme that digests bacterial cell walls.
105
How do mucous membranes fight off pathogens?
--> It lines all animal body cavities and canals that come into contact with the air.
--> It contains goblet cells that secrete mucus, a protective fluid that traps pathogens
--> Cilia flush potential pathogens either out of the body or into the stomach, where the action of acids kill most of them.
106
Describe the work of phagocytic leukocytes.
1. Macrophages circulate in the blood but may move into body tissue (extravasation) during an infection.
2. They concentrate at infection sites due to release of chemicals like histamine from damaged body cells.
3. Pathogens are engulfed when cellular extensions surround the pathogen then fuse, trapping it in internal vesicle
4. Vesicle may fuse with lysosome to digest pathogen with enzymes
5. Some antigenic fragments may be presented on macrophage surface to stimulate antibody production
107
Explain histamines and how they cause allergic reactions.
--> Histamines are produced by basophils and mast cells in the connective tissues
--> They dilate and increase permeability of capillaries, allowing mast cells to engage affected tissues and engage allergens
--> When an allergen enters the body, a B lymphocyte comes into contact with it
--> Plasma cells produce an antibody that circulates in blood and binds to mast cells
--> Mast cells become activated, triggering histamine release
108
How do antihistamines help with allergic reactions?
They reduce capillary permeability, blocking histamine receptors.
109
How does HIV work?
- It specifically targets and infects helper T lymphocytes
- It undergoes a period of inactivity (clinical latency) during which infected helper T cells reproduce
- It becomes active again and spreads, destroying T lymphocytes in the process (lysogenic cycle)
- Antibodies cannot be produced due to low number of helper T cells
- Body becomes susceptible to opportunistic infections
110
How is HIV transmitted?
Through the exchange of bodily fluids -- it can be minimized by using latex protection.
111
What are the four types of immunity?
Natural active
- Occurs during infection
- Active because lymphocytes are activated by antigens on a pathogen's surface
Artificial active
- Injecting or taking antigens by mouth
- Takes time for T and B cells to be activated
Natural passive
- Mother to child through placenta or milk
Artificial passive
- Used during potentially fatal diseases
- Provides an instant response but only temporary as antibodies are not the body's own so memory cells are not created
- e.g. tetanus - injection of antitoxins is given.
112
Define immunization. What are the two types of immunization?
The use of a vaccine or vaccination to provide the recipient with an artificially acquired immunity
--> Whole agent: contains whole but non-virulent microorganism
--> Subunit: contains part of or a product of a microorganism
113
Describe the whole agent type of vaccine?
Live attenuated:
--> Vaccines are made by modifying disease-causing microorganisms in a library
--> The microorganism is weakened; it can still replicate in the body but does not cause illness
--> Risk that it may mutate back into its virulent form
Inactivated vaccines:
--> Made by disease-causing microorganisms
--> Whole dead microorganisms or pieces of dead microorganisms are put into the vaccine.
--> They cannot replicate
--> Dead antigens are weak, so multiple doses often are needed to produce a good immune response.
114
Describe subunit vaccines
- contain purified antigens rather than whole organisms
- not infectious, can be given to immunosuppressed people
- less likely to induce unfavorable immune reactions
- increased effect when given in adjuvants, which also act as foreign agents
115
Describe mRNA vaccines
- introduce mRNA sequence coded for a disease specific antigen into a host cell (T cell)
- antigen is produced within body, recognized by immune system, stimulates antibody and memory cells production
- faster and cheaper to produce
- safer for patient, not produced using infectious elements
116
How did Florey and Chain discover the antibiotic properties of penicillin?
Eight mice infected with pathogenic bacteria. Control group receives no treatment and died. Experimental group receives penicillin injections and survived. Penicillin kills bacteria but not host cells.
117
Name four impacts of antibiotics on bacteria.
- Inhibit protein synthesis
- Inhibit nucleic acid synthesis
- Inhibit cell wall synthesis
- Disruption of cell membrane function
- Block pathways and inhibit metabolism
118
Do antibiotics block processes of eukaryotic cells?
Do they affect viruses? Why or why not?
Nope!
No; viruses are not living and don't have metabolic processes. They infect living cells and use the cell's metabolic processes to spread viral infection.
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How do strains of bacteria become resistant to antibiotics?
--> A mutation causing resistance to an antibiotic occurs in a bacterium.
--> After several generations, a strain evolves with genes enabling resistance
--> The biggest problem is when bacteria exchange genes coding for resistance and develop multiple resistance
120
What are monoclonal antibodies?
Antibodies artificially derived from a single plasma clone (identical specific antibodies)
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How do monoclonal antibodies work?
--> They can recognize and bind to one specific region of an antigen
--> They are used for therapeutic treatment and clinical detection of disease, and are commonly used for immune protection
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How are monoclonal antibodies produced?
Fusing a tumour cell with an antibody-producing plasma cell creates a hybridoma cell, which produce monoclonal antibodies.
--> Injection of antigen
--> Polyclonal antibodies are produced
--> Tumor cells are fused with polyclonal antibodies
--> Hybridoma cells replicate their DNA
--> Hybridoma cells are cultured separately and screened for the right antibody
--> Monoclonal antibodies are harvested
123
Explain zoonosis with regards to pathogens.
Zoonosis is the transmission of a disease from animals to humans. They involve pathogens that can cross the species barrier.
124
Explain antagonistic muscles, and give an example.
Muscles that work in pairs to move body parts in opposite directions.
Three possible answers below!
--> External and internal intercostal muscles
--> Diaphragm and certain abdominal muscles
--> Bicep and triceps
125
Outline the five steps of how hCG is used in pregnancy tests.
1. Test stick with anti-hCG antibodies attached to dye is dipped in urine
2. hCG binds to antibodies
3. hCG binds to monoclonal antibodies attached to the membrane in test stick window
4. Blue line in window indicates presence of hCG
5. Urine reaches next line of monoclonal antibodies (control line used to see if test is working)
