LS7C Chapter 37

What do eukaryotic cells use to burn organic fuels

O2 for ATP production

gas exchange

The transport of O2 and CO2 between an animal and its environment

how do single-celled organisms, simple animals, and plants exchange gases



random movement of molecules from a region of higher concentration toward one of lower concentration

What is the rate of diffusion?

directly proportional to the surface area over which exchange occurs and the concentration difference

rate of diffusion is.....

-inversely proportional to the square of the distance over which diffusion occurs-becomes higher with larger concentration gradients and with increasing temperature

partial pressure

The fractional concentration of a gas relative to other gases present multiplied by the atmospheric pressure exerted on the gases (mmHg)

how does diffusion relate to partial pressure of a gas

gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower.the greater the partial pressure difference between the two areas, the more rapid is the movement of gases.

bulk flow

the movement of a fluid driven by a pressure gradient over a long distance

two steps of bulk flow

1. Ventilation2. Circulation


the movement of an animal's respiratory medium—water or air—past a specialized respiratory surface.


The movement of a specialized body fluid in animals that carries oxygen and carbon dioxide, nutrients and waste products, through the body.

Circulatory fluid in vertebrates and invertebrates

blood (vertebrates)hemolymph (invertebrates)

what does circulatory fluid do

delivers O2 to cells within different regions of the body and carries co2 back to the respiratory exchange surface


P= pressure (both ventilation and circulation require a pump to produce a pressure) Q=FlowR= Resistance to flow

resistance to flow

measures the difficulty of pumping the fluid through a network of chambers and vessels located within the respiratory and circulatory system

if the resistance to flow doubles

the flow rate is halfed

The longer the network of vessels and the narrower the vessels within that network

the greater the vessels' resistance to the fluid (whether air, water, or blood) moving through them.

steps for delivering O2 to animal cells

1. Ventilation: air or water moves over the respiratory exchange surface (lungs) and air containing carbon dioxide out of the lungs2. Diffusion happens! The buildup of O2 favors the diffusion of O2 into the blood or hemolymph across its respitary surface. Oxygen diffuses from the lung into the blood, and CO diffuses out of the blood into the lungs. 3. O2 is transported by the circulation (BULK FLOW) to the tissues 4. Oxygen diffuses from the blood into the cells across the cell membrane and into the mitochondria, where fuel molecules are oxidized for ATP production. CO2 diffuses out of the cells into the blood

what does internal circulation do

serves to maximize the concentration of O2 outside the cells.

tidal respiration

-one cycle of respiration (one inspiration and one expiration) observed during quiet breathing


The drawing of oxygen-rich air into the lungs by the expansion of the thoracic cavity.


The expelling of oxygen-poor air by the elastic recoil of the lungs and chest wall.

Steps of Tidal Ventilation of the Lungs

1. ventilation of the lungs: pressure on the inside becomes lower compared to the outside because the thoracic cavity is expanded. The negative pressure draws air into the lungs 2. Elastic recoil in the tissue causes the air pressure inside the lungs to be higher than outside which results in positive pressure forcing air outside the lungs.


A domed sheet of muscle at the base of the lungs in mammals that separates the thoracic and abdominal cavities and contracts to drive inhalation.

In mammals, inhalation during normal, relaxed breathing is driven by contraction of the ?


What happens when the diaphragm contracts?

The size of the thoracic cavity increases and air flows into the lungs.

What causes exhalation?

elastic recoil of the lungs and chest wall surrounding the thoracic cavity

Intercostal muscles function

Expands and compresses the rib cage in breathing

tidal volume

Amount of air that moves in and out of the lungs during a normal breath (0.5 L)

process of air going into lungs

1. air is taken into the mouth and passes the larynx 2. air then enters the trachea


the hollow muscular organ forming an air passage to the lungs and holding the vocal cords


The central airway leading to the lungs of air-breathing animals, supported by cartilage rings.

two airways of the trachea

primary bronchi

primary bronchi

the two passageways that branch off the trachea and lead to the right and left lungs


Airways in the lungs that lead from the bronchi to the alveoli.


tiny sacs of lung tissue specialized for the movement of gases between air and bloodwhere gas exchange diffusion takes place

pulmonary capillaries

A small blood vessel that supplies the alveolar wall of tetrapod lungs.helps diffusion distance be short

what does moisture do in o2

Moisture helps o2 diffuse across the alveolar wall


chemical produced in the lungs to maintain the surface tension of the alveoli and keep them from collapsing

how do the airways stay moist

mucus secreted by epithelial cells

mucus lining in the airways

traps and removes foreign particles and microorganisms an an animal may breathe in

Respiration is controlled by

voluntary and involantary components of the nervous system


Major artery in the neck leading to the brainA chemosensory structure of the carotid artery that monitors the levels of carbon dioxide and oxygen, and the pH of blood moving to the brain.

aortic bodies

A sensory structure of the vertebrate aorta that monitors the levels of oxygen and carbon dioxide and the pressure of blood moving through the body.

what happens when co2 in the blood is too high

the carotid and aortic bodies stimulate motor neurons that activate the respiratory muscles to contract more strongly and frequently which rids the body of CO2 and increases O2 supply


An iron-containing molecule specialized for oxygen transport.

which cells constitute most of the cellular fraction of blood

red blood cells

white blood cells (1%)

help defend the body against pathogens


blood clotting

what is the densest component of blood

red blood cells


A measure of how much solute can dissolve in a given solvent at a given temperature.

