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Bellas Biology > Topic 4.3 Circulation > Flashcards

Topic 4.3 Circulation Flashcards

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1
Q

What is a mass transport system

A

A transport system which delivers oxygen and nutrients to all cells of the body. It removes waste products which would be toxic.
(In large multicellular)

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2
Q

Features of mass transport

A
  • A system of vessels that carry substances.
  • A way of making sure that substances are moved in the right direction.
  • A means of moving materials fast enough to supply the needs of the organism.
  • A suitable of transport medium.
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3
Q

Fish mass transport

A

Main features:
-Closed circulatory system
-2 chambered heart
-Blood is oxygenated at the gills and is deoxygenated as it ravels around the body

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4
Q

Mammalian mass transport

A

Double circulation:
-Pulmonary- takes blood to the lungs
-Systemic- takes blood around the rest of the body

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5
Q

Blood performs a number of roles

A
  • Transport: oxygen, glucose, CO2, urea, hormones, antibodies.
  • Distributes heat.
  • Part of the immune system.
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6
Q

The components of blood:
Plasma

A

Plays a major role in transporting;
-digested food products from the small intestine to all parts of the body where its needed
-nutrient molecules from a storage areas to the cells that need them
-excretory products from the cells to the organs such as lungs or kidneys
-chemical messages from where they are made to where they cause changes
Also helps maintain a steady body temperature by transferring heat around the system.
It acts as a buffer to pH changes.
(Makes up 55% of blood).

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7
Q

The components of blood:
Erythrocytes

A
  • Approx. 5 million per mm3 of blood.
  • They contain haemoglobin.
  • They are formed in the bone marrow.
  • Mature erythrocytes don’t contain a nucleus and have a limited life of about 120 days.
  • Haemoglobin also carries some of the CO2 produced in respiration back to the lungs.
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8
Q

Adaptations of an erythrocyte

A
  • Biconcave disc shape; large SA:V ratio, so oxygen can diffuse in and out of them rapidly.
  • Having no nucleus leaves more space inside for haemoglobin molecules.
  • Flexible so can fit through smaller capillaries.
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9
Q

The components of blood:
Granulocytes; Neutrophils

A

Part of the non-specific immune system, they engulf and digest pathogens by phagocytosis. They have multi-lobed nuclei.

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10
Q

The components of blood:
Granulocytes; Eosinophils

A

Part of the non-specific immune system. They are stained by red eosin stain. They are important in the non-specific immune response of the body against parasites, in allergic reactions and inflammation and in developing immunity to disease.

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11
Q

The components of blood:
Granulocytes; Basophils

A

Part of the non-specific immune system. They have two lobed nucleus. They are histamines involved in inflammation and allergic reaction.

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12
Q

The components of blood:
Agranulocytes; Monocytes

A

Part of the non-specific immune system. They are the largest leucocytes. They can move out of the tissues to form microphages. They engulf pathogens by phagocytosis.

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13
Q

The components of blood:
Agranulocytes; lymphocytes

A

Small leucocytes with very large nuclei that are vitally important in the specific immune response of the body.

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14
Q

Haemoglobin

A
  • A globular protein made up of 4 polypeptide chains, each with haem (iron) containing group.
  • Each haem can pick up 4 molecules of oxygen.
  • Reversible reaction- oxyhemoglobin is formed in the lungs, then when oxygen dissociates (leaves) haemoglobin in the body tissues it turns back to haemoglobin.
  • Once one O2 molecule joins it makes t easier for another O2 molecules to then load, but as it becomes harder for more to bind.
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15
Q

Partial pressure

A

(pO2 or ppO2)
- Is the same as saying the concentration of oxygen
- As pO2 increases it becomes easier for oxygen to load to haemoglobin
- When pO2 is low, the oxygen dissociates from the haemoglobin

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16
Q

Transport of oxygen

A
  • The haemoglobin molecules that are packed in the red blood cells transport oxygen.
  • Each haemoglobin molecule is a large globular protein made up of four peptide chains, each with an iron-containing prosthetic group, which can pick up four molecules of oxygen.
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17
Q

The Bohr effect

A
  • The way in which haemoglobin takes up and releases oxygen is also affected by the proportion of carbon dioxide in the tissues.
  • When the partial pressure of CO2 is high, the affinity of haemoglobin needs higher levels of oxygen to become saturated and gives up oxygen more easily.
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18
Q

Fetal haemoglobin

A
  • Is found only in the developing foetus.
  • The foetus is dependent on it’s mother for oxygen.
  • The mothers blood runs through the placenta close to the deoxygenated foetal blood.
  • Little oxygen would be transferred if he foetus had the same affinity for oxygen as the mother.
  • Foetal haemoglobin has a higher affinity for oxygen.
  • Therefore can remove oxygen from mothers blood.
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19
Q

