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circulation & gas exchange Flashcards

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1
Q

Diffusion

A

the spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated

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2
Q

Bulk flow

A

the MOVEMENT OF A FLUID due to a difference in pressure b/t 2 locations

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3
Q

Gastrovascular cavity

A

a central cavity with a single opening in the body of certain animals, including cnidarians & flatworms, that functions in both the digestion & distribution of nutrients

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4
Q

Open circulatory system

A

a circulatory system in which fluid called hemolymph bathes the tissues & organs directly & there is no distinction b/t the circulating fluid & the interstitial fluid

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5
Q

Sinuses

A

contraction of 1 or more hearts pumps the hemolymph through the circulatory vessels into interconnected sinuses, spaces surrounding the organs

  • 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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6
Q

Hemolymph

A

in invertebrates with an OPEN circulatory system, the BODY FLUID that BATHES TISSUES

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7
Q

Closed circulatory system

A

a circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid

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8
Q

Blood

A

a connective tissue with a fluid matrix called plasma in which red blood cells, white blood cells, and cell fragments called platelets are suspended

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9
Q

Lymph

A

after entering the lymphatic system of vertebrates by diffusion, the fluid LOST by capillaries is called lymph; its composition is about the same as that of interstitial fluid (colourless)

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10
Q

Arteries

A

convey blood from heart to other tissues

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11
Q

Capillaries

A

microscopic vessels that permeate all tissues

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12
Q

Veins

A

convey blood from other tissues BACK to the heart

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13
Q

Portal Veins

A

conveys blood from one capillary bed to another capillary bed

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14
Q

Double Circulation

A

a circulatory system where the blood moving B/T the HEART & the rest of the BODY (the systemic circuit) is separated from the blood that travels B/T the HEART and the RESPIRATORY SURFACE (the pulmonary circuit)

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15
Q

Pulmocutaneous Circuit

A

a branch of the circulatory system in many AMPHIBIANS that supplies the LUNGS & SKIN

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16
Q

Pulmonary Circuit

A

the branch of the circulatory system that moves blood between the heart and the lungs. (SUPPLIES THE LUNGS)
- The OXYGENATED blood then flows BACK to the heart.

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17
Q

Systemic Circuit

A

the branch of the circulatory system that moves blood B/T the HEART and the REST of the BODY.
- It SENDS OXYGENATED blood out to cells and RETURNS DEoxygenated blood to the heart.

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18
Q

Respiration

A

the UPTAKE of molecular O2 from the environment & the DISCHARGE of CO2 to the environment

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19
Q

Cellular respiration

A

the catabolic pathways of aerobic & anaerobic respiration, which break down organic molecules & use an electron transport chain for the production of ATP

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20
Q

Respiratory medium

A

the CONDITIONS for GAS EXCHANGE vary considerably, depending on whether the respiratory medium-the source of O2-is AIR OR WATER

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21
Q

Solubility

A
  • O2 is NOT very soluble in water (or blood)

- O2 IS soluble in air

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22
Q

Respiratory surface

A
  • specialized in gas exchange is apparent in the structure of the respiratory surface, THE PART OF AN ANIMAL’S BODY WHERE GAS EXCHANGE OCCURS
  • always MOIST (have plasma membrane that must be in contact with an aqueous solution)
  • the movement of O2 & CO2 across moist respiratory surfaces takes place entirely BY DIFFUSION
  • gas exchange is FAST when the AREA for diffusion is LARGE & the PATH for diffusion is SHORT
  • as a result, respiratory surfaces tend to be LARGE & THIN
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23
Q

Gill

A
  • are outfoldings of the body surface that are suspended in the water
  • regardless of their distribution, gills often have a total surface area much greater than that of the rest of the body’s exterior
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24
Q

Lung

A

an infolded respiratory surface of a terrestrial vertebrate, land snail, or spider that connects to the atmosphere by narrow tubes

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25
Q

Ventilation

A

the flow of air or water over a respiratory surface

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26
Q

Tracheal system

A

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

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27
Q

Compare the three types of circulatory systems

A

Gastrovascular Cavity:

  • animals with body shapes that permit them to live WITHOUT a distinct circulatory system
  • in hydras, jellies, & other cnidarians, a central gastrovascular cavity functions in the distribution of substances throughout the body & in digestion
  • an opening at 1 end connects the cavity to the surrounding water

Open Circulatory System:

  • arthropods & molluscs
  • in which the circulatory fluid BATHES the organs directly
  • the circulatory fluid; hemolymph, is also the interstitial fluid that bathes the cells

Closed Circulatory System:

