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Transport In Animals Flashcards

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1
Q

define transport

A

the movement of substances such as oxygen , nutrients , hormones, waste and heat around the body

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2
Q

why do small animals not need a separate transport system

A

because all their cells are surrounded by the environment in which they live. diffusion will supply enough oxygen and nutrients to keep the cell alive

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3
Q

why do larger animals need a separate transport system

A

the diffusion distance becomes too long and diffusion alone will be too slow to supply all the requirements

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4
Q

what factors affects the need for a transport system

A
  • size
  • surface area to volume ratio
  • level of metabolic activity
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5
Q

describe how size effects the need for a transport system

A

the cells inside a large organism are further from its surface - the diffusion pathway is increased . the diffusion rate is reduced , and diffusion is too slow to supply all the requirements . also the outer layer of cells use up the supplies, so that less will reach the cells deep inside the body

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6
Q

describe how surface area affects the need for a transport system

A

small animals have a large surface area to volume ratio
this means that for each gram of tissue in their body they have a sufficient area of body surface through which exchange can occur . however large animals have a smaller surface area to volume ratio . this means that each gram of tissue has a smaller area of body surface for exchange

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7
Q

describe how the level of metabolic activity effects the need for a transport system

A

animals need energy from food, so that they can move around .Releasing energy from the food by aerobic respiration requires oxygen. If an animal is very active , its cells need good supplies of oxygen and nutrients to supply the energy for movement .Animals that keep themselves warm, such as mammals need even more energy

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8
Q

define and describe a single circulatory system

A

the blood flows through the heart once for each circuit of the body. the blood takes the following route
heart-> gills->body->heart

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9
Q

define and describe a double circulatory system

A

the system has two separate circuits. one circuit carries blood to the lungs to pick up oxygen. This is pulmonary circulation. The other circuit carries the oxygen and nutrients around the body to the tissue. this is systematic circulation. blood flows through the heart twice for each circuit of the body. the blood takes the flowing route
heart-> body-> heart-> lungs-> heart

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10
Q

features of a good transport system

A
  • a fluid or medium to carry nutrients ,oxygen and wastes around the body, this is the blood
  • a pump to create pressure that will push the fluid around the body, this is the heart
  • exchange surfaces that enable substances to enter the blood and leave it again where they are needed , these are capillaries
  • tubes or vessels to carry the blood by mass flow
  • two circuits , one to pick up oxygen and another to deliver oxygen to the tissue
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11
Q

advantages of a double circulation

A

will deliver oxygen and nutrients quickly to the parts of the body where they are needed.
the blood can flow more quickly by increasing the blood pressure created by the heart.

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12
Q

describe the single circulation of a fish

A
  • the blood pressure drops as blood passes through the tiny capillaries of the gills
  • blood has a low pressure as it flows towards the body, and will not flow very quickly
  • the rate at which oxygen and nutrients are delivered to respiring tissues, and carbon dioxide and urea are removed is limited

fish are not as metabolically active as mammals ,as they do not maintain their body temperature. therefore they need less energy. their single circulatory system delivers sufficient oxygen and nutrients for their needs

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13
Q

describe the double circulatory system of mammals

A
  • the blood pressure must not be too high in the pulmonary circulation , otherwise it may damage the delicate capillaries in the lungs
  • the heart can increase the pressure of the blood after it has passed though the lungs, so the blood is under higher pressure as it flows to the body and flows more quickly
  • the systematic circulation can carry blood at higher pressure than the pulmonary circulation

mammals are active animals and maintain their body temperature. supplying the energy for activity and the heat needed to keep the body warm requires energy from food . this energy is released from food in the process of respiration. to release a lot of energy, the cells need a good supply of both nutrients and oxygen as well as the removal of waste products

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14
Q

what are the types of circulatory systems

A

single
double
open
closed

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15
Q

describe an open circulatory system

A

this means that blood is not always held within the blood vessels.. instead the blood fluid circulates through the body cavity , so that the tissues and cells are bathed directly in blood

