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A-levle Biology > 3.1.2 - Transport In Animals (set A - Circulatory Systems And Blood Vessels) > Flashcards

3.1.2 - Transport In Animals (set A - Circulatory Systems And Blood Vessels) Flashcards

1
Q

Outline the need for specialised transport systems - give 4 reasons?

A
  • metabolic demands are high - require lots of substances and produce lots of waste products
  • SA:V ratio gets smaller - diffusion distances get bigger and the surface area for substances to exchange across decreases
  • transport of hormones or enzymes to other sites
  • waste products need to be removed from cells and transported to excretory organs
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2
Q

Explain the main features of most circulatory systems?

A
  • have a liquid transport medium that circulates around the system
  • have vessels that carry the transport medium
  • have a pumping mechanism to move fluid around the system
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3
Q

Definite what a mass transport system is?

A

When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body

  • multicellular animials have either an open or closed system
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4
Q

Outline main features of an open circulatory system?

A
  • very few vessels to contain transport medium
  • pumped straight from heart into body cavity (haemocoel)
  • transport medium in haemocoel is under low pressure - comes into direct contact with tissue and cells
  • transport medium returns to heart through open-ended vessel
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5
Q

Briefly describe an open circulatory system?

A

Transport medium pumped straight from heart into haemocoel where its under low pressure and exchanges gases directly with the tissues and cells

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6
Q

Explain what the haemocoel is?

A

The open body cavity of the animal which the transport medium is directly pumped into

  • transport medium under low pressure
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7
Q

Outline the type of circulatory system preset in most insects - explain the features?

A
  • open circulatory system
  • blood called haemolymph (doesn’t carry oxygen or carbon dioxide - transports food and nitrogenous waste products)
  • haemocoel split by membrane - heart extends along length of thorax and abdomen
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8
Q

Explain the function of haemolymph?

A

Transport medium of most insects - doesn’t carry oxygen or carbon dioxide - transports food and nitrogenous waste products

  • also contains cells involved in fighting diseases
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9
Q

Explain a problem with open circulatory systems?

A
  • Haemolymph circulates however steep concentration gradient cannot be maintained - prevents efficient diffusion
  • amount of haemolymph flowing to particular tissues can not be varied to meet changing demands
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10
Q

Outline the main features of a closed circulatory system?

A
  • blood enclosed in vessels - doesn’t directly come into contact with cells
  • heart pumps blood under pressure around body
  • substances diffuses in and out of the vessel walls
  • blood flow to particular tissues can be adjusted
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11
Q

Briefly explain a closed circulatory system?

A

Blood is enclosed within vessels and is pumped around the body under pressure - substances diffuse in and out of the blood through the vessel walls

  • blood pigment carries respiratory gases
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12
Q

Outline an important advantage of closed circulatory systems?

A

Blood flow to particular tissues can be adjusted by widening or narrowing blood vessels

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13
Q

Briefly outline what single circulatory systems are?

A

Blood flows through heart and is pumped around body before returning to the heart (travels once through heart for each complete circulation of the body)

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14
Q

Outline the features of a single circulatory system?

A
  • blood passes through 2 sets of capillaries before retuning to heart
  • first capillary it exchanges O2 and CO2 - second set of capillaries, substances are exchanged between blood an the cells
  • blood returns to heart slowly due to very narrow vessels
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15
Q

Explain why single circulatory systems are often found in low activity animals?

A

Blood pressure in the system drops considerably due to blood passing through two sets of very narrow vessels - blood returns to heart quite slowly

  • limits efficiency of exchange processes
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16
Q

Explain why some active animals like fish are able to have a single circulatory system?

A

Have very efficient system - due to countercurrent gas exchange in the gills, allowing the removal of lots of O2 from water

  • body weight is supported by the water and they do not have to maintain body temperature (reduces metabolic demands)
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17
Q

Outline what a double circulatory system is?

A

Most efficient system for transporting substances around the body - blood travels twice through the heart for each circuit of the body

  • each circuit - to the lungs and to the body only pass through one capillary network
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18
Q

Explain how high pressure is maintained in a double circulatory system?

A

Each circuit - to the lungs and to the body - only passes through one capillary network, which allows a relatively high pressure and fast flow of blood to be maintained

19
Q

Explain the main features of a double circulatory system?

A
  • blood is pumped from heart to lungs to pick up O2 and unload CO2, then returns to heart
  • blood flows through the heart and is pumped out to travel around the body before returning to the heart again
20
Q

Explain the role of elastic fibres in vessels, give brief structure?

A

Composed of elastin - can stretch and recoil providing vessel walls with flexibility

21
Q

Explain the role of smooth muscle in vessels?

A

Contracts or relaxes which changes the size of the lumen - controls blood flow

22
Q

Explain the role of collagen in vessels?

A

Provides structural support to maintain the shape and volume of the vessel

23
Q

Outline the main features of arteries?

