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transport in humans Flashcards

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Biology 101 flashcards
1
Q

double circulation

A

-in pulmonary circulation, deoxygenated blood is transported away from the heart to the lungs, and returns oxygenated blood back to the heart
-in systemic circulation, oxygenated blood is transported away from the heart to the body, and returns deoxygenated blood back to the heart

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2
Q

advantages of a double circulation

A

-blood enters lungs at lower pressure, thus allowing sufficient time for blood to be well oxygenated
-heart pumps oxygenated blood at high pressure to the rest of the body to be distributed to the tissues quickly

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3
Q

components of blood

A

-blood is a fluid tissue
-plasma, red blood cells, white blood cells and platelets

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4
Q

blood plasma

A

-composed mostly water
-helps to transport ‘substances’ around the body, such as nutrients, excretory waste products, hormones, ions and proteins
-helps distribute heat around the body to maintain constant internal environment
-plays a role in blood clotting by transporting blood clotting proteins fibrinogen and prothrombin

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5
Q

red blood cells

A

-produced by bone marrow
-lack in nucleus and mitochondria, hence cannot perform cell division
-after about 120 days, they are destroyed in the spleen and liver

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6
Q

adaptations of red blood cell

A

-circular, biconcave shape increases surface area to volume ratio, for greater diffusion rate of oxygen and carbon dioxide
-presence of haemoglobin allows the red blood cell to bind reversibly with oxygen
-no nucleus allows the red blood cell to carry more haemoglobin to bind to more oxygen
-elastic cell surface membrane allows red blood cells to squeeze through very small lumen of blood capillaries

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7
Q

transport of oxygen by red blood cells

A

-at the lungs, oxygen diffuses from the alveolus into the red blood cells
-at other body organs, haemoglobin releases its oxygen which diffuses into respiring cells

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8
Q

adaptations at high altitudes

A

-people living at high altitudes have higher number of red blood cells to compensate for lower oxygen concentration
-increase number of red blood cells increases the concentration of haemoglobin in the blood
-thus, oxygen can be transported to the body cells faster

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9
Q

why carbon monoxide is toxic to humans

A

-haemoglobin combines permanently with carbon monoxide
-less haemoglobin is available to carry oxygen to respiring cells. as a result, death may occur.

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10
Q

sickle-cell anaemia

A

-red blood cells having mutated haemoglobin that polymerises into long chains when not bound to oxygen, hence distorting the membrane of red blood cells into distinct sickle shape
-results in decreased oxygen-carrying ability of red blood cells, and sickled red blood cells may occlude blood vessels to form blood clot

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11
Q

white blood cells

A

-larger than red blood cells, and are usually lesser in numbers
-produced by bone marrow
-lymphocytes and phagocytes

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12
Q

lymphocytes

A

-large, rounded nucleus
-produce antibodies into the blood plasma that recognises antigens
-an immune response should only be raised when antigens are of foreign sources

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13
Q

functions of antibodies

A

-antibodies neutralise toxins from bacteria, which later will be destroyed by phagocytes
-antibodies bind to antigens on bacteria/ virus, hence enhancing phagocytosis

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14
Q

phagocytes

A

-bean-shaped/ multi-lobed nucleus
-squeeze between gaps in the wall/ endothelium of blood capillary to any infected areas
-they engulf and ingest bacteria/ virus via phagocytosis
-phagosome is formed with the bacteria/ virus enclosed. then the lysosome inside phagocyte fuses with the phagosome to form phagolysosome. then enzymes in lysosomes hydrolyse the bacteria/ virus

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15
Q

blood platelets

A

-fragments of cells produced in bone marrow
-initiate blood clotting to prevent entry of bacteria/ virus and prevent excessive loss of blood

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16
Q

process of blood clotting

A

-damaged tissues and platelets release thrombokinase
-thrombokinase converts prothrombin into thrombin, with calcium ions present
-thrombin converts soluble fibrinogen into insoluble fibrin threads
-fibrin threads trap red blood cells to form a clot

17
Q

blood groups

A

blood group A
-antigen A on red blood cell, antibody b in plasma

blood group B
-antigen B on red blood cell, antibody a in plasma

blood group AB
-antigens A and B on red blood cell, no antibodies in plasma

blood group O
-no antigens A or B on red blood cell, antibodies a and b in plasma

18
Q

agglutination

A

-the clumping of red blood cells with antibodies. hence, blood vessels become blocked.
-antigen A and antibody a will agglutinate
-antigen B and antibody b will agglutinate

19
Q

blood vessels

A

-artery—> arteriole—> capillary—> venule—> vein
-the heart is a muscular organ that contracts to pump blood
-capillaries are the sites of exchange of ‘substances’ within organs

20
Q

arteries

A

-thicker muscular walls/ smaller lumen to withstand the high blood pressure. muscles contract—> artery vasoconstricts—> lumen narrower—> less blood flows through. muscles relax—> artery vasodilates—> lumen wider—> more blood flows through.
-elastic fibres walls to allow stretching and recoiling of artery wall. hence, maintain high blood pressure and push blood along the artery in pulses.