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16
Q

disadvantages of an open circulatory system

A
  • blood pressure is low and blood flow is slow

- circulation of blood may be effected by body movements or lack of body movements

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17
Q

describe closed circulatory systems

A

in larger animals the blood stays entirely inside vessels. a separate fluid called tissue fluid , bathes the tissues and cells

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18
Q

closed systems advantages over open systems

A
  • higher pressure so that blood flows more quickly
  • more rapid delivery of oxygen and nutrients
  • more rapid removal of carbon dioxide and other wastes
  • transport is independent of movements
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19
Q

role of the endothelium in blood vessels

A

this is a thin layer that is particularly smooth in order to reduce friction with the flowing blood

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20
Q

name the main blood vessels

A

artery
vein
capillary

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21
Q

describe artery functions and structure

A

they carry blood away from the heart . the blood is at high pressure so the artery wall must be thick in order to withstand that pressure

the lumen is relatively small in order to maintain high pressure and the inner wall is folded to allow the lumen to expand as blood flow increases

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22
Q

the artery wall consists of three layers , state and describe them

A

inner layer (tunica intima) - consists of elastic tissues which allows the wall to stretch and then recoil to help maintain blood pressure

middle layer (tunica media) - consists of a thick layer of smooth muscle

outer layer (tunica adventitia) - is a relatively thick layer of collagen and elastic tissue. this provides strength to withstand the high pressure and recoil to maintain the pressure

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23
Q

describe arterioles and their structure

A

they are small blood vessels that distribute the blood from an artery to the capillaries.

arteriole walls contain a layer of smooth muscle. contraction of this muscle will constrict the diameter of the arteriole . this increases resistance to flow and reduces the rate of flow of blood. constrictions of the arteriole walls can be used to divert the flow of blood to regions of the body that are demanding more oxygen

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24
Q

describe the function of capillaries and there structure

A

have very thin walls, they allow exchange of materials between the blood and tissue fluid

  • the lumen is very narrow . the red blood cell may be squeezed against the wall of the capillary as they pass along the capillary. this helps to transfer of oxygen ,as it reduces the diffusion path to the tissues. it also increases resistance and reduces rate of flow
  • the walls consist of a single layer of flattened endothelial cells. this reduces the distance for the materials being exchanged
  • the walls are leaky, they allow blood plasma and dissolved substances to leave the blood
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25
Q

describe venules

A

from the capillaries blood flows into small vessels called venules. these collect blood from the capillary bed and lead into the veins

the venule wall consists of thin layers of muscle and elastic tissue outside the endothelium , and a thin outer layer of collagen

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26
Q

describe the function and structure of veins

A

veins carry blood back to the heart , the blood is at low pressure and the walls do NOT need to be thick

  • the lumen is relatively large, in order to ease the flow of blood
  • the walls have thinner layers of collagen, smooth muscles and elastic tissue than in artery walls. they do not need to stretch and recoil and are not actively constricted in order to reduce blood flow
  • they contain valves to help the blood flow back to the heart and to prevent it flowing in the opposite direction . as the walls are thin, the vein can be flattened by the action of the surrounding skeletal muscles . contractions of the surrounding skeletal muscles applies pressure to the blood , forcing the blood to move along in a direction determined by the valves
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27
Q

define blood

A

the fluid used to transport materials around the body

  • is held in our blood vessels
  • consists of a liquid called plasma, containing many blood cells
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28
Q

define plasma

A

is the fluid portion of the blood
-contains many dissolved substances, including oxygen , carbon dioxide, minerals, glucose, amino acids, hormones and plasma proteins

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29
Q

the cells in blood include

A

red blood cells (erythrocytes)
white blood cells (leucoytes)
platelets

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30
Q

define and describe tissue fluid

A

the fluid surrounding the cells and tissues
- formed by plasma leaking out of the capillaries

  • it surrounds the cell in the tissue, and supplies them with oxygen and nutrients they require . as blood plasma leaks from the capillary , it carries all the dissolved substances into the tissue fluid . this movement is mass flow rather than diffusion . waste products from cell metabolism will be carried back into the capillary as some of the tissue fluid returns to the capillary
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31
Q

define hydrostatic pressure

A

the pressure that a fluid exerts when pushing against the sides of a vessel or container

