transport in humans Flashcards
what are the components of blood?
- red blood cells (45%)
- white blood cells (<1%)
- platelets (<1%)
- plasma(55%)
structure of rbc
biconcave disc shape, elastic cell surface membrane, no nucleus and contains haemoglobin
function of rbc
transports oxygen which combines reversibly with haemoglobin, transports some carbon dioxide
structure of white blood cell
lymphocytes have spherical nuclei with non-granular cytoplasm
phagocytes have lobed nuclei with granular cytoplasm
function of white blood cell
defend body against disease
phagocytes engulf bacteria by phagocytosis and digest them
lymphocytes produce antibodies to kill bacteria and neutralize toxins
structure of platelet
cell fragments from cytoplasm of certain bone marrow cells
function of platelet
release materials necessary for blood clotting
stick to surface of damaged blood vessels
structure of plasma
liquid component of the blood, made up of 90% water
functions of plasma
transports:
1. plasma protein involved in clotting
2. digested food (glucose and amino acids) to target cells
3. antibodies
4. hormones from secreting glands to target cells
5. metabolic waste from liver to kidneys for excretion
what do antigens do?
antigens provoke an immune response by producing antibodies (they are found on the surface of rbcs, antibodies found in blood plasma) Viruses and bacteria may present antigens that trigger response by immune system
How are people classified into different blood groups?
depends on which type of antigens and antibodies present in the blood
Blood type A
antigen A and antibodies B
Blood type B
antigen B and antibodies A
Blood type AB
antigens A and B, no antibodies
Blood type O
no antigens, antibodies A and B
What is agglutination?
Antibodies can recognise and bind to their specific antigens on RBCs, causing the RBCs to clump up and agglutinate. It can be lethal as clumping of RBCs can block smaller blood vessels and reduce blood flow, reducing the rate at which nutrients and oxygen is transported to respiring cells for energy to be released
which blood type is compatible with type A?
O and A
which blood type is compatible with type B?
O and B
which blood type is compatible with type AB?
Any
which blood type is compatible with type O?
O
what happens during blood clotting?
- When a blood vessel is injured, platelets begin to collect near the site of the injury and form a barrier called the platelet plug
- When platelets come into contact with the injured area, they become sticky and swell up, releasing certain chemicals
- Thrombinkinase is produced by platelets and damaged tissues which converts prothrombin into enzyme thrombin
- thrombin converts soluble fibrinogen into insoluble fibrin which forms a network of structures across the wounded area
- blood cells and platelets are emeshed into this network to form a blood clot
- serum is plasma without the blooding clotting factors and it is the yellowish remains that forms when blood clots
what is phagocytosis?
it is the process of engulfing and ingestion of foreign particles by phagocytes. in some instances, the phagocytes may be killed with the bacteria, forming a phagolysosome
When are antibodies produced?
when pathogens or diseas-causing organsims enter the bloodstream, lymphocytes are stimulated to produce antibodies
what do antibodies do?
- destroy bacteria
- cause bacteria to clump together and be phagocytosed
- neutralize toxins produced by bacteria
how do vaccines work?
a weakened and dead form of the disease is injected into the bloodstream, directly inducing lymphocytes to produce antibodies
how does organ transplant work?
a diseased or damaged organ can be replaced by a healthy organ from a donor
what is tissue rejection?
the immune system of the organ recipient may see the transplanted organ as a foreign body and produce antibodies against it. This results in tissue rejection
what does the antibody do during the immune response?
it recognises and binds to the antigens of the pathogens in the bloodstream
what is the structure of antibody?
it has two identical binding sites. the shape of the binding site allows the antibody to recognise specific antigens with complementary shape. the different shapes allows antibodies to recognise a large variety of antigens
which cells recognise specific antigens?
T lymphocytes and B lymphocytes
what are the types of immunity?
Humoral immunity and Cellular immunity
what happens during humoral immunity?
B lymphocytes provide immunity against pathogens and antigens in the body fluids
what happens during cellular immunity?
