Biol 3350 Lecture 24 - 30 Study Guide

Flashcards covering the key concepts from lectures 24 to 30 in the Biology 3350 course.

Respiratory system structures in mammals

Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli; alveoli are main gas exchange sites.

Avian respiratory system

Rigid lungs with parabronchi and air capillaries plus air sacs enabling one-way airflow.

Gills structure

Filaments and lamellae with large surface area for gas exchange in water.

Internal vs external respiration

External respiration = gas exchange with the environment; Internal respiration = exchange between blood and tissues.

Ram ventilation

A swimming animal holds its mouth open and 'rams' water through its gills by swimming forward.

Buccal pumping

Opening and closing mouth/gills to keep water moving; whole body movement not necessary.

Continuous breathing

Constant ventilation.

Intermittent breathing

Pauses between breaths.

Gas exchange across skin

Occurs in amphibians and some invertebrates due to thin, moist skin.

Countercurrent exchange

much better than concurrent exchange, which is why gills have blood flow in the opposite direction that water passes through

Cross-current exchange

Air and blood flow perpendicular to each other, high efficiency in birds.

HIF-1

Activated in low oxygen levels, increases genes for red blood cell production and glycolysis.

Responses to low oxygen in humans

Increased breathing, heart rate, and hemoglobin.

Evolutionary changes in high-altitude hypoxia

Higher hemoglobin affinity and increased lung capacity.

Adaptations in diving mammals

Store oxygen in myoglobin, reduce heart rate, tolerate carbon dioxide.

Blood vessels sizes from arteries to veins

Arteries → arterioles → capillaries → venules → veins.

Blood pressure in vessels

Highest in arteries, lowest in veins.

Function of microcirculatory beds

Exchange nutrients, gases, and wastes.

Blood movement through the mammalian heart

Deoxygenated: Body → vena cava → right atrium → tricuspid valve → right ventricle → pulmonary artery → lungs. Oxygenated: Lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aorta → body.

Open circulatory system

blood can be transported in vessels but directly bathes tissues (some invertebrates)

Closed circulatory system

Blood is contained within vessels; high pressure, more efficient, better control.

Systolic pressure

Pressure during heart contraction.

Diastolic pressure

Pressure during heart relaxation.

Osmotic regulation

Organisms actively maintain a constant internal osmolarity regardless of the environment.

Osmotic conformity

Internal osmolarity matches the environment; little energy required.

Metabolic water? How is water lost during metabolism?

Water produced during cellular respiration. Water is lost through processes like exhalation, urine, sweat, and feces during waste removal and temperature regulation.

Effects of dehydration on blood plasma volume

Decreases.

Osmotic U/P ratios

Interpreting iso-, hypo-, and hyperosmotic urine relative to plasma.

ADH (Antidiuretic hormone) function

Binds to receptors in kidney cells and triggers increase in aquaporin in the kidneys

Aldosterone function

Increases sodium reabsorption and potassium excretion in kidneys, triggering water retention.

Structure of the mammalian kidney

Cortex, inner medulla, outer medulla, nephrons, renal pelvis, ureters.

Functions of nephrons

Filtration, reabsorption, and secretion to form urine.

Proximal convoluted tubule (PCT)

Main site of reabsorption of water, glucose, amino acids, and ions.

Distal convoluted tubule (DCT)

Fine-tunes ion balance and pH, adjusting reabsorption based on hormones.

Countercurrent multiplication

Mechanism in the loop of Henle creating osmotic gradients.

Differences in nephron structure across vertebrates

Variation mainly in the length of the loop of Henle; mammals and birds have longer loops for better water reabsorption.

Crustacean urine formation

Filtration occurs in green glands; waste excreted as dilute urine.

Insect urine production

Produced by Malpighian tubules, primarily excreting uric acid.

Why do animals produce ammonia and urea?

Ammonia is toxic but easy to produce; urea is a less toxic form for safer transport and excretion.

Ammonotelic animals

Mostly aquatic animals (e.g., fish) that easily dilute ammonia in water.

Ureotelic animals

Mostly terrestrial vertebrates (mammals, adult amphibians) that need to conserve water.

Lung structure in amphibians and reptiles

Amphibians: simple sac-like lungs

Reptiles: more compartmentalized with greater surface area.

Residual volume in the lungs

Air remaining after exhalation prevents lung collapse.

Functional differences between arteries, veins, and capillaries

Arteries carry away, veins return, capillaries exchange

Know the function of the coronary arteries and general taxa differences in how the myocardium is supplied with oxygenated blood.

Supply heart muscle with oxygenated blood.

Know the main fluids in the body (interstitial fluid, blood plasma, cytoplasm), and the difference between intracellular and extracellular fluids.

ICF = inside (cytoplasm) | ECF = outside (interstitial + plasma)

How do changes in osmotic pressure affect cell volume? How can cells counteract these changes in osmotic pressure?

Osmotic pressure changes cell volume by causing water to move in (swelling in hypotonic) or out (shrinking in hypertonic). Cells counter this by adjusting solutes with ion pumps and other osmoregulation mechanisms to control water movement

Understand how to interpret osmotic U/P ratios and the difference between isomotic, hyposmotic, and hyperosmotic urine (relative to the plasma).

Hyper = higher concentration (saving water)

Hypo = lower concentration (losing water)

Iso = same

How does osmotic pressure in the blood compare to the surrounding water in freshwater and saltwater living animals? How are they adapted to deal with these conditions?