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32
Q

define lymph

A

the fluid held in the lymphatic system, which is a system of tubes that returns excess tissue fluid to the blood steam

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33
Q

define oncotic pressure

A

the pressure created by the osmotic effects of the solutes

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34
Q

describe the formation of tissue fluid

A
  • when an artery reaches the tissues , it branches into smaller arterioles , and then into a network of capillaries. these eventually link up with the venules to carry blood back to the veins . therefore blood flowing into an organ or tissue is contained in the capillaries
  • at the atrial end of the capillary , the blood is at relatively high HYDROSTATIC PRESSURE, this pressure tends to push the blood fluid out of the capillaries through the capillary wall. the fluid can leave through the tiny gaps between the cell in the capillary wall.
  • the fluid that leaves the blood consists of plasma with dissolved nutrients and oxygen. all the red blood cells ,platelets and most of the white blood cells remain in the blood , as do the plasma proteins . these are too large to be pushed out through the gaps in the capillary wall
  • this tissue fluid surrounds the body cells, so exchange of gas and nutrients can occur across the plasma membranes. the exchange occurs by diffusion , facilitated diffusion and active uptake .oxygen and nutrients enter the cells , carbon dioxide and other waste leave the cell
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35
Q

describe returning to the blood ( formation of tissue fluid )

A

the blood pressure at the venous end of the capillary is much lower.This allows some of the tissue fluid to return to the capillary carrying carbon dioxide and other waste substances into the blood
not all the tissue fluid re enters the blood
-some tissue fluid is directed into another tubular system called the LYMPH system
-this drains excess tissue fluid out of the tissues and returns it to the blood system in the subclavian vein in the chest
-the fluid in the lymphatic system is called lymph and is similar in composition to the tissue fluid. it will contain more lymphocytes, as they are produced in the lymph nodes

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36
Q

what are lymph nodes

A

are swellings found at intervals along the lymphatic system, which have an important part to play in the immune response

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37
Q

feature :hydrostatic pressure - state blood plasma , tissue fluid and lymph

A

BP- high
TF- low
L- low

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38
Q

feature: oncotic pressure- state blood plasma , tissue fluid and lymph

A

BP- more negative
TF- less negative
L-less negative

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39
Q

feature : cells- state blood plasma , tissue fluid and lymph

A

BP-red blood cells, neutrophils, lymphocytes
TF-some neutrophils especially in infected areas
L- lymphocytes

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40
Q

feature: proteins - state blood plasma , tissue fluid and lymph

A

BP-plasma proteins
TF- few proteins
L- few proteins

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41
Q

feature: fats- state blood plasma , tissue fluid and lymph

A

BP-transported in lipoproteins
TF-few fats
L- more fats , especially near the digestive system

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42
Q

describe the movement of fluids

A

the hydrostatic pressure of the blood is not the only influence on the movement of fluid into and out of the capillary. The tissue fluid has its own hydrostatic pressure, and the oncotic pressure of the solutes also has an influence

  • the hydrostatic pressure of the blood tends to push fluid out into the tissue
  • the hydrostatic pressure of the tissue fluid tends to push fluid into the capillaries
  • the oncotic pressure of the blood tends to pull water back into the blood
  • the oncotic pressure of the tissue fluid pulls water into the tissue fluid

the net result of these forces create a pressure to push fluid out of the capillary at the arterial end and into the capillary at the venule end

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43
Q

the right side of the heart pumps ? blood to the lungs to be ?

