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Wjec Biology Unit 2 > 2.3 Animals > Flashcards

2.3 Animals Flashcards

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1
Q

Closed circulatory system

A

Blood travels through blood vessels with the impetus being generated by a muscular pump or heart

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2
Q

Organisms with a closed circulation system

A

Earthworms, fish, mammals

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3
Q

Open circulation system

A

Blood bathed all the cells and organs of the body
Blood = haemolymph
Is in the body cavity or haemocoel

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4
Q

Advantages of closed circulation system

A

Blood is repressurized when it leaves the gas exchange surface
Faster and more efficient circulation to tissues

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5
Q

Single circulation

A

Blood passes through the heart once in each circulation

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6
Q

Example of single circulation

A

Fish

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7
Q

Describe fish circulatory systems

A

closed single
2 chambers - atrium and ventricle
Contain haemoglobin
Loses pressure around the circuit - slower circulation

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8
Q

Double circulatory system

A

Blood passes through the heart twice in one circulation of the system

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9
Q

Example of double circulatory system

A

Humans

Mammals

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10
Q

Pulmonary circulation

A

Right side of heart

To lungs for gas exchange

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11
Q

Systemic circulation

A

Left side

Blood return to heart and pumped out to tissues

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12
Q

Order of blood vessels

A

Artery –> arteriole –> capillary –> venule –> vein

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13
Q

Outermost layer of blood vessels

A

Tunica externa
Collagen rich connective tissue
Resist stretching of blood vessel due to hydrostatic pressure of blood

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14
Q

Middle layer of blood vessels

A

Tunica media
Contains elastic fibres and muscle tissue
Allow blood vessel to expand to accommodate blood flow

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15
Q

Innermost layer of blood vessels

A

Single layers of endothelium cells
Smooth surface with little friction and resistance to blood flow
Surrounded by tunica intima

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16
Q

Artery structure

A

Thick tunica externa with collagen fibres - resist overstretching under pressure
Thick layer of muscle and elastic tissue to provide elastic recoil aiding propulsion of blood and maintaining blood pressure
Relatively small lumen to maintain pressure of blood

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17
Q

Arterioles structre

A

Similar structure to arteries
More muscle
To constrict and dilate to control flow of blood to capillaries

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18
Q

Capillaries struture

A

Tissue not an organ
Single layer of flattened cells - short diffusion path
Extensive capillary beds - massive surface area
Pressure lowers as blood passes through capillaries - greater cross-sectional area
Narrow- greater resistance to blood flow and blood flow slows
Smaller diameter than rbc so rbc have to bend to squeeze through

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19
Q

Veins structure

A

Large lumen - little resistance to blood flowing at low pressure
Tunica media and externa thin as less resistance to pressure is needed
Blood kept flowing by skeletal muscles squeezing on veins to push blood forward
Valves at intrevals

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20
Q

Venules structute

A

Many join larger veins

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21
Q

Is the eyepiece graticule magnified when the objective lens is altered

A

No

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22
Q

What is meant by the flow in the aorta, arteries and arterioles being described as pulsatile?

A

Pressure goes up when the ventricles contract and drops when ventricles relax

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23
Q

Where is the pressure highest

A

In the main arteries leaving the heart

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24
Q

Why does the pressure drop from the aorta to the arteries to the arterioles

A

Total cross-sectional area of smaller vessels is larger so they have more resistance to the flow of blood

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25
Q

Why is there no pulsatile flow in the capillaries and what can the flow now be described as

A

There are no elastic fibres in the walls

Flow becomes laminar

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26
Q

Label

A 
A aorta
C pulmonary vein
B superior vena cava
F inferior vena cava
D pulmonary vein
E coronary artery
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27
Q

What separates the right and left sides of the heart

A

Septum

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28
Q

What are the walls of each chamber

A

Cardiac muscle
Specialised skeletal muscle
Resistant to tiring
Labelled as myocardium

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29
Q

Right atrioventricular valve

A

Tricuspid

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30
Q

Left atrioventricular valve

A

Bicuspid valve

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31
Q

What prevent the valves turning inside out

A

Chordae tendineae

Heart strings

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32
Q

Look

A
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33
Q

Which direction is movement of blood

A

High to low pressure

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34
Q

Atrial systole

A

Atria contracting
Ventricles relax
Pressure in atria higher than in ventricles
Blood pushed through open AV valves into ventricles

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35
Q

Ventricular systole

A

Pressure rises in ventricles
Blood pushed against AV valves closing them
Semi-lunar valves open
Blood pushed upwards into arteries

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36
Q

Diastole

A

Ventricles relax
Pressure falls below arteries
Semi-lunar valves close
Pressure in ventricles drops until below that of atria - blood flows from veins through atria and ventricles start to fill

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37
Q

What happens at 1

A

Ventricles contract

AV valves close

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38
Q

2

A

Semi lunar valves open

Blood flows out into the aorta

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39
Q

3

A

Blood tries to flow back into ventricle from aorta so semi lunar valves close

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40
Q

4

A

AV valves open

Cycle begins again

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41
Q

Why is the heart described as being myogenic?

