water balance, blood and immunity Flashcards
describe the structure of cell membranes
phospholipid bilayer
very flexible,
excellent insulators,
dynamic,
selectively permeable
embedded with proteins
describe the phospholipid bilayer
made up of a phosphate head (hydrophilic, lipophobic) and fatty acid tails (hyrophobic, lipophilic)
functions of the cell membrane
osmosis
diffusion
cell to cell communication
types of membrane proteins
integral
peripheral
enzymes
structural
communication
what are integral proteins
span the hydrophobic core of the lipid bilayer (all the way through membrane)
examples of integral proteins
receptors
transporters
what are peripheral proteins
associated with only the phosphate head of the bilayer (only top of membrane)
what are membrane enzymes
membrane enzymes catalyse chemical reactions on the cell membrane
what do structural proteins do
anchor the cell membrane to the intracellular skeleton to the EC matrix
how is an electrochemical gradient made?
he ions creating the concentration gradients are charged particles there is also a difference in charge across the membrane
different mechanisms of movement of particles across the membrane
- diffusion
- active transport
- osmosis
- filtration
describe the process of endocytosis
invagination of cell membrane to form a vesicle which eventually disintegrates on the cytoplasmic surface of the membrane releasing contents
describe the process of exocytosis
the reverse process: cells migrate to cell membrane where a vesicle is formed and enters the cell
define diffusion
molecules spread from regions of high concentration to regions of low concentration until the concentration is uniform throughout the volume
factors favouring diffusion
- temperature,
- concentration gradient,
- size of the molecule, and
- the presence of a membrane
describe passive diffusion
substance moves directly through the lipid bilayer
requirements for passive diffusion
molecules must be small, uncharged and lipophilic (hydrophobic)
describe facilitated diffusion
substance requires assistance from membrane proteins to cross the lipid bilayer
difference between facilitated diffusion and active transport
- Active transport involves transport proteins, and facilitated diffusion does not
- active transport pumps molecules against their electrochemical gradient
what is meant by carrier mediated transport systems
- proteins with binding sites for the solutes they transport
- after binding they undergo a change in shape which exposes the binding site on the other side of the membrane
define osmosis
net movement of H2O from regions of high concentration to regions of low concentration
what does osmolarity mean
the total number of particles in a solution
osmolarity of normal human plasma
285 (300) osmols
what is tonicity
the number of non-penetrating particles in a solution
what happens to cells in hypotonic solutions
they swell as water enters down a chemical gradient
what happens to cells in hypertonic solutions
they shrink as water leaves down a chemical gradient
what is an isosmotic solution
a solution with the same total number of solute particles as normal ECF (300)
what does hypo-osmotic mean
fewer total solute particles
what does hyper-osmotic mean
greater total solute particles
what is an isotonic solution
a solution with the same number of non-penetrating solute particles as normal ECF
what does hypotonic mean
fewer non-penetrating solute particles
what does hypertonic mean
greater non-penetrating solute particles
what does hypertonic mean
greater non-penetrating solute particles
what causes intravascular haemolysis
this is due to lysed (burst) cells introducing protein into ISF, which increases tonicity of ECF in an uncontrolled manner
role of the immune system
is the body’s ability to resist or eliminate potentially harmful foreign materials (pathogens)
major cells of the innate immune system
- dendritic cells
- complement cells
- Natural killer cells
- basophils - least common cell
-phagocytes
what are phagocytes
cells of the immune system that track down, engulf and destroy bacteria, pathogens and damaged or dead cells
types of phagocytes
neutrophils and monocytes
stages of phagocytosis
- movement of the phagocyte toward the microbe
- attachment of microbes to phagocyte surface
- endocytosis of microbe and formation of phagosome
- fusion of phagosome with lysosome
- killing of microbe through digestion by enzymes
- discharge of waste materials
role of eosinophil
role is to help combat parasitic infections
what are cytokines
