Animal Physiology Exam #2 Flashcards

Active recall for Lecture 5-9 notes. Active testing topics such as Ohms Law, Digestion, etc. can be found in the study guide/notes.

Why must animals constantly eat even if they aren't growing, and why aren't biological molecules broken down into basic atoms (like C, H, O) during digestion?

1. Individual molecules deteriorate and cells need replacement.

2. Animals need the specific chemical-bond energy and molecular building blocks found in amino acids/monosaccharides to rebuild their own tissues.

What is the specific chemical process used to break bonds in carbohydrates, proteins, and lipids, and what molecule must be added to the reaction?

Hydrolysis; requires the addition of Water (H2O).

Out of the 20–22 amino acids, how many are "essential," and what does that classification imply about the body's storage capacity?

10 are essential; they cannot be stored in the body and must be consumed daily.

Briefly describe the gut region and its specific chemical environment:

1. Foregut/Stomach

2. Midgut/Duodenum

3. Accessory (Pancreas)

1. Stomach: Acidic (HCl/Pepsin).

2. Duodenum: Neutral/Alkaline (Chemical digestion/absorption).

3. Pancreas: Bicarbonate (Neutralizes acid) and enzymes.

Which specific region of the vertebrate gut is known as the "workhorse" for chemical digestion and nutrient absorption?

The Midgut (Small Intestine/Duodenum).

Distinguish between Digestive Enzymes and Hormones based on their "Location of Secretion."

Enzymes are secreted into the Lumen (exocrine) to catalyze hydrolysis.

Hormones are secreted into the Bloodstream (endocrine) to act as messengers.

Contrast the pH requirements of Pepsin vs. Trypsin and explain the transition between them.

Pepsin (Stomach) = pH 3; Trypsin (Small Intestine) = pH 8.

The transition is managed by Bicarbonate from the Pancreas neutralizing the stomach acid.

Name the three phases of digestion and their primary neural/hormonal trigger.

1. Cephalic: Sight/Smell (Vagus Nerve).

2. Gastric: Stretch/Protein in stomach (Gastrin).

3. Intestinal: Acidic chyme in duodenum (Secretin/CCK/GIP).

What two physical/chemical triggers in the stomach cause the release of Gastrin, and what does Gastrin then stimulate?

Triggered by stomach distension (stretch) and the presence of protein; stimulates the release of HCl and Pepsinogen.

When acidic chyme enters the duodenum, which two hormones are released, and what are their targets?

1. Secretin: Stimulates Pancreas to release Bicarbonate.

2. CCK: Stimulates Pancreas (enzymes) and Gallbladder (bile).

What is the role of GIP (Gastric Inhibitory Peptide) during the intestinal phase?

It inhibits gastric motility and secretions (slowing down the stomach) to allow the small intestine time to process the food.

Why are HCl and Pepsin stored as inactive precursors (Pepsinogen), and what prevents them from digesting the stomach wall itself?

They are stored as Proenzymes to prevent "autodigestion" (digesting the cells that make them). The Mucus layer and bicarbonate protect the stomach lining.

What are the two primary substances the Pancreas secretes into the duodenum to facilitate digestion?

1. Digestive Enzymes (Proteases, Lipases, etc.).

2. Bicarbonate (to neutralize stomach acid).

Identify the cell types in the Pancreas that secrete Insulin vs. Glucagon.

Beta Cells = Insulin; Alpha Cells = Glucagon.

What is the normal resting blood glucose range for a human, and at what level do "hypoglycemic" symptoms (confusion/dizziness) typically begin?

Normal: 80–100 mg/100 mL; Symptoms begin below 50 mg/100 mL.

Name the three specific enzymes insulin regulates in the liver to lower blood sugar.

1. Activates Glucokinase (traps glucose/sugar via phosphorylation so it cannot leak back out of the cell).

2. Activates Glycogen Synthetase (stores glucose/sugar).

3. Inhibits Glycogen Phosphorylase (prevents breakdown/sugar release).

Where is Bile produced, where is it stored, and what is its mechanical function?

Produced in the Liver; stored in the Gallbladder; its function is to emulsify lipids (break fat into smaller droplets for enzymes).

Compare Urea and Uric Acid in terms of "Cost to Produce" and "Solubility."

Urea: Medium energy cost, High solubility (requires water to flush).

Uric Acid: High energy cost, Low solubility (saves maximum water).

If a marine fish produces very little urine to save water, how does it get rid of its nitrogenous waste?

It excretes ammonia directly across the Gills via diffusion.

Why is Uric Acid the only viable option for a bird embryo in a hard-shell egg?