A

deoxygenated

oxygenated

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44
Q

the left side of the pumps ? blood to the rest of the body

A

oxygenated

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45
Q

in humans the heart lies just off centre towards the ? of the chest cavity

A

left

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46
Q

the main part of the heart consists of a firm, dark red muscle called

A

cardiac muscle

47
Q

what are the two main pumping chambers in the heart

A

ventricles and atria

48
Q

define atrio ventricular valves

A

valves between the atria and the ventricles, which ensure that blood flows in the correct direction

49
Q

define cardiac muscles

A

specialised muscles found in the walls of the heart chambers

50
Q

define semilunar valves

A

valves that prevent blood re entering the heart from the arteries

51
Q

what chambers are above the ventricles

A

atria

52
Q

lying over the surface of the heart are

A

coronary arteries

53
Q

what do coronary arteries do

A

supply oxygenated blood to the heart muscle

54
Q

what are the consequences of restricted blood flow (eg if coronary arteries become restricted )

A

reduces delivery of oxygen and nutrients such as fatty acids and glucose

this may cause angina or a heart attack

55
Q

describe the route of blood through the heart starting at the atria

A
  • the atria receives from the major veins
  • deoxygenated blood from the body flows though the vena cava into the right atrium
  • oxygenated blood from the lungs flows through the pulmonary vein to the left atrium
  • from the atria blood flows down the artio ventricular valves into the ventricles
  • deoxygenated blood leaving the right ventricle flows to the pulmonary artery leading to the lungs , where it is oxygenated .
  • oxygenated blood leaving the left ventricle flows into the aorta , this carries blood to a number of arteries that supply all parts of the body
  • at the base of the major arteries , where they exit the heart, are the semilunar valves , these prevent the blood returning to the heart as the ventricles relax
56
Q

what do tendinous chords do

A

prevent the valves from turning inside out when the ventricle walls contract

57
Q

a wall of muscle called the septum separates ?

A

the ventricles from each other . this ensures that the oxygenated blood in the left side of the heart and the deoxygenated blood In the right side are kept separate

58
Q

describe the structure, function and blood pressure of the atria

A

the muscle of the atrial walls is very thin. This is because these chambers do not need to create much pressure

there function is to receive blood from the veins and push it into the ventricles

59
Q

describe the structure , function and blood pressure of the right ventricle

A

the walls of the right ventricle are thicker than the walls of the atria . this enables the right ventricle to pump blood out of the heart. the right ventricle pumps deoxygenated blood to the lungs , the lungs are in the chest cavity beside the heart , so that the blood does not need to travel very far . also the alveoli in the lungs are very delicate and could be damaged at high blood pressure

60
Q

describe the structure , function and blood pressure of the left ventricle

A

the walls of the left ventricle can be two or three times thicker than those of the right ventricle . the blood from the left ventricle is pumped out through the aorta and needs sufficient pressure to overcome the resistance of the systematic circulation

needs to get blood all the way around the body

61
Q

describe the cardiac muscle structure

A

consists of fibres that branch , producing cross bridges. these help to spread the stimulus around the heart and also ensure that the muscles can produce a squeezing action rather than a simple reduction length

there are numerous mitochondria between the muscle fibrils to supply energy for contractions

the muscle cells are separated by intercalated discs , which facilitate synchronised contractions. Each cell has a nucleus and is divided into contractile units called sarcomeres

62
Q

define the cardiac cycle

A

the sequence of events in one full beat of the heart

63
Q

what is the role of the heart

A

is to create pressure that pushes blood around the blood vessels

64
Q

what are the three parts of the cardiac cycle

A

diastole
atrial systole
ventricular systole

65
Q

describe diastole

A

the muscular walls of all four chambers relax, elastic recoil causes the chambers to increase in volume allowing blood to flow in from the veins

66
Q

describe ventricular systole

A

both right and left ventricles pump together. contractions start at the apex of the heart so that blood is pushed upwards towards the arteries

67
Q

describe atrial systole

A

both right and left atria contract together .the muscle in the walls is thin so only a small increase in pressure is created by this contraction. This helps to push blood into the ventricles stretching their walls and ensuring they are full of blood

