Animal Physiology Final Exam

Fall 2025

best predictor of animal physiology

size

Genotype +_______ = phenotype

environment

What’s Cheaper, regulation or conformity?

Conformity

Unidirectional Flow

highly efficient lungs where “air” moves in one continuous direction, allowing for continuous gas exchange and higher oxygen uptake

Unidirectional Flow in Birds

using air sacs to move air through looped airways (parabronchi) in a single direction, maximizing oxygen extraction

Unidirectional flow in Lizards/Iguanas

lungs that have interconnected chambers (brachial tubes) for continuous airflow.

Unidirectional Flow in Fish

the one-way movement of water through their gills

Countercurrent Exchange

Maintains a constant gradient for heat or O₂ transfer, good for keeping extremities warm

Concurrent exchange typically allows how much transfer?

80/20

What alternative respiratory surfaces do some fish use

Gills, skin, buccal cavity, intestine, and swim bladder

What does a low P50 mean?

High oxygen affinity, better binding

What does high P50 mean?

Easier Oxygen unloading (low oxygen affinity)

What type of circulatory system do mammals have

Closed system with heart

Who has open circulatory systems

Insects (low pressure, high blood volume)

Arteries

Arteries carry blood away heart

Veins

veins carry blood to heart.

What adaptation helps animals at high altitudes

Lower P50 → higher O₂ affinity

What macromolecule has the most energy per gram?

Lipids

What increases metabolic rate?

Reproduction, digestion

What decreases metabolic rate

Hibernation, estivation (summer sleep)

What is the thermal neutral zone

Range where metabolic rate is minimal for thermoregulation. Lower than body temperature

How does body size affect metabolism

Smaller animals: higher mass-specific MR. Larger animals: higher overall MR.

Endotherm

Endotherms = mammals, birds.

Ectotherms

reptiles, amphibians, most fish.

Homeotherm definition

maintains constant internal temperature

Poikilotherm

an animal that cannot regulate its body temperature except by behavioral means such as basking or burrowing.

Poikilotherm example

Desert animals such as kangaroo rats

Why does water feel colder than air?

Conducts heat better than air.

What is a brain-cooling adaptation in dogs

Carotid rete (countercurrent heat exchange), they pant (advantage over rabbits)

Temperature specific sex determination

form of environmental sex determination in which the incubation temperature during a critical period of embryonic development, known as the thermosensitive period (TSP), determines the sex of the offspring (found in turtles, lizards, etc.)

What kidney adaptation helps desert animals retain water

Very long loops of Henle → highly concentrated urine.

Why are Antarctic fish considered “homeothermic”

Environment is constantly near freezing.

Osmoregulation

regulates everything, total solute concentration

Ionoregulation

Regulation of specific ions (e.g., Na⁺, Cl⁻, K⁺).

What muscle type supports long-distance migration?

Slow-twitch (red, high myoglobin)

What muscle type do sprinters use

Fast-twitch (white)

What type of feedback controls most hormone levels?

Negative feedback

What hormone signals nighttime

melatonin

What does progesterone do during pregnancy (think birth control)

Supports estrogen and maintains pregnancy

Thyroid hormone function?

Regulates metabolic rate and body temperature.

What cells support sperm development

Sertoli cells

What cells produce testosterone?

Leydig cells

Birds have how many ovaries?

One functional ovary (usually left).

Which animals have two hemipenes?

Snakes, lizards, sharks.

What species show temperature-dependent sex determination?

Many reptiles.

How do stronger stimuli affect neurons?

Increase frequency of action potentials.

Why are vertebrate neurons fast?

Myelination (insulation).

Where are graded potentials measured?

Dendrites and the cell body.

Cockroach nervous system type?

Polysynaptic

What animals have giant axons

Many invertebrates (e.g., squid).

What structures sense rotational balance in vertebrates

Semicircular canals.

Semicircular canals evolved from what?

lateral line

Sperm from what type of cells

Stroli

Testosterone from what type of cells

ladig

Why do Birds have one ovary

to reduce body weight for efficient flight

What is the lateral line system for?

Detecting water movement; analogous to vestibular system.

What provides more energy PER GRAM: sugars or fats?

fats (lipids)

Olfaction

airborne smell

Accessory olfaction

VNO = pheromones

What is the vomeronasal organ used for?

Detecting pheromonal cues.

What does a cup eye detect?

Light only; no image.

What is the limitation of a pinhole eye?

Dim image; needs lots of light.

Example of sensory arms race?

Bats' echolocation vs moths' anti-detection adaptations.

Do diving animals have specialized hemoglobin for oxygen storage?

No. Diving animals do not have special hemoglobin; they rely on myoglobin, lung volume, and blood volume instead.

How is circulation organized in birds

Birds have separate pulmonary and systemic circulatory systems, allowing efficient oxygen delivery.

Which animal shows a stronger Bohr shift: vole or capybara?

Vole — small mammals have a stronger Bohr shift to enhance oxygen unloading in active tissues.

Bohr Shift

shift in the oxygen dissociation curve caused by changes in the concentration of carbon dioxide or the pH of the environment.

What does a strong Bohr shift indicate?

Greater hemoglobin sensitivity to pH and CO₂, improving oxygen release during high metabolism.

How does the nervous system evolve over time?

Evolution adds new structures onto existing ones; older systems are not replaced.

What effect do organic phosphates (e.g., 2,3-BPG) have on hemoglobin?

They shift the oxygen dissociation curve right, decreasing oxygen affinity (↑ P50).

What does a rightward shift in P50 mean physiologically?

Hemoglobin releases oxygen more easily to tissues

Do camels undergo estivation?

No. Camels tolerate heat and dehydration but do not estivate.

How does whole-body metabolic rate relate to animal size?

Whole-body metabolic rate positively correlates with size — larger animals have higher total metabolism.

How does mass-specific metabolic rate relate to size?

Mass-specific metabolic rate is higher in smaller animals, despite lower total metabolism.