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Biology > Topic 1: Circulatory systems > Flashcards

Topic 1: Circulatory systems Flashcards

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1
Q

What does the need for a heart and circulatory system depend on?
(3 points)

A
  1. The surface area to volume ratio – linked to size
  2. {Metabolic rate/activity level/demand for oxygen}
  3. Body shape eg. flattened
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2
Q

Why do amoeba (unicellular) not have a circulatory system?

3 points

A
  1. has a LARGE surface area to volume ratio
  2. has a {LOW METABOLIC RATE/activity level/oxygen demand}
  3. oxygen can DIFFUSE from the gas exchange surface (cell membrane/body surface) through the cytoplasm fast enough to keep the Amoeba alive
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3
Q

Why do flatworms (multicellular) not have a circulatory system?
(4 points)

A
  1. still has a fairly large surface area to volume ratio (but smaller than Amoeba)
  2. has a low demand for oxygen
  3. flattened body means no cell is very far from the gas exchange (body) surface
  4. oxygen can diffuse from the body surface then from cell to cell fast enough to keep the flatworm alive
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4
Q 
Key Summary
(Circulatory systems) Why do very small organisms not need a {transport system/heart and circulation}?
(4 points)
A
  1. Large surface area to volume ratio
  2. Diffusion is sufficient to supply cells with oxygen fast enough to meet oxygen {requirements/demand} and keep the organism alive
  3. All cells are close to body surface (read the question – cannot say if made of only one cell!)
  4. Usually have a low metabolic rate, so low demand for oxygen
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5
Q

Larger multicellular organisms have a _______surface area to volume ratio

oxygen needs to travel a ________ _________ to get from the gas exchange surface (lungs, gills) to the very innermost cells

cells nearest the gas exchange surface use up oxygen and nutrients before they can reach inner cells

A

smaller

greater distance

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6
Q

What does a good transport system need?

3 points

A
  1. A fluid to carry nutrients and oxygen (eg. blood)
  2. A PUMP to move the fluid around the body (eg. heart)
  3. EXCHANGE SURFACES to allow oxygen and nutrients to:
    - enter the fluid/blood (eg. lungs, gills)
    - to leave the blood at places where nutrients are needed (cells/tissues)
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7
Q 
Key Summary
(Circulatory systems) Why do larger organisms need a mass transport system?
(5 points)
A
  1. To move molecules quickly between gas exchange surfaces and cells
  2. As many cells are far away from body surface or heart
  3. SMALL SURFACE AREA TO VOLUME RATIO
  4. TO OVERCOME THE LIMITATIONS OF DIFFUSION - diffusion is NOT {sufficient/fast enough} to supply cells with oxygen + remove carbon dioxide efficiently enough to keep the organism alive
  5. Higher metabolic rate, more active , higher demand for oxygen
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8
Q 
Key Summary
(Circulatory systems) What is the importance of a circulatory system?
(3 points)
A
  1. Overcomes the limitation of diffusion
  2. HEAT TRANSFER - helps regulate body temperature in endotherms
  3. TRANSPORTS blood around the body to deliver oxygen to cells/remove carbon dioxide
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9
Q

What are the types of circulatory systems? give examples for each type
(3 types)

A
  1. Open circulatory system (eg. molluscs and arthropods, including insects)
  2. Closed, single circulatory system (eg. fish)
  3. Closed, double circulatory system (eg. mammals)
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10
Q 
Key definition
(Circulatory systems) Open circulatory system definition (3 points)
A

(1) lower pressure blood circulates inside a body cavity , (2) NOT inside blood vessels, and (3) bathes body organs.

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11
Q

Explain how an open circulatory system works (3 points)

A
  1. A simple heart causes the blood to circulate around the cavity
  2. The organs are bathed in a ‘blood/fluid’ and diffusion of nutrients and waste takes place between the blood and organs
  3. Blood is under low pressure
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12
Q

An open circulation works for invertebrates because they…
(2 points)

So… (2 points) (give explanation above points)

A
  1. ARE SMALL (large surface area to volume ratio) so the blood doesn’t have far to travel)
  2. HAVE A LOW METABOLIC RATE

SO

  1. Movement of blood to the heart is fast enough without blood vessels
  2. Diffusion is fast enough to supply tissues with nutrients and remove waste
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13
Q

Eventually as organisms get larger and they need a ______ ________.

Blood stays in _________.

