transport in humans

1. identify main blood vessels to and from the heart, lungs, liver, kidneys

To the heart,

• Pulmonary veins

• Upper vena cava (blood from the head, neck and arms)

• Lower vena cava (blood from the rest of the body)

From the heart,

• pulmonary arteries

• Aorta

To the lungs,

• pulmonary artery 

From the lungs,

• pulmonary veins

To the kidney,

• renal artery

From the kidney,

• renal vein

To the liver,

• hepatic portal vein (from the small intestine)

• Hepatic artery

From the liver,

• hepatic vein

2. Relate structure of arteries, veins and capillaries to their functions

Arteries

• Thick elastic walls, withstand the high blood pressure in the artery

• Elasticity, enables artery wall to stretch and recoil, helps to push the blood in spurts along the artery, gives rise to the pulse

Veins

• Walls of the vein is not as thick and muscular as the arteries, blood pressure is lower than in the arteries

• Contains less elastic tissue

• Have valves, to prevent the backflow of blood

Capillaries

• Walls are partially permeable, enable certain substances to diffuse quickly through them

• Numerous branches, provide a large surface area for the exchange of substances between blood and the tissue cells

• Numerous branches, cross-sectional area of blood vessels increase, lowers the blood pressure, flow of blood slows down giving more time for the exchange of substances

• Walls made up of only a single layer of flattened cells, shorten diffusion distance between the exchange of substances between the blood and tissue cells

3. Describe the transfer of materials between capillaries and tissue fluid

• tissue fluid: transports dissolved substances between the tissue cells and the blood capillaries

• dissolved food substances and oxygen diffuse from the blood in the blood capillaries into the tissue fluid, then they move into the cells

• Metabolic waste products diffuse from the cell into the tissue fluid, then transferred through the blood capillaries walls into the blood

4. State the components of blood and their roles in transport and defence

RBC

• Haemoglobin for oxygen transport 

• Haemoglobin binds reversibly with oxygen to form oxyhaemoglobin 

• When oxygen conc. is low, oxyhaemoglobin releases its oxygen to tissue cells

plasma

• Contains mainly water and substances such as glucose, salts, proteins, amino acids, fats, vitamins, hormones, excretory products such as urea, red and white blood cells

Transports:

• blood cells around the body

• Nutrients from the small intestine to other parts of the body

• Excretory products from organs where they are produced to excretory organs for removal

• Hormones from endocrine glands to target organs

WBC

• Phagocytes & lymphocytes 

Phagocytes 

• Perform Phagocytosis, where it engulfs and destroys foreign particles such as bacteria

Lymphocytes

• produces antibodies 

Antibodies,

• recognise foreign particles

• Destroy disease-causing organisms such as bacteria and viruses

• Causes bacteria to clump together for easy ingestion by phagocytes

• Neutralise the toxins produced by bacteria

platelets

• when blood vessels are damaged, platelets are activated

• Release an enzyme thrombokinase which converts plasma protein prothrombin into thrombin

• Thrombin converts soluble fibrinogen into insoluble fibrin threads

• Fibrin them forms a mesh across the damaged surface and traps red blood cells, forming a clot

• clot seals the wound, preventing excess loss of blood, preventing foreign particles from entering the bloodstream

5. List the different ABO blood group and describe all possible combinations for the donor and recipient in blood transfusion

• agglutination: where antibodies in the blood plasma of recipient would react with the antigens of red blood cells of donor

6. Describe the structure and function of the heart in terms of muscular contraction and the working of valves

Function

• Supply the body and its organs with blood

Structure

Atria

• Right and left atrium

• Receives blood from the veins

• Have comparatively thin muscular walls, since they only force blood into the ventricles that lie directly below them, does not require high pressure

Ventricles

• right and left ventricle

• Have comparatively thick muscular walls

• Left ventricle is thicker walls, pumps blood around the whole body and requires high pressure

• Right ventricle has thinner walls, only pumps blood to the lungs, which is close to the heart

Median septum

• muscular wall that separated the left and right sides of the heart, run down the middle of the heart

• Prevents the mixing of deoxygenated blood in the right side with oxygenated blood in the left side

• Mixing them will reduce the amount of oxygen carried to the rest of the body 

Tricuspid valves

• prevents backflow of blood from the right ventricle to the right atrium 

Bicuspid valve

• prevents backflow of blood from the left ventricle to the left atrium

Aortic valve (semi-lunar valve in the aorta)

• prevents backflow of blood from the aorta to the left ventricle 

Pulmonary valve (semi-lunar valve in the pulmonary artery)

• prevents backflow of blood from the pulmonary artery to the right ventricle

7. outline the cardiac cycle in terms of what happens during systole and diastole 

Systole

• Ventricular and atrial muscles contract

Diastole

• Ventricular and atrial muscles relax

Cardiac cycle

1. Atrial muscles contract (systole), forcing blood into the ventricles

2. After a short pause, ventricle muscles contract (systole), causing a rise in pressure inside the ventricles. The rise in pressure causes the bicuspid and tricuspid valves to close and prevent backflow of blood back into the atria. This produces a loud ‘lub’ sound. The semi-lunar valves open, blood flows from the right and left ventricles into the pulmonary artery and the aorta respectively.

3. Ventricular muscles relax (diastole), causing a fall in pressure. The semi-lunar valves will close to prevent the backflow of blood from the pulmonary artery and the aorta to the ventricles. This produces a softer ‘dub’ sound. The bicuspid and tricuspid valves open and blood flow from the atria into the ventricles.

4. Ventricles must contract again (systole). The whole cycle repeats again

8.  Describe coronary heart disease in terms of the occlusion of coronary arteries and list the possible causes and preventative measures 

• Fatty substances such as cholesterol and saturated fats are deposited on the inner surface of the coronary arteries

• Narrows the lumen, increases blood pressure

• Rough inner surface

• Increase the risk of blood clot being formed in the artery

• The supply of blood and oxygen to the heart muscles may be cut off

• Muscles of the heart is unable to carry out aerobic respiration to release energy for activities of the muscle cells

• Heart muscle cells may be damaged, heart attack occurs

Possible causes 

Unhealthy diet

• diet high in cholesterol, saturated fats and salt contents

• Increases the risk of high blood pressure and heart attack

Smoking

• contains CO and nicotine

• Increase the risk of coronary heart disease

• Nicotine increases blood pressure and the risk of blood clotting in the arteries

Genetic factor

• high blood pressure and high blood cholesterol can run in the family

Age

• the risk of heart attack increases with age

Sedentary lifestyle 

• lack of exercise and being inactive lead to the build-up of fatty deposits that block the arteries

• Increased risk of getting coronary heart disease 

Preventative measures

• Healthy diet. Animal fats in the diet should be substituted with polyunsaturated plant fats, which do not stick to the inner surfaces of arteries. May lower the cholesterol levels in blood

• Smoking should be avoided. Contains CO and nicotine which increases the risk of getting coronary heart disease 

• Regular physical exercise. It has long-term beneficial effects in the circulatory system. Strengthens the heart and maintains the elasticity of the arterial walls. The risk of hypertension and high blood pressure can be greatly reduced.