Animal Physiology Exam 3

Why isn’t diffusion alone sufficient for gas exchange?

Too slow, circulatory system is needed for bulk flow

Key fluids involved in O2 and CO2 transport

blood, hemoglobin, plasma

Key fluids involved in O2 and CO2 transport contain….

respiratory pigments

Two major goals of the circulatory system

Maximize O2 delivery to tissues, prevent CO2 buildup

CO2 build up causes…

imbalance in acid/base balance

First step of O2 transport

Ventilation, AKA breathing.

Step 2 of O2 transport

Diffusion, lungs take O2 from air and move to blood

Step 3 of O2 transport

Circulation- blood takes O2 to tissues

What allows tissues to be metabolically active?

Mitochondria which needs O2 to function

Step 4 of O2 transport

Diffusion happens again. O2 diffuses from tissues to mitochondria 

Function of respiratory pigment

increase blood O2 carrying capacity by 30-100x

Respiratory pigment used by mammals

hemoglobin- red, iron based

Respiratory pigment used by arthropods

hemocyanin- blue, copper based

respiratory pigment used by worms

hemorythrin- iron based, purple color

PO2 of the Hb Dissociation curve

how much O2 available in gas mixture or liquid

PO2 of an artery

95-100 mmHg

PO2 of veins

40mmHg

P50 in the Hb Dissociation Curve

PO2 when 50% of hemoglobin (Hb) is saturated 

Right shift on the Hb Dissociation Curve

lower affinity for O2 to bind to Hb

Right shift on the Hb Dissociation Curve can be caused by/happens with

increased temperatures, low pH

left shift on the Hb Dissociation Curve

higher affinity for O2 to bind to Hb

Bohr effect

hemoglobin's affinity for oxygen decreases as the concentration of carbon dioxide (𝐶𝑂2) and hydrogen ions (𝐻+) increases, leading to greater oxygen release in tissues that need it most

Less affinity for O2 to bind to Hb means…

more free O2 to get out into tissues

Key adaptation: High altitude effect on O2

increased affinity for O2, less O2 in air= need to hold onto more. Decreased P50 (left shifted dissociation curve)

Key adaptation: Diving mammals effect

increased levels of hemoglobin and myoglobin, larger blood volume (increase how much O2 they can take in by holding more blood)

What is myoglobin?

Where O2 is stored in muscles. Acts as O2 buffer and reserve

Myoglobin can ______ in extreme exercise to delay _____

myoglobin can release O2 in extreme exercise to delay anaerobiosis

anaerobiosis/anaerobic respiration

When oxygen supplies dwindle, some organs rely on anaerobic respiration, which is less efficient but provides energy without oxygen and produces lactic acid as a byproduct.

monomers with their own curve that bond very tightly to O2

myoglobin

Ectotherm O2 affinity

Temperature dependent, rising temp= lower O2 affinity, higher temp= more O2 released (lower affinity)

Hypoxic conditions can cause an increase production of…

Red blood cells and hemoglobin

Warm stagnant water fish have…

specialized gills with large exchange surfaces and diffusion barriers

7% of CO2…

dissolved into blood

23% of CO2….

Synthesized into carbamino compounds, amino groups that form proteins

70% of CO2…

converted into bicarbonate ions

CO2 to bicarbonate ions reaction

CO2 + water (carbonic anhydrase middle man) to H2CO3- (carbonic acid) to CO3 (bicarbonate) +1 H+

Bicarbonate ____ out of RBC in exchange for ___

Bicarbonate diffuses out of RBC in exchange for chloride (Cl-) to keep ± balance

Haldean effect 

Deoxygenated hemoglobin binds carbon dioxide more readily to aid in CO2 uptake at tissues with goal of taking it to lungs

O2 and CO2 transport are…

coupled. Ventilation, circulation and metabolism all interact

Comparative highlights: Fish

countercurrent exchange in gills

Comparative highlights: Birds

Cross current flow in peribronchi: air and blood flow at right angles which allow blood leaving lungs to pick up O2 (very efficient!)

Comparative highlight: Mammals

tidal ventilation in alveoli (breathing)

Comparative highlights: insects

tracheal system with direct diffusion

Some circulatory system functions (Other than CO2 and O2 transport)

Heat distribution, movement of immune cells, force filtration through kidneys

Types of circulatory systems

open and closed 

All circulatory systems rely on…

Pumps, a set of conduits (vessels) and fluid

Fluid in open circulatory systems

hemolymph

Open circulatory systems usually found in…

inverts: molluscs and arthropods 

Fluid in an open circulatory system is not ___ and has ____ pressure

not confined in vessels and has low to no pressure

Pros for an open circulatory system

Low energy expenditure, ideal for animals with low metabolic rates

Cons for open circulatory system

less control over distribution of fluid

Closed circulatory systems commonly found in …

vertebrates, annelids and cephalopods

Functions of a closed circulatory system

Keeps circulating fluid completely enclosed in vessels, allows heart to maintain/generate higher pressure

Pros of a closed circulatory system

efficient and fast delivery of fluid, essentials for animals with high or variable metabolic rates, allows heart to maintain/generate higher pressure

Invertebrates with closed circulatory systems

annelids

Intermediate circulatory systems

in between closed and open systems

Organisms with intermediate circulatory systems

cephalopods and insects 

Insect intermediate circulatory system

open but separate tracheal gas delivery system

Tracheal gas delivery system

air filled tubes throughout body deliver O2 directly. Fluid circulatory system just focuses on nutrient transport and pressure maintenance

Cephalopod intermediate circulatory system

very sophisticated and high pressure, 3 hearts, provides tight and precise control.