Tissue fluid which bathes the cells is now separated from the _______.

A

closed circulation

vessels

blood

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14
Q 
Key definition
(Circulatory systems) Closed circulatory system definition
(1 point)
A
  1. higher pressure blood circulates inside blood vessels eg. arteries and veins
Organisms with closed circulatory systems:
vertebrates
some invertebrates (e.g. earthworm)
reptiles
amphibians
fish
birds
mammals
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15
Q

(Circulatory systems) Advantages of a closed circulatory system (over an open circulatory system)
(4 points)

A
  1. blood at a HIGHER PRESSURE
  2. so blood flows FASTER TO BODY TISSUES
  3. O2 and nutrients are delivered MORE quickly to cells
  4. waste and CO2 are removed MORE quickly from cells
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16
Q

Explain single circulatory systems
(2 points)

Give an example of an organism with a single circulatory system

A
  1. Blood PASSES THROUGH THE HEART ONCE during each complete circuit of the body.
  2. Blood travels from the heart to the gas exchange surface, then to body tissues/cells, then back to the heart.

Example: Fish

17
Q

Explain single closed circulatory systems

5 points

A
  1. Blood in blood vessels
  2. blood PASSES THROUGH THE HEART ONCE during each complete circuit of the body
  3. 2 chamber heart
  4. blood from heart to gill capillaries, then from gills to rest of the body capillaries (at lower blood pressure than in double circulation), then back to the heart
  5. relatively LOW oxygen demand, LOW metabolic rate, cold-blooded
18
Q 
Key definition
(Circulatory systems) Double circulatory systems definition (5 points)

Give 4 examples of organisms with a double circulatory system

A

(1) blood passes through the heart twice for each circulation of the body - (2) heart to lungs (3) then back to heart (pulmonary circulation), (4) heart to body tissue/organs (5) then back to heart (systemic circulation)

Examples: amphibians, reptiles, birds, mammals

19
Q

Explain double closed circulatory systems

6 points

A
  1. Blood in blood vessels
  2. HIGHEST BLOOD PRESSURE TO ORGANS
  3. blood passes through the heart twice for each circulation of the body
  4. 4 CHAMBER HEART - right side the heart transports blood to lungs (pulmonary circulation) and left side transports blood to the body (systemic circulation)
  5. MOST EFFICIENT OXYGEN DELIVERY TO TISSUES
  6. CAN CREATE DIFFERENT PRESSURES
20
Q

Key Summary
(Circulatory systems) Advantages of a double circulatory system (+ heart divided into right and left sides)
(4 advantages)

A
  1. Oxygenated + deoxygenated blood CANNOT MIX - so tissues receive maximum oxygen and waste is removed efficiently
  2. Allows birds and mammals to MAINTAIN A CONSTANT BODY TEMPERATURE, sustain a high metabolic rate and be more active
  3. Blood travels through heart twice in one circuit of body allowing different pressures to be created by each side of heart
    - HIGH PRESSURE, OXYGENATED BLOOD, FASTER TO BODY FROM LV
    - low pressure, deoxygenated, slower blood sent to the LUNGS
    STOPS DELICATE LUNG CAPILLARIES FROM BURSTING
  4. REPRESSURISATION- blood returning from the lungs receives an extra ‘boost’ to decrease systemic circulation time
21
Q 
Key Summary
(Circulatory systems) Why do {many/larger} animals need a heart and circulation? (7 points)
A
  1. HEART GENERATES PRESSURE TO PUMP OXYGENATED BLOOD AROUND THE BODY, allowing MASS TRANSPORT (mass flow)
  2. animals have a SMALL SURFACE AREA TO VOLUME RATIO
  3. TO OVERCOME THE LIMITATIONS OF DIFFUSION - diffusion is not sufficient to meet oxygen requirements of cells
  4. many cells are far away from gas exchange surface
  5. to carry/circulate blood around the body to {DELIVER OXYGEN TO CELLS / REMOVE CARBON DIOXIDE FASTER}
  6. they may have a higher metabolic rate/higher demand for oxygen/higher activity
  7. helps REGULATE BODY TEMPERATURE IN {ENDOTHERMS/warm blooded animals} - as it transfers heat around the body
22
Q

Define mass transport system

2 points

A
  1. Substances are transported in the flow of a fluid

2. with a mechanism for moving the fluid around the body. (e.g. heart and circulatory system)

Biology (95 decks)

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