68
Q

the action of

ARTIO-VENTRICULAR VALVES

A

after systole , the ventricle walls relax and recoil

  • the pressure in the ventricles rapidly drops below the pressure in the atria
  • blood in the atria pushes the atrio ventricular valves open
  • blood entering the heart flows straight through the atria and into the ventricles
  • the pressure in the atria and the ventricles rise slowly as they fill with blood
  • the valves remain open while the atria contracts , but close when the atria begin to relax
  • this closure is caused by a swirling action in the blood around the valves when the ventricle is full
  • as the ventricle begins to contact the pressure of the blood in the ventricle rises
  • when the pressure rises above that in the atria, the blood starts to move upwards
  • this movement fills up the valve pocket and keeps them closed
  • the tedious cords attached to the valves prevent them turning inside out
  • this prevents the blood flowing back into the atria
69
Q

the action of valves

SEMILUNAR VALVES

A
  • before ventricular contractions , the pressure in the major arteries is higher than the pressure in the ventricles
  • this means that the semilunar valves are closed
  • ventricular systole raises the blood pressure in the ventricles very quickly
  • once the pressure in the ventricles rises above the pressure in the major arteries , the semilunar valves are pushed open
  • -the blood is under very high pressure so it is forced out of the ventricles in a powerful spurt
  • once the ventricle walls have finished contracting, the heart muscles starts to relax (diastole)
  • elastic tissue in the walls of the ventricles recoil
  • this stretches the muscles out again and returns the ventricle to its original size
  • this causes the pressure in the ventricles to drop quickly
  • as it drops below the pressure in the major arteries, the blood starts to flow towards the ventricles
  • the semilunar valves are pushed closed by the blood collecting in the pockets of the valves
  • this prevents blood returning to the ventricles
  • this pressure wave created when the left semilunar valve closes is the pulse that we can easily feel at the wrist or neck
70
Q

the pressure changes in the heart cause

A

the opening and closing of the valves

71
Q

describe how the structure of the artery walls plays a large part in creating a more even flow

A
  • the artery walls close to the heart have a lot of elastic tissue
  • when blood leaves the heart , these walls stretch
  • as blood moves on and out the aorta, the pressure in the aorta drops
  • the elastic recoil of the walls helps maintain the blood pressure in the aorta
  • the further the blood flows along the arteries , the more the pressure drops and the fluctuations become less obvious
  • it is important to maintain the pressure gradient between the aorta and the arterioles , as this keeps the blood flowing towards the tissue
72
Q

define bradycardia

A

a slow heart rhythm

73
Q

define a ectopic heartbeat

A

an extra beat or an early beat of the ventricles

the patient often feels as if a heartbeat has been missed

74
Q

define fibrillation

A

uncoordinated contractions of the atria and ventricles

75
Q

define myogenic muscle

A

muscles that can initiate its own contractions

76
Q

define electrocardiogram

A

a trace that records the electrical activity of the heart

77
Q

define purkyne tissue

A

consists of specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles

78
Q

define sino-atrial node (SAN)

A

the hearts pacemaker , it is a small patch of tissue that sends out waves of electrical excitation at regular intervals in order to initiate contractions

79
Q

define trachycardia

A

a rapid heart beat

80
Q

out of the atrial muscles and the ventricular muscles , which one contracts at a higher frequency

A

atrial muscles

81
Q

where is the SAN located

A

top of the right atrium

82
Q

SAN initiates ? waves of excitation per minute

A

55-80

83
Q

describe the contractions of the atria (excitation )

A
  • the wave of excitation quickly spreads over the walls of both atria
  • it travels along the membranes of the muscle tissue
  • as the wave of extinction passes , it causes the cardiac muscles to contract
  • this is atrial systole
84
Q

what part of the heart is unable to conduct a wave of excitation

A

the tissue at the base of the atria, so it cannot spread directly down the ventricle walls

85
Q

where is the atrio-ventricular node (AVN) located

A

at the top of the interventricular septum

86
Q

describe what the atrio-ventricular node does

A

this is the only route that can conduct the wave of excitation through to the ventricles . the wave of the excitation is delayed in the node. this allows time for the atria to finish contracting and for the blood to flow down to the ventricles before they begin to contract

keeps the atria and ventricles synchronised

87
Q

describe the contractions of the ventricles (excitation )

