Chapter 42 Gas Exchange And Circulation BIOL 2130

Aerobically active tissues require oxygen to carry out metabolism and must get rid of the waste product, carbon dioxide

As the planets warms, aquatic habitats such as a pond will contain less dissolved oxygen, reducing the ability of fishes to acquire oxygen for their respiratory needs.

Vulnerable to predation

Large surface area

This statement is true. Digestive organs such as the stomach and part of the small intestine also develop from the foregut.

False. The lungs stay relatively inflated even upon exhalation because the pressure inside the chest cavity is always negative.

An alveolus is a tiny sac in the lung that functions as an interface between air and blood.

epithelial cells capillary wall extracellular fluid

False. The PCO2 levels affect the diffusion of carbon dioxide; the driving force for the diffusion of oxygen from hemoglobin into tissues is the difference in PO2 levels between the blood (100 mm Hg when oxygenated) and body tissues (40 mm Hg at rest).

As bicarbonate ions (HCO3-).

The binding of one oxygen molecule to hemoglobin stimulates the binding of other oxygen molecules. This interaction is called cooperative binding.

as bicarbonate ions (HCO3 -)

Acidic. If not carried by hemoglobin, hydrogen ions would reduce the pH, or increase the acidity, of the blood.

combined with hemoglobin

it permits rapid uptake of oxygen in the lungs and greater delivery of oxygen once blood reaches capillaries in the body's tissues. Cooperative binding is critical to the high rate of oxygen transport in the circulatory system.

Pulmonary veins carry oxygenated blood from the lungs to the left atrium

left atrium

Blood enters the right atrium from the superior and inferior venae cavae.

inferior vena cava Blood enters the inferior vena cava from the capillaries of the abdominal organs and hind limbs.

Insects have an open circulatory system. However, their tracheal respiratory system is able to provide oxygen directly to the tissues as well.

Muscle contraction reduces the volume of veins, increasing blood pressure and, thereby, increasing the velocity of blood flow. This is a key response when a person enters of period of intense physical activity.

Ventricular systole

Diastole

Ventricles

Capillaries. The very high total cross-sectional area of capillaries means that blood flow there is very slow, providing opportunity for diffusion into and out of the blood.

oxygen; dense

terrestrial; less; aquatic

evaporation; ions, water; ions, water

Fick's law of diffusion

countercurrent

high

CO2

ventilation

diffusion at the respiratory surface

circulation

diffusion at the tissues

cellular respiration

ventilation and diffusion

oxygen in tissues, carbon dioxide for environment

21%

0.04%

partial pressure

partial pressure

multiply the atmospheric pressure at a given level by the fraction of air that is O2.

The PO2 is 160 mm Hg.

the partial pressure gradient between the tissues and the air is little so fewer O2 diffuses in the tissues than we are used to

30

hot water

heir blood flow to tissues would need to increase dramatically to meet oxygen demand

less

bogs have decomposers that quickly use up any excess oxygen in cellular respiration, so they have less oxygen

tops

shallow ponds they have a higher SA:V ratio

yes because they are in contact with more air bubbles

A: Large amount of air, because the oxygen-carrying capacity of warm water is low. B: Small amount of air, because the oxygen-carrying capacity of cold water is higher and because algae contribute oxygen to the water through photosynthesis. C: Small amount of air, because sedentary animals require relatively little oxygen.

thin skin prone to water loss and too dependent on wet or humid environments

diffusion constant depending on solubility of gas ad temperature

are for gas exchange

distance (thickness of diffusion barrier)

difference in partial pressure of gas on either side of barrier to diffusion

large area for gas exchange (3 human's lungs could fill a baseball court stretched out) small distance (thin respiratory surface), high difference in P2 and P1,

cillia or specialized structures to bring water to it

mouth; gills.

stiff slap that covers the gills. pumps with the mouth whenever they need

fast fish open their mouths while they swim to force deoxygenated water out of their body

inbetween gill arches

gill lamellae

countercurrent

If concurrent flow occurred, less oxygen would be transferred from water to blood because the partial pressure gradient driving diffusion would fall to zero partway along the length of the capillary.

the difference down a gradient between the tissues will be consistent (10% difference every time), and the start and end of a system has a large percentage range.

the start of the systems will have a large gap, and end the same number (start 0 and 100, end 50) then diffusion will stop in both blood and water.

it extracts all the oxygen to the blood it needs instead of having an egalitarian oxygen diffusion with water and ensures constant P2-P1 difference.

water

gain; loose

air-filled tubes in insects

openings in insects exoskeletons that can be closed to minimize loss of water by evaporation

alternately compressed and dilated as muscles contract and relax

if the volume occupied by a fixed amount of gas increases, the gas pressure decreases. if the volume declines, the gas pressure increases.

increases; decreases; enters

decreases, increases, out

they have large cross-sectional area for gas exchange (trachea)

the diameter of their trachease would be so large that their would not be enough space in their bodies for much else (muscles, tissues)

at that specific point in time the oxygen levels (p2-p1) were super high so they could support adequate ventilation.

carries inhaled oxygen to narrow tubes called bronchi

little bronchi that enclose both of these structures branches.

bronchioles; capillary networks

lungs

lungs lined directly with blood vessels

like 40 times more surface area for respiration

draws air in through nose and contracts throat, forcing air into oral cavity, then lungs.