small proteins which communicate with other cells by binding to specific receptors on these cells producing signalling molecules which lead to many biological effects
roles of cytokines
- differentiation
- activation
- chemotaxis
- enhancing cytotoxicity
what are primary lymphoid organs
places where blood cells are produced and receive their early ability to interact with antigens (maturation)
examples of primary lymphoid organs
found in bone marrow and thymus
what are secondary lymphoid organs
sites of lymphocyte activation by antigens, the development of adaptive immune response to antigens by T and B cells
where are secondary lymphoid organs found
lymph nodes, spleen, mucosal immune system and tonsils
function of lymph nodes
inducing adaptive immune responses to antigens carried from the tissues by lymph
what can T helper cells not do
they cannot kill infected cells
role of cytotoxic t cells
directly kill virus infected cells via perforins and granzymes
function of B cells
producing antibodies directed against specific antigens
where are B cells produced
produced and matured in bone marrow
what are antibodies
proteins that are produced as an immune response against antigens
what are the 2 regions of antibodies
- upper region = antigen binding region which is specific and interacts with antigens
- lower region = Fc region
5 types of antibodies
- IgM = first class to be produced
- IgA = protects mucosal surfaces and resistant to stomach acid
- IgG = main type of antibody. Binds to many kinds of pathogens and protects body from infection
- IgE = defends against parasites, causes allergies
- IgD = unkown function
function of the compliment system
- direct lysis of target cells
- enhance immune response
- enhance phagocytosis (opsonization)
characteristics of active immunity
- the transfer of antibodies or lymphocytes specific for the microbe
- produced by hosts own immune system
- takes weeks to develop
- memory cells produced
- protection is permanent
characteristics of passive immunity
- individuals who have not yet encountered a particular antigen
- transfer of antibodies/cells from other individuals
- happens immediately
- no memory cells are made
- protection is temporary
average circulating volume in a typical adult male
5L of blood circulating the body (1L lungs, 3L in systemic venous circulation, 1L in heart and arterial circulation)
functions of blood
- plasma = carriage of physiologically active compounds
- platelets = clotting
- white blood cells = defence
- red blood cells = carriage of gas
- thermoregulation
- maintenance of ECF pH
what is oncotic pressure
a form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that causes a pull on fluid back into the capillary
abundancy and lifespan of erythrocytes
- most abundant blood cell, red blood cell
- 120 day lifespan
lifespan of platelets
10 days
lifespan of platelets
10 days
function of a red blood cell
carries oxygen from the lungs to all parts of the body
function of erythropoietin
a protein concerned with gas transport
what enhances secretion of erythropoietin
when oxygen delivery to kidneys is reduced (hypoxia) this may be due to:
- haemorrhage
- anaemia
- cardiac dysfunction
- lung disease
5 main types of white blood cells
neutrophils, eosinophils and basophils are granulocytes
monocytes and lymphocytes are agranulocytes
most abundant white blood cell
neutrophils
least abundant white blood cell
basophils
describe red blood cells
- erythrocytes
- erythropoiesis (red blood cell formation) is accelerated by erythropoietin and turns an erythroblast into an erythrocyte
what happens to monocytes
they migrate to connective tissues where they become macrophages and live for 3 months
how is leukopoiesis controlled
leukopoiesis is controlled by a cocktail of cytokines
function of platelets
- adhere to damaged vessel walls and exposed connective tissue to mediate blood clotting
- they do not adhere to healthy intact endothelium
role of thrombopoietin in platelet formation
regulating the expansion and maturation of megakaryocytes
what is meant by haematocrit
measures the volume of red blood cells compared to the total blood volume
normal haematocrit
40-50%
what can effect haematocrit levels
- Living at a high altitude.
- Pregnancy.
- Significant recent blood loss.
- Recent blood transfusion.
- Severe dehydration.
what is blood viscosity
how thick blood is compared to water
effect of haematocrit on blood viscosity
50% increase in haematocrit increases viscosity by approximately 100%
effect of temperature on blood viscosity
increase in temp decreases viscosity (1 degree to 2%)
effect of flow rate on blood viscosity
decreased flow rate increases viscosity