Animal Phys Final Flashcards
Cells store energy in what two main forms?
Reducing energy
High energy covalent bonds
Describe carbs
- Have many hydroxyl (-OH) groups
- Glucose is most common carb form
- Used for energy metabolism
- Used as a substrate in biosynthesis to form new or more complex carbs
Describe monosaccharides
- Used for energy and as biosynthesis substrate
- Monosaccharides, also called simple sugars, are the simplest forms of sugar and the most basic units from which all carbohydrates are built. Simply, this is the structural unit of carbohydrates. They are usually colorless, water-soluble, and crystalline shaped organic solids
Describe Complex Carbs
- Polysaccharides that are used for energy storage (i.e insulin, starch) and formation of structural molecules (chitin, cellulose)
Note: Amylose + amylopectin = starch
Glycogen synthesis = ______
Glycogen degradation = ______
glycogenesis
glycogenolysis
Describe the process of glycogenisis
- Glycogen synthase is inactive
- Protein phosphatase activates the complex
- Glycogen (n glucose) interacts with the active glycogen synthase and is converted to glycogen (n+1 glucose)
- Upon conversion protein kinase inactivates glycogen synthase and returns it back to it’s inactive state
Describe the process of glycogenolysis
- Glycogen phosphorylase is inactive
- Glycogen phosphorylase kinase activates the glycogen phosphorylase
- Glycogen (n+1 glucose) interacts with the active glycogen phosphorylase and is converted to back to glycogen (n glucose)
- Upon conversion Glycogen phosphorylase phosphatase inactivates the glycogen phosphorylase and returns it to back to its inactive state
Describe the process of ANAEROBIC glucose metabolism / breakdown
- Overall Rxn: Glucose + 2 ADP + 2 NAD+ → 2ATP + 2 pyruvate + 2 NADH + 2 H-
- Happens in cytoplasm
- Produces intermediates for synthesis of various molecules (Carbs, nucleic acid, amino acids or fatty acids)
- End product, pyruvate, can be used in further catabolic processes
Describe AEROBIC pyruvate oxidation
- Converts carbs (glucose) to pyruvate within cytoplasm
- Pyruvate is carried into the mitochondria
- Pyruvate Dehydrogenase (PDH) oxidises pyruvate to form acetyl-CoA + NADH
Note: Lactate and amine can also be turned into pyruvate
Describe AEROBIC oxidation of NADH
- Glycolysis can only continue if NADH is oxidised to NAD+ and H+
- Two “redox shuttles” carry reducing equivalents (H+ atoms) from cytoplasm ←→ mitochondria:
α - glycerophosphate shuttle
Malate-aspartate shuttle
Oxidation of NADH in the Absence of O2
- NADH is oxidised in the cytoplasm
- Buildup of NADH in cyto means drop in NAD+
- This would inhibit glycolysis (since NAD+ is an important substrate) - Pyruvate + NADH + H+ ←→ lactate + NAD+
- Catalysed by the enzyme lactate dehydrogenase (LDH)
Note: Other anaerobic pathways form less toxic end products and more ATP than lactase (2 ATP)
For example, succinate (4 ATP) and propionate (6 ATP)
Describe lipids
- Lipids are used for energy metabolism, cell structures (e.g membranes), and signalling
Describe fatty acids
- Saturated = No double bonds between carbons
- Unsaturated = One or more double bonds between some carbons
- Fatty acids are a more dense form of energy storage than carbs
Describe the process of fatty acid oxidation
- β-oxidation
- Takes place in mitochondria
- Consumes an ATP to make 1 NADH, 1 FADH and 1 Acetyl-CoA
- Acetyl-CoA is then oxidised in next step
What is the degradation process of glucose to ATP?
- Glycolysis:
* Anaerobically happens in cytoplasm, one glucose is broken down into two pyruvates
* Glucose + 2 ADP + 2 NAD+ → 2ATP + 2 pyruvate + 2 NADH + 2 H- - Pyruvate oxidation:
* Pyruvate is carried into the mitochondria
* Pyruvate is oxidised by Pyruvate Dehydrogenase (PDH) to form acetyl-CoA + NADH
* Can be done aerobically or anaerobically - Acetyl CoA is either converted to ketones or sent to the Kreb’s cycle
- In the tricarboxylic acid cycle (TCA aka Krebs) acetyl-CoA is converted to CO2, NADH (x3), FADH2 (x1), GTP (x1)
- These reducing agents are oxidised at the ETC to release energy which creates the gradient that drives ATP synthesis/phosphorylation
Describe ketones
- Some tissues cannot metabolise fatty acids , but they can metabolise ketones. So ketones are pretty much a form of acetyl-CoA that can be stored, or used by any type of tissue.