21
Q

veins

A

-lesser muscular and less elastic wall than artery/ larger lumen for blood to flow slowly and smoothly
-presence of semi-lunar valves to prevent backflow of blood
-surrounded by skeletal muscles for muscle contractions on the veins to move the blood forward

22
Q

capillaries

A

-one-cell thick endothelium to allow movement of substances across quickly and to provide large surface area to volume ratio for exchange of substances between blood and tissue cells quickly
-branched into dense network to increase the total cross-sectional area for blood flow to be very slow, hence more time for the exchange of substances

23
Q

comparison 1 - nature of walls

A

artery - thicker muscular and a lot elastic fibres
capillary - one-cell thick endothelium
vein - less muscular and less elastic fibres

24
Q

comparison 2 - size of lumen

A

artery - small lumen
capillary - very small lumen
vein - large lumen

25
Q

comparison 3 - valves

A

artery - absent except pulmonary arteries and aorta
capillary - absent
vein - presence of semi-lunar valves

26
Q

comparison 4 - function

A

artery - carry blood away from the heart towards body organs
capillary - exchange of substances between blood and tissue cells
vein - carries blood back into the heart from body organs

27
Q

comparison 5 - direction of blood flow

A

artery - away from heart
capillary - from arteries to veins
vein - back into heart

28
Q

comparison 6 - nature of blood

A

artery - oxygenated
capillary - oxygenated at arteriole end and deoxygenated at venule end
vein - deoxygenated

29
Q

comparison 7 - pressure of blood flow

A

artery - high blood pressure
capillary - low blood pressure
vein - lowest blood pressure

30
Q

comparison 8 - speed of blood flow

A

artery - blood flow fast and in pulses
capillary - blow flow the slowest and smoothly
vein - blood flow slowly and smoothly

31
Q

transfer of materials

A

-fluid from blood plasma escapes through the walls of capillaries to form tissue fluid
-nutrients and oxygen diffuse from blood capillaries into tissue fluid and then into cells
-urea and carbon dioxide diffuses from cells into tissue fluid then into blood capillaries

32
Q

structure of the heart

A

-right side of heart completely separated from left side by median septum, to prevent mixing of oxygenated and deoxygenated blood
-atria have relatively thinner muscle walls than ventricles. distance between atria and ventricles is relatively short. thus, lesser cardiac muscles are contracted during atria systole.
-left ventricle has relatively thicker muscle walls than right ventricle, so as to contract stronger to pump blood quickly to the rest of body.

33
Q

stage 1 of the cardiac cycle - total diastole

A

-all muscles are relaxed and blood flows into the heart
-bicuspid and tricuspid valves will open when pressure in the atria more than pressure in ventricles to allow flow of blood from atria into ventricles
-oxygenated blood enters the left atrium and deoxygenated blood enters the right atrium

34
Q

stage 2 of cardiac cycle - atrial systole

A

-muscles of atria contract, but the muscles of ventricles remain relaxed
-bicuspid and tricuspid valves are opened fully. blood is pumped into the ventricles from the atria.
-aortic and pulmonary valves remain closed

35
Q

stage 3 of cardiac cycle - ventricular systole

A

-muscles of the ventricles contract, while the muscles of the atria begin to relax
-the increase of blood pressure in the ventricles closes the bicuspid and tricuspid valves, preventing backflow of blood into respective atria
-the ventricular blood pressure continues to increase and exceeds the blood pressure in the aorta and pulmonary arteries, forcing the aortic and pulmonary valves open. thus, blood is pumped from heart into respective arteries.

36
Q

stage 1 of cardiac cycle - ventricular diastole

A

-as the ventricle muscles start to relax, pressure within ventricles falls
-this closes the aortic and pulmonary valves, preventing backflow of blood into respective ventricles

37
Q

coronary heart disease

A

-coronary arteries branch out from the aorta, runs on the outside of the heart to the heart muscles
-function of coronary arteries is to supply oxygen and nutrients to the heart muscles
-if the coronary artery faces occlusion, heart muscles may be deprived of oxygen and nutrients. hence, heart muscles unable to respire to release energy for its contraction.
-if the occlusion is not treated in time, the heart muscles may die/ heart attack

38
Q

risk factors and preventive measures

A

risk factors
-high-fat diet rich in cholesterol and saturated fats
-emotional stress
-smoking
-sedentary lifestyle

preventive measures
-proper diet low in cholesterol and/ or zero saturated fats
-avoid smoking
-regular physical exercise
-proper stress management

39
Q

treatment options

A

-balloon angioplasty
-coronary artery bypass graft

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