Circulation and gas exchange Flashcards

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1
Q

How can oxygen and CO2 move between cells?

A

small nonpolar molecules like oxygen and Co2 can move between cells and surroundings by diffusion
this takes a long time though

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2
Q

How do sponges do gas exchange?

A

sponges are just a collection of cells which communicate directly with water so diffusion is sufficient for gas exchange and nutrients

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3
Q

How do small animals perform gas exchange?

A

small animals (flatworms and jellies) can meet demands by exchanging gases directly with the environment through diffusion but they also have the gastrovascular cavity which facilitates diffusion of gases and nutrients to cells deep in the body

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4
Q

Discuss the advantages of the open system

A

lower hydrostatic pressure= less energy consumed

ex- spiders use the hydrostatic pressure to extend legs

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5
Q

more “advanced” animals have a closed circulatory system Why?

A

More reliable
higher blood pressure because everything is contained (push liquid through) this allows for efficient delivery of oxygen and nutrients to cells of large animals
very through can direct the blood where it needs to go, control the blood flow to different parts of the body as you need (direct blood to certain part)

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6
Q

open circulatory system

A

don’t have blood vessels heart pumps blood to top of animal and it trickles down
fluid is called hemolymph which directly bathes organs
ex- arthropods and most molluscs

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7
Q

closed circulatory system

A

blood cells remain within vessels and is kept separate from the interstitial fluid
fluid is blood
one or more hearts pump blood into large vessels that branch into smaller ones and infiltrate organs
chemical exchanges occur between blood and interstitial fluid then to body cells
ex- annelids (earthworms) cephlapods (octupuses and squids)

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8
Q

What are the 3 types of blood vessels

A
  1. Artery
  2. Veins
  3. capillaries
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9
Q

Artery

A

vessel taking blood away from the heart to the capillary beds/ other organs
Much higher blood pressure than in veins because they are delivering blood from the pump to the capillary bed walls are thicker and stronger

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10
Q

Vein

A

vessel taking blood from other tissues to the heart

Low pressure because blood has already gone through a capillary bed

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11
Q

Capillaries

A

microscopic vessels that permeate all tissues
So small that blood cells go single file
Really low pressure because they are tiny

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12
Q

Portal veins

A

conveys blood from one capillary bed to another capillary bed
Big fat
Low pressure

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13
Q

What distinguishes arteries and veins?

A

direction in which they carry blood not whether if they take oxygenated or deoxygenated blood

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14
Q

What color are oxygenated and deoxygenated blood?

A

Whether oxygen rich or poor depends on which circuit
Oxygenated blood is red
Deoxygenated is also red

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15
Q

Which direction can blood flow in..

A

within each blood vessel blood can flow in only one direction

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16
Q

How do large animals perform gas exchange?

A

they need a circulatory system because diffusion cannot happen because their body is too large

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17
Q

atria

A

receive blood entering heart and transfer to ventricle

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18
Q

Diffusion

A

is the net movement of anything from a region of higher concentration to a region of lower concentration
is driven by a gradient in concentration.

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19
Q

Bulkflow

A

Animals rely on bulk flow (or other active mechanism) to obtain oxygen and release carbon dioxide (hence breathing, fish sweep water across gills, frog swallowing)
the movement of a fluid due to a difference in pressure b/t two locations

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20
Q

Sinuses

A

spaces surrounding the organs
contraction of 1 or more hearts pumps the hemolymph through the circulatory vessels into interconnected sinuses,
within the sinuses, chemical exchange occurs b/t the hemolymph & body cells
relaxation of the heart draws hemolymph back in through pores, which are equipped with valves that close when the heart contracts
body movements help circulate the hemolymph by periodically squeezing the sinuses

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21
Q

Hemolymph

A

the fluid within the hemocoel of invertebrates that exchange nutrients and waste within internal tissue

