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Wjec Biology Unit 2 > 2.3 Animals > Flashcards

2.3 Animals Flashcards

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
Why is there no pulsatile flow in the capillaries and what can the flow now be described as
There are no elastic fibres in the walls | Flow becomes laminar
26
Label
``` A aorta C pulmonary vein B superior vena cava F inferior vena cava D pulmonary vein E coronary artery ```
27
What separates the right and left sides of the heart
Septum
28
What are the walls of each chamber
Cardiac muscle Specialised skeletal muscle Resistant to tiring Labelled as myocardium
29
Right atrioventricular valve
Tricuspid
30
Left atrioventricular valve
Bicuspid valve
31
What prevent the valves turning inside out
Chordae tendineae | Heart strings
32
Look
33
Which direction is movement of blood
High to low pressure
34
Atrial systole
Atria contracting Ventricles relax Pressure in atria higher than in ventricles Blood pushed through open AV valves into ventricles
35
Ventricular systole
Pressure rises in ventricles Blood pushed against AV valves closing them Semi-lunar valves open Blood pushed upwards into arteries
36
Diastole
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
37
What happens at 1
Ventricles contract | AV valves close
38
2
Semi lunar valves open | Blood flows out into the aorta
39
3
Blood tries to flow back into ventricle from aorta so semi lunar valves close
40
4
AV valves open | Cycle begins again
41
Why is the heart described as being myogenic?
Heart is stimulated to beat from within its muscle wall
42
What does the SAN do
Spread out a wave of excitation across both atria so that they start contracting
43
What does it mean if cells are depolarized
They contract
44
What does it mean if cells are repolarized
They are relaxed
45
What prevents the wave of excitation passing to the ventricles?
Layer of fibrous tissue between atria and ventricles
46
Where does the wave of excitation spread after passing the layer of connective tissue
The AVN
47
AVN
Atrioventricular node | Located in septum at the atrioventricular junction
48
SAN
Sinoatrial node | Group of cells in right atrium
49
What does the AVN do
* 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
Why is it important that the bundle of His is at the apex of the heart?
Ventricles will contract from apex upwards so blood is pushed to arteries
51
Where does the wave of excitation go after bundle of His
Passes through Purkinje fibres in muscle of ventricles | It spreads upwards through ventricles so contraction begins at apex
52
What is an ECG
Electrocardiogram Graphical trace produced from electrodes placed around the chest that detect electrical changes in the heart during a cardiac cycle
53
What is P
Wave of depolarisation of the atrial walls | Causes atrial systole
54
What is the QRS complex
Depolarisation of ventricular walls | Causing ventricular systole
55
What is T
Repolarisation of the ventricular walls | During ventricular diastole
56
Shape of red blood cells
Biconcave
57
Advantages of the biconcave shape of the red blood cell
* 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
Structure of haemoglobin
Quaternary 4 polypeptide chains 2 alpha 2 beta Prosthetic group containing iron
59
How many oxygen molecules can haemoglobin carry
4 | 8 atoms
60
Term for oxygen and haemoglobin combined
Oxyhemoglobin
61
What is it called when oxygen diffuses into the erythrocyte and bind to the haemoglobin inside
Loading | Association
62
What is it called when haemoglobin unloads oxygen at the body tissues
Dissociation
63
Will haemoglobin load or unload in an in the lungs where capillaries have air high in ocygen
Associate | Load
64
If a tissue has a high rate of aerobic respiration it will have a low partial pressure of oxygen- what will the haemoglobin do?
Unload more oxygen
65
What relationship does the oxygen dissociation curve show?
Relationship between oxygen partial pressure and how much oxygen is carried by haemoglobin
66
What does the % above the oxygen dissociation curve represent?
How much oxygen has been released to tissues
67
Why is the curve of a oxygen dissociation curve sigmoid
Haemoglobin binds co-operatively
68
What does it mean than haemoglobin bind co-operatively with oxygen
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
What shape is the oxygen dissociation curve
Sigmoid
70
What does it mean when the oxygen dissociation curve levels off above 10kPa
Haemoglobin is fully saturated
71
What is different about the haemoglobin of organisms that has adapted to live in low oxygen environments eg high altitudes
It has a higher affinity for oxygen
72
What happens to oxygen dissociation curve of haemoglobin with higher affinity
Shifts left so haemoglobin is fully saturated at lower partial pressures of oxygen
73
Why does foetal haemoglobin have a higher affinity for oxygen than adult haemoglobin
So a foetus can absorb oxygen from the mother's blood at all partial pressures of oxygen
74
Disadvantage of a curve to the left in an oxygen dissociation diagram
Oxyhaemoglobin doesnt dissociate as easily
75
What is myoglobin
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
Once carbon dioxide diffuses into the red blood cell what happens
It dissolves in water to form carbonic acid | This is catalysed by carbonic anhydrase
77
What happens after carbonic acid if formed in the red blood cell
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
What is the chloride shift and why does it happen
When chloride ions diffuse into the red blood cell to maintain electrochemical neutrality in the cells
79
What happens to the proton that had formed from dissociation of the carbonic acid
Binds to haemoglobin which displaces the oxygen from the oxyhemoglobin Oxygen dissociates and diffuses into the cells
80
How is 85% of carbon dioxide carried
In the plasma as hydrogen carbonate
81
How is about 10% of carbon dioxide carried
Diffuses into rbc and attaches to haemoglobin to forms carbaminohaemoglobin
82
How is about 5% of carbon dioxide carried
Dissolves in the plasma to form carbonic acid
83
How does a high rate of respiration lead to the oxyhaemoglobin dissociating at a higher partial pressure of oxygen than usual
``` 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
Which way does the oxygen dissociation curve shift as carbon dioxide production increases
Shifts right
85
What is it called when the oxygen dissociation curve shifts right
Bohr effect
86
What does blood transport
``` Oxygen CO2 Heat Hormones Glucose Urea ```
87
Hormone transport in blood
Endocrine system secretes hormones directly into blood Transported right around the circulatory system Effect only target organs - have cell receptors
88
Urea transport in blood
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
What is tissue fluid
Fluid that bathes all cells
90
What does tissue fluid NOT contain
Plasma proteins
91
How do various substances pass from plasma and red blood cells into the tissues and then into cells
Diffusing through tissue fluid
92
What is in tissue fluid
``` Oxygen Fatty acids Amino acids Glucose Hormones Ions Waste products - pass out of cells ```
93
Functions of tissue fluid
Bathe all cells Help maintain constant environment around cells Supply oxygen, glucose, hormones and ions into cells Remove waste from cells
94
What are fenetrations
Gaps between the single layer of endothelial cells in the capillaries Make capillaries leaky
95
How is tissue fluid formed
* 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
How is tissue fluid reabsorbed?
* 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
Is the rate of tissue fluid formation or rate of reabsorption greater?
Tissue fluid formation
98
What is done with the excess tissue fluid
It diffuses into blind ending lymph vessels | Lymph circulates in lymphatic system and drains into the blood stream through the thoracic duct
99
What is oedema
Swelling caused by more tissue fluid being formed that can be reabsorbed or drained
100
What can cause oedema
Kwashiorkor - severe protein deficiency Blockage of lymph vessels High blood pressure - increases hydrostatic pressure

Wjec Biology Unit 2 (5 decks)

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