Uric acid is insoluble and precipitates as a solid. If the embryo produced Urea, it would dissolve in the egg's water and reach toxic/osmotic levels that would kill the embryo.

Why is Ammonia (NH_3) so dangerous to the body? (Name 3 reasons).

1. Raises pH (Alkalosis).

2. Disrupts membrane potentials.

3. Causes brain swelling and convulsions.

Describe the "Plasticity" of a Python's gut after a meal.

The gut mass doubles or triples in size within 24 hours of eating to handle the massive influx of nutrients, then shrinks back down to save energy during fasting.

Distinguish between BMR and SMR.

BMR (Basal): Endotherms (at rest, fasting, in thermoneutral zone).

SMR (Standard): Ectotherms (at rest, fasting, at a specified temperature).

Define SDA and explain why your metabolic rate rises after eating a large steak.

SDA is the "tax" or energy cost of processing food (digestion, absorption, storage). High protein meals typically have a higher SDA.

Define the 4 heat exchange mechanisms and identify which one is the "Emergency Exit" for heat.

1. Conduction (Contact).

2. Convection (Fluid movement).

3. Radiation (EM waves).

4. Evaporation (Emergency exit; 1g H2O = 585 cal lost).

What is the typical Q10 for physiological processes, and what happens to enzymes at extreme high temperatures?

Q10 is usually 2–3. High temps denature proteins/enzymes and can reduce hemoglobin's affinity for oxygen.

How do animals adjust their membrane lipids to maintain fluidity in the cold vs. the heat?

Cold: Increase unsaturated fats (to prevent freezing/stiffening).

Warm: Increase saturated fats (to prevent melting/excess fluidity).

Is a fever a failure of thermoregulation? Explain the role of the Thalamus/Hypothalamus.

No; it is a regulated resetting of the set-point via pyrogens. The hypothalamus (thermostat) decides a higher temperature is the "new normal" to fight infection.

Name the 3 determinants of the rate of heat transfer.

1. Surface Area.

2. Temperature Gradient.

3. Specific Heat Conductance (Insulation like fur/blubber).

Which part of the neuron is the "Trigger Zone" and which part typically lacks voltage-sensitive ion channels?

Axon Hillock is the trigger zone. Dendrites generally lack voltage-sensitive channels (they receive graded signals).

In a biological membrane, what represents Resistance, Capacitance, and Current?

Resistance: Permeability via Ion channels, resistance decreases by opening more channels.

Capacitance: The Lipid bilayer, which stores and separates electrical charge.

Current: Movement of ions.

Define Resting Potential and identify the 3 specific properties that establish it.

When would you use the Nernst Equation vs. the Goldman (GHK) Equation?

Nernst: Calculate equilibrium for one specific ion.

Goldman: Calculate actual membrane potential (V_m) by accounting for all permeable ions (Na, K, Cl).

Why does a 30g mouse have a higher "Mass-Specific" metabolic rate than a 400,000kg whale?

Surface Area to Volume Ratio: Smaller animals have more surface area relative to their volume, causing faster heat loss and requiring a higher metabolic "burn" per gram of tissue to maintain temperature.

What was the mathematical error in the "LSD and the Elephant" study?

Researchers used Linear Scaling (assuming the dose scales 1:1 with weight) instead of Allometric Scaling. They ignored that metabolic processes and drug clearance rates do not increase linearly with body size.

If an animal’s RQ is 0.7 vs. 1.0, what does this tell you about their fuel source?

0.7 = Lipids/Fats; 1.0 = Carbohydrates. (0.83 is protein).

Define the "Critical Partial Pressure" (P_c) in an Oxyregulator.

The environmental O_2 level below which an animal can no longer maintain a constant metabolic rate and begins to "conform" (MR drops).

Why is a 20°C (68°F) room comfortable for a human, but 20°C water feels dangerously cold?

Water has a much higher Thermal Conductivity than air, meaning it pulls heat away from the body via Convection/Conduction significantly faster.

How does a fish in the Arctic adjust its cell membranes compared to a fish in the Tropics?

The Arctic fish increases Unsaturated Fatty Acids (double bonds) to keep membranes fluid at low temps; the Tropical fish has more Saturated Fatty Acids to keep them from becoming too liquid.

What is the specific role of UCP1 (Thermogenin) in Brown Adipose Tissue (BAT)?

It uncouples the mitochondria, allowing protons to leak across the membrane to generate Heat instead of ATP.

How does a Tuna maintain a warm core in cold water?