A

Heart is stimulated to beat from within its muscle wall

42
Q

What does the SAN do

A

Spread out a wave of excitation across both atria so that they start contracting

43
Q

What does it mean if cells are depolarized

A

They contract

44
Q

What does it mean if cells are repolarized

A

They are relaxed

45
Q

What prevents the wave of excitation passing to the ventricles?

A

Layer of fibrous tissue between atria and ventricles

46
Q

Where does the wave of excitation spread after passing the layer of connective tissue

A

The AVN

47
Q

AVN

A

Atrioventricular node

Located in septum at the atrioventricular junction

48
Q

SAN

A

Sinoatrial node

Group of cells in right atrium

49
Q

What does the AVN do

A
  • Delay the wave if excitation to allow the atria to complete contraction and the ventricles to fill - this makes sure than ventricles contract after the atria
  • passes wave of excitation to the bundle of His in septum
50
Q

Why is it important that the bundle of His is at the apex of the heart?

A

Ventricles will contract from apex upwards so blood is pushed to arteries

51
Q

Where does the wave of excitation go after bundle of His

A

Passes through Purkinje fibres in muscle of ventricles

It spreads upwards through ventricles so contraction begins at apex

52
Q

What is an ECG

A

Electrocardiogram
Graphical trace produced from electrodes placed around the chest that detect electrical changes in the heart during a cardiac cycle

53
Q

What is P

A

Wave of depolarisation of the atrial walls

Causes atrial systole

54
Q

What is the QRS complex

A

Depolarisation of ventricular walls

Causing ventricular systole

55
Q

What is T

A

Repolarisation of the ventricular walls

During ventricular diastole

56
Q

Shape of red blood cells

A

Biconcave

57
Q

Advantages of the biconcave shape of the red blood cell

A
  • large surface area - maximise oxygen diffusion
  • short diffusion path for oxygen
  • thin central section - flexibility to squeeze through capillaries
  • no nucleus or organelles - maximise number of haemoglobin
  • no mitochondria - no oxygen used up whilst transported
58
Q

Structure of haemoglobin

A

Quaternary
4 polypeptide chains
2 alpha 2 beta
Prosthetic group containing iron

59
Q

How many oxygen molecules can haemoglobin carry

A

4

8 atoms

60
Q

Term for oxygen and haemoglobin combined

A

Oxyhemoglobin

61
Q

What is it called when oxygen diffuses into the erythrocyte and bind to the haemoglobin inside

A

Loading

Association

62
Q

What is it called when haemoglobin unloads oxygen at the body tissues

A

Dissociation

63
Q

Will haemoglobin load or unload in an in the lungs where capillaries have air high in ocygen

A

Associate

Load

64
Q

If a tissue has a high rate of aerobic respiration it will have a low partial pressure of oxygen- what will the haemoglobin do?

A

Unload more oxygen

65
Q

What relationship does the oxygen dissociation curve show?

A

Relationship between oxygen partial pressure and how much oxygen is carried by haemoglobin

66
Q

What does the % above the oxygen dissociation curve represent?

A

How much oxygen has been released to tissues

67
Q

Why is the curve of a oxygen dissociation curve sigmoid

A

Haemoglobin binds co-operatively

68
Q

What does it mean than haemoglobin bind co-operatively with oxygen

A

As each oxygen molecule bind to haemoglobin it causes a conformational shape change in the protein which makes it easier yo bind to the next oxygen molecule

69
Q

What shape is the oxygen dissociation curve

A

Sigmoid

70
Q

What does it mean when the oxygen dissociation curve levels off above 10kPa

A

Haemoglobin is fully saturated

71
Q

What is different about the haemoglobin of organisms that has adapted to live in low oxygen environments eg high altitudes

A

It has a higher affinity for oxygen

72
Q

What happens to oxygen dissociation curve of haemoglobin with higher affinity

A

Shifts left so haemoglobin is fully saturated at lower partial pressures of oxygen

73
Q

Why does foetal haemoglobin have a higher affinity for oxygen than adult haemoglobin

