BI1002 circulatory system Flashcards
Explain the essential functions of circulatory systems
distribution of nutrients
support for metabolism
distribution of water and electrolytes
transport and distribution of hormones
(fluid to circulate, propulsive mechanism, tubes/channels, valves/septa-one way flow)
Compare and contrast the features of open and closed circulatory systems
open: fluid is open to body cavities/cells
most molluscs, arthropods and some annelids
lower P system
less efficient
closed: fluid enclosed in system/doesnt contact cells directly
all vertebrates, cephalopod mollscs, annelids
higher P system
more efficient
features of open CS
inclomplete system of vessels
circulation of fluid known as haemolymph
haemolymph flows through vessels and freely percolates through intercellular space
heart may propel haemolymph through vessels
insects use trachael systems to transport nutrients
features of a closed CS
complete/continuous system of blood vessels
fluid=blood
heart propels blood through vessels
intercellular spaces filled with interstitial fluid(diffusion from blood)
lymph in lymphatic vessels
pump: anatomy of heart can vary
distribution:circulation patterns vary(single/double)
Explain the forces that influence flow through vessels
(EFFICIENT)
O2 carriers in blood/haemolymph
gas exchange in respiratory system/in tissue
efficient delivery of nutrients and O2:
diversification of de/oxygenated fluids to target organs
fast flow of fluids
closed CS: change in P is high and resistance is high
open CS: change in P is low and resistance is low
TF both can maintain high flow rate
Outline the key features of the mammalian cardiovascular system
FUNCTION:
distribution of O2 and nutrients
transport of CO2 and removal of metabolic waste products
distribution of water, electrolytes and hormones
thermoregulation
immune system infrastructure
ARRANGEMENT:
4 chambered heart
blood supplies to systemic vascular beds run in parallel
pulmonary circulation runs in series
high P system
Explain the term ‘cardiac output’ and discuss how cardiac output can be altered by heart rate and stroke volume
(L/min)CARDIAC OUTPUT: the total volume of blood pumped by the heart in 1minutes
heart rate(bpm) X stroke volume(L/beat)
HR changed by:
autonomic nervous system
circulating hormones(adrenaline)
SV changed by:
intrinsic control-degree of stretch in cardiac muscle
extrinsic control- sympathetic stimulation
Describe the conduction of electrical activity through the heart and explain how this relates to the ECG waveform
EC coupling in cardiac myocytes:
action potential occurs in cell membrane
long AP=calcium channels to open(enters cell)
calcium induced calcium release-entering calcium causes more calcium to be release from within cell
influx of calcium causes muscular contraction
P wave-depolarisation of atria
PRinterval-conduction through AV node
QRS complex(Rwave)-depolarisation of ventricles
QTduration-ventricular depolarisation/repolarisation
Twave-repolarisation of ventricles
Describe the events of the cardiac cycle
- Atrial systole (ventricular diastole)-atria contract/ventricles relaxed to allow filling
- Isovolumic contraction of the ventricles (ventricular systole)
- Ventricular ejection(AV valves closed/aortic pulmonery valves open)
- Isovolumic relaxation of the ventricles
- Passive ventricular refilling
Explain the forces governing flow of blood/haemolymph through the vessels of the circulation (factors influencing pressure and resistance)
P in circulation:
BP-difference between P in system and the ambient P - 2 components:
dynamic pressure produced by the pump
hydrostatic pressure of the fluid
changing resistance:
vessel radius causes greatest changes resistance(inr. = decr.)
vessel length
fluid viscosity
RESISTORS:
in series-connected along single path: adding resistors increases total resistance of system
in parallel-connected along multiple paths: adding resistors decrease total resistance of system(how body works)
function of blood vessels
ARTERIES:
conduit for blood to capillary beds
act as P reservoir to drive blood into arterioles
damp oscillation in P and flow
control differential distribution to different organs and tissues
VEINS:
conuit for blood to return to heart
act as a blood reservoir
flow influences by external forces
Outline mechanisms to alter vascular tone and explain how this can influence the resistance of blood vessels
CONTROL OF VASCULAR RESISTANCE:
changes in smooth muscle =:
vasoconstriction
vasodilation
CONTROL OF SMOOTH MUSCLE TONE:
neurotransmitters-eg. noradrenaline, ACH
hormones-eg. adrenaline, vasopressin, atrial naturetic peptide
endothelium derived substances-eg. endothelin, NO
metabolites/related factors-eg. hypoxia, H+, CO2
other locally produced factors-eg. histamine, prostaglandin
other factors-eg. pressure, heat.
arterial pulse pressure wave
rise in pressure due as aortic valve opens
peak=systolic pressure
isovolumic contraction occurs(ejection)
notch in decreasing P-closure of valve
trough=diastolic pressure
isovolumic relaxation
effects of gravity
(giraffes)
higher blood pressure
when upright:(bigger differences than human)
head=75
heart=250
feet=400
vasoconstriction of vessels in lower body
when bent over:
vasodilation of vessels in lower body
aortic pressure decreases
hearts position in thorax
in chest cavity
behind sternum
centre left
on top of diaphragm
between lungs and mediastinum
bulges into left lung=smaller left lung
held in position by pericardium+lg. blood vessels entering/leaving