A
  • contain elastic fibres, smooth muscle and collagen
  • elastic fibres help even out surges of blood
  • blood transported under high pressure
  • endothelium lining is smooth for easy blood flow
  • Carry oxygenated blood
24
Q

Outline the importance of elastic fibres in arteries?

A
  • enables vessel to stretch to withstand force of blood as its pumped from the heart, and increase blood volume - collagen prevents overstretching
  • recoil and return to original length between contractions of the heart - evening out surges of blood, gives a continuous flow
25
Q

Outline and explain 3 adaptions arteries have?

A
  • smooth endothelium - allows for easy blood flow
  • elastic fibres which allowing vessel to stretch to increase blood flow and maintain pressure + evens out surges allowing for continuous flow
  • collagen prevents elastic fibres from overstretching
26
Q

Outline what arterioles are - give brief structure?

A

Vessels which link arteries and capillaries

  • smooth muscle and less elastin (little pulse surge) in walls
  • smooth muscles allows constriction and dilation to control blood flow to individual organs
27
Q

Explain why arterioles have less elastic fibres but more smooth muscle than arteries?

A
  • Have little pulse surge, so do not need much elastic fibre to recoil and relax to even out surges
  • have more smooth muscle to control blood flow - contracts to constrict vessel (vasoconstriction) and relax to dilate vessel (vasodilation)
28
Q

Outline what capillaries are - give brief structure?

A

Extremely small blood vessels that link arterioles with the venules by forming an extensive network through tissues

  • lumen is narrow enough that RBCs move in single file
  • large gaps between endothelial cells in the walls
29
Q

Explain the significance of gaps within capillary walls?

A

Large gaps between endothelial cells that make up capillary walls allow movement of substances into surrounding cells

30
Q

Outline an explain 3 ways capillary’s are adapted for their role?

A
  • provide a very large SA for diffusion of substances in and out
  • total cross-sectional area of capillaries is greater than arteriole supplying them - rate of blood flow falls, increasing time for diffusion
  • walls are single endothelial cell thick - short diffusion path
31
Q

Why is the cross-sectional area of capillaries being larger than supplying arteriole important?

A

Results in the rate of blood flow falling - slower movement of blood through capillaries allows for more time for the exchange of substance by diffusion between blood and the cells

32
Q

Outline what veins are - give brief structure?

A

Carry deoxygenated blood at low pressure from cells towards heart - join to form 2 main vessels (inferior vena cava and superior vena cava)

  • walls contain lots of collagen, relatively little elastic fibre
  • wide lumen and smooth, thin endothelium
33
Q

Outline what venules are and the role they play - give brief structure?

A

Link capillaries with the veins - several join together to form vein

  • have very thin walls and little smooth muscle
34
Q

Explain why veins do not have a pulse?

A

Surfers from the heart pumping are lost - due to blood passing through narrow capillaries

  • do however hold larger reservoir of blood - 60%
35
Q

Give the features of veins?

A
  • blood pressure is low compared to arteries
  • valves to prevent back flow of blood
  • walls contain lots of collagen, relatively little elastic fibres
  • wide lumen - higher blood volume
  • smooth endothelium - easy blood flow
36
Q

Explain 3 ways veins are adapted to return blood whilst under low pressure?

A
  • contain one-way valves which open so blood can pass through and close if blood starts flowing backwards
  • bigger veins run between big, active muscles which force blood towards the heart
  • breathing movements of the chest act as a pump
37
Q

Outline how breathing movements of the chest helps veins transport deoxygenated blood to the heart?

A

Acts as a pump - the pressure changes and squeezing action moves blood in the veins of the chest and abdomen towards the heart

38
Q

Outline how veins running between major muscles helps them return deoxygenated blood to the heart?

A

Veins run between big, active muscles - when they contract they squeeze the veins, which forces the blood towards the heart

  • valves then prevent back flow when the muscles relax
39
Q

Which type of veins contain valves?

A

Medium-sized veins (majority of the venous system)- have valves

40
Q

Explain the two exceptions of type of blood carried by arteries?

A

Carry oxygenated blood from the heart to tissues of body - except the pulmonary artery whcih carries deoxygenated blood from the heart to the lungs

  • umbilical artery during pregnancy carries deoxygenated blood from fetus
41
Q

Explain the two exceptions of type of blood carried by veins?

A

Carry deoxygenated blood from the tissues to the heart - except the pulmonary vein which caries oxygenated blood from the lungs to the heart

  • umbilical vein - carries deoxygenated blood from the placenta
42
Q

How are arteries adapted for withstanding high pressure?

A

Thick muscular walls - contain lots of collagen and elastic fibres

43
Q

Explain why veins have thin walls?

A

Transport blood at lower pressure - have less muscular and elastic tissue

A-levle Biology (24 decks)

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