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Biology: Alex > Topic 1 - Heart and Circulation > Flashcards

Topic 1 - Heart and Circulation Flashcards

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1
Q

Define mass flow

A

The transport of substances in bulk from one part of an organism to another

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2
Q

Why can larger organisms not rely only on diffusion

A

Low surface area to volume ratio

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3
Q

Mass transport allows organisms to overcome:

A

The limitations of diffusion

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4
Q

Main function of exchange surfaces?

A

To establish and maintain differences in conc and pressure

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5
Q

Two examples of mass flow systems

A

Xylem and phloem in a plant

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6
Q

Name 4 features of a mass flow system

A
  1. A system of vessels to carry substances
  2. A means of making sure substances are moving in right direction
  3. A means of maintaining conc gradient so that substances move fast enough to meet organisms needs
  4. Suitable transport medium
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7
Q

2 types of circulatory system

A

Closed - mammals

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8
Q

Summary of open circulation

A
  1. Simple heart pumps blood into cavities surrounding insects organs
  2. Substances diffuse in/out of cells directly into blood
  3. Heart relaxes, blood is drawn back into heart though small calves along length of heart
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9
Q

Closed circulatory systems are generally for…

A

Larger animals that are more active

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10
Q

Critical structural difference between open and closed circulation

A

Closed: blood is enclosed in tubes (arteries, veins, capillaries)

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11
Q

Main advantage of closed system

A

Blood is forced along narrow channels, creating higher blood pressure

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12
Q

Why is higher blood pressure better

A

Blood travels faster so more efficient at delivering substances around the body

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13
Q

What type of circulatory system do fish have

A

Single

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14
Q

What’s the main feature of single circulation

A

Blood only flows through heart once for each circulation

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15
Q

3 steps of single circulation

A
  1. Heart pumps deoxygenated blood to gills
  2. Gas exchange takes place as blood passes through gills (large SA)
  3. Blood leaves gills, oxygenates body, returns to heart
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16
Q

Describe simply double circulation

A

1) right ventricle pumps deoxygenated blood to lungs to be oxygenated
2) blood returns to heart, pumped a second time from left ventricle to rest of body

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17
Q

Advantages of double circulation

A
  • blood can be pumped at power pressure to lungs, reducing risk of vessel damage
  • blood returning from lungs gets an extra boost, speeding circulation around the body
18
Q

Two types circulation in humans:

A

Pulmonary circulation- low pressure, from heart to lungs, (40mmHg)

Systemic circulation- high pressure, carries blood from heart to body and back, (120mmHg)

19
Q

Structure of capillaries

A

Smaller diameter means RBCs have to flex to pass though, slows down so more time for diffusion
-
Endothelium is permeable to water and dissolved substances
-
Small pores in walls

20
Q

Structure of arteries near the heart

A

Middle layer is composed of elastic fibres, allowing them to dilate then elastically recoil

21
Q

Structure of arteries further from the heart

A

Supplied with neurones that can stimulate vasodilation/constriction

22
Q

Structure of arterioles

A

Smallest type of arteries, consist of endothelium with a few muscle fibres wrapped around them

23
Q

Structure of veins

A 
Much less muscle and elastic fibres in middle layer, so wall is thinner 
-
Diameter of lumen is greater
-
Valves to prevent back-flow
24
Q

How do skeletal muscles help to circulate blood?

Venous return

A

Contract, squeezing veins, create higher pressure in vein

25
Q

What coronary arteries

A

Can not get from 4 chambers directly

26
Q

Cardiac cycle =

A

One complete sequence of contraction and relaxation

27
Q

2 main stages of cardiac cycle

A

Diastole: heart relaxes, fills with blood

28
Q

What happens in atrial systole

A 
Atria contract
-
This pushes blood into ventricles
-
Opens atrio-ventricular valves
29
Q

What happens in ventricular systole

A 
Ventricles contract 
-
Atria relax
-
A/V valves close
-
Blood enters aorta and pulmonary vein, opening semi-lunar valves
30
Q

What happens in ventricular diastole

A 
Ventricles relax
-
Semi-lunar valves close
-
Pressure in ventricles fall so blood flows into them from atria 
-
A/V valves open
31
Q

What is cardiac diastole

A

When both atria and ventricles are relaxed at the same time

32
Q

What artery takes blood from heart to body at high pressure

A

Aorta

33
Q

How is the left ventricle structural adapted for us function

A

Has thicker more muscular walls

34
Q

What is the function of atrioventricular valves?

A

Stop backflow when ventricles contract

35
Q

Where are semi-lunar valves found?

A

Aorta

36
Q

What’s the function of semi lunar valves

A

Stop blood flowing back into the heart

37
Q

Four structural features of an artery

A 
Elastic tissue
-
Thick muscle layer 
-
Lumen 
-
Folded endothelium
38
Q

4 features of a vein

A 
Large lumen 
-
Think muscle wall
-
Valves 
-
Endothelium
39
Q

What are capillaries for?

A

Metabolic exchange- substances are exchanged between cells and capillaries

40
Q

Contraction is…

A

Systole

41
Q

Relaxation is of the heart is…

A

Diastole

Biology: Alex (44 decks)

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