3.2 Transport in animals Flashcards
1
Q
What is a double circulatory system?
A
A circulatory system in which the blood flows through the heart twice for each circuit of the body.
2
Q
What is a single circulatory system?
A
A circulatory system in which blood flows through the heart once for each circuit of the body.
3
Q
Why dont small organisms need a transport system?
A
All their cells are surrounded (or are very close to) their environments so that they can rely diffusion to supply them with enough oxygen and to nutrients survive.
4
Q
What factors cause larger organisms to require a transport system?
A
- Size
- Surface area
- Level of metabolic activity
5
Q
Why does the size of an organism affect its need for a transport system?
A
For bigger animals:
- Diffusion pathway is increased
- Diffusion rate is reduced so the diffusion is too slow to supply all the requirements.
- Outer layers of cells use up all the supplies, less will reach the cells inside.
6
Q
How does an animals level of metabolic activity affect the need for a transport system?
A
A more active animal that moves about a lot and those that keep themselves warm, require a lot of energy from aerobic respiration. This means all the its cells need a good supply and nutrients and oxygen for the energy of movement.
7
Q
What features will a good transport system include?
A
- A fluid to carry nutrients, oxygen and wastes around the body.
- A pump to create pressure that will push the fluid around the body.
- Exchange surfaces that enable substances to enter the blood and leave again where they are needed.
- Tubes or vessels to carry blood by mass flow.
- Two circuits- one to pick up oxygen and the other to deliver it.
8
Q
What sort of circulatory system does a fish have?
A
A single closed circulatory system.
9
Q
What sort o0f circulatory system does a mammal have?
A
A double closed system.
10
Q
Compare a single and double circulatory system.
A
The blood pressure in a single circulatory system in lower than the blood pressure in a double circulatory system. This means that the flow of blood is lower in a single circulation system compared to that of a double circulation system.
11
Q
Why do fish have single circulation systems if they’re not as efficient as double circulation systems?
A
They’re not as metabolically active as mammals as they do not need to maintain their body temperature. Therefore their single circulatory system delivers efficient oxygen and nutrients for their needs.
12
Q
Define arteries.
A
Blood vessels that carry blood away from the heart.
13
Q
Define arterioles.
A
Small blood vessels that distribute blood from an artery to the capillaries.
14
Q
Define capillaries.
A
Very small vessels with very then walls.
15
Q
What is a closed circulatory system?
A
A circulatory system in which the blood is held in vessels.
16
Q
What is an open circulatory system?
A
One in which the blood is not held in vessels.
17
Q
What are veins?
A
Vessels that carry blood back to the heart.
18
Q
What are venules?
A
Small blood vessels that collect blood from capillaries and lead into the veins.
19
Q
Where is the blood in an open circulatory system?
A
The blood circulates through the body cavity, so that the tissues and cells are bathed directly in blood.
20
Q
How does blood circulate in insects?
A
Insects have a muscular pumping organ, like the heart, that lies just under the upper surface of the body. Blood from the body enters the heart through pores called ostia. The heart then pumps the blood towards the head by peristalsis. At the forward end of the heart, near the head, the blood simply pours out into the body cavity. This circulation continues when the insect is at rest however, is aided by body movements.
21
Q
What is an ostia?
A
Pores in an insect the allows blood to enter it’s heart.
22
Q
What is peristalsis?
A
The way an insect pimps blood towards the heart.
23
Q
What are 2 disadvantages of an open circulation system?
A
- Blood pressure is low so blood flow is low.
- Circulation of blood may be affected by body movements or lack of body movements.
24
Q
What advantages does a closed circulation system have compared to an open circulation system?
A
- Higher pressure, so that the blood flows quicker.
- More rapid delivery of oxygen and nutrients.
- More rapid removal of carbon dioxide and other waste.
- Transport is independent of body movements.
25
What characteristic does all blood vessels have?
All blood vessels have an **inner lining** made of a single layer of cells, called the **endothelium**. This is a thin layer made of **squamous epithelium cells** that are **smooth which reduces friction** of blood.
26
What are the characteristics of an artery?
* **Artery wall is thick** to withstand pressure.
* **Lumen is relatively small** in order to maintain high pressure.
* **Inner wall is folded** to allow the lumen to expand as blood flow increases.
27
What does an artery wall consist of?
* **Inner layer** consists of a **thin layer of elastic tissue** which allows the wall to stretch and then recoil to help maintain blood pressure.