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22
Q

Blood Lymph/Interstitial fluid

A

is a solution that bathes and surrounds the cells of multicellular animal

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23
Q

Double Circulation

A

circulatory system consisting of separate pulmonary and systematic circuits in which blood passes through the heart after completing each circuit
(blood moving between the heart and the rest of the body- systematic- is separated from the blood that travels between the heart and the respiratory surface

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24
Q

Pulmocutaneous Circuit

A

a branch of the circulatory system in amphibians that supplies the lungs and the skin

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25
Q

Pulmonary Circuit

A

supplies the lungs

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26
Q

Systemic Circuit

A

supplies oxygenated blood to and carries deoxygenated blood away from the organs and tissues throughout the body

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27
Q

Respiration

A

also called gas exchange

the uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment

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28
Q

Gill

A

outfoldings of the body surface that are suspended in the water

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29
Q

Ventilation

A

the flow of air or water over a respiratory surface

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30
Q

describe the fish circulatory system

A

have a single circuit (blood just goes round and round)
Blood collects in the atrium then enters the ventricle
contraction of ventricles pumps blood to arteries that leads to gills to collect oxygen and get rid of CO2 and then to body releasing oxygen before returning to heart
have a 2 chambered heart
heart receives only deoxygenated blood

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31
Q

What are the advantages and disadvantages of single circulation?

A
  1. By passing through the gill capillaries blood pressure drops as blood is delivered to the rest of the body reducing the efficiency of circulation
  2. The heart has to rely on deoxygenated blood for its own metabolic needs
    Not as efficient because you use a lot of blood pressure
    works well in animals with low metabolic demands
32
Q

describe the amphibian circulatory system

A

have 2 different circuits
1 goes to lungs or skin (Pulmocutaneous Circuit)
1 goes to body to feed oxygen and collect waste
the right atrium collects blood from the body and the left atrium collects blood from respiratory surfaces
both atria empty into a single ventricle but Little ridge that keeps oxygenated and deoxygenated blood separated(directs blood flow)
Beneficial because the heart gets oxygen and can be used more readily
when the ventricle contracts the oxygen rich blood from the left atrium is sent via the systematic circuit to the rest of the body and the deoxygenated blood from the right atrium is sent to the respiratory surface for oxygenation
When you push blood through tiny capillaries you reduce the blood pressure a lot (very efficient)
3 chambered heart; 2 atria and single ventricle

33
Q

describe the reptile circulatory system

A

did same thing as amphibians
septum for separating ventricle into 2 chambers to separate pulmonary and systematic blood
in most its incomplete some mixing of the blood flows within the ventricle
Crocodilians close the septum completely into different chambers and blood doesn’t mix
Single ventricle

34
Q

describe the circulatory system of birds and mammals

A

Mammals have 4 chambered heart; 2 distinct muscles
2 circuits
a complete wall separates the heart into 2 ventricles
left side= receives and pumps only oxygen rich blood
right side= receives and pumps only oxygen poor blood
the left and right pumps are 2 different pumps housed in a single organ the heart
Atria contract before ventricles

35
Q

How are the evolutions of the circulatory system beneficial

A

the ridge in amphibians and incomplete septum in reptiles provide an ability to send oxygen poor blood to the respiratory surface and oxygen rich blood to the body
the 4 chambered hearts of birds and mammals are needed to maximize blood flow needed to support metabolic rates associated with endothermy

36
Q

pulmonary arteries

A

carries deoxygenated blood from right ventricle to the lungs

37
Q

pulmonary veins

A

carry oxygenated blood from lung to left atrium

38
Q

aorta

A

largest vessel- artery

transfers blood from the left ventricle to the rest of the body

39
Q

superior vena cava

A

carries oxygen poor blood from head neck and forelimbs and empties into right atrium

40
Q

inferior vena cava

A

drains blood from trunk and hind limbs

41
Q

What is the circulatory path in humans?