Freshwater aquatic animals

Blood is more concentrated (hyperosmotic) than surrounding water, so water enters the body; they adapt by excreting lots of dilute urine and actively taking up salts through gills/skin

How does osmotic pressure in the blood compare to the surrounding water in freshwater and saltwater living animals? How are they adapted to deal with these conditions?

Ocean invertebrates

Often isosmotic (osmoconformers) with seawater, so little net water movement; they adapt by tolerating high internal salt levels with minimal osmoregulation.

How does osmotic pressure in the blood compare to the surrounding water in freshwater and saltwater living animals? How are they adapted to deal with these conditions?

Ocean fish

Blood is less concentrated (hyposmotic) than seawater, so they lose water; they adapt by drinking seawater, excreting excess salts through gills, and producing small amounts of concentrated urine

What are some ways that fish that migrate between freshwater and saltwater adjust to deal with their new environment?

Adjust by reversing osmoregulatory mechanisms, such as changing ion transport in their gills, altering kidney function, and adjusting how much water they drink or excrete to maintain salt and water balance in each environment.

What is anhydrobiosis? In what type of environments is it expected to evolve?

survival in a dried state; evolves in species that live in places with

temporary/fluctuating water

How is the integument of terrestrial animals altered to deal with water loss?

Terrestrial animals reduce water loss through integumental adaptations like thick, keratinized skin (reptiles, mammals), waxy or lipid-rich layers, and waterproof coverings such as scales, feathers, or fur, which all help limit evaporation and conserve body water.

How HIF-1 is made

2 subunits, α and β subunits

Adaptations in human populations

increased lung capacity

• More capillaries supplying tissues, positive selection on HIF related genes (Tibetan highlanders)

• Higher RBC volume in the blood (Andean highlanders)

• Higher RBC volume can have costs- increased clotting/blockages

Adaptations seen in other animals

increase in O2 affinity of hemoglobin . Tibetan antelope retains fetal form of hemoglobin as an

adult!

Diving mammals

conserve O2 to heart and brain. Use little metabolism by gliding, delaying digestion. Allow lungs to compress at deep deaths – avoid buoyancy and decompression sickness.

Towards the heart

vena cava, veins, venule, capillary

Away from the heart

Aorta, artery, arteriole, capillary

What is in between an arteriole and a venule

Network of capillaries (capillary bed)

Teleost has how many chambers?

2

Turtle has how many chambers?

3

Frog has how many chambers?

3

Mammal has how many chambers?

4

Bird has how many chambers?

4

myocardium

heart muscle

Coronary arteries branch off aorta (carrying oxygenated blood) and deliver

oxygenated blood to heart muscle ASAP

Spongy myocardium

blood from the heart lumen bathes the myocardium to deliver O2

Closed circulatory system

blood stays in blood vessels (all vertebrates)

Vasoconstriction

increases blood pressure

Vasodilation

decreases blood pressure

Interstitial fluids

fluids found between cells in tissues

Extracellular fluids

Blood plasma (liquid part of the blood aside from red/white blood cells)

Aldosterone is a

mineralocorticoids (steroid hormone), produced in the adrenal cortex

More aldosterone

more sodium retention, therefore increased water retention to balance osmotic pressure. Ultimately increases blood pressure.

Low blood pressure triggers the

renin-angiotensin-aldosterone system (RAAS)

Renin (enzyme) production in kidneys increases →

angiotensin (peptide hormone) & aldosterone (steroid hormone) secretion increases

Aldosterone increases

Na+ retention, and fluid retention

Activates sodium-potassium pumps, also increases

permeability via sodium channels, more sodium reabsorbed

RAAS system corrects for drops in blood pressure, but too much

hypertension

Angiotensin converting enzyme (ACE) converts to

angiotensin II

Angiotensin II triggers

aldosterone release from adrenals

Aldosterone increases sodium reabsorption in the kidneys

increasing osmotic pressure of the blood

Nephrons

• Blood flows into the glomerulus

(ball of capillaries)

• Blood plasma filtered through

Bowman’s capsule, podocyte

cells

• This fluid is called filtrate

• Larger molecules or cells are too

big to pass in – no rbc or wbc, no

large proteins

• Passes through loop of Henle

and then to collecting ducts →

ureters → bladder

High osmotic pressure in inner medulla draws water out via

osmosis

In molluscs filtrate is from the

pericardial cavity! 1 or 2 kidneys/renal sacs

Insects can produce concentrated urine, because of

high water reabsorption through the rectal pads

Terrestrial animals

Rarely ammonotelic because water is required to keep up with removing the ammonia. They tend to be ureotelic.

• Urea requires less water to remove and can be kept at higher concentrations (lower toxicity than ammonia)

• Ammonia can be converted into urea via enzymes but it is a little bit costly. 4-5 ATP per urea molecule formed.

Gas exchange occurs in

alveoli, function is to increase the surface area where diffusion occurs

Diaphragm drives expansion

of the lungs

Central pattern generator for breathing in humans

in brain stem (pre-Botzinger complex)

Actual gas exchange happens in

air capillaries that branch from bronchi

Amphibians and reptiles have simple lungs

often unicameral (one chamber)

Amphibians use pressure from raising floor of

buccal cavity to push air into lungs

Gas exchange in across skin most extreme in

amphibians

• BUT not only amphibians

The amount that we breathe in and out is called the _____ and this is not the entire capacity of the lungs

tidal volume

Hypoxia-inducible factors (HIFs)

transcription factors

Kidney Cortex

Outer region of the kidney; contains glomeruli and parts of nephrons where filtration of blood begins.

Kidney Inner medulla

Middle layer containing loops of Henle and collecting ducts; helps create osmotic gradients for water and salt