- Ketogenesis:
1. Fatty acids converted to acetyl-CoA
2. Acetyl-CoA converted to ketones
3. Ketone bodies can move through circulation - Ketolysis
1. Ketones are broken down to acetyl-CoA Which can then participate in oxidative phosphorylation
Note:
Describe the ETC
- Has five multisubunit protein complexes embedded within the inner membrane between the intermembrane and the matrix. -
- There’s also two electron carries (ubiquinone and cytochrome c)
- Complex I reduces NADH to pump H+ ion from the matrix into the intermembrane space or to complex II
- Complex II turns FAD → FADH, and then cyclically reducing FADH back into FAD and omitting an electron to complex III
- Complex III hands the electron over to cytochrome c which then delivers the electron over to complex IV
- Complex IV oxidises cytochrome c and is itself reduced by cytochrome c. Complex IV uses O2 and adds it to H to get a water molecule byproduct and pumps an electron into the intermembrane space
- Electron buildup in intermembrane space creates gradient that drives protons through ATP synthase, phosphorylating ADP–>ATP
- Generates a proton gradient, heat, water and reactive oxygen species as final products
Describe phosphocreatine
- Is used for muscle energy, found within the myofibril
- Phosphocreatine pretty much just acts as a transporter of phosphate from the main ATP supply chain (the mito) to the sister branch producer (the muscle)
- Reaction is reversible so relative rate of ATP versus phosphocreatine production depends on ratio of concentration of substrates/products
-Phosphocreatine can also move throughout cell (like ATP) - Thus, it can enhance flux of high energy phosphate molecules from site of synthesis (e.g. mitochondria) to site of hydrolysis (e.g. muscle sarcomeres)
What is 31P-NMR Spectroscopy
- Measures ATP turnover
- Detects change in NMR spectra as Pi groups shift between ATP and inorganic phosphate
Pros:
* Accounts for aerobic, anaerobic metabolism, etc.
* Accurate over extremely short time scales. E.g. A single muscle contraction
Cons:
* Logistically difficult
* Subject must be restrained, possibly anaesthetised
* Equipment not portable, and complicated
Describe direct calorimetry
- Measurement of heat of chemical/physiological processes (unit can be ‘calorie’)
Pros:
* Quite accurate under many conditions
* Accounts for aerobic and anaerobic energy production
Cons:
* Subject must be restrained
* Equipment heavy and complicated
* Makes assumptions about anabolic versus catabolic activity
What is Hess Law?
Any anatomical fuel source will always exhibit the same total amount of energy released (as heat) regardless of what intermediate states occur during their breakdown
In scaling relationships what are two things that are factors of volume , and two that are factors of surface area?
Some things are a factor of volume (internal size of animal):
- Total metabolic rate
- Total heat production (cellular respiration byproduct)
Some things are a factor of surface area:
- Respiration (how many cells require air)
- Absorption/expulsion (for animals who do so via skin membranes, like heat loss through skin or water absorption)
Note: Ratio between surface area and volume is 2:3. So, BMR can be predicted to scale with an exponent of 0.667
- Kleiber was the one to find significance and to quantitate the relationships
If resting animal cells (regardless of animal size) had a similar metabolic rate (i.e heat production), larger animal would have relatively ____ surface area for dissipating extra heat
Why?
less
As animals grow in size their inside (volume) gets “more bigger” than their outside (surface area).
Define thermal inertia
The tendency of a material (animal) to resist thermal change.
In our case an animal with a high metabolic rate in relation to it’s size would have low thermal inertia, like a mouse. So it’s losing heat relatively faster than it’s larger counterpart, a rat for example.
Define basal metabolic rate
- Metabolic rate of homeothermic animal at rest inideal conditions
- Does not scale proportionally to volume.
- Slowest metabolic rate (unless in torpor/hibernation)
In ____ ____, the growth rates of different body parts differ from that of the whole body. In contrast, in ____ ____, body parts grow at the same rate as the rest of the body.
allometric growth
isometric growth
What are the terms that correlate with each definition?
- The capacity to do work
- The transfer of energy by a force (mass x acceleration) acting on an object as it is displayed (force x distance)
- The rate at which work is done
Energy
Work
Power
What is the respiratory quotient and some important things to note about its ratios?
- When respiring the body uses three different substrates. By isolating mitochondria and observing the rate of CO2 production/O2 consumption we are given the RQ. The RQ can help us determine which substrate is being used as fuel
Carbs: When RQ ≈ 1, O2 consumed = CO2 produced
Lipids: When RQ ≈ 0.7, O2 consumed > CO2 produced
Proteins: When RQ ≈ 0.85, O2 consumed > CO2 produced
What is the respiratory exchange ratio (RER) and how does it differ from the respiratory quotient?
- Respiratory Exchange Ratio (RER) directly measures Vol CO2 released/Vol O2 absorbed at the mouth
- Respiratory quotient, on the other hand, measures directly at the tissue
Endurance training burns ____, bursts of strength require ____
lipids
carbs
How does the ATP/O stoichiometric relationship vary with fuel type?
- In order for isolated cells to produce a given # of ATP molecules: 14.9 – 18.7% more O2 required when oxidising fats, compared to carbs
- Sugar is the more O2-efficient fuel source
What is the difference between metabolism and metabolic rate?