A
Left ventricle  
Aortas  
Arterioles  
Systematic capillaries  
Venules  
Veins (vena cava analogous to the aorta)  
Right atrium  
Right ventricle  
Pulmonary arteries  
Lung capillaries  
Pulmonary vein 
Left atrium
42
Q

What are some examples of portal veins?

A

the hepatic portal vein carries blood between capillaries in the digestive tract to capillaries in the liver
the hypophyseal portal vessels that carry blood between the hypothalamus and the pituitary gland
the renal portal system that carries blood from the glomerulus to capillaries that surround kidney tubules.

43
Q

partial pressure

A

the pressure exerted by a particular gas in a mixture of gases
ex- the pressure exerted by oxygen in air

44
Q

A gas always undergoes net diffusion..

A

from a region of higher partial pressure to a region of lower partial pressure

45
Q

What is atmospheric pressure of O2 exposed to air sea level?

A

water exposed to air at sea level has a PO2 of 160 mm Hg, the same as in the atmosphere
the concentrations of O2 in the air and water differ because O2 is much less soluble in water than in air

46
Q

What does partial pressure apply to?

A

Partial pressures also apply to gases dissolved in a liquid, such as water. When water is exposed to air, an equilibrium is reached in which the partial pressure of each gas in the water equals the partial pressure of that gas in the air

47
Q

Compare water and air as respiratory media

A

The conditions for gas exchange vary considerably, depending on whether the respiratory medium—the source of O2—is air or water.

Compared to water, air is much less dense and less viscous, so it is easier to move and to force through small passageways. As a result, breathing air is relatively easy and need not be particularly efficient.

Gas exchange with water as the respiratory medium is much more demanding. The amount of O2 dissolved in a given volume of water varies but is always less than in an equivalent volume of air
Water’s lower O2 content, greater density, and greater viscosity mean that aquatic animals such as fishes and lobsters must expend considerable energy to carry out gas exchange.

48
Q

Describe the mechanisms by which gases move across the respiratory surface into the circulatory system, within the circulatory system, and from the circulatory system to the tissues.
a. Relate the mechanisms used by an animal to its size.

A

in simple animals, such as sponges, cnidarians, and flatworms, every cell in the body is close enough to the external environment that gases can diffuse quickly between all cells and the environment

In many animals the bulk of the body’s cells lack immediate access to the environment. The respiratory surface in these animals is a thin, moist epithelium that constitutes a respiratory organ.

The skin serves as a respiratory organ in some animals, including earthworms and some amphibians. Just below the skin, a dense network of capillaries facilitates the exchange of gases between the circulatory system and the environment

49
Q

Explain the Types of respiratory systems in Small and/ or simple invertebrates

A

Porifera cnidaria Platyhelminthes
No respiratory system needed
All cells in contact with surrounding medium(water)

50
Q

Explain the Types of respiratory system in Insects

A

Open circulatory system
Don’t have lungs and don’t convey any gases through circulatory system
Spiracle/ tracheal respiratory system(breathe through this)
he largest tubes, called tracheae, open to the outside The finest branches extend close to the surface of nearly every cell, where gas is exchanged by diffusion across the moist epithelium that lines the tips of the tracheal branches
Trachea permeate everything
Every cell is really close to outside
No oxygen in hemolymph

51
Q

Tracheal system

A

in insects a system of branched air filled tubes that extends throughout the body carries oxygen directly to cells

52
Q

Explain the Types of respiratory system in Aquatic vertebrates

A

Closed circulatory system
ventilation
Gills (localized structure that collects oxygen from water and is distributed through blood)
Do same thing as large aquatic invertebrates
Countercurrent- Water flows one way blood the other and that maximizes diffusion of oxygen into and CO2 out of blood (gradient favour oxygen
Oxygen partial pressure is higher on water than blood

53
Q

Explain the Types of respiratory system in Aquatic vertebrates

A

Closed circulatory system
ventilation
Gills (localized structure that collects oxygen from water and is distributed through blood)
Do same thing as large aquatic invertebrates
Countercurrent- Water flows one way blood the other and that maximizes diffusion of oxygen into and CO2 out of blood (partial pressure gradient favour oxygen)
very efficient
Oxygen partial pressure is higher on water than blood