Myglobin

A

A respiratory pigment food in the muscle tissue vertebrates.
-Red protein (gives red meat its colour)
-Much higher affinity for oxygen than haemoglobin
-Doesn’t give up oxygen easily (acts as an oxygen store)
-When carbon dioxide levels are high, the oxygen store is released

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20
Q

Haemoglobin binding with oxygen

A

Hb + 4O2 ⇌ HbO8
(forward- in lungs)
(backward- in tissues)

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21
Q

pO2 in alveoli

A
  • The partial pressure (or oxygen tension) in the alveoli is relatively high and under these conditions haemoglobin will become saturated with oxygen.
  • The blood then carries the oxygen around the body to respiring cells, where the partial pressure of oxygen is low.
  • Under these conditions oxyhaemoglobin gives up its oxygen.
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22
Q

Clotting blood

A

Wound:
- Damaged cells release platelets.
- Platelets release thromboplastin (enzyme).
- Thromboplastin and calcium ions cause prothrombin (soluble protein) to change into its active form thrombin.
- Thrombin catalyses fibrinogen into fibrin- forms the clot
(Cells, salts cholesterol, and other substances build up and harden, forming a plaque that narrows the artery).

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23
Q

Blood circulation pathway

A

Vena cava->right atrium->tricuspid valve->right ventricle->semilunar valve->pulmonary artery->lungs->pulmonary vein->left atrium->bicuspid valve->left ventricle->semi lunar valve->aorta->body

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24
Q

Blood vessel pathway

A

Artery–> arteriole–> capillary–> venue–> vein

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25
Q

Arteries

A
  • Carries blood from the heart to the tissues.
    -Thick walls with smooth elastic layers to resist high pressure and muscle layer to aid pumping.
    -Small lumen.
    -No valves (except in heart).
    -Blood at high pressure.
    -Blood (usually) oxygenated.
    -Arteries nearest the heart have more elastic fibres, those further from the heart have a greater proportion of muscle tissue.
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26
Q

Veins

A
  • Carry blood towards the heart.
  • Tiny venules lead from capillary network merging into larger vessels leading back to the heart.
  • Can hold a large volume of blood.
  • Relatively low pressure.
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27
Q

Capillaries

A
  • The capillary network link the arterioles and venules.
  • Capillaries branch between cells so substances can diffuse between cells and the blood quickly.
  • Blood travels relatively slow through them giving more opportunity for diffusion to occur.
  • Thin walls, no elastic fibres or smooth muscle.
  • One cell thick.
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28
Q

Cardiac cycle

A

1) Atrial systole:
-atria contract
-forcing blood into ventricles
2) Ventricular systole:
-ventricles contract
-force blood out into the pulmonary vein and artery
—>Between contractions there is a diastole
-heart relaxes and fills with blood
At rest: 0.8 seconds

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29
Q

Heart contractions

A
  • Atrial Systole:
    -The atria contract, pushing blood into the ventricles.
  • Ventricular Systole:
    -The ventricles contract.
    -The pressure increases, closing the atrioventricular valves to prevent back flow
    -Semilunar valves open.
    -Blood flows into the arteries.
30
Q

Heart relaxation

A

Cadiac Diastole.
- Blood enters the atria, increasing the pressure and pushing open the atrioventricular valves.
- This allows blood to flow into the ventricles.
- Pressure in the heart is lower than the arteries, so semilunar valves remain closed.

31
Q

Heart muscle is myogenic

A

The heart contractions originate from within the heart muscle.
Controlled by cardiovascular centre in the medulla of the brain (rather than by nerve impulses).

32
Q

Atrial contraction steps

A

1) Sino-atrial node releases nerve impulses over the atria.
2) The band of non-conducting tissue prevent impulses passing down the ventricles.
3) SAN impulses stimulate atrio-ventricular node (AVN) to send impulses passing down the bundle of His.
4) Impulses pass up the ventricle through the purkyne fibres.
5) Ventricles contract forcing blood out the ventricles.

33
Q

ECG

A
  • Used to investigate the rhythms of the heart by producing a record of the electrical activity of the heart.
  • The rhythm of the heart results from the spread of a wave of polarisation through the specialised tissue.
  • 12 electrodes and leads are attached to the body.
  • Information is fed back from each of the electrodes, giving 12 views of the heart.
34
Q

ECG while exercising

A

Sometimes an ECG is carried out while a patient is exercising (known as a stress test) because some heart conditions show up only during exercise.

