chapter 6 - transport in humans

Question 1

heart

Answer 1

muscle that pumps blood to different parts of the body

Question 2

arteries

Answer 2

blood vessels that carry blood away from the heart

• transports oxygenated blood (except pulmonary arteries) from the heart to other parts of the body
• walls are thick, muscular and elastic to withstand the high blood pressure of blood flowing within
• the elasticity helps the artery wall to stretch and recoil to push blood forward.
• contraction and relaxation of the arterial walls to divert blood to certain organs at certain times (vasodilation and vasoconstriction during thermoregulation)

Question 3

veins

Answer 3

blood vessels that carry blood to the heart

• transports deoxygenated blood back to the heart
• blood that is the vein has lower pressure and speed, thus blood tends to backflow. veins therefore have valves to prevent backflow of blood
• walls are generally thinner than that of the arteries and blood flows more smoothly and slowly

Question 4

blood capillaries

Answer 4

microscopic blood vessels that arise from branches of the arterioles

• large surface area - numerous branches of capillaries
• short diffusion distance - walls of capillaries is one cell thick
• short concentration gradient - continuous blood flow through the capillaries

Question 5

differences between arteries and veins

Answer 5

• both have muscular and elastic tissue
• both have one cell thick endothelium
• arteries have thicker muscular tissue while vein have thinner, less muscular tissue.
• arteries have more elastic tissue while veins have less elastic tissue
• arteries have narrow lumen while veins have wide lumen
• arteries have no valves while veins have valves

Question 6

tissue fluid

Answer 6

colourless liquid that fills the spaces between cells in tissues. transports dissolved substances between blood capillaries and tissues cells. plasma proteins, RBC, platelets remain in blood plasma while smaller molecules like glucose, oxygen, AA, urea, carbon dioxide and white blood cells diffuse out.

Question 7

red blood cells

Answer 7

• transport oxygen to rest of body
• circular and biconcave shape to increase surface area to volume ratio for faster rate of diffusion of oxygen
• contains oxygen that binds with oxygen o form oxyhemoglobin for transport of oxygen
• lacks nucleus for more space to store and transport more oxygen
• flexible an can change shape to squeeze through narrow capillaries easily.

Question 8

plasma

Answer 8

• transports blood cells, ions, soluble food substances, hormones, carbon dioxide, urea, vitamins, plasma, proteins (fibrinogen, antibodies, and prothrombin)
• carries hormones to target organs
• made up of mostly water as a solvent for various substances

Question 9

white blood cells

Answer 9

lymphocytes : produces antibodies in response to toxins or foreign particles in blood. antibodies will recognise, attach to and destroy pathogens by rupturing bacterial surface membrane. this causes pathogens to agglutinate for easy engulfing and ingestion by phagocytes. they can also neutralise toxins produced by bacteria

phagocytes : engulf and ingest foreign particles like bacteria, where this process is known as phagocytosis

Question 10

platelets

Answer 10

contains an enzyme that catalyses the conversion of soluble fibrinogen to insoluble fibrinogen thread. fibrin threads entangles with red blood cells to form blood lots that seal wounds

Question 11

blood clotting process

Answer 11

damaged tissues and platelets produced an enzyme known as thrombokinase . thrombokinase catalyses the conversion of inactive prothrombin to active thrombin in the presence of calcium ions. thrombin catalyses the conversion of soluble fibrin to insoluble fibrin threads, that entangles RBCs and forms a clot, sealing the wound and prevents excessive loss of blood and entry of bacteria

Question 12

agglutination

Answer 12

antibodies are found in plasma, produced by the white blood cells
antigens provoke an immune response involving antibodies

certain antibodies react with certain antigens, causing agglutination which could be fatal as it blocks blood vessels and prevents blood forming flowing

Question 13

antibodies and antigens of different blood types

Answer 13

A : anti-B + A antigen
B : anti-A + B antigen
O : anti-A and anti B + no antigens
AB : no antibodies + A and B antigens

when checking, compare donor’s antigens and recipients antibodies

Question 14

ventricles vs atrium muscles

Answer 14

ventricles have thicker muscular walls than atria, atria only forces blood into the ventricles, and less force and pressure is needed due to the shorter distance. ventricles have to force blood out of heart to the other parts of the body, thus higher force and pressure is needed

Question 15

coronary arteries

Answer 15

transport oxygenated blood containing glucose from the heart muscles for respiration to release energy

Question 16

cardiac cycle

Answer 16

1. passive filling : both atria and ventricles muscles are relaxed. right and left atria are filled with deoxygenated blood from the vena cava and pulmonary vein respectively and oxygenated blood flows into the right and left ventricle
2. atrial systole : both atrium muscles contract, increasing the pressure and forcing blood into the ventricles
3. ventricular systole : ventricular muscles contract and pressure of the ventricles increases beyond the pressure in the atria. this results in the closure of the bicuspid and tricuspid valves to prevent backflow of blood into the atria, resulting in a lub sound
4. when the pressure in the ventricles is higher than the pressure in the aorta, the semilunar valves are forced open. blood is forced out of the pulmonary and systemic circulation via the pulmonary artery (right) and the aorta (left)
5. ventricular diastole : muscles on ventricles relax and pressure decreases below than the pressure of arteries, resulting in the closure of the semilunar valves to prevent backflow of the blood into the ventricles, resulting in a dub sound
6. when pressure in ventricle < pressure in atrium, biscuspid and tricuspid valves open

Question 17

coronary heart disease

Answer 17

excessive fats accumulated on inner walls of coronary arteries. this leads to teh artery walls to become rough and hard, causing the lumen to be narrower. this reduces blood supply and decreases oxygen and glucose transport to the heart

Question 18

causes and preventions of coronary heart disease

Answer 18

causes : diet rich in fats, stress, smoking and lack of exercise

preventions : exercise, healthy diet, stress management, not smoking

Question 19

role of muscle fibres in small artieries

Answer 19

smaller artists have a larger proportion of muscle fibres which contract during vasoconstriction and relax during vasodilation to bring about regulation of blood pressure, diverting of blood flow and regulating of blood temperature for homeostatic control.