lungs are like balloons kept deflated by having pressure around the lung that can allow it to expand and differ

inhalation

exhalation

exhalation

inhalation

inhalation

exhalation

exhalation

exhalation

inhalation

exhalation

air passages not lined by a respiratory surface

exhalation is an active process. you can inhale/exchange more volume of gas BUT 150mL are still not exchanged

lung empties formerly posterior air that had just occupied lungs to anterior sacs. new air goes to posterior air sacs.

no

lungs fill with air from posterior sacs. the anterior sacs release its air.

very little dead space, gas exchange is constant and continuous like fish, and blood is crosscurrent, which is better than mammal spiderwebs but less efficient than fish countercurrency.

medullary center

PO2 of blood decreases because muscles need it more, PCO2 of blood increases because muscles need to get rid of it.

CO2, which it rapidly reacts with water to make carbonic acid so it can make a bicarbonate ion.

Common features include large surface area, short diffusion distance (a thin gas exchange membrane), and a mechanism that keeps fresh air or water moving over the gas exchange surface. Only fish gills use a countercurrent exchange mechanism; only tracheae deliver oxygen directly to cells without using a circulatory system; only mammalian lungs contain alveoli—small air sacs surrounded by capillaries where gas exchange occurs.

The PO2 decreases as oxygen is used up, the PCO2 increases as CO2 diffuses into the blood from tissues but cannot be exhaled, and the pH drops as the CO2 dissolves in blood to form bicarbonate and H+ ions.

platelets

plasma

red blood cells

bone marrow

its nuclei

hemoglobbin

not very well

tetromere

heme

bound into the hemoglobin of RBCs

dissolves into plasma, which still can move to tissues

results in s-curve and 80-100 in hemoglobin to 75-60 while exercising

not a big difference in resting or exercising O2, not much is taken up

all four subunits of hemoglobin unload oxygen at the same time

four subunits release independentily and gain and lose oxygen in direct proportion to PO2 of oxygen in blood, an only a small response to PO2 changes.

right

with lower pH the hemoglobin is more likely to release oxygen in tissues with Low pH

PCO2 and heat lowers the pH, so when its in excess oxygen is HIGH demand and more likely to unload

their dirty blood was almost completely stripped of oxygen because their muscles needed so much, while their arteries had consistent levels

fetal.

pH drop or temperature rise. makes O2 more likely to release, lowers % saturation.

gotta be a fetus and increases hemoglobin saturation

H2CO3 from CO2 + H2O

carbonic anhydrase

when it converts CO2 to bicarbonate theres less CO2 and thusly a higher PCO2 affinity in RBCs

plasma.; stays in RBCs

hemoglobin. takes up H+ so its not in the plasma lowering the pH

Protons leave hemoglobin and react with bicarbonate agian to make CO2 and diffuses out of the lung

O2

picks up lots of oxygen

releases more oxygen

The curves of Tibetans should be shifted to the left relative to the curves of people adapted to sea level—meaning that Tibetans' hemoglobin should have a higher affinity for oxygen at all partial pressures.

in low oxygen demand animals, hemolymph pumped by heart in low-pressure limited vessels that come in direct contact with tissues

tracheal respiratory system gives direct oxygen, making up up for low oxygen blood

blood is continuous circuit pressured by heart to flow. can be selective like crabs (open) and chose wear it needs to focus.

arteries / arterioles

veins / venules

arteries

veins

capillaries

capillaries

aorta

vessel diameter increases, flow resistance is reduced so flow increases in tissues it sends to.

vessel diameter smaller, slow flow to blood and more blood resistance

large veins to prevent dirty back flow

fluid enters capillary from lymphatic duct or interstitial fluid

blood pressure high; fluid leaves to ducts

blood pressure low; fluid enters capillary

fluid leaves capillary and excess enters lymphatic ducts

swelling and pain

atrium

atrium

ventricle

ventricle

one atrium and one ventricle, one circuit serving whole body

ventricles partitioned, 4 chambers, 2 circuits

pulm artery

pulm veins

take dirty blood from body to lungs

clean/oxygenated

dirty/carbonated

takes clean blood from lungs to body

dirty, body, heart (indirectly lungs)

clean, heart, body

Atrium

heart murmur

contraction

Air from the alveoli mixes with air in the dead space in the bronchi and trachea on its way out of the body. This dead-space air is from the previous inhalation (PO2 = 160 mm Hg; PCO2 = 0.3 mm Hg), so when the alveolar air mixes with it, the partial pressures in the exhaled air reach levels intermediate between those of inhaled and alveolar air.

pacemaker cells

RA's SA node

Without the delay at the AV node, the ventricles would not have the chance to fully fill with blood from the atria. Consequently, the volume of blood ejected from the ventricles would decline.

systole

diastole

hypertension

low to none

intermediate

yes

baroreceptors

Output = Heart rate x SV

1. increase in SV and 2. heart rate, 3. prioritize blood by constricting veins and arterioles

blood vessels are hard and less elastic

heart tissue dies of apoxia

A myocardial infarction occurs when some of the heart tissue dies due to a lack of oxygen. It is not the same as when the heart stops beating. Only a massive infarction could interfere with proper pumping of the heart and stop it from beating.