Lecture 20 Circulation and gas exchanges

Question 1

How are structure and function related in the exchange and circulation of oxygen and carbon dioxide? (Specialized structures)(watch video)

Answer 1

with a large surface area mediate gas exchange with the environment

The walls of the alveoli share a membrane with the capillaries. That’s how close they are. This lets oxygen and carbon dioxide diffuse, or move freely, between the respiratory system and the bloodstream. Oxygen molecules attach to red blood cells, which travel back to the heart.

Question 2

How are structure and function related in the exchange and circulation of oxygen and carbon dioxide? (Networks of highly branched, thin-walled vessels)(watch video)

Answer 2

maximize exchange efficiency by showing efficiency by slowing fluid flow and maximizing surface area

Question 3

How are structure and function related in the exchange and circulation of oxygen and carbon dioxide? (pump heart) (watch video on this)

Answer 3

drives the flow of fluid through the circulatory system

The structure of the heart allows it to effectively pump blood through the circulatory system, while the structure of blood vessels facilitates the exchange of gases and nutrients between the blood and body tissues.

Overall, the heart’s efficient function as a pump and the intricate network of blood vessels enable the continuous exchange of oxygen and carbon dioxide, supporting cellular respiration and sustaining bodily functions. This integration of structure and function ensures that oxygen is delivered to tissues and organs while carbon dioxide, a waste product, is removed from the body.

Question 4

How are structure and function related in the exchange and circulation of oxygen and carbon dioxide? (wide, thick-walled vessels)(watch video)

Answer 4

offer minimal resistance to fluid flow, enabling circulation throughout the body

Question 5

diffusion

Answer 5

small molecules can move between cells and their surroundings

only efficient over small distances b/c the time it takes to diffuse is

Question 6

why is diffusion only efficient over small distances

Answer 6

because the time it takes to diffuse is proportional to the square of the distance

Question 7

Gastrovascular cavities

Answer 7

In some animals, many or all cells are in direct contact with the environment.

ex. Flatworms have a gastrovascular cavity and a flat body that minimizes diffusion distances

Question 8

What is gastrovascular cavities

Answer 8

a structure found in primitive animal phyla. It is responsible for both the digestion of food and the transport of nutrients throughout the body (has one opening to an environment)

Question 9

endocrine system

Answer 9

releases signaling molecules (hormones) into the bloodstream

a hormone may affect one or more regions throughout the body

Question 10

Hormones

Answer 10

release signaling molecules

Question 11

cellular respiration formula

Answer 11

C6H1206 + 6O2 > 6CO2 + 6H2O + Energy (ATP + heat)

Question 12

circulation and gas exchange
(what system is involved)

Answer 12

circulatory system plays a part

respiratory system: take O2 from the environment and releases CO2

Question 13

Equilibrium

Answer 13

a state in which opposing forces for influences by balanced

-a state of physical balance
-a calm state of mind

Question 14

partial pressure

Answer 14

the pressure exerted by a particular gas in a mixture of gases

Question 15

What is the Circulatory system (and what are the 3 basic components)

Answer 15

connects the fluid that surrounds cells with the
organs that exchange gases, absorb nutrients,
and dispose of wastes

3 basic components:
* A circulatory fluid (hemolymph or blood)
* A set of interconnecting vessels
* A muscular pump, the heart

Question 16

Open circulatory system

Answer 16

Hemolymph - interstitial fluid that bathes body cells

● Heart pumps hemolymph through vessels
● from vessels into sinuses: gas exchange
● from vessels into spaces around organs
● Heart relaxes - draws hemolymph back

ex (most common). The tracheal system of insects consists of a network of branching tubes throughout the body.

The tracheal tubes supply O2 directly to body cells.

The respiratory and circulatory systems are separate.

Question 17

What liquid is involved in Closed circulatory system

Answer 17

Blood - (confined to vessels) different from interstitial fluid

Question 18

Hemolymph

Answer 18

circulatory fluid (interstitial fluid that bathes body cells)

Question 19

What type of system is Cardiovascular system and what are the 3 types of blood vessels

Answer 19

closed circulatory system

The three main types of blood vessels are
● arteries
● veins
● capillaries

blood flows one way in this vessel

Question 20

what direction does blood in the artery flow

Answer 20

away from the heart (Arteries and veins are distinguished by the direction of blood flow, not by O2 content)

Question 21

what direction does blood in the vein flow

Answer 21

toward the heart (Arteries and veins are distinguished by the direction of blood flow, not by O2 content)

Question 22

Velocity of blood

Answer 22

flow is slowest in the capillary beds, as a result of the high resistance and large
total cross-sectional area.

Question 23

why is blood flow in capillaries slow

Answer 23

for the exchange of materials

Question 24

types of circulatory systems

Answer 24

single circulation and double circulation

Question 25

Single circulation

Answer 25

blood leaving the heart passes through two
capillary beds before returning

Bony fishes, rays, and sharks have single circulation with a two-chambered heart

Question 26

double circulation

Answer 26

Oxygen-poor and oxygen-rich blood are
pumped separately from the right and left sides of the heart

Amphibians, reptiles, and mammals have double circulation

Question 27

4 chambered heart

Answer 27

Mammals and birds have a four-chambered heart with
● two atria
● two ventricles

● left side of the heart
pumps and receives only
oxygen-rich blood,
● right side receives and
pumps only oxygen-poor
blood.