54
Q

Explain the Types of respiratory systems in Terrestrial vertebrates

A

Closed circulatory system
Lungs
US

55
Q

Explain the Types of respiratory system in

Crustaceans

A

Open circulatory system
Gills (have oxygen in this, only work in water but are centralized organs so to get oxygen to rest of body you need to pass through blood)
Oxygen carrying pigment in hemolymph

Insect system doesn’t work in all animals because the bigger the animal is the harder it is to move the gases passively out

56
Q

How do Amphibians breathe?

A

Positive pressure breathing
inflating the lungs with forced airflow. During the first stage of inhalation, muscles lower the floor of an amphibian’s oral cavity, drawing in air through its nostrils. Next, with the nostrils and mouth closed, the floor of the oral cavity rises, forcing air down the trachea. During exhalation, air is forced back out by the elastic recoil of the lungs and by compression of the muscular body wall.
Basically, gulp air in using muscles in the mouth
Pushing air into lungs do gas exchange and open mouth and release gas out
Inflate lungs

57
Q

How do Birds breathe?

A

Positive pressure- Circular breathing.. Sort of
Lungs don’t inflate and collapse like ours
Air goes one way through
Air pulled into air sacs
when they exhale air in air sacs gets pushed across the lungs into different air sacs
When it breathes again air gets pulled again
Lungs don’t fill with air it just passes
Very efficient always oxygenated air and that is why they can breathe at higher elevations than mammals
Countercurrent flow

58
Q

How do Mammals breathe?

A

Negative pressure breathing (we don’t push air into lungs we pull it in)
Diaphragm pulls down and lungs expand and air pressure decreases inside air gets pulled in
Air pulled into lungs using primarily the diaphragm
We pull air in and let it out frogs push air in and let it out
the human chest cavity is always at a lower pressure then outside environment

59
Q

Control breathing in humans

A
  1. Voluntary
  2. Detection of low cerebrospinal fluid pH in the medulla
  3. Detection of low O2 levels in aorta and carotid arteries signals brain stem
  4. Pons detecting low oxygen levels in some arteries
60
Q

positive pressure breathing

A

a breathing system in which air is forced into the lungs

61
Q

What are the features that make ventilation in birds highly efficient?

A
  1. when birds breathe, they pass air over the gas exchange surface in only one direction
  2. incoming fresh air does not mix with air that has already carried out gas exchange.
62
Q

negative pressure breathing

A

a breathing system in which air is pulled into the lungs

63
Q

bohr shift

A

a lowering of the affinity of hemoglobin for oxygen caused by a drop in pH
facilitates the release of oxygen from hemoglobin in the vicinity of animal tissues

64
Q

Is oxygen soluble in water or air?

A

Oxygen is not very soluble in water or blood its very soluble in air
Still follows partial pressure gradient (some will still move in to blood passively but not very much)

65
Q

Hemoglobin

A

(a pigment helps)- uses iron (some use other pigments)
Attract oxygen molecules- have very high affinity for oxygen
also helps transport CO2 and assists in buffering the blood
consists of four subunits (polypeptide chains), each with a cofactor called a heme group that has an iron atom at its centre and it will passively go into bloodstream following partial pressure gradient but it will also get grabbed by the heme groups
Each iron atom binds one molecule of O2
a single hemoglobin molecule can carry four molecules of O2
all respiratory pigments, hemoglobin binds O2 reversibly, loading O2 in the lungs or gills and unloading it in other parts of the body.
Increases bloods ability to hold oxygen 50 times

66
Q

What does Hemoglobin exhibit?

A

exhibits cooperativity
When O2 binds to one subunit, the others change shape slightly, increasing their affinity for O2. When four O2 molecules are bound and one subunit unloads its O2, the other three subunits more readily unload O2, as an associated shape change lowers their affinity for O2

67
Q

respiratory pigments

A

a protein that transports oxygen in blood or hemolymph

68
Q

What is the role of respiratory pigments?