* **Middle layer** consists of a **thick layer of smooth muscle**.
* **Outer layer** is relatively **thick layer of collagen and elastic tissue**. This provides strength to withstand the high pressure, and recoil to maintain the pressure.
28
Why may arterioles constrict?
When arterioles constrict, it increases the resistance to the flow and reduces the rate of flow of blood. Constriction of the arteriole walls can be used to **divert the flow of blood** to regions of the body that are demanding more oxygen.
29
Describe the structure of a capillary.
* Capillaries have very **thin walls.**
* Their **lumen is very narrow**- similar to the diameter of a red blood cell, helping to transfer oxygen as it reduces the diffusion path to the tissues.
* The wall consist of a **single layer of flattened endothelial cells**- reducing the distance for the materials being exchanged.
* **The walls are leaky**, they allow blood plasma the dissolved substances to leave the blood.
30
What do the venules do?
They collect the blood from the capillary bed and lead into the veins.
31
What does the structure on a venule consist of?
Thin layers of muscle and elastic tissue outside the endothelium, and a thin layer of collagen.
32
What is the structure of a vein like?
* The **lumen is relatively large**, in order to ease the flow of blood.
* The walls have thinner layers of collagen, smooth muscle and elastic tissue than in artery walls. They no not need to stretch and recoil, and are not actively constrict is order to reduce blood flow.
* Contraction of the surrounding skeletal muscle applies pressure of the blood, forcing the blood to move along in a direction determined the **valves**.
33
What is hydrostatic pressure?
The **pressure** that a **fluid exerts** when pushing against the sides of a vessel or container.
34
What is lymph?
The **fluid held in the lymphatic system**, which is a system of the tubes that returns excess tissue fluid to the blood system.
35
What is oncotic pressure?
The **pressure created by the osmotic effects** of the solutes.
36
What is plasma?
The fluid portion of the blood.
37
What is tissue fluid?
The fluid surrounding the cells and tissues.
38
What does plasma contain?
many dissolved substances, including, oxygen, carbon dioxide, glucose, amino acids, hormones, plasma proteins and many blood cells including, erythrocytes, leucocytes and platelets.
39
What is another word for red blood cells?
Erythrocytes.
40
What is another word for white blood cells?
Leucocytes.
41
How is tissue fluid and blood plasma similar?
Tissue fluid and blood plasma are similar, however, tissue fluid does not contain most of the cells found in the blood, and plasma proteins.
42
How is tissue fluid formed?
Tissue fluid is formed by plasma leaking from the capillaries.
43
Where is tissue fluid found?
It surrounds the cells in the tissue.
44
What does tissue fluid do?
It supplies tissues with the oxygen and nutrients that they require. AS blood plasma leaks from the capillary, it carries all the dissolved substances into the tissue fluid.
45
What is it called when the blood plasma leaks into the tissue fluid?
This movement is called **mass flow**. NOT DIFFUSION.
46
What happens to waste products and tissue fluid?
Waste products from cell metabolism will be **carried back into the capillary** as some of the tissue fluid returns back to the capillary.
47
What occurs at the arterial end of a capillary in the formation of tissue fluid?
At the arterial end of the capillary, the blood is at relatively **high hydrostatic pressure**, therefore, this **pushes the blood fluid out of the capillary** through the capillary wall through tiny gaps between cells in the capillary wall.
48
What remains in the blood when tissue fluid is formed?
All the reds blood cells. platelets,the plasma proteins and most the white blood cells remain in the blood. This is because **they're too large** to be pushed through the gaps in the capillary wall.
49
How does the uptake of gases and nutrients occur from the tissue fluid to the tissues?
The tissue fluid surrounds the body cells, so the exchange of gases and nutrients occurs across the plasma membrane occurs by **diffusion, facilitated diffusion and active transport**.
50
What does the pressure being lower at the venous end of the capillary allow?
This allows some (NOT ALL) of the tissue fluid to return to the capillary carrying carbon dioxide and other waste substances into the blood.
51
If not all the tissue fluid re-enters the blood, what happens to it?
* Some tissue is directed into the lymphatic system.
* This drains excess tissue fluid out of the tissues and returns it to the blood system in the subclavian vein in the chest.
52
What is lymph?
The fluid in the lymphatic system is called lymph and is similar in composition to the tissue fluid. It will **contain more lymphocytes**, as these are produced in the lymph nodes.
53
What has influence which causes movement of fluid into and out if the capillary?