Mammals and birds are endotherms and require more O2 than ectotherms.

Question 28

considerations for gases (what does gas diffusion do and gas exchange)

Answer 28

Gas diffusion increases with surface area
and decreases with distance.

Gas exchange is the uptake of O2 from
the environment and the discharge of CO2
to the environment.

Respiratory surfaces are built to maximize
the surface area and have the blood/cells
as close to the air/water as possible

Question 29

Mammalian Respiratory System: gas exchange at lungs (what are the steps)

Answer 29

air gets warm and humid

air gets directed to the lungs

the mucus traps particles

Gas exchange

Question 30

Alveoli: gas exchange

Answer 30

● Gas exchange takes place in
alveoli, air sacs at the tips of
bronchioles.
● Oxygen diffuses through the
moist film of the epithelium and
into capillaries.
● Carbon dioxide diffuses from the
capillaries across the epithelium
and into the air space.

Question 31

What is Breathing

Answer 31

● The process that ventilates the lungs is
breathing, the alternate inhalation and
exhalation of air.
● Mammals ventilate their lungs by negative
pressure breathing, which pulls air into the
lungs.
● Lung volume increases as the rib muscles and diaphragm contract.

Question 32

Breathing (steps)

Answer 32

1. Inhalation: Diaphragm contracts (moves down)

rib cage expands as muscles contract

2. Exhalation: diaphragm relaxes (moves up)

rib cage gets smaller as rib muscles relax

Question 33

Control of Breathing in Humans

Answer 33

Breathing is regulated by involuntary
mechanisms.

The breathing control centers are found in
the medulla oblongata of the brain.

Question 34

medulla oblongata (control in breathing)

Answer 34

regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid.

Question 35

negative feedback loop

Answer 35

normal range > stimulus: change in internal variable > sensor > control center > response > normal range (slide 39)

Question 36

Homeostatic control

Answer 36

normal blood ph (7.4) > blood pH falls due to rising levels of CO2 in tissues

Medulla detects decrease in pH of cerebrospinal fluid. (slide 40)

Question 37

Homeostatic control

Answer 37

slide 41 and 42

Question 38

oxygen solubility in water

Answer 38

1. Oxygen has low solubility in water.
   (Air can hold ~30x as much oxygen as water: At 15o C, 1 liter of air contains 209 ml O2 , 1 liter of water has maximum of 7 ml O2)
2. If the partial pressure of gas in water is greater than in the atmosphere, the gas ‘boils’ out of the water

Question 39

why can oxygen happily travel through the blood dissolved?

Answer 39

oxygen has low solubility in water

Question 40

Respiratory pigments

Answer 40

proteins that transport oxygen, greatly
increase the amount of oxygen that blood can carry.

Arthropods and many molluscs have hemocyanin, with copper as the oxygen-binding component.

Most vertebrates and some invertebrates use hemoglobin.

In vertebrates, hemoglobin is contained within erythrocytes.

Question 41

Hemoglobin

Answer 41

A single hemoglobin molecule can
carry four molecules of O2, one
molecule for each iron- containing
heme group.

The hemoglobin dissociation curve
shows that a small change in the
partial pressure of oxygen can
result in a large change in delivery
of O2. (slide 46-48)

Question 42

Does CO2 decrease the blood pH?

Answer 42

Yes (slide 49)

Question 43

Bohr shift

Answer 43

effect of pH on hemoglobin dissociation (slide 50)

CO2 produced during cellular respiration lowers blood pH and decreases the affinity of
hemoglobin for O2

Hemoglobin plays a minor role in transport of
CO2 and assists in buffering the blood.

Question 44

Evolutionary Adaptation in Double Circulation

Answer 44

● Some vertebrates with double circulation
are intermittent breathers.
● Frogs and other amphibians have a
three-chambered heart: two atria and
one ventricle.
● A ridge in the ventricle diverts most of
the oxygen-rich blood into the systemic
circuit and most oxygen-poor blood into
the pulmocutaneous circuit.
● When underwater, blood flow to the
lungs is nearly shut off.

Question 45

Gills

Answer 45

● Gills are outfoldings of the body that create a large surface area for gas exchange.
● Very vascularized.
● Ventilation moves the respiratory medium over the respiratory surface.
● Aquatic animals move through water or move water over their gills for ventilation.

Question 46

what happens to the gas when the partial pressure of gas in water is greater than the atmosphere

Answer 46

If the partial pressure of gas in water is greater than in the atmosphere, the gas ‘boils’ out of the water because O2 has low solubility

(think of aquatic animals)

Question 47

countercurrent exchange

Answer 47

exchange of a substance between two fluids flowing in opposite directions (gills are countercurrent exchange of water and blood)

Question 48

Gills: countercurrent exchange

Answer 48

● Fish gills use a countercurrent exchange
system, where blood flows in the opposite
direction to water passing over the gills.
● Blood is always less saturated with O2
than the water it meets.
● In fish gills, more than 80% of the O2
dissolved in the water is removed as water
passes over the respiratory surface.

Question 49

hemoglobin(important compartment of red blood cells) (proof of adaptation)

Answer 49

If some heritable traits are advantageous,
individuals with these traits will produce more
offspring that survive to reproduce, and this will increase the frequency of these traits in the next generation.

Question 50

Does fetal hemoglobin bind stronger to oxygen?

Answer 50

binds to oxygen more strongly than
adult hemoglobin