Metabolism: The set of processes by which cells and organisms
acquire, rearrange, and void commodities (e.g. elements or
energy) in ways that sustain life
Metabolic rate: An animal’s rate of energy consumption; the
rate at which it converts chemical-bond energy to heat
and…work. (rate of power)
Describe chamber respirometry and it’s pros/cons
- Animal enclosed in a chamber
where you are flowing air from outside through the chamber and measuring how the air changed from entering and exiting the chamber as a result of how the animal affected it - Pros
- Easiest approach
- More sure that all expired gases accounted for
- More accurate
- Quality of air provided (environment) easier to control
- Cons
- Animal constrained, less natural behaviour
- Risk of asphyxiation
- Can be messy
- Animal may do all its functions in chamber
Describe chamber respirometry in a closed system and it’s pros/cons
- Used on small things. You dont let air recirculate through thus the animal rebreathes the air and continuously raises the CO2 and water vapour level, decreases oxygen level. Can measure pressure change.
Pros
- More sure that all expired gases accounted for
- Quality of air/water provided (environment) easier to control
Cons
- Risk of asphyxiation if O2 level gets too low, CO2 level gets too high
- More accurate with longer time scales
- Activity state must be known or constant
- Switching between rest and activity complicates calculations
Describe mask respirometry and its pros/cons
- A variant of flow-through chamber respirometry in which the chamber only covers the mouth/nose/head
- Done when most oxygen is exchanged utmostly through inhalation/exhalation
Pros:
Small volume, faster flow rates mean even greater temporal resolution; animal can behave nearly naturally
Cons:
Poorer signal to noise ratio; composition of gases harder to control; must assume gas concentrations in surrounding ambient air
Fill in the blanks
Given that during and after exercise, O2 consumption rates are high, what would you expect to happen as you approach and persist through rest?
- Initially O2 consumption levels and ATP turnover rates are high, and begin to decline
- Even when rest is reached O2 remains high because :
1. lactate goes through cori cycle to replenish glycogen stores and is also used as a substrate in oxidative phosphorylation in aerobic tissue
2. Rebuilding phosphocreatine at expense of ATP (now largely being generated aerobically)
Describe Lactate
A byproduct of anaerobic glycolysis. Glucose is broken down into pyruvates in the cytoplasm, however there’s no oxygen so it can’t move to the mitochondria. Acid (H+) is attached to pyruvate and that is lactate. It acts as a buffer for acidity. The hydrogen can also be removed later and combined with oxygen to form water.
What is the cori cycle?
Two lactates in the liver have their hydrogens removed and then combine to form a glucose which returns to tissue to rebuild glycogen
Tf is glycogen and why do I forget?
This stored form of glucose is made up of many connected glucose molecules and is called glycogen. When the body needs a quick boost of energy or when the body isn’t getting glucose from food, glycogen is broken down to release glucose into the bloodstream to be used as fuel for the cells.
Define the standard metabolic rate
Same as BMR, except for poikilothermic animal, at a defined environmental temperature
What is the order in which fuel sources are consumed over time of physical exertion
Define the resting metabolic rate
Metabolic rate of animal at rest under defined conditions
Not necessarily during quiescent (inactive) phase, or totally post-absorptive, or within TNZ
What is the field metabolic rate?
The realised metabolic rate of an animal in the wild
What is the difference between maximum aerobic metabolic rate (VO2max) and supramaximal metabolic rate?
- Maximum Aerobic Metabolic Rate (VO2max) is the maximum SUSTAINABLE VO2 seen
during intense aerobic exercise
or when homeotherm is exposed to very cold temps. The
Supramaximal Metabolic Rate is above the VO2max but isn’t sustainable. - Analogy:
VO2max = ultramarathon running
SMR = 100m burst
What is the daily energy expenditure?
- Total energetic cost of a day of life
- NOT a metabolic RATE, an energy amount
- Useful for considering ecology, survival, etc.
The whole animal metabolic rate is _____ in small animals than it is for big animals. However the mass-specific metabolic rate (MR/kg) is _____ in smaller animals than in larger animals.
lower
higher
What are the equations for whole-animal metabolic rate and for mass-specific metabolic rate?
Rate of heat production should be a function of ____
(The size of all the cells consuming energy and producing heat )
Rate of heat loss should be a function of ___ ____
(Heat is lost to environment across surfaces)
volume
surface area
What is the total thermal energy equation?
Total thermal energy = ∆Heat = ∆Hmetab + ∆Hconvec + ∆Hrad + ∆Hevap
What are the four types of heat exchange?
- Convection:
*Transfer of thermal energy between an object and an external medium that is moving - Radiation:
* Emission of electromagnetic radiation - Evaporation:
* Water molecules absorb thermal energy from a surface when making the transition from liquid to vapour - Conduction:
* Transfer of thermal energy between one object or fluid to another
What is Fouriers Law?
What are Bergmann and Allen’s rules and why do they make sense?
Bergmann’s rule:
- Animals living in cold environments tend to be larger because larger animals exchange heat less than smaller ones due to their smaller surface area-volume ratio
Allen’s rule:
- Body form or shape is linear in warm climates and more rounded and compact in cold climates. Being round and compact = less surface with more volume
Note:
The more volume = greater metabolic heat output
The less surface area = less loss of heat to environment
Match definitions to terms
- Poikilotherms:
- Homeotherm:
- Endotherm:
- Ectotherms:
A. Body temp derived from environment
B. Body temp varies
C. Body temp produced metabolically
D. Body temp is stable
1-B
2-D
3-C
4-A
What is regional endothermy and what is an example of regional heterothermy?