**Hydrostatic pressure** of the blood and **oncotic pressure** on the tissue fluid.
54
How does tissue fluid flow in and out of a capillary?
* The **hydrostatic pressure** of the blood tends to **push fluid out into the tissues**.
* The **hydrostatic pressure** of the tissue tends to **push fluid into the capillaries**.
* The **oncotic pressure** of the blood tend to **pull water back into the blood**.
* The **oncotic pressure** of the tissue fluid **pulls water into the tissue fluid**.
55
What are the atrio-ventricular valves?
**Valves between the atria and ventricles**, which ensure that the blood flows in the correct direction.
56
What are cardiac muscles?
specialised muscle found in the walls of the heart chambers.
57
What are ventricular valves?
Valves that prevent blood re-entering the heart from the arteries.
58
What is the blood like on the right side of the heart and where is the blood being pumped to?
The right side pumps **deoxygenated blood to the lungs** to be oxygenated.
59
What is the blood like on the left side of the heart and where is the blood being pumped to?
The left side **pumps oxygenated blood to the rest of the body**.
60
What does the heart consist of?
The main part of the heart is made of the **cardiac muscle**. There's **2 main pumping chambers**- the **ventricles**. Above the ventricles, are two thin walled chambers- the **atria**. Lying over the surface of the heart are the **coronary arteries**, that supply blood to the heart.
61
What can happen if the coronary artery becomes constricted or blocked?
It restricts the blood flow to the heart, reducing the delivery of oxygen and nutrients like fatty acids and glucose. This can cause **angina** or a **heart attack**.
62
What are the two upper chambers of the heart called?
The atria.
63
What are the two lower chambers of the heart called?
The ventricles.1
64
What are the 4 chambers of the heart called?
* Right atrium
* Left atrium
* Right ventricle
* Left ventricle
65
What blood vessel pumps deoxygenated blood from the body into the heart?
The **vena cava** pumps the deoxygenated blood into the **right atrium**.
66
What blood vessel pumps oxygenated blood from the lungs to the heart?
The **pulmonary vein** pumps the oxygenated blood into the left atrium.
67
Where does the blood flow after entering an atrium?
From the atria, the blood flows down through the **artio-ventricular valves** into the **ventricles**.
68
What are attached to the atrio-ventricular valves?
Attached to the valves are **tendinous cords**, which prevent the valves from turning inside out when the ventricle walls contact.
69
What is the muscle called that separates the right ventricle to the left ventricle of the heart?
The **septum**. It ensures that the oxygenated and deoxygenated blood don't mix.
70
Which side of the heart contains oxygenated blood?
Left side.
71
Which side of the heart contains deoxygenated blood?
Right side.
72
Which blood vessel contains deoxygenated blood leaving the heart?
The **pulmonary artery** leaves from the right ventricle to the lungs.
73
Which blood vessel contains oxygenated blood leaving the heart?
The **aorta**, leaving from the left ventricle it carries blood to a number of arteries that supply all the parts of the body.
74
What are semilunar valves?
Found at the base of major arteries, where they exit the heart, are semilunar valves. These prevent blood returning to the heart as ventricles contract.
75
What is the structure and pressure like in the atria?
The muscle of the **atrial walls is very thin**. This is because these c**hambers do not need to create much pressure** because their function is to receive blood from the veins and push it into the ventricles.
76
What is the structure and pressure like in the right ventricle?
Walls of the right ventricle is **thicker than the walls of the atria** so that it can **pump blood out of the heart**. However, the blood does not need to travel very far as the deoxygenated blood is going to the lungs. Also the **alveoli in the lungs could be damaged by very high blood pressure**.
77
What is the structure and pressure like in the left ventricle?
The walls of the left ventricle can be **2 or 3 times thicker than the wall of the right ventricle**. The blood from the left ventricle is pumped out via the aorta and needs sufficient pressure the **overcome the resistance of the systematic circulation**.
78
What does cardiac muscle consist of?
Cardiac muscle consist of **fibres that branch**, producing **cross-bridges**. These help to spread stimulus around the heart, and also **produce a squeezing action** rather than just a simple reduction of length.
79
What is the structure of cardiac muscle?
* Numerous mitochondria between muscle fibrils (**myofibrils**) to supply energy for contraction.
* The muscle cells are separated by **intercalated discs**, which facilitate synchronised contraction.
* Each call has a nucleus and is divided into contractile units called **sarcomeres**.
80
What is the cardiac cycle?
The sequence of events in one full beat of the heart.
