BIOL1008 Chapter Notes - Chapter 5: Abdominal Aorta, Chordae Tendineae, Jugular Vein
8 Jun 2018
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MODULE 3.2. Circulatory System
3.1. Composition of Blood
The 7 functions of blood
1. Transport of gases, nutrients and waste products
2. Transport of processed molecules
3. Transport of regulatory products
4. Regulation of pH and osmosis
5. Maintenance of body temperature
6. Protection against foreign substances
7. Clot formation
- The main constituents of blood are plasma, erythrocytes/red blood cells,
leukocytes/white blood cells and platelets/thrombocytes
- Plasma is composed of water, salts, nutrients, wastes, dissolved gases, plasma
proteins
- Haematocrit is the term used to describe the percentage of blood made up of red
blood cells
- Erythropoietin (EPO) is a hormone released by the kidneys in response to
reduced/lowered oxygen carrying in blood. It stimulates erythrocyte production by
red bone marrow. Some athletes seek to increase their performance by injecting
themselves with erythropoietin in an attempt to increase the oxygen carrying capacity
of the circulatory system thus enabling muscles to work aerobically under higher loads
and/or for longer duration. Unfortunately, this practice can be dangerous as
increasing red blood cell numbers increases the viscosity/thickness of blood and
therefore increases the risk of vessel occlusion/blockage
- Anaemia results from a decrease in the haemoglobin content of red blood cells and/or
a decrease in the number or changes in the size of these cells. The heart rate increases
and there is a lack of energy and fatigue as a result of the decreased oxygen transport
3.1.1 Blood Vessels
Vessel
Function
Arteries
Carry blood away from the heart
Arterioles
Connect arteries to capillaries
Capillaries
Site of nutrient and gas exchange
Venules
Connect capillaries to veins
Veins
Return blood to the heart
Characteristics
Artery
Vein
Cross section
Usually round
Usually oval
Size of lumen
Small relative to thickness of wall
Large relative to thickness of
wall
Thickness of wall
Thick muscular wall
Thin wall
Particularity
Internal and external elastic layer
Valves
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How does an artery differ functionally from a vein?
Arteries carry blood away from the heart, whereas veins carry blood towards the heart
irrespective of the state of oxygenation of the blood
- Systemic circulation is the blood flow through the body. Blood is carrying O2 and
nutrients for the body, so arteries are carrying oxygenated blood, O2 concentration
decreases across capillaries, and veins carry deoxygenated blood to the heart
- In the pulmonary circulation, blood flow is from the right side of heart to the lungs
and back again. Upon leaving the heart, blood has high CO2, so arteries are carrying
deoxygenated blood, lung capillaries remove CO2 and add O2, and pulmonary veins
carry oxygenated blood back to the left side of the heart
3.1.2. Major Arteries
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Document Summary
The 7 functions of blood: transport of gases, nutrients and waste products, transport of processed molecules, transport of regulatory products, regulation of ph and osmosis, maintenance of body temperature, protection against foreign substances, clot formation. The main constituents of blood are plasma, erythrocytes/red blood cells, leukocytes/white blood cells and platelets/thrombocytes. Plasma is composed of water, salts, nutrients, wastes, dissolved gases, plasma proteins. Haematocrit is the term used to describe the percentage of blood made up of red blood cells. Erythropoietin (epo) is a hormone released by the kidneys in response to reduced/lowered oxygen carrying in blood. It stimulates erythrocyte production by red bone marrow. Some athletes seek to increase their performance by injecting themselves with erythropoietin in an attempt to increase the oxygen carrying capacity of the circulatory system thus enabling muscles to work aerobically under higher loads and/or for longer duration.