- The ability to conserve metabolically derived heat to maintain the temperature of certain tissues elevated above ambient temperature
- Tuna, unlike most fish, maintain heat in red muscles which are kept more towards the core of their bodies, which minimises heat loss via diffusion to the environment.
What is temporal endothermy?
Phase of time where body temperature is maintained. This includes torpor, which lasts less than a day, and hibernation/aestivation which lasts much longer
What are the three thermal zones of homeotherms?
- Thermoneutral zone:
- Optimal range for physiological processes; metabolic rate is minimal - Upper critical temperature (UCT)
- Metabolic rate increases as animal induces a physiological response to prevent overheating - Lower critical temperature (LCT)
- Metabolic rate increases to increase heat production
- Animals differ in the width of their thermoneutral zone, UCT, and LCT
What are the three (kinda 5) thermal zones of poikilotherms?
- Preferred temperature:
- Ambient temperature for optimal physiological function - Incipient lethal temperature:
- Ambient temperature at which 50% of animals die
* Incipient upper lethal temperature (IULT)
* Incipient lower lethal temperature (ILLT) - Range of tolerance
- Range of ambient temperatures between IULT and ILLT
What’s the difference between eurytherms and stenotherms?
Stenotherms can tolerate only a narrow range of ambient temperatures. Eurytherms can tolerate a wide range of ambient temperatures and occupy a greater number of thermal niches
How does thermogenesis by ion pumping work?
- Ion-pumping membrane proteins produce heat
For example, billfish heater organs which are modified muscles that don’t contract.
Heat is produced in these muscle tissues by:
- Reduction of ATP → ADP + P by Ca+2ATPase which pumps Ca+2 through the sarcoplasmic reticulum
- When substrate is catabolised from Ca+2 and ATP → ATP + P
- From the NADH → O2 ETC process in the mitochondria
How can insects produce heat prior to flight?
- They have a carbohydrate metabolism in flight muscles. Within these muscles opposing enzymes are activated, constantly anabolising and catabolising ATP → ADP + P → ATP to produce heat as a byproduct
- They also contract antagonising flight muscles, thus the muscle does not contract yet remains tense. Energy is expended and heat is produced without movement required. This is a coordinated version of shivering
- Finally the frequency and orientation of their wings are controlled to avoid generating lift – wing buzzing
What is a homeoviscous adaption?
- Maintenance of membrane fluidity at different temperatures by changing membrane lipids (cholesterol content). This is done by:
- Decreasing the length of fatty acid chains increases fluidity
- Adding double bonds to fatty acids (unsaturation) increases fluidity
- Changing the polar head of the lipid to either:
* Phosphatidylcholine (PC): to decrease fluidity
* Phosphatidylethanolamine (PE): to increase fluidity
How is membrane fluidity affected by temperature?
- Low temperatures cause membrane lipids to solidify
- High temperatures increase membrane fluidity
___ ____ exhibit enzyme
activity in relation to temp
that underpins difference in
performance
LDH alleles
What are psychotrophs?
- Animals that thrive at low temperatures
- Psychrotrophs possess cold adapted enzymes
1. Fewer weak bonds
2. Enzymes breathe (jiggle) more easily at low temperature - But cold-adapted enzymes are more vulnerable to temperature dependent unfolding
Describe freeze-avoidance
Animals can allow their tissues to freeze in a controlled, safer way. They can do this by producing antifreeze molecules which are proteins or glycoproteins that depress the freezing point by non colligative actions (depend on the identity of the dissolved species and the solvent). This disrupts ice crystal formation by binding to small ice crystal and preventing growth
Describe freeze-tolerance
- Animals use behavioural and physiological mechanisms to prevent ice crystal formation (e.g frogs)
- Two mechanisms of freeze-tolerance
1. Produce nucleators outside of the cell which control the location and kinetics of ice crystal growth. So the extracellular fluid freezes, but intracellular fluid remains liquid
2. Produce intracellular solutes to counter the movement of water into the cell
What are the advantages of a higher body temp?
↑ growth, development, digestion, biosynthesis
What are internal thermostats?
- Exactly as the name suggest, how the body knows/perceives the temperature.
- In mammals info from central and peripheral thermal sensors is integrated in the hypothalamus
which sends signals to the body to alter rates of heat production and dissipation - In birds the thermostat is located on the spinal cord
What is shivering thermogenesis?
- Uncoordinated myofiber contraction that results in no coordinated net muscle work but results in heat as a byproduct.
- It is unique to mammals and birds
- Cannot be sustained for long, the muscles will eventually run out of nutrients
- When the muscles are in use, prevents locomotion
What is brown adipose tissue and how does it work? (BAT)
- Tissue found in small mammals and newborns in cold climates.
- Within the tissue there’s a high density of mitochondria which produce a protein called UCP1 (Uncoupling Protein 1) which work by:
1. The sympathetic nervous system activates UCP which uncouples the mitochondrial ETC and proton pumping from ATP synthesis. This creates a futile cycle where H+ ions move through the UCP gradient, but don’t produce ATP
2. This means that fatty acid oxidation must occur to produce energy (releasing more heat as byproduct compared to ETC)
What is a Blastula (or blastocyst)?
