Transport in Man Flashcards
What are the four main components of blood?
Plasma, red blood cell (erythrocytes), white blood cell (leucocytes), platelets (thrombocyte)
What is plasma and state the dissolved substances
Approximately 55% blood’s volume
90% water, 10% dissolved substances
Substances include—
Mineral ions: sodium, potassium, calcium, magnesium, chloride, bicarbonate ions
Soluble food substances: glucose, amino acids
Metabolic waste products: CO2, urea, uric acid, creatinine
Plasma proteins: fibrinogen, prothrombin, antibodies, albumin
Hormones
Function of red blood cells (erythrocytes)
Transport oxygen fro the lungs to the organs of the body
Structural features of red blood cells
Haemoglobin present: binds reversible with oxygen to form oxyhaemoglobin, transports O2 around the body
Absence of nucleus: more space available for more haemoglobin to be stored and more oxygen to be transported
Biconcave shape: increases SA:V ratio, allowing quick diffusion of oxygen in and out of the cell
Elastic and flexible membrane: allows cells to change its shape while squeezing through small capillaries
What is the effect of carbon monoxide on haemoglobin?
Carbon monoxide binds tightly with haemoglobin to form carboxyhaemoglobin
Less haemoglobin is available to bind with oxygen, so less O2 transported in the body
What is sickle cell anaemia and what are its symptoms?
Genetic disease: the gene for haemoglobin contains a mutation, producing mutant haemoglobin with a sickle shape
Symptoms include:
Cells getting stuck in blood cells, blocking them
Prevents delivery of oxygens and nutrients to cells and removal of carbon dioxide and waste from cells
May cause organ swelling or severe pain during blood vessel clogging
What is red blood cell production regulated by and what is it released by in response to?
Red blood cell production is regulated by the hormone erythropoietin, which kidneys released in response to a decrease in oxygen
What is acclimatisation?
In mountainous areas, lower partial pressures of oxygen result in an initial drop of fitness levels
Body responds by producing more red blood cells, thus more haemoglobin is available for the transport of oxygen around the body
Traits of leucocytes (white blood cells)
Colourless due to lack of haemoglobin
Irregularly shaped cells with the presence of a nucleus (phagocytes)
Mobile and able to change shape to squeeze through the gaps in capillary walls
Phagocytes are irregular, lymphocytes have a round nucleus
What is phagocytosis and what cells are involved?
Phagocytosis is the process where phagocytes engulf and digest bacteria After phagocytosis (endocytosis), these cells die and form pus
Phagocytosis by phagocytes (white blood cell, type of leucocytes)
What do lymphocytes do?
They produce antibodies and have a round nucleus, with a small amount of granular cytoplasm
What do antibodies produced by lymphocytes (leucocytes) do?
Antibodies can neutralise toxins produced by bacteria
Antibodies can bind to the surface of bacteria, causing them to rupture
Antibodies can bind to the surface of bacteria, tagging them, allowing phagocytes to recognise them and carry out phagocytosis
Antibodies can cause bacteria to clump together, so that they can be easily ingested by phagocytes
What is transplantation?
The replacement of diseased tissue or organs by healthy donor ones
What is tissue rejection?
Tissue rejection is when the recipient’s immune system may recognise the transplant organ/tissue as foreign bodies
Lymphocytes may respond by producing antibodies to destroy the transplanted organ
How to prevent tissue rejection during transplantation?
- Tissue/donor matching: ensuring donor tissue is from a donor genetically close to the recipient (close relatives)
- Using immunosuppressant drugs to inhibit the recipient’s immune system, reducing the chance of tissue rejection but increasing susceptibility to infection
Platelets and function and formation of blood clots (thrombocytes)
Not true cells, but fragments of larger bone marrow cells called megakaryocytes
When an injury first occurs, platelets gather and release substances that attract other platelets. The platelets become sticky and form a temporary platelet plug.
Blood clots defend the body by:
- Preventing the excessive loss of blood from a cut
- Preventing entry of bacteria into a cut
Describe the process of blood clotting
Damaged tissues and platelets will release the enzyme thrombokinase. Together with calcium ions in blood plasma, the thrombokinase will convert inactive prothrombin (in plasma) to active thrombin.
Thrombin will convert soluble fibrinogen to form insoluble fibrin threads, forming a blood clot consisting of a network of fibrin threads that trap blood cells
What are the antigens on rbc and antibodies in plasma for each blood type?
A: A-antigen and antibody B
B: B-antigen and antibody A
AB: A-antigen, B-antigen and no antibodies
O: no antigens and A antibody, B antibody
What is agglutination and when does it occur?
Agglutination is the clumping of red blood cells
When antigen A/B binds with antibody A/B (respectively), fatal
What do the walls of arteries and veins consist of?
Three layers—
Innermost:
Endothelium, minimises resistance to fluid flow
Middle: smooth muscle tissue and elastic fibres
Smooth muscle in the arteries and veins allow vasoconstriction adn vasodialation
Outer: connective tissue like collagen fibres
What are arteries and their structure and function?
Blood vessels that carry blood AWAY from the heart, oxygenated except for pulmonary
Thick muscular walls: allow the diameter of the blood vessels to be adjusted, control the blood pressure inside the vessel and regulate blood flow
Numerous elastic fibres: elasticity for blood vessel to stretch and recoil, accommodate blood pressure increases and prevent bursting
Size of arteries/veins walls relative to lumen size
The walls of arteries are thicker, walls of veins are thinner, deoxygenated apart from pulmonary
Relative to the lumen size
What are veins and their structure and function?
Blood vessels that carry blood towards the heart
Thinner, less muscular and less elastic walls: blood pressure in veins is lower, less muscular tissue needed to support the vessel
Semilunar valves present: prevent blood back flow and allow one directional flow
Veins located between largest muscles of the body: contraction of body muscles (eg leg) help push blood back to the heart, against gravity
What are varicose veins?