A

So a foetus can absorb oxygen from the mother’s blood at all partial pressures of oxygen

74
Q

Disadvantage of a curve to the left in an oxygen dissociation diagram

A

Oxyhaemoglobin doesnt dissociate as easily

75
Q

What is myoglobin

A

Different respiratory pigment found in muscle cells
Only binds to 1 oxygen molecule
Loads at much lower partial pressure of oxygen so acts as an oxygen store to delay the onset of anaerobic respiration

76
Q

Once carbon dioxide diffuses into the red blood cell what happens

A

It dissolves in water to form carbonic acid

This is catalysed by carbonic anhydrase

77
Q

What happens after carbonic acid if formed in the red blood cell

A

It dissociates into protons and hydrogen carbonate ions
The hydrogen carbonate ions diffuse into the plasma
Chloride ions diffuse into the red blood cell

78
Q

What is the chloride shift and why does it happen

A

When chloride ions diffuse into the red blood cell to maintain electrochemical neutrality in the cells

79
Q

What happens to the proton that had formed from dissociation of the carbonic acid

A

Binds to haemoglobin which displaces the oxygen from the oxyhemoglobin
Oxygen dissociates and diffuses into the cells

80
Q

How is 85% of carbon dioxide carried

A

In the plasma as hydrogen carbonate

81
Q

How is about 10% of carbon dioxide carried

A

Diffuses into rbc and attaches to haemoglobin to forms carbaminohaemoglobin

82
Q

How is about 5% of carbon dioxide carried

A

Dissolves in the plasma to form carbonic acid

83
Q

How does a high rate of respiration lead to the oxyhaemoglobin dissociating at a higher partial pressure of oxygen than usual

A 
More carbon dioxide diffuses into rbc
More carbonic acid formed
More dissociation 
More protons released
More oxyhemoglobin to dissociate
More oxygen released to cells
84
Q

Which way does the oxygen dissociation curve shift as carbon dioxide production increases

A

Shifts right

85
Q

What is it called when the oxygen dissociation curve shifts right

A

Bohr effect

86
Q

What does blood transport

A 
Oxygen 
CO2
Heat
Hormones
Glucose
Urea
87
Q

Hormone transport in blood

A

Endocrine system secretes hormones directly into blood
Transported right around the circulatory system
Effect only target organs - have cell receptors

88
Q

Urea transport in blood

A

Made in liver
Transports via hepatic vein to vena caba through right side of heart to lungs and then into aorta
Blood that goes to kidneys in renal artery is filtered and returned to renal vein with less urea

89
Q

What is tissue fluid

A

Fluid that bathes all cells

90
Q

What does tissue fluid NOT contain

A

Plasma proteins

91
Q

How do various substances pass from plasma and red blood cells into the tissues and then into cells

A

Diffusing through tissue fluid

92
Q

What is in tissue fluid

A 
Oxygen
Fatty acids
Amino acids
Glucose
Hormones
Ions
Waste products - pass out of cells
93
Q

Functions of tissue fluid

A

Bathe all cells
Help maintain constant environment around cells
Supply oxygen, glucose, hormones and ions into cells
Remove waste from cells

94
Q

What are fenetrations

A

Gaps between the single layer of endothelial cells in the capillaries
Make capillaries leaky

95
Q

How is tissue fluid formed

A
  • high hydrostatic pressure of arterioles forces fluid out through fenestrations
  • as plasma proteins are too large to leave they lower the water potential of blood
  • opposing force to hydrostatic pressure as osmotic gradient between tissue fluid and blood means water enters capillary by osmosis
  • At arterial end of the capillary the hydrostatic pressure difference exceeds water potential difference so net movement is out of the capillary
96
Q

How is tissue fluid reabsorbed?

A
  • as fluid is lost as blood passes through capillary the hydrostatic pressure of blood is reduced
  • loss of water = lower water potential
  • at venule end - osmotic difference exceeds hydrostatic pressure difference
  • water reabsorbed into blood by osmosis
97
Q

Is the rate of tissue fluid formation or rate of reabsorption greater?

A

Tissue fluid formation

98
Q

What is done with the excess tissue fluid

A

It diffuses into blind ending lymph vessels

Lymph circulates in lymphatic system and drains into the blood stream through the thoracic duct

99
Q

What is oedema

A

Swelling caused by more tissue fluid being formed that can be reabsorbed or drained

100
Q

What can cause oedema

A

Kwashiorkor - severe protein deficiency
Blockage of lymph vessels
High blood pressure - increases hydrostatic pressure

Wjec Biology Unit 2 (5 decks)

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