A
  • after this short delay, the wave of excitation is carried away from the AVN and down a specialised conducting tissue called the purkyne tissue
  • this runs down the interventricular septum
  • at the base of the septum, the wave of excitation spreads out over the wall of the ventricles
  • as the excitation spreads upwards from the base of the ventricles it cause the muscles to contract
  • this means that the ventricles contact from the base upwards
  • this pushes the blood up towards the major arteries at the top of the heart
88
Q

what is a sinus rhythm

A

a normal heartbeat

89
Q

in electrocardiograms , the trace of a healthy person has a particular shape , what does P, QRS and T stand for

A

P- shows excitation of the atria
QRS- excitation of ventricles
T- diastole

90
Q

define affinity

A

a strong attraction

91
Q

define dissociation

A

means releasing the oxygen from the oxyhaemoglobin

92
Q

define fetal haemoglobin

A

the type of haemoglobin only found in the fetus

93
Q

define haemoglobin

A

the red pigment used to transport oxygen in the blood

94
Q

oxygen is transported in ? , these cells contain the protein ?

A

red blood cells (erythrocytes )

haemoglobin

95
Q

what are erythrocytes also know as

A

red blood cells

96
Q

describe the haemoglobin structure

A

is a complex protein with four subunits , each consists of a polypeptide chain and a haem group . the haem group consists of a single iron ion in the form of FE+. this iron ion can attract and hold an oxygen molecule
the haem group is said to have a high affinity for oxygen . each haemoglobin molecule can carry 4 oxygen

97
Q

haemoglobin + oxygen =

A

oxyhaemoglobin

98
Q

describe the transport of oxygen in relation to haemoglobin

A

oxygen is absorbed into the blood as it passes the alveoli in the lungs. oxygen molecules diffusing into the blood plasma enter the red blood cells . here they become associated with the haemoglobin . this means that the oxygen binds reversibly to the haemoglobin . this takes the oxygen molecules out of solution and so maintains a steep concentration gradient, allowing more oxygen to enter the blood from the lungs and diffuse into the cells

the blood carries oxygen from the lungs back to the heart , before travelling around the body to supply the tissues. in the body tissues, cells need oxygen for aerobic respiration . therefore the oxyhaemoglobin must be able to release the oxygen, this is called dissociation

99
Q

the ability of haemoglobin to associate with and release oxygen depends on the….

A

concentration of oxygen in the surrounding tissue

100
Q

what is partial pressure measure in

A

units of pressure kPa

101
Q

the concentration of oxygen is measured by the relative pressure that it contributes to a mixture of gas is called the

A

partial pressure

102
Q

haemoglobin can associate with oxygen in a way that produces an ? shaped curve. what is this called

A

s

haemoglobin dissociation curve

103
Q

describe the haemoglobin dissociation curve

A

1st oxygen hard to bind, 2nd and third easy to bind, 4th hard to bind

at low oxygen concentrations tension,, the haemoglobin doesn’t readily associate with oxygen molecules . this is because the haem groups that attract the oxygen are in the centre of the haemoglobin molecule , this makes it difficult for the oxygen molecule to reach the haem group and associate with It. this difficulty in combining with the first oxygen molecule accounts for low levels of saturation of haemoglobin at low oxygen tensions

as the oxygen tension rises , the diffusion gradient into the haemoglobin molecule increase. eventually , one molecule enters the haemoglobin molecule and associates with one of the haem groups. this causes a slight change in the shape of the haemoglobin molecule, known as a conformational change . it allows more oxygen molecules to enter the haemoglobin molecules and associates with the other haem groups relatively easily. this accounts for the steepness of the curve as oxygen tensions rises

as the haemoglobin approaches 100% saturation , the curve levels off, creating an s shaped curve

104
Q

on a haemoglobin dissociation curve what part of the body does the bottom left hand part of the curve represent , and what does the top right hand part of the curve show

A

muscles

lungs

105
Q

describe fetal haemoglobin

A

simple- higher affinity, more saturated , to take from mothers blood to fetal blood, mothers becomes less saturated because fetal blood has it

  • fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin
  • therefore the haemoglobin dissociation curve is to the left of the curve of adult haemoglobin
  • this is because fetal haemoglobin must be able to associate with the oxygen in an environment where the oxygen tension is low enough to make adult haemoglobin release oxygen
  • in the placenta , where the oxygen tension is low, fetal haemoglobin will absorb oxygen from the surrounding fluid , this reduces the oxygen tension even further. as a result , oxygen diffuses from the mothers blood into the placenta . this reduces the oxygen tension within the mothers blood, which in turn makes the maternal haemoglobin release more oxygen (dissociation )
106
Q

define carbonic anhydrase

A

the enzyme that catalyses the combination of carbon dioxide and water

107
Q

define chloride shift

A

the movement of chloride ions into the erythrocytes to balance the charge as hydrogencarbonate ions leave the cell

108
Q

define bohr shift

A

the effect that extra carbon dioxide has on the haemoglobin ,explaining the release of more oxygen

109
Q

define haemoglobinic acid

A

the compound formed by the buffering action of haemoglobin as it combines with excess hydrogen ions

110
Q

what are the three ways in which carbon dioxide is transported in the body

A
  • about 5% is dissolved directly in plasma
  • about 10% is combined directly with haemoglobin to form a compound called carbaminohaemoglobin
  • -about 85% is transported in the form of hydrogencarbonate ions
111
Q

describe the formation of hydrogencarbonate ions

A
  • carbon dioxide in the blood plasma diffuses into the red blood cells . here it combines with the water to form a weak acid called carbonic acid, this reaction is catalysed by the enzyme carbonic anhydrase
  • CO2+H20–> H2CO3
  • carbon dioxide + water –> carbonic acid
  • this carbonic acid dissociates to release hydrogen ions and hydrogencarbonate ions
  • H2CO3–> HCO3~ + H+
  • the hydrogencarbonate ions diffuse out of the red blood cell into the plasma . the charge insdie the red blood cell is maintained by the movement of chloride ions from the plasma into the red blood cells, this is called the chloride shift
  • the hydrogen ions building up in the red blood cell could cause the contents of the red blood cells to become very acidic .to prevent this , the hydrogen ions are taken out the solution by associating with haemoglobin to produce haemoglobinic acid. the haemoglobin is acting as a buffer
112
Q

what does a buffer do

A

a compound that maintains a constant PH

113
Q

effects of increasing carbon dioxide concentration (partial pressure/haemoglobin )

A

blood entering respiring tissues carries oxygen as oxyhaemoglobin . the partial pressure of oxygen in the respiring tissues is lower than that in the lungs , because oxygen has been used in respiration. as a result , the oxyhaemoglobin begins to dissociate and release oxygen to the tissues . this means that the haemoglobin is available to take up the hydrogen ions , forming haemoglobinic acid. where the tissues are very active ,there is more carbon dioxide released. this has a dramatic effect on the haemoglobin

114
Q

describe the bohr effect

A
  • carbon dioxide enters the red blood cells forming carbonic acid, which dissociates to release hydrogen ions
  • these hydrogen ions affect the PH of the cytoplasm, making it more acidic
  • as with any protein , changes in PH can effect the tertiary structure of he haemoglobin .the increased acidity alters the tertiary structure of the haemoglobin and reduces the affinity of the haemoglobin for oxygen
  • the haemoglobin is unable to hold as much oxygen and the oxygen is released from the oxyhaemoglobin to the tissues

where tissues are respiring more, there will be more carbon dioxide . as a result there will be more hydrogen ions produced in the red blood cells . this makes the oxyhaemoglobin release more oxygen , so when more carbon dioxide is present , haemoglobin becomes less saturated with oxygen. this is reflected in a change to the haemoglobin dissociation curve , which shifts to the right

this bohr effect results in more oxygen being released where more carbon dioxide is produced in respiration . this is just what the muscles need for aerobic respiration to continue

Biology (10 decks)

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