The cephalopod lifestyle requires….

Quick O2 delivery and metabolic waste clearance

Heart functions in cephalopods

2 brachial hearts: control arms, 1 systemic: controls entire body other than arms

Sophistication of circulatory systems is ______ to our ____ metabolic needs

Sophistication development is parallel to our increasing metabolic needs

Fish circulatory system: Representing the start of development

Simple, single circuit, 2 chambered heart (1 atrium, 1 ventricle), low systemic pressure

Why does the fish circulatory system have low systemic pressure? 

Gill capillaries are delicate and cannot handle high pressure

Amphibian circulatory system: representing more sophisticated

incomplete double circuit, 3 chambered heart (2 atria and 1 ventricle), some oxygenated/deoxygenated blood mixing occurs

What is the positive tradeoff that occurs with deoxygenated and oxygenated amphibian blood mixing?

tremendous body flexibility and the ability to shunt blood towards skin for gas exchange when diving

Reptile circulatory system: Closer to most sophisticated 

3 chambered heart + a partial septum, can actively control shunting depending on on behavior, modest pressure difference in systemic and pulmonary circuits 

partial septum

partially divided ventricle, ALMOST 2 chambers but not yet

Birds/mammal circulatory system: Full evolutionary leap

Double circulation, four chambered hearts

What 2 circuits does the bird/mammal system fluid make?

Systemic and pulmonary, heart can generate 2 separate pressures

Systemic mammal/bird circulatory pressure

rapidly and readily delivers O2 to tissues, high pressure

Pulmonary mammal/bird circulatory pressure

less pressure to protect fragile and tiny vessels in lungs

Why do lungs often have small, fragile vessels?

To allow for O2/CO2 diffusion (only works over distances of 1mm or less)

Advantages of mammal/bird circulatory system

no mixing of de/oxygenated blood, allows for high systemic pressure

Ohm’s Law

Flow (Q) = Delta P/R : pressure difference/resistance (R= 1/2^4

Ohm’s Law equation takeaway

Small change in radius of vessels= big change in flow

Arteries

Pressure reservoirs, biggest vessel, connect directly to heart, thick and elastic

“Pressure reservoirs”

arteries, control blood pressure out of heart

Arterioles

connect arteries to capillaries, comprised of smooth muscle, resistance vessels

Smooth muscles of arterioles allows for….

efficient contraction and dilation

“resistance vessels”

Arterioles because they contract and dilate frequently which effects resistance 

Capillaries

Smallest vessels, site of gas exchange, thin and delicate, slow flowing

Capillary walls are __ thick

1 cell layer thick, allowing for diffusion

Veins

hold majority of blood, large diameter, thin walls, stretch easily, can return blood to heart quickly. 

“volume reservoir”

veins, hold majority of blood volume at rest.

Intrinsic circulation control

Local control, allows tissue to control own blood flow

(Intrinsic control) Metabolic vasodilation

If a tissue becomes more active and produces more CO2, nearby arterioles will dilate to keep balance in check

Myogenic response (intrinsic control)

Opposite of vasodilation, arterioles constrict when stretched too much (the overstretched vessels cause pressure to fall which reduces ability to flow)

Extrinsic control

system wide

Two examples of extrinsic control systems

Autonomic nervous system, endocrine control over heart

Two major hormones of endocrine control over heart (extrinsic control)

Epinephrine (adrenaline) and angiotensin 2 (vessel tensing) both adjust vessel diameter and blood pressure

Short term control of blood pressure governed by….

baroreflex

Baroreflex

adjusts heart function/vessel tone based on stretch receptors, prevents of from fainting and stabilizing circulation when moving

Long term blood pressure control

healthy heart habits

Comparative Adaptations in Circulatory Control: Diving mammals

Peripheral vasoconstriction so they can conserve O2 for brain/heart while diving

Comparative Adaptations in Circulatory Control: ectotherms

Temp dependent cardiac output, lower temp= drop in heart rate

Comparative Adaptations in Circulatory Control: Birds

Huge hearts compared to body size which allows for maintenance of really effective O2 delivery during flight

Comparative Adaptations in Circulatory Control: Fish

Delicate gill capillaries and pressure constraints to prevent damage to these. 

Animals must maintain ___, ____ and ____ balance

fluid, osmotic and ion