  • a circulatory fluid; blood is CONFINED TO VESSELS & is distinct from the interstitial fluid
  • 1 or more hearts pump blood into large vessels that branch
  • chemical exchange occurs b/t the blood & the interstitial fluid, as well as b/t the interstitial fluid & body cells
  • Annelids (including earthworms), cephalopods (including squids & octopuses), & all vertebrate
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28
Q

Discuss the advantage the OPEN system has over the closed system

A

Open:
- the lower hydrostatic pressures associated with OPEN circulatory systems make them LESS costly in terms of energy expenditure
- in some invertebrates, open systems serve additional functions:
EX: spiders use the hydrostatic pressure generated by their open circulatory system to extend their legs

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29
Q

Summarise the evolution of the vertebrate circulatory system

A
  • in most ancient vertebrates (jawless, bony, & cartilaginous fish), the heart consists of 2 chambers: an atrium & a ventricle
  • the blood passes through the heart once in each complete circuit, an arrangement called SINGLE CIRCULATION
  • blood collects in the atrium, then enters the ventricle
  • contraction of the ventricle pumps blood to the arteries that lead to the gills
  • in the capillaries of the gills, O2 diffuses into the blood as CO2 leaves the blood
  • from the gills, the blood travels to the rest of the body, releasing O2 before returning to the heart
  • other vertebrates evolved a DOUBLE CIRCULATION, where the blood moving b/t the heart & the rest of the body (the systemic circuit) is separated from the blood that travels b/t the heart & the respiratory surface (the pulmonary circuit)
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30
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, AKA sponges, cnidarians & flatworms, every cell in the body is close enough to the external environment that gases can diffuse quickly b/t all cells & the environment
  • in many animals, however, 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 & some amphibians
  • below the skin, a dense network of capillaries facilitate the exchange of gases b/t the circulatory system & the environment
  • b/c the respiratory system must remain moist, earthworms & many other skin-breathers can survive for extended periods only in damp places
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31
Q

Compare water and air as respiratory media

a. Discuss the properties of the different respiratory surfaces used in each medium

A

O2 is plentiful in AIR (makes up 21% of Earth’s atmosphere by volume)

  • compared to water, air is much LESS DENSE & LESS VISCOUS, so it is easier to move & to force through small passages
  • therefore, breathing air is EASY

gas exchange with WATER as the respiratory medium is much MORE DEMANDING
- 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, & GREATER VISCOSITY mean that aquatic animals such as fishes & lobsters must expend considerable energy to carry out gas exchange
page 986

32
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
33
Q

Interstitial fluid

A

the fluid filling the spaces b/t cells in most animals

34
Q

Fishes closed circulatory system that evolved:

A

basically a single circuit

- 2 chambered heart

35
Q

Amphibians closed circulatory system that evolved:

A
  • 2 different circuits
  • 3 chambered heart (ridge that keeps blood separated)
  • circuit to lungs/skin
  • and one that goes to all the body tissues to feed them the oxygen & collect CO2 waste
  • 2 pumps so maintain a lot of blood pressure & you don’t lose it after going through 1 capillary bed before going to another one
  • linkage b/t 2 circuits
36
Q

Reptiles closed circulatory system that evolved:

A
  • do same (AS AMPHIBIANS) with the ridge to separate blood but put a more solid wall instead of a ridge just to keep the separation a little bit better
  • single ventricle
  • some linkage b/t 2 circuits
37
Q

Mammalian closed circulatory system that evolved:

A
  • 4 chambered heart
  • 2 distinct muscles that contracts independently more or less
  • 2 circuits (no linkage b/t them)
38
Q

Why is 2 different circuits (like in the amphibians) more beneficial over the single circuit (in the fishes)?

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 A TON, 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
39
Q

Insects and many other invertebrates have an OPEN circulatory system, what does this mean?

A

NO vessels (pulls “blood” up & then dump it, soaks down through body but NOT in blood vessels)

40
Q

More “advanced” animals have a CLOSED circulatory system, why?

A
  • more reliable
  • maintains higher blood pressure
  • allows differential control of blood flow to different body parts
  • ensures every cell has access to highly oxygenated blood
  • can deliver blood further away from the heart
41
Q

What is the circulatory path?

A

artery = vessel taking blood from the heart to the capillary beds
vein = vessel taking blood from the capillary beds to the heart
- whether oxygen-rich or -poor depends on which circuit
- not based on if they contain oxygen or not

42
Q

Oxygenated blood is…

A

red

43
Q

Deoxygenated blood is…

A

red

44
Q

What are the 4 types of blood vessels?