81
What is the role of the heart?
To create pressure that pushes blood around the blood vessels.
82
What do the valves in the heart do?
The valves ensure that the blood flows in the correct direction.
83
What are the 3 stages during the cardiac cycle?
* Atrial systole
* Ventricular systole
* Diastole
84
What happens during atrial systole?
**Both right and left atria contact together**. The muscle in the wall 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 to ensure they are full of blood.
85
What happens during ventricular systole?
**Both the right and left ventricles pump together**. Contraction starts at the apex (base) of the heart so the blood is pushed upwards towards the arteries.
86
What happens during diastole?
**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.
87
What happens during the cardiac cycle, starting after systole?
The ventricular walls relax and recoil, causing:
* pressure in the ventricles rapidly drop below pressure in the atria.
* Blood in the atria pushes atrio-ventricular valves to open.
* Blood entering the heart flows straight through the atria and into the ventricles.
* Pressure in the atria rises as they fill with blood.
* Valves remain open while the atria contact, 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.
* Ventricle contacts, increasing the pressure.
* When pressure rise above that in the atria, blood starts to move upwards.
* this ,movement fills the valve pockets and keeps them closed and the tendinous cords attached to the valves prevent them from turning inside out.
* This prevents blood flowing back into the atria.
88
How do the semilunar valves work?
* Before ventricular contraction, the pressure in the major arteries is higher than the pressure in the ventricles, this **keeps the semilunar valves closed.**
* Ventricular systole increases the pressure in the ventricles very quickly.
* Once the blood is under very high pressure, it is forced out of the ventricles.
* Once the ventricle have finished contacting, the heart goes into diastole.
* Elastic tissue in the walls of the ventricles recoil, stretching the muscle out so the ventricle returns to its original size.
* This causes pressure to drop in the ventricles quickly.
* As it drops below the pressure in the major arteries, the blood starts to flow back towards the ventricles.
* **The semilunar valves are pushed closed by the blood collecting in the pockets of the valves, preventing blood returning to the ventricles.**
89
What is the pulse we can feel on our wrist or neck?
We can feel a pulse caused by a pressure wave when the semilunar valve close.
90
Label a graph of pressure changes in the heart.
91
What does a graph showing pressure changes at different parts of the blood system look like?
92
What is bradycardia?
A slow heart rhythm.
93
What word can you use to describe a slow heart rhythm?
Bradycardia.
94
What is an ectopic heartbeat?
An extra beat or an early beat of the ventricles.
95
What word could you use to describe an extra beat or an early beat of the ventricles.
An ectopic heartbeat.
96
What can you call a trace that records the electrical activity of the heart?
An elecrocardiogram.
97
What is fibrillation?
Uncoordinated contraction of the atria and the ventricle.
98
What can you call uncoordinated contraction of the atria and the ventricle.
Fibrillation.
99
What is myogenic muscle?
Muscle that can initiate its own contraction.
100
What is Purkyne tissue?
Purkyne tissue consists of **specially adapted muscle fibres** that **conduct the wave of excitation** from the AVN down the septum to the ventricles.
101
What is the SAN?
The **sino-atrial node** is the heart's **pacemaker.** It is a small patch of **tissue that sends out waves of electrical excitation** at regular intervals in order to initiate contractions.
102
What does tachycardia mean?
A rapid heart rythum.
103
What word can be used to describe a rapid heart rhythm?
Tachycardia.
104
Why is the heart described as myogenic?
It contracts and relaxes rhythmically on it's own.
105
How is a heartbeat initiated and controlled?
At the top of the right atrium, near the point where the vena cava empties blood into the atrium, is the **sino-atrial node (SAN**), a small patch of tissue that generates electrical activity. The **SAN initiates a wave of excitation at regular intervals**.
106
What happens during the contraction of the atria after the SAN has released a wave of excitation?
* 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 excitation passes, it causes that cardiac muscle cells to contact**.
* This is an **atrial systole**.
107
What happens to the wave f excitation when it reaches the base of the atria?
The tissue at the base of the atria is **unable to conduct to wave of excitation**, so cannot spread directly down to the ventricle walls. At the top of the ventricular septum, it another node- the **atrio-ventricular node (AVN).** This is the only route the wave can travel to the ventricles- the **wave is delayed in the node** to allow time for the atria to finish contacting and for blood to flow down into the ventricles before they begin to contact.