They occur when semilunar valves cannot function properly, so blood flows backwards and veins bulge and enlarge
Do arteries and veins have valves?
All arteries do not have valves apart from aortic valve and pulmonary valve
All veins have semi-lunar valves present
Differences in arteries and veins (blood pressure, flow of blood)
Artery blood pressure higher
Vein blood pressure lower
Artery blood flow rapid
Vein blood flow sluggish, tendency for back flow
Pathway of blood from arteries to veins
Arteries to arterioles to capillaries to venules to veins
Structure and function of capillaries
Capillary walls are one cell thick: shorter distance and quicker diffusion of substances between blood and body cells
Small gaps between the endothelial cells: causes tissue fluid to leak from the plasma, gaps allow leucocytes to squeeze through but not large molecules
Large network of capillaries: large total SA for diffusion, lower blood pressure for more time to diffuse
What is tissue fluid and its function?
It is a fluid that bathes the cells of most tissues
Tissue fluid functions to provide a medium for diffusion to allow for the exchange of materials between the capillaries and body cells
What pushes plasma out of blood?
Hydrostatic pressure: blood pressure against the capillary wall
Movement of substances in tissue fluid
Useful (oxygen and glucose and food substances): diffuse from the blood into tissue fluid into body cells
Waste (carbon dioxide and urea): diffuse from the cells into tissue fluid into blood
What is the main tissue present in the heart?
Cardiac muscle tissue
What does the cardiac cycle refer to?
The events that occur during a single heartbeat:
The atria are collection chambers that fill up with blood
Blood is forced from the atria to the ventricles and out of the heart
The systole phase, contraction of walls of chambers of the heart
The diastole phase, relaxation of the walls of the chambers of the heart
Pathway of blood flow through the heart on the right
Deoxygenated blood from the rest of the body enters (relaxed) right atrium via (superior and inferior) vena cava
Wall of right atrium contracts (atrial systole), BP in right atrium higher than right ventricle
Tricuspid valve opens
Blood forced from right atrium to right ventricle
“Lub” sound: backflow of blood from ventricle to atrium prevented by closing tricuspid valve
Wall of right ventricle contracts (ventricular systole), BP in right ventricle higher than pulmonary artery
Semi-lunar valve in pulmonary artery opens, blood forced into artery to lungs
Right ventricle walls relax (ventricular diastole)
“Dub” sound: backflow of blood from pulmonary artery into right ventricle prevented by closing semi-lunar valve
Pathway of blood through the heart on the left
Oxygenated blood from the lungs is transported into (relaxed) left atrium via pulmonary vein
Walls of left atrium contract (atrial systole), BP in left atrium higher than left ventricle
Bicuspid valve opened
Blood forced into left ventricle
“Lub” sound: backflow of blood from left ventricle to left atrium prevented by closing bicuspid valve
Walls of left ventricle contract (ventricular systole), BP in left ventricle higher than in aorta
Semi-lunar valve in the aorta opens, blood forced into aorta to rest of the body
Left ventricle walls relax (ventricular diastole)
“Dub” sound: semi-lunar valve in the aorta closed to prevent backflow of blood from aorta to left ventricle
What are the function of coronary arteries?
They supply oxygenated blood and glucose to the heart muscle, since heart muscles require a constant supply of glucose and oxygen, the raw materials of respiration
Heart muscles have a high energy demand, due to the muscular contractions of the heart beating
What is coronary heart disease and what are its causes?
Coronary heart disease is when the blood supply and oxygen to the heart is reduced or cut off due to occlusion of the coronary arteries (atherosclerosis)
The narrowing of the lumen of the coronary arteries due to fatty deposits increases the blood pressure in the coronary arteries and reduce the amount of blood flow to the heart muscles
How can blood supply to the heart muscle is completely cut off, and what does it cause?
Due to a blood clot (thrombosis), a heart attack occurs
Causes of coronary heart disease and corresponding preventative measures
Diet high in trans fat and saturated fat (diet low in aforementioned substances, high in polyunsaturated fat)
High stress lifestyle (proper stress management)
Lack of exercise / sedentary lifestyle (regular physical exercise strengthens heart and maintains elasticity of arterial walls
Smoking cigarettes, CO increases chance of thrombosis (don’t)
What are angioplasty treatments for coronary heart disease?
Minimally invasive and less effective, restore blood flow
Balloon: catheter with angioplasty balloon inserted into artery with fatty deposit
Stent: collapsed mesh tube threaded along ballon and inserted into artery with fatty deposit
What is coronary bypass
Surgical replacement of damaged or blocked coronary arteries taken from another part of the body
Advantages and disadvantages of double circulation
Advantages:
Blood entering lungs at lower pressure, blood has sufficient time to be oxygenated
Blood pumped into the systemic circulation at high pressure, allowing oxygenated blood to quickly reach tissues
Disadvantages:
In amphibians, turtles, snakes, lizards, incomplete septum does not separate ventricle into left and right, slight mixing of oxygen erased and deoxygenated blood
What is a septum?
A muscular wall that separates the left and right side of the heart, preventing mixing of oxygenated and deoxygenated
What are chordae tendineae
Fibrous connective tissue that holds the atrioventricular valves in the correct orientation (bicuspid in left and tricuspid in right)
State the relationship between velocity of blood flow and total surface area exposed by blood vessel
The velocity of blood flow is inversely proportional to the total surface area exposed by the blood vessel
What is blood pressure?
The force exerted by the blood against the walls of the blood vessel
Why does blood pressure increase the closer the blood is to the heart?
The contraction of muscular walls of the heart generates blood pressure