35
Q

Cardiovascular disease

A
  • 33% of deaths in the UK.
  • 30% under 75.
36
Q

Atherosclerosis

A
  • Hardening of the arteries.
  • Build up of plaque.
  • Can begin in late childhood and continues through life.
  • Plaques are particularly likely to form in the arteries of the heart (coronary arteries) and neck (carotid arteries).
37
Q

The formation of atherosclerosis

A
  1. Damage to the artery wall- this can lead to a build up of cholesterol
  2. Blood, platelets form a cap over the plaque which narrows the artery
  3. Fibrin can cause red blood cells to become trapped
  4. This can cause a blood clot (thrombosis)
  5. If this happens in a coronary artery it can cause a heart attack
38
Q

Aneurysms

A
  • Area of artery is narrowed by plaque.
  • Blood builds up behind the blockage.
  • Artery bulges and the wall is put under more pressure than usual.
  • Weakened artery may split, leading to massive internal bleeding
  • Massive blood loss and drop in blood pressure are often fatal.
    –> If aneurysms are diagnosed, they can be treated by surgery before they burst.
39
Q

Raised blood pressure

A
  • The narrowed arteries cause raised blood pressure.
  • This can cause damage in other organs.
  • The high pressure damages the tiny blood vessels where your kidney filters out urea.
  • If the pressure inside them gets higher, proteins may be forced through the walls.
40
Q

Heart disease

A

The most common heart diseases are angina and myocardial infarction, both closely linked to atherosclerosis.

41
Q

Risk factors contributing to coronary artery heart disease

A
  • Old age
  • Male
  • Obesity
  • High alcohol intake
  • Lack of exercise
  • High blood pressure
  • Cigarette smoking
  • High levels of stress
  • High blood cholesterol levels
  • Family history (genetic)
42
Q

Non- modifiable risk factors

A
  • Genes
  • Age
  • Sex
43
Q

Modifiable risk factors

A

(Lifestyle)
- Smoking
- Exercise
- Weight
- Stress
- Diet

44
Q

Non- modifiable risk factors: Genes

A
  • Studies show there is a genetic tendency in some families and ethnic groups to develop atherosclerosis or other CVDs.
  • There are a variety of genetic tendencies- the arteries may be more easily damaged.
45
Q

Non- modifiable risk factors: Age

A

As you get older, your blood vessels begin to lose their elasticity and to narrow slightly, making you more likely to suffer from atherosclerosis and CVDs, particularly heart disease.

46
Q

Non- modifiable risk factors: Sex

A
  • Under the age of 50, men are statistically more likely to suffer from atherosclerosis than women.
  • The female hormone oestrogen appears to reduce the build-up of plaque, giving women some protection against atherosclerosis until the menopause when oestrogen levels fall.
47
Q

Modifiable risk factors: Smoking

A
  • 9 out of 10 people need heart bypass surgery or stents as a result of atherosclerosis are smokers.
  • Studies found that some of the chemicals in tobacco smoke can damage the artery lining making the build up of plaque more likely, and cause the arteries to narrow, raising blood pressure and increasing the risk of atherosclerosis.
48
Q

Modifiable risk factors: Exercise

A
  • Regular exercise helps lower blood pressure, prevent obesity and diabetes (lowers the risk of atherosclerosis).
  • Various studies have shown that exercise both reduces the formation of plaques in the arteries and also keeps plaques that are present more stable and less likely to rupture.
49
Q

Modifiable risk factors: Weight

A
  • Studies suggest that being overweight is a very important indicator of risk of developing atherosclerosis.
  • This is because other factors that are a direct result of being overweight do increase the risk of atherosclerosis
  • These include:
    -High blood pressure: increases the risk of damage to blood vessels linings and so of plaque formation
    -Type 2 diabetes: this can result in damage to the lining of the blood vessels increasing the risk of plaque formation.
50
Q

Modifiable risk factors: Stress

A
  • High stress levels increase the risk of atherosclerosis in a number of ways.
  • Stress causes the release of cytokines that trigger an inflammatory response in the blood vessels, leading to plaque rotation.
  • It also tends to raise blood pressure.
51
Q

Modifiable risk factors: Diet

A
  • The relationship between fat in the diet and cholesterol in the blood is further complicated by complicated by lipoproteins which transport lipid around the body.
52
Q

Tissue fluid

A
  • Tissue fluid is the liquid that surround the cells, allowing for transport between blood and cells
  • Capillary walls are partially permeable
  • Tissue fluid is the result of an interplay of:
    -Hydrostatic pressure
    -Osmosis (Oncotic pressure-changing water potential of capillaries as water moves out)
53
Q

Hydrostatic pressure

A
  • This is the pressure of the blood from the heart contractions- it forces fluid out of the capillaries.
  • Fluid moves out through tiny gaps in the capillary walls.
  • Dissolved gases and nutrients move with it.
  • Larger plasma proteins and cells do not.
54
Q

Osmosis in capillaries

A
  • A net loss of water from the capillaries gives them a more negative water potential.
  • Water moves down the water potential into the capillaries.
55
Q

What is lymph?