108
What is the AVN
The **atrio-ventricular node** if found at the **top of the interventricular septum**- the **wave of excitation is delayed here** to allow time for the atria to finish contacting and for blood to flow down to the ventricles before they start to contact.
109
What happens to the wave of excitation after it has been delayed at the the AVN?
* After the short delay, the wave of excitation is carried away from the AVN and **down specialised conducting tissue called Purkyne tissue.**
* This runs down the **intraventricular septum.**
* At the base of the septum, the wave of excitation spreads out over the walls of the ventricles.
* As the excitation **spreads upwards from the apex of the ventricles**, it causes the muscles to contract.
* This means that the ventricles contact from the base upwards.
* This pushes the blood upwards towards the major arteries at the top of the heart.
110
What can you use to measure the activity of the heart?
An elerocardiogram.
111
What does an electrocardiogram inculde?
It involves attaching a **number of sensors to the skin**. Some of the **electrical activity** generated by the heart **spreads** through the tissues next to the heart **outwards to the skin**. The sensors on the skin **pick up the electrical excitation** created by the heart and **convert it in to a trace**.
112
Draw and label a normal electrocardiogram.
* Wave P shows the excitation of the atria.
* QRS indicates the excitation of the ventricles.
* T shows diastole.
113
What condition does this person have?
Brachycardia
114
What condition does this person have?
Trachycardia.
115
What condition does this person have?
Atrial fibrillation: the atria beating more frequently than the ventricles- no clear P waves.
116
What condition does this person have?
Ectopic heartbeat- the patient often feels like a heartbeat has ben lost.
117
What does affinity mean?
A strong attraction.
118
What does dissociation mean?
Means releasing the oxygen from the oxyhaemoglobin.
119
What is fetal haemoglobin?
The type of haemoglobin usually only found in the fetus.
120
What is haemoglobin?
The red pigment used to transport oxygen in the blood.
121
What does haemoglobin become when it takes up oxygen?
Oxyhaemoglobin.
122
What is the structure of haemoglobin?
Haemoglobin is a complex protein with **4 subunits**. Each subunit consists of a **polypeptide chain** and a **haem group**. The haem group contains a single **iron ion**. This iron ion can attract can hold an oxygen molecule.
123
How can you describe the relationship between oxygen and the iron ion in haemoglobin?
The haem group has a **high affinity for oxygen**. Each haem group can hold one oxygen so, a haemoglobin molecule can carry 4 oxygen molecules.
124
How does oxygen bind to a erythrocyte?
Oxygen is absorbed into the blood as it passes the alveoli in the lungs. Oxygen molecules diffusing into the blood plasma enter red blood cells. Here **they become associated with the haemoglobin.**
125
How can we describe the reaction between oxygen and haemoglobin?
Reversible.
126
What affects the ability of haemoglobin to associate and release oxygen?
The **concentration of oxygen in the surrounding tissues**. The concentration of oxygen is measured by the relative pressure that it contributes to a mixture of gases. This is called **partial pressure** of oxygen, or **oxygen tension** (KPa)
127
What us partial pressure?
The concentration of oxygen is measured by the relative pressure that it contributes to the mixture of gases.
128
With a normal liquid, how would you expect the relationship of concentration on oxygen absorbed and the oxygen tension surrounding it?
Directly proportional.
129
What shape curve is produced in a graph showing how much oxygen associates with haemoglobin compared to the concentration of oxygen surrounding it?
S shape curve.
130
What is the S-shaped curve that shows how oxygen associates with haemoglobin called?
The haemoglobin dissociation curve.
131
How does oxygen associate with haemoglobin at low oxygen tension?
At low oxygen, the haemoglobin **does not readily associate with oxygen molecules**. This is because the **haem groups are in the centre of the haemoglobin molecule**- this makes to difficult for the molecule to reach the haem group and associate with it.
132
Why is it difficult for the first oxygen molecule to associate with haemoglobin?
Low oxygen tensions.
133
What is the conformational change?
When the first oxygen molecule associates with the haemoglobin, the **haemoglobin slightly changes shape**. It allows more oxygen to associate with haem groups more easily.
134
What does a haemoglobin dissociation curve look like?
135
How is fetal haemoglobin different to adult haemoglobin?
Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin.
136
How is a fetal haemoglobin dissociation curve different to an adult haemoglobin dissociation curve?
The haemoglobin dissociation curve is to t**he left of the curve** for adult haemoglobin because fetal haemoglobin **must be able to associate with oxygen in an environment where oxygen tension is low** enough to make adult haemoglobin release oxygen.