A sphere of undifferentiated cells that forms shortly after initial bout of cell division
Note:
It implants in your uterine wall, eventually becoming the embryo and then the fetus
What is gastrulation and what are the steps?
The process of invagination and differentiation into 2 or 3 cell layers of a blastocyte. Every animal except sponges experiences this phenomenon
- Blastopore begins to form along the flat bottom of the blastocyte
- Some cells inside the blastocyte break loose and form mesenchyme
- Some mesenchyme attach themselves top the top of the blastocyte (archenteron) and then extend villi to the roof
- The villi contract, drawing the blastopore upwards, developing the invagination
- The opening of the invagination becomes the anus of the animal, the archenteron becomes the mouth
Describe a batch-reactor stomach
- Ingested food enters and leaves the stomach pouch through a SINGULAR tube.
- Stomach composition changes with time
Describe a continuous-flow stirred-tank stomach
- Ingest food continuously enters the stomach through one tube, continuously exits through another
- Food that enters is stirred/mixed and barely digested before leaving
- Stomach composition does not change with time when in a steady state
Describe a plug-flow reactor stomach
- Continuous input and output of food is pushed through the tube by an axial gradient (e.g peristalsis)
- Stomach composition does not change with time at any point along the reactor
What are the guts in order from ingestion to defecation?
- Headgut
- Foregut
- Midgut
- Hindgut
Acronym:
He Fancies Mean Head
What does the hindgut do and what organs are associated with it?
- The hindgut is all about waste storage but in many animals plays a huge role in ion-hydration balance
- Large intestine/colon/coclea/rectum
What does the midgut do and what organs are associated with it?
- Responsible for digestion and absorption of nutrients
- Small intestine, duodenum, ilium, jejunum
What do the foregut and headgut do and what organs are associated with em?
- Responsible for ingestion conduction, food storage and digestion
- Esophagus, stomach
Describe goblet cells
- Found in small intestine and respiratory tract
- Produce mucus which help protect the tissues from the gastric acid
Describe parietal cells
- Made in the stomach gastric pits
- Produce hydrochloric acid (HCl) which breaks down food and kills bacteria
Describe chief cells
- Made in the stomach gastric pits
- Create pepsinogen which is activated by HCl. When activated it becomes pepsin which breaks down proteins
Describe chyme
- Increases the surface area of food by breaking it down into a thick semifluid mass.
- Also stimulates digestive glands (gallbladder and pancreas) to secrete their respective solutions (bile, digestive enzymes, and bicarbonate).
What are the two types of mammalian stomachs and how do they differ?
- Monogastric:
* A singular stomach compartment
* Humans - Digastric (Ruminant):
* Four stomach compartments
* These mammals must regurgitate
Describe the movement within the intestine in animals
- Small animals can get away with using cilia to facilitate the movement of food particles along the gut system, large animals cannot. Therefore we use a process called peristalsis which pushes food via a wave of circular muslce contraction, followed by alternating waves of longitudinal muscle contractions
Note: Segmentation can occur where a bolus (block of semifluid digested food) that is two big is cut in half by the contraction of circular muscles pinching it in half
How are the types of carbs (glycogen, starch, disaccharides, cellulose) digested and where?
How does the digestion of glycogen/starch work?
- Monomers are broken apart by salivary or pancreatic amylase
- Produces either maltose (disaccharide) or limit dextrins (oligosaccharide)
Note:
Amylase can only break down the a-1,4 linkages (linear) of the monomers, they however cannot breakdown the a-1,6 linkages.
Match the disaccharide to the monosaccharide products it yields
- Sucrose
- Lactose
- Maltose
A. Glucose + Glucose
B. Glucose + Fructose
C. Glucose + Galactose
1-B
2-C
3-A
When must we rely on symbiotic gut microflora?
- When our small intestine must breakdown cellulose or inulin because we lack the essential enzyme to do it ourselves.
How do termites acquire gut microflora?
- Symbiotic protists help termites digest the cellulose and lignin (wood poly-aromatic alcohols) but eventually termites must moult to grow. Unfortunately, digestive tract lining also gets molted so they lose the flora. In order to regain it, they must eat their nestmates’ feces
How are carbohydrates absorbed at the brush border?
Note: brush border
are a stria of microvilli on the plasma membrane of an epithelial cell (as in a kidney tubule) that is specialized for absorption.
How are the midguts of small flying invertebrates specialised
- They require more absorption per unit surface area because they need to optimise their stomach size to efficiency ratio
- To do this they have increased villi length (increase SA), and also leaky guts which allow passive movement of sugars and AA
How are the foreguts of small flying invertebrates specialised
- Have a lil pouch called a crop to store shit, since they gotta use their forearms to fly
Describe the post-absorption processing of toxins
- Orally ingested toxins are dissolved either in the stomach where they are then absorbed in the blood stream through the epithelial cells, or by the small intestine
- Once in the system they are brought to the liver which inactivates the toxin or excretes it to gull blader
How can fibre help constipation?
- Fibre is a carb, hydrophilic
- Retains more water in small intestine, large intestine has less water which encourages excretion of water from large intestine.