Using the Rete Mirabile (Countercurrent Heat Exchange), where warm venous blood from the muscles transfers heat to cold arterial blood coming from the gills.

Distinguish between Colligative and Non-colligative antifreeze.

Works by high concentration of solutes (Glycerol). Non-colligative: Specific proteins (AFPs) bind to ice crystals to stop them from growing.

How do wood frogs survive freezing without dying?

They are Freeze Tolerant; they allow ice to form in the Extracellular Fluid but protect the inside of the cell (ICF) using high concentrations of glucose/urea.

In evolutionary physiology, what is a "Spandrel"?

A phenotypic trait that is a byproduct of evolution/structure rather than a direct adaptation for a specific function.

Why is the Na+/K+ ATPase pump called "Electrogenic"?

Because it pumps out 3 Na+ for every 2 K+ it brings in, resulting in a net loss of positive charge from the cell (contributing to the negative V_rest).

What determines the "Driving Force" on a specific ion?

The difference between the actual Membrane Potential (V_m) and that ion’s Equilibrium Potential (E_ion).

Is V_rest a true equilibrium? Why or why not?

No, it is a Steady State. It requires a constant input of energy (ATP) to maintain the concentration gradients.

At rest, is the membrane more permeable to Sodium or Potassium? How do we know?

Potassium (K+). We know because V_rest (-70mV) is much closer to E_K (-90mV) than to E_Na (+60mV).

If a Maine crab and a Bahamas crab have similar locomotion speeds, what is this an example of?

Acclimatization/Evolutionary Adaptation. The Maine crab has likely adjusted its enzyme isoforms or membrane fluidity to function optimally at lower temperatures.

How does ADH (Vasopressin) change the concentration of urine?

It increases the number of Aquaporins in the Collecting Duct, allowing more water to be reabsorbed into the body, making urine more concentrated.

Why does a Kangaroo Rat have a much longer Loop of Henle than a human?

A longer loop creates a larger concentration gradient in the medulla, allowing for maximum water reabsorption (essential for desert survival).

What is "Metabolic Depression" and when is it used?

A regulated reduction in MR to survival extreme stress (hypoxia, heat, drought) by shutting down expensive processes like protein synthesis.

What are the three factors that trigger Insulin release?

1. High blood glucose.

2. GI hormones (GIP).

3. Parasympathetic (Vagus) stimulation.

Where is the majority of glycogen stored in the body?

The Liver and Skeletal Muscle.

How is Trypsinogen converted into its active form, Trypsin?

By the enzyme Enterokinase, which is located on the brush border of the small intestine.

Does Bile chemically digest fats?

No. It mechanically emulsifies them (breaks them into small droplets) so that Lipase can chemically digest them.

How can cold-water fish maintain high activity levels?

By expressing different LDH (Lactate Dehydrogenase) isoforms that have higher substrate affinity at low temperatures.

What is the specific function of HSPs during thermal stress?

They act as Molecular Chaperones to help denatured proteins refold correctly.

Why are Respiration, Circulation, and Temperature Regulation interrelated in terrestrial endotherms? (Provide examples).

High T_b requires a high Metabolic Rate. This necessitates:

Respiration: To provide the increased O_2 required for aerobic ATP production.

Circulation: To rapidly deliver that O_2/fuel to tissues and move metabolic heat to the skin for dissipation or core for retention.

During exercise, breathing and heart rate increase simultaneously to support the biochemical demand for ATP.

Why doesn't the digestive system break down fragments into even smaller pieces (atoms) even though it would facilitate absorption?

The ATP cost to reassemble atoms into proteins/fats is higher than the energy gained from the food.

Contrast "Negative Feedback" in normal cooling vs. "Resetting the Set Point" during a fever.

Normal cooling: The body detects a deviation from 37°C and works to return to it. Fever: The Hypothalamus physically changes the goal to 39°C; the body then treats 37°C as "too cold" and shivers to reach the new target.

Why does an animal that excretes Urea require more water than one that excretes Uric Acid?

Urea is highly soluble and osmotically active. It "pulls" water with it into the urine to remain in solution, whereas Uric Acid precipitates as a solid, leaving the water behind to be reabsorbed.

Name the two primary ways evolution has increased the speed (conduction velocity) of action potentials.

1. Increasing Axon Diameter (Invertebrate strategy - reduces resistance).

2. Myelination (Vertebrate strategy - allows saltatory conduction/jumping).

If a diabetic cannot utilize glucose, how does the body generate ATP from fats and proteins?

Fats: Broken into Fatty Acids/Glycerol —> Beta Oxidation —> Acetyl CoA.