T lymphocyte cells provide a defense against abnormal cells and pathogens within living cells
structure of artery
- Thick muscular walls (larger ratio of external diameter to diameter of lumen as compared to vein)
- elastic walls
- muscles in wall
structure relation to function of artery
- able to withstand high pressure of blood pumped directly from the heart
- walls of artery able to stretch and recoil to push blood in spurts, giving rise to pulse and unidirectional flow of blood
- muscles in artery contract and relax, regulating the lumen size, determines the amount of blood that passes through per unit time
structure of vein
- thinner walls with less elastic and muscular tissues (smaller ratio of external diameter to lumen diameter)
- presence of semi-lunar valves
structure relation to function of vein
- blood is further away from the heart thus it has lower pressure, thick walls are unnecessary
- prevent backflow of blood and ensures unidirectional blood flow
structure of capillary
- one-cell thick endothelium
2. narrow lumen
structure relation to function of capillary
- allows rapid exchange of substances between blood and body tissue cels
- forces rbcs to move in a single file, reducing the rate of blood flow and increasing time for exchange of material
why do arteries driectly connected to the heart have semi-lunar valves?
To prevent backflow of blood when the heart relaxes
how does blood move along the veins?
the veins are situated between skeletal muscles, with the major veins being situtated near bigger muscles. When these muscles contracts, the blood is pushed and pumped back towards the heart. presence of semi-lunar valves prevents backflow of blood and keeps the blood moving in one direction
what are the processes involved in exchange of substances?
active transport, diffusion, osmosis and bulk transport
what factors affect the rate of exchange?
length of diffusion pathway, blood velocity, hydrostatic pressure gradient, concentration gradient, surface area to volume ratio
why does the hydrostatic pressure gradient affect rate of exchange of substances?
the formation of tissue fluids is determined by the hydrostatic pressure difference between blood in the capillaries and the interstitial fluids outside the cells. For new tissue fluid to be formed, hydrostatic pressure has to be higher in the blood relative to the tissue fluids outside. the formation of tissue fluid affects the exchange of materials betwen blood and cells, and the hydrostatic pressure gradient affects the formation of tissue fluid, it is one of the factors.
exchange of substances between blood and tissue cells
oxygen, glucose and dissolved nutrients diffuse out of the arterial end of the capillary network and nto the tissue fluid and into the the cells.
waste materials diffuse out of the cells, into the fluid and then into the capillary at the venule end of the capillary network
how to prevent the body from swelling from water retention?
lymphatic system. The hydrostatic pressure of lymph in lymphatic capillaries is lower than that of interstitial fluids so liquids enter the lymphatic capillaries. lymph empties into the subcalvian veins (liquid leaves interstitial fluid and re-enters blood)
Double circulation
Pulmonary circulation
systemic circulation
what happens during the pulmonary circulation?
deoxygenated blood is pumped from the heart to the lungs for oxygenation and oxygenated blood is pumped from the lungs back to the heart
what happens during systemic circulation?
oxygenated blood from pulmonary circulation is pumped from the heart to the body tissues and back to the heart
what are the advantages of double circulation?
- keeping oxygenated and deoxygenated blood separate improves the efficiency of oxygen distribution
- slow blood flow in pulmonary circulation allows for adequate gaseous exchange in the lungs
what is the heart made up of?
it is made up of cardiac muscle which allows it to contract strongly to generate a force large enough for blood to be pumped through the entire circulatory system. thicker wall, more musuclar, more strongly it can pump the blood
what is the flow of blood through the heart?
blood from the rest of the body enter the right atrium of the heart via superior and inferior vena cava, enter the right ventricle and leaves for the lungs through the pulmonary artery. blood re-enters the heart via the pulmonary vein and into the left atrium before entering the left ventricle and exiting the heart to the rest of the body through the aorta
What is the cardiac cycle?
it is the sequence of events that occur during one heartbeat. there is one diastole and one systole phase that occurs.
what happens during atrial systole and ventricular diastole?
both atrium contract simultaneously and atrial pressure increases, opening the atrioventricular valves. Blood is pushed into ventricles, increasing ventricular pressure.
ventricles relax and ventricular pressure decreases. pressure in aorta and pulmonary artery causes slight backflow of blood which causes semi-lunar valves to close, producing a “dub” sound
what happens during atrial diastole and ventricular systole?
as ventricular pressure increases, the blood pushes against the semi-lunar valves, causing them to open. atrioventricular valves close, producing a lub sound. chordae tendinae prevents valves from inverting into the atria.
blood enters both the atrium, causing the atrioventricular valves to open due to the build-up of atrial pressure
what is the coronary artery?
small blood vessel that carries oxygenated blood to the heart muscles
what is coronary heart disease?
it is when the coronary arteries are blocked or narrowed which reduces the supply of oxygenated blood to the heart muscles.
what is coronary heart disease caused by?
usu caused by atherosclerosis which is the build up of fatty substances such as cholesterol and saturated fats deposited along the inner walls of the coronary arteries . this causes their lumens to narrow and develop rougher surfaces, higher risk of thrombosis