A
  1. Arteries: convey blood from heart to other tissues
  2. Veins: convey blood from other tissues back to the heart
  3. capillaries: microscopic vessels that permeate all tissues
  4. portal veins: convey blood from one capillary bed to another capillary bed
45
Q

Rank the blood vessels from highest pressure to lowest pressure…

A
  1. arteries - b/c deliver blood from pump to capillary bed
  2. portal veins - (big fat veins) low pressure but not as low as the veins after them
  3. veins - b/c blood has already gone through capillary bed
  4. capillaries - b/c they are so tiny
46
Q

Why does the insect system not work in larger animals?

A

b/c the bigger it is the harder it is to passively move the gases in & out

  • can’t pull air in far enough & effectively enough
  • it’s not efficient at all for very large bodies
  • crustaceans do a better job by moving O2 around in their blood & they gather O2 from their gills (need to distribute O2 from these local centres throughout the body so they need O2 carrying blood unlike the insects)
47
Q

Small &/or simple invertebrates respiratory system…

A

ex: porifera, cnidarians, platyhelminths
- no respiratory “system” needed
- b/c they don’t have to move anything around, don’t need any special organs to move gases around/in & out
- ALL cells in contact with surrounding medium

48
Q

Porifera respiratory system…

A

pull water through & all the cells are constantly bathed in water

49
Q

Cnidaria respiratory system…

A

very small, even if they are not, their body tissues are skinny, super thin, water is brought inside & pumped right out so all cells are VERY close to water outside

50
Q

Platyhelminthes respiratory system…

A

small and VERY flat, so none of the cells are very far away from the outside of their body

51
Q

What is the insects respiratory system?

A
  • open circulatory system
  • spiracle/tracheal respiratory system
  • NO oxygen in hemolymph
  • NO lungs & don’t convey only gases via their circulatory system so oxygen is not transported around their bodies/hemolymph
  • don’t breathe through mouths, they BREATH THROUGH SPIRACLES that lead to the trachea
  • chemical counter current exchange
52
Q

What is the crustaceans respiratory system?

A
  • open circulatory system
  • GILLS (work in water, not in air)
    • centralized organs
      • so in order to get the oxygen from these gills to the rest of the body you have to transport it though blood
  • OXYGEN-carrying pigment IN hemolymph
    • carry CO2 & oxygen in hemolymph
    • to move oxygen around their bodies
53
Q

What is the aquatic vertebrates respiratory system?

A

ex: fishes
- closed circulatory system
- GILLS (localized structure that collects oxygen from the water & has to be distributed, so oxygen is distributed in aquatic vertebrates)
- COUNTERCURRENT GAS EXCHANGE

54
Q

What is the terrestrial vertebrates respiratory system?

A
  • closed circulatory system
    • transport O2 via circulatory system b/c this is a centralized location where we’re gathering the oxygen to distribute it through the body in lungs
  • LUNGS (control evaporation)
    • have to keep respiratory membranes moist so we can get gases across them & into our tissues easily
55
Q

What is the Amphibians way of breathing?

A

POSITIVE pressure breathing (b/c they’re pushing air into their lungs)

  • basically gulp air in using muscles in the mouth
    • push air out of mouth but mouth is closed so it goes to the lungs so they inflate their lungs this way
      • do gas exchange & then basically open mouths to release air back out
56
Q

What is the Birds way of breathing?

A

POSITIVE pressure breathing system
- circular breathing…sort of (air goes 1 way through)
- air pulled into air sacs
- air pushed THROUGH the lungs into other air sacs
chemical counter current exchange

57
Q

What is the Mammals way of breathing?

A

NEGATIVE pressure breathing

- air pulled into lungs using primarily the diaphragm

58
Q

What is chemical counter current exchange?

A

means water flows 1 direction & blood flows opposite direction, it always maintains a nice partial pressure gradient in concentration b/t these 2 surfaces & just breathes much more efficiently

59
Q

What is the control of breathing in humans?

A
  1. voluntary (inhale & exhale, with motor side of brain, sends motor commands down through spinal cord & you can control them)
  2. DETECTION of LOW CEREBROSPINAL FLUID PH in the medulla
    H20 + CO2 H2CO3 H+ + HCO3-
  3. DETECTION of LOW O2 LEVELS in aorta & carotid arteries signal brain stem
  4. pons…somehow
    • body temp, breathing rate etc. that you’re not aware of occur in brainstem
60
Q

How much is the partial pressure of oxygen?

A

about 160 mmHg

61
Q

The partial pressure of gas is…

A

always the same

62
Q

What helps move O2?