137
Why is oxygen tension low around a fetus?
The oxygen is the mothers blood stream must supply all her body cells oxygen for respiration and in the placenta, where the oxygen tension is low, fetal haemoglobin will absorb oxygen for the surrounding fluid, reducing the oxygen tension even further, resulting to more oxygen diffusing to the placenta.
138
What is carbonic anhydrase?
The **enzyme** that **catalyses the combination of carbon dioxide and water**.
139
What is a chloride shift?
The movement of chloride ions into the erythrocytes to balance the charge as hydrogen-carbonate ions leave the cell.
140
What is the Bohr effect?
The **effect that extra carbon dioxide** has on the haemoglobin, explaining the release of oxygen.
141
What is haemoglobinic acid?
The compound formed by the **buffering action** of haemoglobin as it combines with **excess hydrogen ions**.
142
How is carbon dioxide transported in the blood?
* 5% is **dissolved directly in the plasma**.
* 10% is **combined directly with haemoglobin** to form a compound called **carbaminohaemoglobin**.
* 85% is **transported in the form of hydrogencarbonate ions** (HCO3-)
143
What is created when carbon dioxide in directly combined with haemoglobin?
Carbaminohaemoglobin.
144
How do hydrogencarbonate ions form?
* Carbon dioxide in the blood diffuses into the red blood cells where is combines with water to form a weak carbonic acid- this is catalysed by carbonic anhydrase
* This carbonic acid dissociates to release hydrogen ions (H+) and hydrogencarbonate ions (HCO3-).
* The hydrogencarbonate ions diffuse out of the red blood cells into the plasma. The charge inside the red blood cell is maintained by the shift of chloride ions from the plasma into the red blood cells (the chloride shift).
145
What prevents hydrogen ions building up in red blood cells?
Once the hydrogencarbonate ions diffuse out of the red blood cells, hydrogen ions could build up which, could become very acidic. To prevent this, the **hydrogen ions and taken out of solution by associating with haemoglobin** to produce **haemoglobinic acid** (HHb) The haemoglobin is acting as a buffer.
146
What is the molecule HHb?
Haemoglobinic acid
147
What is the molecule HCO3-
Hydrogencarbonate ions.
148
What is the molecule H2C03
Carbonic acid.
149
What happens to the oxyhaemoglobin as it travels around the body?
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 the **oxygen has been used in respiration**- as a result, **oxyhaemoglobin begins to dissociate and release oxygen to the tissues**.
150
What happens to haemoglobin after it has released its oxygen?
The haemoglobin is available to take up the hydrogen ions, forming haemoglobinic acid.
151
What does the Bohr effect include?
* 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.
* This pH change/ 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 oxygen is released from the oxyhaemoglobin to the tissues.
152
Summarise the Bohr effect?
Where tissues are respiring more, there will be **more carbon dioxide**. As a result, there will, be **more hydrogen ions** in the red blood cells. This makes the **oxyhaemoglobin release more oxygen**.
153
What happens to the haemoglobins oxygen saturation if there is more carbon dioxide?
When there is more carbon dioxide, haemoglobin becomes less saturated with oxygen.
154
What is the Bohr shift?
When more carbon dioxide, haemoglobin becomes less saturated with oxygen. This is reflected in a change the the haemoglobin dissociation curve , which shifts downwards and to the right- the Bohr shift.
155
How does the Bohr effect occur?
* Carbon dioxide enters red blood cells forming carbonic acid, Which dissociates, forming **hydrogen ions**.
* These hydrogen ions affect the pH of the cytoplasm, making it **more acidic**.
* As with any protein, changes in the protein pH can **affect the tertiary structure** of the haemoglobin. The increased acidity alters the tertiary structure of the haemoglobin and **reduces the affinity of the haemoglobin for oxygen.**
* The haemoglobin in unable to hold as much oxygen, and oxygen, and **oxygen is released** from the oxyhaemoglobin to the tissues.
156
What happens in the red blood cells if a person is doing lots of exercise?
**Carbon dioxide** in the blood plasma diffuses into the red blood cells where it forms **carbonic acid**, then **dissociates into hydrogen ions and hydrogencarbonate ions**. Lots of hydrogen ions makes the plasma in the red blood cell **acidic**, altering the **tertiary structure** of the haemoglobin. This **reduces** the haemoglobin's **affinity for oxygen**, leading to **more oxygen being released** to the respiring tissues.
