transport in human Flashcards
explain what is meant by double circulation
blood flows through the heart twice in one circuit
state the advantage of double circulation
ensures that blood is pumped at low pressure to the lungs so that the blood can be fully oxygenated and the oxygenated blood is pumped at high pressure to all body cells at a fast rate to ensure that it is evenly distributed to all body cells
identify and describe the 2 circulations in human transport, detailing where gaseous exchange takes place
- pulmonary circulation: carries oxygenated blood from lungs to the heart and deoxygenated blood from heart to lungs. gaseous exchange happens in lungs
- systemic circulation: carries oxygenated blood from heart to rest of body and deoxygenated blood from rest of body to heart. gaseous exchange happens in body cells
blood is a ___
fluid tissue
state the 4 components of blood
- plasma (55%)
- RBCs (45%)
- WBCs (<1%)
- platelets (<1%)
state the 2 main functions of blood
- transport oxygen, food substances, waste minerals, hormones, heat from one part of the body to another
- protect the body by preventing entry of foreign bodies and fighting infections
describe the composition of plasma
90% water, 10% dissolved substances
substances dissolved in plasma are:
* mineral ions
* digested food substances (e.g. glucose)
* metabolic waste products (e.g. urea)
* plasma proteins (e.g. antibody, fibrinogen)
* hormones
state the function of erythrocyte
transport oxygen from lungs to other parts of the body
state how erythrocytes are adapted for their function
- presence of haemoglobin –> haemoglobin binds reversibly to oxygen to form oxyhaemoglobin which helps to transport oxygen in the red blood cell around the body
- absence of nucleus –> more space available for more haemoglobin to be packed in cell cytoplasm and more oxygen to be hence transported
- circular and biconcave –> increase SA:V of cell, allowing for quicker diffusion of oxygen in and out of cell
- elastic and flexible cell surface membrane –> cell can change its shape while squeezing through small capillaries
briefly describe the term “phagocytes”
consists of macrophages and neutrophils, which engulf and digest foreign bodies via phagocytosis
state 4 ways in detail how antibodies protect our bodies
- destroy bacteria by attaching to them and causing bacteria surface membrane to rupture
- cause bacteria to agglutinate so they can be easily ingested by phagocytes
- neutralise toxins produced by bacteria
- attach to viruses and prevent them from binding to host cell
state the scientific name for platelets, and describe what it is
thrombocyte
not true cells but fragments of larger bone marrow cells called megakaryocytes
state the function of platelets, and its importance
play a role in blood clotting by forming “sticky plugs” at wound sites, which prevents excessive loss of blood from wound and further entry of pathogens through the wound
outline the mechanism of blood clotting
- damaged tissue and platelets release the enzyme thrombokinase which catalyses the conversion of prothrombin into thrombin in the presence of calcium ions
- thrombin in turn catalyses the conversion of soluble fibrinogen into insoluble fibrin threads that form a mesh and trap blood cells
prothrombin and thrombin are the same thing, just one is inactive one is active
true/false: blood group O has no antigens in red blood cells
false. it has no A and B antigens, but does have antigens
what is agglutination?
fatal clumping of red blood cells that occurs when a cell containing an antigen is mixed with its corresponding antibody. this occurs in the recipient
fill in this table
describe arteries
- blood vessels that carry blood away from heart
- ALL transport oxygenated blood EXCEPT pulmonary artery
- bloow flow is rapid and under high pressure
- thick muscular and elastic walls that can withstand the high pressure of blood flowing through
- thick elastic walls allow walls to stretch and recoil to push the blood along it in spurts, maintaining the high pressure of blood flowing through (memorise this one)
- branch to form arterioles
- arterioles branch to form capillaries
describe veins
- blood vells that carry blood toward heart
- ALL carry deoxygenated blood EXCEPT pulmonary vein
- blood flow is slow and under low pressure
- relatively thinner muscular and elastic walls (than artery) as blood flows through it at lower pressure
- semilunar valves present to prevent backflow of blood into vein by ensuring unidirectional flow of blood in veins
- located between large muscles of body, and the contraction of these skeletal muscles squeeze the veins and push the blood along, up toward heart
- capillaries unite to form venules
- venules join to form veins
what are capillaries?
microscopic blood vessels that connect arteries and veins
describe how capillaries are adapted for its function
- walls are one-cell thick and partially permeable –> provide shorter diffusion distance for quick diffusion of dissolved substances through it
- highly-branched –> increase SA:V for efficient diffusion of dissolved substances through it
- small lumen –> slow the flow of red blood cells so there is more time for oxygen to diffuse to tissue cells
why is there tissue fluid?