Where are hemoglobin produced?

red blood cells (gives cells their red appearence)

how many peptide units are in hemoglobin


function of the peptide units in hemoglobin

each one of the peptide units surrounds a heme group that contains an iron atom, which reversibly binds to an O2 molecule the binding of hemoglobin to O2 results in the removal of O2 from the solution, keeping the po2 of the red blood cell below that of the blood plasma. o2 continues to diffuse into the cell, the removal of O2 into the plasma keeps po2 of the plasma below that of the lung alveolus, and o2 continues to diffuse from the lungs into the blood.

oxygen dissociation curve

A curve on a graph that shows how saturated with oxygen hemoglobin is at any given partial pressure.

cooperative binding of hemoglobin

-as each individual O2 molecule binds, it increases the affinity of the next heme group for the additional O2 molecule- results in a sigmoidal dissociation curve

cooperative process

binding at one site changes the protein conformation in a way that facilitates further binding at other sites


stores oxygen in muscle cellsonly contains a single heme group

mammls extract o2 from their mothers hemoglobin by expressing a form of hemoglobin that has a higher affinity for o2

The O2 dissociation curve for fetal hemoglobin is shifted to the left of the curve for maternal hemoglobin (Fig. 37.15a), allowing the fetal hemoglobin to extract O2 from the mother's circulation.

PH falling

Ph falling means an increase in H+ concentration, and it happens when Co2 is released from cells during exercise, or wheen not enough o2 is produced which creates lactic acid

what happens when Ph falls

The affinity of hemoglobin for O2 decreases, shifting the O2 dissociation curve to the rightBecause hemoglobin's affinity for O2 is reduced, more O2 is released to cells for aerobic ATP synthesis.

Carbon and PH

Carbon dioxide also reacts with the amine (NH2) groups of hemoglobin, reducing hemoglobin's affinity for O2. when released from respiring tissues, CO2 promotes increased O2 delivery both through its direct effect on hemoglobin and through its contribution to a decrease in blood pH by the Bohr effect. Whereas the production of CO2 promotes O2 release at the tissues, its elimination at the lung increases hemoglobin's affinity for O2, thereby enhancing O2 uptake.

closed circulatory system

system in which blood is contained within a network of blood vessels

how are animal circulatory systems organized

to have blood flow over long distances in a relatively few large diameterss vessels with low resistance to flow


carry blood away from the heart


Blood vessels that carry blood back to the heart


small vessels that receive blood from the arteries


A very small blood vessel, arranged in finely branched networks connecting arterioles to venules, where gases, nutrients and waste products are exchanged by diffusion with surrounding tissues.


A blood vessel into which capillaries drain as blood is returned to the heart.

what happens when animals become active after a period of resting and feeding

blood flow must be increased to their muscles and reduced to their digestive organs

how is resistance to flow affected

radius of vessels The narrowing of the blood vessels dramatically increases the resistance to flow, thereby reducing the rate of blood flow larger vessels offer less resistance, so more blood can flow through them

what happens as the rate of cellular respiration increases

cells release more CO2, which acts as a signal to the smooth muscles in the arteriole walls to relax

layers of artery wall

collagen and elastin

collegen in the artery wall

resist the expansion of the arterial wall during pressure pulses.

what causes an aneurysm

weakness in arterial wall (thin collagen and elastin)

What happens to blood collected from local capillary network s

return to the heart from progressively longer veins that drain into the largest two veins (venae cavae)

vena cava

One of two large vessels (superior and inferior) that return deoxygenated blood to the right atrium of the heart.

what happens as a result of low blood pressure

blood tends to accumulate within the veins

most important mechanism used to return blood to the heart

muscle contractions that occur during exercise which exert pressure on the veins

why doesn't the blood plasma lose all its water and ions over time?

blood pressure forces water, certain ions, and other small molecules to move from capillaries into the surrounding interstitial fluid but proteins and blood cells remain in the capillaries, and their concentration increases with the removal of water, which causes the water to flow back into the capillaries by osmosis

lymphatic system

the network of vessels through which lymph drains from the tissues into the blood.


fluid that enters the lymphatic system

process of excess interstitial fluid being returned to the blood stream

1. vessels merge together draining the lymph into lymphatic ducts 2. these ducts empty into the venous system and the heart 3. lymphatic vessels have one-way valves that assist the return of lymph to the circulatory system as well as local musvle contractions

what happens when an animal is dehydrated or has lost blood

there is a decrease in blood pressure because the posterior pituitary gland releases ADH into the circulation. the higher resistance to flow from the arteries increases blood pressure

What does ADH do?

causes arteries to constrict increasing their resistance to flow

How does homeostasis restore itself when the blood pressure is low

1. Animals reduce the supply of blood to the limbs by constricting arterioles, which helps maintain BP in the heart, brain, and kidneys 2. Sympathetic neurons synapsing on the smooth muscles of arterioles stimulate muscles to contract

sympathetic neurons

neurons of the autonomic system that prepare the body for danger or excitement

how is homeostasis restored when blood pressure is too high

1. sympathetic neurons that synapse on the smooth muscles are inhibited 2. This causes smooth muscles to relax 3. Smooth muscles relaxing reduces resistance to the arterioles and causes increased blood flow


The narrowing of a vessel by the contraction of smooth muscle, which in turn increases resistance and decreases blood flow.


The widening of a vessel by the relaxation of smooth muscle, which in turn decreases resistance and increases blood flow.