- Keeps stool soft making defecation easier
Describe the insulin response in glucose homeostasis
- When a meal is had, glucose levels rise and is absorbed.
- Insulin is released
- Stimulates glucose uptake (conversion to glycogen or by being consumed)
- Promotes lipogenesis while suppressing lipolysis, and hence free fatty acid flux into the bloodstream decreases (so glucose must be used for fuel)
Counter:
5. If glucose level is too low, glucagon instructs the liver to convert glycogen to glucose, making glucose more available in the bloodstream
WTF is wegovy/ozempic?
- Drug used for diabetic treatment
Wegovy works by helping to regulate food intake and appetite. GLP-1 targets areas of the brain that help to regulate appetite, especially after eating. It also slows how quickly the stomach empties, which makes you feel fuller for longer. In addition to this, Wegovy enhances the production of insulin.
What is biotransformation for secretion?
- Altering the structure of a lipophilic toxin in the digestive system so that it becomes hydrophilic, and easier to excrete
- Can also inactivate and activate drugs as well (somehow idk)
Talk to me bout some sugar absorption (I am in steep mental decline)
- Sugar uptake is constrained at multiple steps:
1. How fast it can be delivered via circulatory system.
2. How fast it can be taken up by the liver or muscles and then oxidised - Glucose is used up more fully and faster than fructose, however a mixture of the two works best
- Human liver takes up all fructose ingested before distribution. Free fructose in our diets leads to rise in obesity, promotes lipogenesis
- Human muslces take up surcose and use it as a substrate to help catabolise ADP+Pi –> ATP
What is the difference between pulmonary and systemic (venous) circulation?
Pulmonary =
- Movement of blood between the lungs and heart.
- Shorter time to complete cycle.
- Have thick muscular walls
Systemic =
- Movement of blood between the heart and body.
- More vascularity
- Have thin elastic walls
Notes: It takes less pressure from the right side of heart to drive flow thru pulmonary than it does for the left to pump blood through the systemic circulation
Talk to me bout insect open circulatory system
Have a heart (ostia) and store hemolymph in sinuses surrounding organs. The primary hemolymph (circulatory fluid) is pumped through a muscular heart into an arterial system and then eventually the fluid is dumped out into the general extracellular fluid bathing the tissues of the animal. The hemolymph contains nutrients, excrement or harmful-organism deteriorators which osmotically diffuse into whatever centres they’re needed at. Close to the heart there are openings where the fluid can reenter the heart to be pumped again.
Describe oxidation dissociation curves
- Represents oxygen saturation (y-axis) as a function of the partial pressure of oxygen (x-axis)
- P50 = Partial pressure at which pigment heme groups are 50% saturated. On a graph, the x-value where half of the total y-value occurs
- The higher the PO2 level at P50 the more effective it is
- The shape of the oxygen dissociation curve of Hb is sigmoidal, whereas that of Mb is not (it is hyperbolic); only the sigmoidal curve is characteristic of the cooperative process.
What are the differences between polycythemia and anaemia?
Polycythemia: Proportion of RBC in blood is much higher than average
Anaemia: Proportion of RBC in blood is much lower than average
What is the Bohr Effect?
Hint: ties to Hb
How does elevation affect relative gas partial pressures in the:
1. lumen of the lung
2. Lung capillaries
3. Diffusion gradient
Describe the ventilation oscillations that occur in birds, mammals and some reptiles?
(axial musculoskeletal oscillations)
Inspiration (diaphragm lowers, rib cage expands via contraction of external intercostals) creates negative pressure in lungs because pleural space (between ribs and lungs) cannot expand (fluid filled). Exhalation causes rise in diaphragm and contraction of internal intercostals compresses rib cage.
What is the difference between anatomical and physiological deadspace?
Anatomical:
- The volume of oxygen which is not used in gas exchange, it never even reaches the alveoli, it is just taken into the respiratory system and then expired without change
Physiological:
- Physiologic dead space includes all the non-respiratory parts of the bronchial tree included in anatomic dead space, but also factors in alveolar deadspace (unperfused alveoli)
What is the difference between functional residual capacity (FRC) and residual volume (RV0 in the lungs?
FRC is the volume of air left in the lungs at the end of a normal expiration. It is the combination of residual volume (RV) and the expiratory reserve volume. RV is the amount of air that cannot be expelled from the lungs at the end of a forced expiration.
What is the difference between expiratory and inspiratory reserve volume?
The inspiratory reserve volume is the amount of air a person can inhale forcefully after normal tidal volume inspiration; the expiratory reserve volume is the amount of air a person can exhale forcefully after a normal exhalation
What is Ficks equation?
Describe countercurrent in terms of respiration
- Between the alveolar sacs and blood
- Countercurrent = two factors (CO2, O2) move in opposite directions of eachother during exchange interaction
- In respiration, O2 from alveoli move oppositely (to blood) than CO2 from the blood (to alveoli)
- Eventually the CO2:O2 ratio in both blood and alveoli will be equal, thus diffusion gradient fades and no more net movement occurs.