- cells in capillary walls do not fit exactly together, so there are small gaps in between
- plasma can leak out from blood
- hydrostatic pressure is the main force pushing plasma out of blood
- hence, minute spaces between tissue cells contain a colourless liquid known as tissue fluid
describe the composition of tissue fluid
contain dissolved substances such as glucose and amino acids, and waste products like urea and hydrogencarbonate ions
what is/is not present in tissue fluid:
- RBC
- WBC
- proteins
- proteins is not found in tissue fluid, as it is too large to pass through gaps between capilalry walls
- phagocytes can squeeze through gaps of capillary walls to enter tissue fluid, but NOT RBCs
describe how substances move between blood plasma and body cells
- oxygen and soluble food substances diffuse quickly through walls of capillaries from blood plasma to tissue fluid surrounding body cells, as blood moves along capillaries down concentration gradients
- carbon dioxide and waste products diffuse from body cells to tissue fluid, and subsequently into blood plasma, to be carried away to various organs to be removed from the body, down concentration gradients
describe the heart
- muscular organ that pumps blood around the body
- consists of mainly cardiac muscles which contract and relax to circulate blood through blood vessels
- has 4 chambers: 2 atria and 2 ventricles
contrast left and right side of heart
- left side receives oxygenated blood from lungs and pumps it to all parts of body except lungs
- right side receives deoxygenated blood from body (except lungs) and pumps it to the lungs
contrast oxygenated and deoxygenated blood
- oxygenated: high conc. of oxygen, low conc. of carbon dioxide
- deoxygenated: high conc. of carbon dioxide, low conc. of oxygen
state the function of median septum
prevents oxygenated blood in left side from mixing with deoxygenated blood in right side
state the general function of heart valves
ensures blood flows unidirectionally, hence preventing the backflow of blood from ____ to ____
identify the valves in the heart and state where they are found
- semilunar valves: pulmonary artery, aorta
- bicuspid valve: between left atrium and left ventricle
- tricuspid valve: between right atrium and right ventricl
explain why blood pressure in pulmonary artery is not as high as that in aorta
- right ventricular wall is less muscular then left ventricular wall
- less force is generated within right ventricle when its muscles contract
explain why ventricular walls are thicker and more muscular than atrial walls
muscular walls of ventricles contract to pump blood to the rest of the body, a further distance, so the walls are thicker and more muscular to exert a higher pressure, ensuring blood reaches all areas of the body
muscular walls of atria contract to pump blood only to the ventricles, a shorter distance, so the walls are thinner and less muscular, as blood can be pumped at a lower pressure
explain why walls of right ventricle are thinner and less muscular than left ventricle
right ventricle pumps blood to lungs, a shorter distance from the heart, so less pressure has to be exerted when right ventricle contracts
left ventricle pumps blood around the whole body, a further distance, so higher pressure has to be exerted when left ventricle contracts
describe what happens at each stage of the cardiac cycle:
1. atrial systole
2. ventricular systole
3. diastole
1,
* muscles surrounding both atria contract, increasing pressure in atria
* blood is forced into ventricles
* tricuspid and bicuspid valve open to allow blood to pass through
* semilunar valves close to prevent backflow of blood into vena cava and pulmonary vein
2,
* muscles surrounding both ventricles contract, increasing pressure in ventricles
* blood from ventricles is pumped out of heart into pulmonary artery and aorta
* tricuspid and bicuspid valve close to prevent backflow of blood into atria
* semilunar valves in pulmonary artery and aorta open to allow blood to pass through
3,
* muscles surrounding both atria and ventricles relax, decreasing pressure in all chambers
* blood enters the relaxed atria and ventricles
* tricuspid and bicuspid valve open to allow blood to pass through
* semilunar valves in pulmonary artery and aorta close to prevent backflow of blood into ventricles
describe pressure changes in the LEFT side of heart during cardiac cycle
atrial systole:
* muscles of atrial wall contract, further increasing atrial pressure
* bicuspid valve is already open to allow blood to flow through it
* blood therefore flows from left atrium to left ventricle, down pressure gradient
* as aortic pressure is higher than ventricular pressure, semilunar valves close to prevent backflow of blood from aorta into left ventricle
ventricular systole
* muscles in left ventricular wall contract, increasing ventricular pressure beyond atrial pressure
* bicuspid valve closes (“Dub”) to prevent backflow of blood from left ventricle to left atrium
* ventricular pressure further increases beyond aortic pressure
* semilunar valves open
* blood therefore flows from left ventricle into aorta, down pressure gradient
* meanwhile, atrial diastole takes place
* muscles in atrial wall relax, causing atrial pressure to decrease
* atrium begins to fill with blood from pulmonary vein, increasing atrial pressure
ventricular diastole
* muscles in left ventricular wall relax, decreasing ventricular pressure until lower than aortic pressure
* semilunar valves close (“Lub”) to prevent backflow of blood from aorta into left ventricle
* ventricular pressure decreases further until lower than atrial pressure
* bicuspid valve opens to allow blood to flow from left atrium to left ventricle, down pressure gradient