Proteins: Deaminated into Amino Acids —> Keto acids —> Enter Krebs Cycle at various stages.

What is the "Panglossian Paradigm"?

The faulty assumption that every biological trait is an optimal adaptation. It cautions scientists that some traits may be neutral byproducts of history or physics (Spandrels).

What is the difference between "Metabolic Depression" and "Hibernation/Torpor"?

Metabolic Depression is a general reduction in MR to survive extreme stress (like hypoxia).

Hibernation/Torpor is a specific, regulated drop in T_b and MR to save energy during seasonal cold or food scarcity.

Contrast the "Energy Budget" of an Ectotherm (e.g., Lizard) vs. an Endotherm (e.g., Mouse) of the same size.

The Endotherm spends ~90% of its energy just maintaining body temperature (high cost, high activity).

The Ectotherm spends very little on heat, allowing it to put more energy into growth and reproduction (low cost, limited activity).

Compare the "Invertebrate" vs. "Vertebrate" strategy for increasing conduction velocity. What is the disadvantage of the Invertebrate way?

Invertebrate: Increase Axon Diameter. Disadvantage: Takes up massive physical space (can only have a few "giant" axons).

Vertebrate: Myelination. Advantage: Allows for thousands of fast, small axons in a compact space.

Why is oxygen so important for cellular (internal) respiration, and at what specific steps is CO_2 made in the cells?

Oxygen: Acts as the final electron acceptor in the Electron Transport Chain (ETC). CO_2: Produced during the Transition Reaction (Pyruvate —> Acetyl CoA) and the Krebs Cycle.

Compare ATP yield and function of anaerobic vs. aerobic metabolism (include specific examples).

Anaerobic: Yields 2 ATP/glucose; fast but leads to fatigue. Used for sprints/bursts.

Aerobic: Yields ~36-38 ATP/glucose; slow but sustainable. Used for endurance/migration. Requires O_2 as the final electron acceptor in the ETC.

Give an example of how an animal’s exercise performance (behavior) is intimately linked to the biochemical mechanism making ATP.

Sprints/Bursts: Rely on Phosphagens and Anaerobic Glycolysis (Fast ATP, low yield, leads to fatigue). Endurance/Migration: Relies on Aerobic Catabolism (Slow ATP, high yield, sustainable).

Explain why respiration, circulation, and temperature regulation in terrestrial animals are closely interrelated.

High body temperature (T_b) requires a high Metabolic Rate (MR). To support high MR, the animal needs increased Oxygen (Respiration) and a rapid transport system (Circulation) to deliver fuel and remove waste/heat.

Explain how the anatomy (structure) of the Pancreas and Liver is suited to their specific functions.

Pancreas: Dual exocrine/endocrine structure; exocrine ducts lead directly to the duodenum to deliver bicarbonate/enzymes immediately where acidic chyme enters.

Liver: High surface area and direct blood connection (portal system) to process nutrients; gallbladder attachment allows for immediate release of bile to emulsify fats.

Contrast the efficiency of countercurrent vs. concurrent systems in physical transport.

Countercurrent: Fluids flow in opposite directions, maintaining a favorable concentration gradient across the entire length of the surface, allowing for near 100% transfer.

Concurrent: Fluids flow in the same direction and reach equilibrium (50/50) halfway, stopping all net transfer.

Sequential Feedback Control in Protein Digestion.

1. Cephalic/Gastric Phase: Vagus nerve and stomach stretch/protein trigger Gastrin.

2. Action: Gastrin stimulates HCl and Pepsinogen release.

3. Intestinal Phase: Acidic chyme in the duodenum triggers Secretin (bicarbonate) and CCK (enzymes).

4. Inhibition: GIP then slows gastric motility to prevent the small intestine from being overwhelmed.

Distinguish between ectotherms and endotherms using physiological, biochemical, and behavioral examples.

Endotherm (e.g., Mouse):
Physiological: Shivering/sweating.

Biochemical: UCP1 in Brown Fat (BAT) for heat; Behavioral: Seeking shade or huddling.

Ectotherm (e.g., Lizard):
Physiological: Changing skin color/blood flow.

Biochemical: Different LDH isoforms for cold; Behavioral: Basking in the sun.

Define Resting Potential and identify the 3 specific properties that establish it.

Active Transport: Na^+/K^+ ATPase pump (3 Na^+ out/2 K^+ in) creates an electrogenic deficit.

Selective Permeability: High $K^+$ leak through channels keeps V_m near the K^+ equilibrium potential (E_K).

Fixed Anions: Large, negatively charged proteins trapped inside the cell.