4.4 Flashcards
features of cardiac muscle 3
- v good blood supply - coronary artieries
- contains lots of myoglobin - stores oxygen for rest
- can carry on contracting w/o rest/fatigue
whats the function of the tendonous chords in heart
present valves from being turned inside out bc of pressure exerted when ventricles contract
structure of artery
- smooth endothelial cells in middle, elastic fibres - resist pulse surges, narrow lumen
why r the endothelial cells smooth
reduce friction - blood can flow easier
advantages of double circulatory system in mammals
- blood can be pumped at higher P - body gets O2 quicker r
- oxygenated + deoxygenated can be split - most efficient
how does width of lumen of artery change
clsoerto heart = larger lumen size
closer to organs = smaller - regulates blood flow
why is a single circulatory system in bony fish okay
they have a lower metabloic demand for O2 so they can manage w this system
what are the 3 stages of the cardiac cycle
- Atrial systole, blood returns to heart at low pressure, atria filled w blood - increases P in atria - pushes AV valves open so atria contracts blood
- ventricular systole = ventricles contract blood out thru arteries, AV valves close from P of blood + SL valves open
- diastole = period of relaxation (heart muscles relax), ventricle P decreases, P + A valves close, heart refills blood into atria
what is the myogenic stimulation of heart
SAN generates wave of electrical activity at regular intervals and it causes atria to contract from top down
but this excitation doesn’t directly pass down directly into ventricles as it is blocked by a band of non conducting collagen = annulus fibrous
AVN = the one gap in the annulus fibrous - so only route for cardiac muscle + transmission
Bundle of his = in septum - there is a slight delay before AVN passes impulse on to ensure atria has stopped contracting.
purkyne fibres = contract ventricles from bottom up - blood goes OUT
what are the 2 types of leucocytes
granulocytes, agranulocytes
what r the granulocytes
neutrophils
eosinophils
basophils
agranulocytes
monocytes
lympocytes
function of neutrophils + their appearance
- engulf + digest pathogens
- multi-lobed nucleus - changes shape, grainy cytoplasm
functions of eosinophil + appearance
- 2 lobed nucleus , bright red orange granules
- effective against parasites , inflammation
functions of basophil + appearance
- produce histamines involved in inflammation + allergic reactions
- 2-lobed nucleus, dense + dark granules
functions of monocytes + appearance
- form macrophages + engulf pathogens
- LARGEST - horse-shoe shaped nucleus
functions of lymphocytes + appearance
make antibodies to defend body
v large nuclei
what is present in blood
- plasma
- erythrocytes
- leucocytes: neutrophils, eosinophils, monocytes, lymphocytes
- platelets
function of blood 3
transport
defence
formation of lymph + tissue fluid
formation of blood clot
- platelets release thromplastin and at right conc of [Ca2+], thromboplastin catalyses conversion of prothrombin into thrombin
- thrombin converts fibrinogen (soluble) -> fibrin (insoluble) - creates mesh at cut to prevent things entering + leaving
what do platelets release
serotonin - serotonin = blood vessels contract - cuts off blood supply at cut
thromboplastin
what is atherosclerosis
-= build up off yellow fatty depositis/plaques in arteries -> formation of clots -> block blood flow
effect of health on atherosclerosis
- stroke, angina, heart attack, aneurysm, high BP
risk factors for atherosclerosis
genes, age, sex, smoking, obesity, lack of exercise, stress