A

help animals transport most of oxygen
circulate with the blood or hemolymph and are often contained within specialized cells
The pigments greatly increase the amount of O2 that can be carried in the circulatory fluid

69
Q

What if we didn’t have hemoglobin?

A

Without hemoglobin our ability to metabolize will greatly reduced without this we would only have 1/50 th of oxygen available to us

70
Q

What happens when oxygen is chronically in short supply

A

If oxygen is chronically in short supply (we exhale and inhale a lot)
More hemoglobin (more red blood cells) will be made and/ or…
Different isoforms with higher O2 affinity will be made
Variety of different versions of hemoglobin can be made that have different affinities to oxygen, so oxygen can be pulled in easier

71
Q

What happens to hemoglobin in different conditions?

A

Changes shape in different conditions
Affinity varies depending on how many oxygen molecules are already attached to it
As more and more attach it becomes more and more attracted (very flexible molecules)
The production of CO2 during cellular respiration promotes the unloading of O2 by hemoglobin in active tissues
CO2 reacts with water, forming carbonic acid, which lowers the pH of its surroundings
Low pH decreases the affinity of hemoglobin(the shape of the hemoglobin changes shape so that it can releases oxygen easily) for O2, called the Bohr shift
where CO2 production is greater, hemoglobin releases more O2, which can then be used to support more cellular respiration.

72
Q

carbonic anhydrase

A

an enzyme that assists carbon dioxide to diffuses from plasma into erythrocytes and reacts with water forming carbonic acid

73
Q

Explain how CO2 is transported within the circulatory system

A

Only about 7% of the CO2 released by respiring cells is transported in solution in blood plasma. The rest diffuses from plasma into erythrocytes and reacts with water forming carbonic acid
When blood flows through the lungs, the relative partial pressures of CO2 favour the diffusion of CO2 out of the blood
As CO2 diffuses into alveoli, the amount of CO2 in the blood decreases
This decrease shifts the chemical equilibrium in favour of the conversion of HCO−3 to CO2, enabling further net diffusion of CO2 into alveoli
the PCO2 gradient is sufficient to reduce PCO2 by roughly 15% during passage of blood through the lungs.

74
Q

Explain respiratory surfaces

A

, the cells that carry out gas exchange have a plasma membrane that must be in contact with an aqueous solution. Respiratory surfaces are therefore always moist.

The movement of O2 and CO2 across moist respiratory surfaces takes place entirely by diffusion. The rate of diffusion is proportional to the surface area across which it occurs and inversely proportional to the square of the distance through which molecules must move. (gas exchange is fast when the area for diffusion is large and the path for diffusion is short. As a result, respiratory surfaces tend to be large and thin)

75
Q

Why is 2 different circuits more beneficial over the single circuit?

A
  1. the blood returning to the heart is fully oxygenated to be used more readily
  2. when you push blood through tiny little capillaries you reduce the blood pressure, very little blood pressure left over by the time you set through all of this stuff
    - with fish there is a whole other capillary bed to get through so it isn’t as efficient
76
Q

Using examples, explain when the ventilation of respiratory surfaces is required

A

movement of the respiratory medium over the respiratory surface, a process called ventilation maintains the partial pressure gradients of O2 & CO2 across the gill that are necessary for gas exchange
to promote ventilation, most gill-bearing animals either move their gills through the water or move water over their gills

EX: crayfish & lobsters have paddle-like appendages that drive a current of water over the gills, whereas mussels & clams move water with cilia
octopuses & squids ventilate their gills by taking in & ejecting water, with the side benefit of locomotion by jet propulsion
fishes use the motion of swimming or coordinated movements of the mouth & gill covers to ventilate their gills
in both cases, a current of water enters the mouth, passes through slits in the pharynx, flows over the gills, & then exits the body