A
  • Not all fluid passes back into the capillaries.
  • The excess output needs to be collected to avoid tissue swelling.
  • This net access is drained into the vessels of the lymphatic system- this fluid is known as lymph.
56
Q

How does lymph work?

A
  • Lymph passes through the lymphatic system and drains back into the circulatory system.
  • Lymph contains lymphocytes.
  • Lymphocytes help filter out foreign materials from the lymph.
  • Movement if lymph is cause largely by contraction of nearby muscles, valves and smooth muscle in their walls.
  • Similar to tissue fluid but can contain fats, more proteins and white blood cells.
57
Q

Lymphatics

A

Lymphatics are tiny bind-ending vessels found in most body tissues and join up to return fluid to the blood through an opening into the subclavian veins.

58
Q

Arrangement of oxygen molecules on haemoglobin

A
  • The first oxygen molecule that binds to the haemoglobin alters the arrangement of the molecule making it easier for the fooling oxygen molecules to bind.
  • The final oxygen molecule binds several hundred times faster than the first.
  • The same process happens in reverse when oxygen dissociates; it gets progressively harder to remove the oxygen.
59
Q

Diffusion of oxygen in the lungs

A
  • Oxygen moves into the red blood cells from the air in the lungs by diffusion.
  • The free oxygen concentration in the cytoplasm of the red blood cells stays low because the oxygen is picked up and bound to the haemoglobin.
  • This maintains a steep concentration gradient from the air on the lungs to the red blood cells, so more and more oxygen diffuses in.
60
Q

Saturation of blood with oxygen

A
  • As a result of the strong affinity of haemoglobin for oxygens small change in proportion of oxygen in the surrounding air can have a big effect on the saturation of the blood with oxygen.
  • So in the lungs the haemoglobin loads up rapidly with oxygen.
61
Q

Oxygen in the blood when exercising/resting

A
  • When your at rest or exercising gently, only about 25% of the oxygen carried by haemoglobin os released into cells.
  • There is another 75% reserve in the transport system for when you are very active.
62
Q

Carbaminohaemoglobin equation

A

CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+

63
Q

Carbonic anhydrase in CO2 transportation

A
  • The enzyme carbonic anhydrase controls the rate of the reaction between carbon dioxide and water to form carbonic acid.
  • In the body tissues there is a high concentration of carbon dioxide in the blood, so carbonic anhydrase catalyses the formation of carbonic acid.
  • In the lungs the carbon dioxide concentration is low, so carbonic anhydrase catalyses the reverse reaction and free carbon dioxide diffuses out of the blood and into the lungs.
64
Q

Carbon dioxide effect on oxygen dissociation

A
  • Oxygen dissociates from oxyhemoglobin where the pO2 is low.
  • If H+ ions can bind with Hb, the must compete with oxygen.
  • In respiring tissue:
    -More CO2 produced
    -More competition for Hb
    -More oxygen dissociation
65
Q

3 ways carbon dioxide is transported

A
  • Waste CO2 diffuses from the respiring cells of the body tissues into the blood along a concentration gradient.
  • 5% is dissolved in plasma
  • 20% combines with haemoglobin
  • 75% carries in rbcs as hydrogen carbonate ions
66
Q

The umbilical vein

A

During pregnancy, it carries oxygenated blood from the placenta into the foetus.

67
Q

The structure of the chambers and their functions

A
  • Atria: thin-walled and elastic, so they can stretch when filled with blood.
  • Ventricles: thick muscular walls pump blood under high pressure. The left ventricle is thicker than the right because it has to pump blood all the way around the body.
68
Q

Why are two pumps (left and right) needed instead of one?

A
  • To maintain blood pressure around the whole body.
  • When blood passes through the narrow capillaries of the lungs, the pressure drops sharply and therefore would not be flowing strongly enough to continue around the whole body.
  • Therefore it is returned to the heart to increase the pressure.
69
Q

The nodes involved in heart contraction

A
  • Sinoatrial node (SAN): wall of right atrium.
  • Atrioventricular node (AVN): in between the two atria.
70
Q

What do o show?

A

Saturation of haemoglobin with oxygen (in%), plotted against partial pressure of oxygen (in kPa). Curves further to the left show the haemoglobin has higher affinity for oxygen.

71
Q

How does the Bohr effect alter the position of an oxyhemoglobin dissociation curve?

A

Curve shifts to the right because haemoglobin’s affinity for oxygen has decreased.

Bellas Biology (34 decks)

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