More in depth: Concurrent exchange is a reasonable approximation of gas exchange. Inhaled air comes into alveoli sacs where the pulmonary circuit comes from the heart and exchanges deoxygenated air for oxygenated air. Blood will have low CO2, and the air will have comparatively high PO2, the difference will drive the diffusion of oxygen. As that blood moves from arteriol → ventricle the blood is losing oxygen, and after a while the oxygen levels in both the sac and the blood will be about equal which in turn reduces the gradient of diffusion until there is no more net diffusion.
Countercurrent exchange, like in gills. In this system water moves through the buccal cavity past the gill arches. However the blood flow, deoxy comes from the edge of gill arch → upstream, relative to water flow, towards the head of the fish then to the rest of the circulation. Water and blood flow in opposite directions
Describe cross current (counter and concurrent) exchange in bird respiratory systems?
- Air Sacs are air storage areas ensure unidirectional flow of air through parabronchi (the main site of gas exchange) because the air doesn’t need to be exhaled for the gas exchange to occur
- Birds inhale by expanding their rib cage and exhale by compressing their rib cage
- Very efficient system, needs to be because of the massive oxygen demand of flight, and the low oxygen supply at high altitudes
Note: Tarzan couldn’t breathe through a reed because of the long area of dead space added to breathing. That tube is hard to pass clean fresh air through and remove old air from. This means in swans with long ass necks (kinky) have to work harder to pump the air through that.
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Describe Respiratory Evaporative Water Loss:
- Gas exchange between environment and tissues must occur in MOIST membranes because the oxygen must first be dissolved before going through tissues. Thus when you inhale, the air from environment is originally not as humid as it will be in your lungs.
- Air comes in, is warmed and water must be evaporated into the air to humidify it. When we breathe it back out we can recoup a portion of the water but some of it is lost
- You would lose less water in humid jungles, lose more in cool deserts.
What are the two types of nephrons in the mammalian kidney?
- Juxtamedullary: Nephron is found mostly in the cortical section but is partially juxtaposed into the medullary section as well. Juxtamedullary nephrons (15% of nephrons) concentrate and dilute urine
- Cortical: Nephron is found entirely within the cortex/cortical area. Cortical nephrons (85% of all nephrons) mainly perform excretory and regulatory functions
What is the process of glucose and amino acid intake?
- Very similar to carb absorption in intestine
1. An Na/K ATPase pumps K from peritubular fluid (between baso mem and capillary) to inside the basolateral membrane, and Na oppositely. Consumes ATP but creates a diffusion gradient
2. Since the basolateral membrane Na conc. is now low, the cotransporter SGLT2 facilitates the diffusion of Na into the baso mem from tubular fluid (from high to low) and also draws in glucose with it.
3. Now glucose conc. is high in baso mem. but low in capillary so the GLUT2 complex pumps the glucose into capillary (high to low)
Describe blood pH regulation
- Carbon dioxide is exchanged from tissues into the blood
- Carbonic anhydrase (CA) combines CO2 with water to form HCO3 + H
- The H+ ion is pumped out of cell by a Proton ATPase pump, into tubular lumen
- The HCO3 is pumped into the blood by a Cl-antiporter, Cl enters the cell from the blood as the exchange
- Na is pumped from tubular lumen into cell,
- Lumen is now acidified and positively charged, enhancing the electrochemical gradient for Na into the cell
- To decrease the CO2 levels we can either expire more CO2 (shift right) or the kidney can filter out H ions, and reabsorb the HCO3. Less H+ means equation shifts left, returns to equilibrium
Note: This equation is at equilibrium, meaning that the conc. of both sides is equal at all times. The ratio is 1:1<–>1:1, but say CO2 is at higher levels (0.8:0.2) it shifts the equation to the other side, leading to increased conc. of both products on the other side
How does urine help buffer H+ and regulate pH?
- Nitrogenous waste products are filtered from the blood and excreted into urine
- The H+ ions from either the bicarbonate (in blood-pH reg.) or from the breakdown of NH4 –> NH3 + H, are pumped into the urine.
- To avoid the urine pH getting to acidic due to influx of H+ ions, the ions combine with NH3 or HOP2 in the urine, which buffers them and reduces their impact on the pH level
Note: If pH < 4.5 the H+ ATPase pump won’t work, that’s why the pH balance is important.
How does vasopressin regulate blood pressure?
- Regulation of BP is intimately intertwined with the kidney
1. Osmoreceptors in the hypothalamus detect high plasma osmolarity (High electrolye, low water) OR stretch receptors & baroreceptors detect low BP
2. These factors stimulate vasopressin (aka ADH) which increases the water reabsorption
of the collecting duct by
increasing number of
aquaporins (holes), this concentrates the urine - Retaining more water and excreting more ions increases your blood pressure and lowers plasma osmolarity
How does vasopressin stimulate the formation of aquaporins?
What is the process of the Renin-Angiotensin-Aldosterone blood pressure regulation?
- Renin secreted from juxtaglomerular cells when blood pressure or glomerular filtration rate (GFR) lower than normal
- Renin converts angiotensinogen (-gen means precursor and inactive form) to angiotensin I
- Angiotensin converting enzyme (ACE) on epithelia of blood vessels converts angiotensin I to angiotensin II
- Angiotensin II causes synthesis and release of aldosterone from adrenal cortex
- Aldosterone stimulates Na+ and water reabsorption from filtrate and enhances K+ excretion
What is the difference between direct current (DC) and alternating current (AC)?