A
  • hemoglobin (a pigment) helps
    • attract O2 molecules, O2 has a high affinity
  • increases blood’s ability to hold O2 approx. 50 fold
  • hemoglobin exhibits “cooperativity”
    • changes shape in various conditions
  • passively go into bloodstream, just following partial pressure gradient but it’s also gonna be grabbed onto by the heme group (cofactor, that has a iron atom at its centre) which attract oxygen
63
Q

What happens if O2 is chronically in short supply?

A
  • we can change our physiology a little
  • MORE hemoglobin (more red blood cells) will be made, &/or…
    • so there is more vehicle in our circulatory system to move O2 around
  • different hemoglobin isoforms with higher O2 affinity will be made
64
Q

What is gas exchange (respiration)?

A

is the movement of O2 from the OUTSIDE environment TO the cells within tissues, and the REMOVAL of CO2 in the OPPOSITE direction.

65
Q

What are the 2 main disadvantages in the single circuit of fish?

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 is forced to rely upon deoxygenated blood for its own metabolic needs
    - though less efficient than the other vertebrate systems, it works well enough in these animals, which generally have relatively low metabolic demands
66
Q

Ostia

A

Ostia are the inhalant pores in the body of sponges.

  • Water enters the body of sponges through ostia and reaches the spongocoel.
  • It then flows out of the body through osculum.
  • Ostia is present only in sponges i.e. phylum Porifera as sponges have a porous body.
67
Q

Discuss the advantages the open system over the gastrovascular cavity

A

Open system:

  • circulatory fluid bathes the organs DIRECTLY
  • of larger crustaceans, such as lobsters & crabs, includes a more extensive system of vessels as well as an accessory pump

Gastrovascular:

  • only simple animals (hydra, jellies, & cnidarians)
  • fluid bathes BOTH the inner & outer tissue layers, facilitating exchange of gases & cellular waste
  • ONLY the cells lining the cavity have DIRECT access to nutrients released by digestion
  • however, b/c the body wall is a mere 2 cells think, nutrients need diffuse only a short distance to reach the cells of the outer tissue layer
68
Q

Positive Pressure Breathing

A

a breathing system in which air FORCED into the lungs

69
Q

Negative Pressure Breathing

A

a breathing system in which air is PULLED into the lungs

70
Q

What is hemoglobin and what does it do?

A
  • vertebrate hemoglobin consists of 4 subunits (polypeptide chains), each with a cofactor called a heme group that has an iron at its centre
  • each iron atom binds 1 molecule of O2; hence, a single hemoglobin molecule can carry 4 molecules of O2
  • so it INCREASES blood’s ability to hold O2
  • exhibits “cooperativity”
71
Q

What is the Bohr effect?

A

a lowering of the affinity of hemoglobin for O2, caused by a drop in pH
- it facilitates the release of O2 from hemoglobin in the vicinity of active tissue

72
Q

Like low pH, HIGH temp causes a

A

REDUCTION in the O2 affinity, FAVOURING unloading

- helpful under exercise conditions

73
Q

Describe how oxygen is transported within the circulatory system

A
  • gas exchange in mammals occurs IN ALVEOLI, air sacs clustered at the tips of the tiniest bronchioles
  • oxygen in the air entering the alveoli DISSOLVES in the MOIST FILM lining their inner surfaces & rapidly diffuses across the epithelium into a web of capillaries that surrounds each alveolus
  • net diffusion of CO2 occurs in the opposite direction, from the capillaries across the epithelium of the alveolus & into the air sac

OR IDK

Although oxygen dissolves in blood, only a small amount of oxygen is transported this way. Only 1.5 percent of oxygen in the blood is dissolved directly into the blood itself. Most oxygen—98.5 percent—is bound to a protein called hemoglobin and carried to the tissues. *

74
Q

Explain how CO2 is transported within the circulatory system

A

Carbon dioxide can be transported through the blood via three methods.

  1. It is dissolved directly in the blood
  2. bound to plasma proteins or hemoglobin, or
  3. converted into bicarbonate.
  • The majority of carbon dioxide is transported as part of the bicarbonate system. Carbon dioxide diffuses into red blood cells. *
75
Q

Carbonic anhydrase

A

An enzyme present in red blood cells, carbonic anhydrase, aids in the conversion of carbon dioxide to carbonic acid and bicarbonate ions. *

76
Q

What do respiratory pigments do?

A
  • animals transport most of their O2 bound to these proteins
  • circulate with the blood or hemolymph & are contained within specialized cells
  • greatly INCREASE the amount of O2 that can be carried in the circulatory fluid

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