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Biology > Heart and the cardiac cycle > Flashcards

Heart and the cardiac cycle Flashcards

(49 cards)

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1
Q

What is the role of arterioles?

A
  • Take blood from artery to capillary
  • A layer of smooth muscle which contracts restricting and slowing blood flow
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2
Q

State two disadvantages of open circulatiory system

A
  • Blood pressure is low and blood flow is therefore slow
  • Circulation can be affected by body movement
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3
Q

What is the inner tissue lining of a blood vessel called? What is its role?

A
  • Endothelium
  • Reduced friction with the flowing blood
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4
Q

Describe thre structural layers of an artery

A
  • Thick layer of elastic tissue - allow walls to stretch and recoil
  • Thick layer of thick muscle
  • Thick layer of collagen and elastic tissue - provide strength to withstand the high pressure and recoiling against the msucle
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5
Q

Describe how cappilaries are adapted for exchange

A
  • Narrow lumen - maintain high pressure
  • Single layer of endothelium cell - reduce diffusion distance
  • Permeable walls - allow blood plasma and dissolved substance to leave the blood
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6
Q

What are the 4 blood components?

A
  • Red Blood Cells (erythrocytes)
  • White Blood Cells (lymphocytes)
  • Platelets
  • Plasma
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7
Q

Definition of tissue fluid

A

Fluid that surrounds cells in tissues

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8
Q

Definition of hydrostatic pressure

A

Pressure exerted by a liquid

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9
Q

Definition of oncotic pressure

A

Pressure exerted by plasma proteins in capillaries

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10
Q

How to calculate pressure filtration?

A

Pressure filtration = hydrostatic pressure – oncotic pressure

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11
Q

Describe the difference between an open and closed circulatory system

A
  • Closed circulatory system – the blood is moved inside vessels
  • Open circulatory system – no blood vessels
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12
Q

Describe the difference between a single and double circulatory system

A
  • Single – Blood passes through the heart once, for each circuit of the body
  • Double – Blood passes through the heart twice, for each circuit of the body.
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13
Q

Function of artery

A

Carry blood from the heart to the rest of the body

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14
Q

Function of arteriole

A

Branch off the arteries to carry blood to the tissues

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15
Q

Type of blood carried by artery (apart from pulmonary artery)

A

Oxygenated

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16
Q

Pressure of blood in arteriole

A

High

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17
Q

Thickness of wall of artery

A

Very thick

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18
Q

Type of blood carried by arteriole

A

Oxygenated

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19
Q

Pressure of blood in artery

A

Very high

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20
Q

Thickness of wall of artery

21
Q

Structures present in wall of artery

Study These Flashcards
A
  • Very thick layer of smooth muscle
  • Thick layer of elastic tissue
  • thick layer of collagen
22
Q

Diameter of lumen in artery

Study These Flashcards
A

Narrow, but has folded endothelium, so it can expand

23
Q

Diameter of lumen in arteriole

24
Q

Structures present in wall of arteriole

Study These Flashcards
A
  • Thick layer of smooth muscle
  • Thinner layer of elastic tissue
25
Function of capillary
Exchange of substances between the blood and the cells
26
Pressure of blood in capillary
Very low
27
Thickness of wall of capillary
One cell thick
28
Structure present in wall of capillary
Endothelium
29
Diameter of lumen of capillary
Very narrow
30
Function of venule
Connect the tissues to veins
31
Type of blood carried in venule
Deoxygenated
32
Pressure of blood in venule
Low
33
Thickness of wall in venule
Thin
34
Structure present in wall of venule
Very thin layer of smooth muscle and elastic tissue
35
Diameter of lumen of venule
Wider
36
Function of vein
Carry blood from the tissues back to the heart
37
Type of blood carried by vein (apart from pulmonary vein)
Deoxygenated
38
Pressure of blood in vein
Low
39
Thickness of wall of vein
Thin
40
Structure present in wall of vein
Very thin layer of smooth muscle and elastic tissue
41
Diameter of lumen of vein
Wider
42
Describe how tissue fluid and lymph are formed from plasma
1. At the start of the capillary network, near the artery, the hydrostatic pressure in the blood is high 2. This forces small molecules out of the blood into the tissue fluid 3. At the end of the capillary network, near the vein, the hydrostatic pressure in the blood is lower 4. However, the oncotic pressure of the blood is high 5. This is because the blood has a lower water potential than the tissue fluid 6. Most water re-enters the blood, by osmosis 7. Excess tissue fluid enters the lymph capillaries 8. The lymphatic system returns the fluid to the blood
43
Compare the differences and similarities between blood, tisse fluid and lymph
* All: Phagocytes, water, dissolved solutes, protein (only a few in tissue fluid, only antibodies in lymph) * Blood and lymph: Lymphocytes * Only blood: Red blood cells, platelets
44
Explain why red blood cells are not found in tissue fluid or lymph
* Red blood cells are too large to pass through the capillary endothelium into the tissue fluid. * The lymph is formed from the tissue fluid.
45
What is the value of oncotic pressure?
3.3kPa
46
What is the structure of haemoglobin and how it is adapted to its function?
* It is a complex protein with 4 subunits * Each subunit consists of a polypeptide chain and a haem (non-protein) group * The haem group contains a single iron (Fe 2+) atom which can attract and hold one oxygen molecule * The haem group is said to have an affinity for oxygen * Each haem group can hold one molecule of oxygen * So each haemoglobin molecule can carry 4 molecules of oxygen
47
How does haemoglobin carry oxygen?
* At low pO2 the Hb does not readily take up oxygen * This is because the haem groups are in the centre of the molecule thus making it difficult for oxygen to reach them to associate with them * As the pO2 rises the diffusion gradient into the Hb molecule increases and eventually one oxygen molecule will diffuse into the Hb and associate with a haem group * This slightly changes the shape of Hb * This is called conformational change/ positive cooperativity * This allows more oxygen molecules to diffuse into the Hb * This allows more oxygen molecules to diffuse into the Hb * This accounts for the steepness of the oxygen dissociation curve as the pO2 rises * One the Hb contains 3 oxygen molecules it finds it difficult to gain the 4th molecule. So it is difficult to achieve 100% saturation even when the pO2 is high
48
What is positive cooperativity/ conformational change in haemoglobin?
Binding of first oxygen changes haemoglobin's shape This increases the affinity for oxygen
49
How does foetal Hb adapt to its environment?
* Foetal Hb has a higher affinity for O2 than adult Hb * If it was the same, no O2 would transfer in the placenta * In the placenta the adult Hb runs close to the Foetal Hb so adult Hb releases oxygen to foetal Hb

Biology (7 decks)

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