- Direct current (DC) there is a continuous flow of charge from the cathode (-) to the anode (+)
- In alternating current (AC) the flow moves in one direction and slows down at some point and then turns back around
e.g action potentials
Note: Some biological phenomena behave like DC currents. e.g. Blood pressure (acts LIKE a DC current – flow of fluid, not charge)
What is the equation for the work required to move ions across a chemical gradient?
What is the equation for the work required to move ions across an electrical gradient?
What is the Nernst Equation
What is the Goldmans Equation
Describe compound action potentials
CAP is the SUMMED action potentials from many individual nerve cells
When the motoneuron discharges one action potential, it makes all its muscle fibres fire. When you record this activity from the muscle, you are recording superimposed action potentials (summed APs) of all muscle fibres firing simultaneously. The recorded activity is the “compound action potential”.
How does ion channel refractory behaviour makes AP propagation
unidirectional from site of
initiation?
- Imagine a transect down the neuron, and you’re looking at Na channels along the way. There is a net influx of sodium and the hodgkin cycle going strong. The channels beyond the first are still closed because their microenvironment has not become depolarised to the threshold. However with the influx of Na diffusing away down the membrane, the wave will cause depolarisation at site #2 which allows it to begin firing and starting its hodgkin cycle.
- Now the original channel which is now UPSTREAM has begun its refractory period. So even though now there is an influx of positive current into the cytosol and along the membrane in both directions, upstream and downstream. The downstream is ready to go, it is able to respond to the depolarisation whereas upstream they are not ready for that signal yet, thus the depolarisation proceeds unidirectionally downstream.
- This process repeats and makes up the action potential
What are the steps of saltatory conduction?
- An action potential is generated
- Na+ enters the axon and spreads toward the next node
- Elevation of intracellular [Na+] depolarizes the membrane at the next node causing voltage-gated Na+ channels to open there (AP).
- APs “jump” or “leap” from node to node – hence, ‘saltatory’ conduction
Describe electrical synapses
https://www.youtube.com/watch?v=pKgHV0b7ZHYNote
How do electrical synapses work?
What are rectifying electrical synapses?
Why do graded potentials travel short distances?
Explain a fast chemical synapse (4 steps)
- Presynaptic axon terminal at rest separated by synaptic cleft. All ligand channels are closed and not bound. Vesicles closed.
- Action potential arrives, vesicles fuse with terminal membrane, depolarization occurs. Voltage-gated sodium at nodes of Ranvier opens alongside potassium channels. Free intracellular Ca is low at this point → causing brief rise in intracellular Ca levels due to external influx.
- The transmitter binds to postsynaptic receptor proteins. Ligand-gated and ion channels open on the postsynaptic membrane to allow transmission. (this must happen fast or else ligand-gated channels will keep opening → hyperpolarization)
- The transmitter removed from cleft, fused membrane recycled.
What is the antagonist of the neuroreceptor acetylcholine (ACh) and how does it work?
Nicotinic synapse:
ACh OR Nicotine bind to Nicotinic-ACh receptors causing the gate to open and then subsequent depolarization of the postsynaptic membrane. The gate closes after the influx of potassium and sodium. If there is no ACh or Nicotine on the channel, it will remain closed.
Explain reverse potential
When current Ix for one ion is equal and opposite to the other
Erev = (½) (Ex+Ey)
What are the 4 functional neural zone
- Signal recognition (dendrites, change membrane potential)
- Signal integration (axon hillock, signal converts to AP)
- Signal conduction (Axon, where AP travels down the axon)
- Signal transmission (Axon terminals, release of electrical synapse)
Acronym
Racist Individuals Cause Turmoil
Explain spatial summation
What is the organization of the skeletal muscle
Tendon connects muscle to bone. Muscle cells are multinucleated. Myofibril is where the change in length occurs (where the actin and myosin are)
Explain the structure of the sarcomere
- Made of thick and thin filaments (actin and myosin/troponin). Each thick filament reacts with 6 thin, each thin reacts with 2 thick.
- From z-z line
- I band has no thick filaments, gets shorter in compression
- A band cannot shorten
- H zone is region where thin exists without thick, shortens in compression
Explain the process of Ca+ release from the sarcoplasmic reticulum (6 steps)
- Depolarisation (along t-tubule) causes conformational change in DHP-R receptor (very brief), thus Ca release increases dramatically
- Increased free calcium results in more being bound to troponin. With more Ca2+ bound there is a conformational change and troponin interacts with tropomyosin to move it from its resting position next to actin which was blocking access to myosin-binding site
- Myosin is now free to bind to actin, initiating cycles of cross-bridge formation release
- As soon as there is an increase in free calcium, there is an increase in Ca-ATPase pump activity
- Increased Ca-ATPase pumping lowers free calcium levels, resulting in less Ca being bound to troponin - this results in conformational changes that lead to tropomyosin moving back into place blocking access to the myosin binding sites on actin
- Once the myosin binding site is blocked, the cycle of cross-bridge formation-release occurs
https://www.youtube.com/watch?v=4ihWJ0TKn-g
What is the process of smooth muscle contraction?
