cardiovascular and nervous systems Flashcards
where is the heart found
mediastinum
what is the heart enclosed in
the pericardium which is like a sac of fluid which prevents overstretching
what are the three layers of the heart wall
epicardium - where the pericardium adheres to
myocardium- cardiac muscle found
endocardium - smooth layer so less resistance to blood
what are 4 roles of the valves
initiate cardiac excitation
conduct action potential along ventricle
strengthen cardiac contractions
ensure single direction of blood flow
what are two problems to do with the valves
stenosis- valve wont open properly so heart has to pump harder
regurgitation- wont close properly so blood leaks backwards
what causes the heart to beat
SA node generated action potential at autorhythmic fibres which constantly fire (no resting potential)
Conducted by av node which slows it down
bundle of His is the only place where action potential travels down
action potential is conducted by purknje fibres up to semi lunar valves
how might fluid be lost from the circulatory system
leaked out from the circulatory system as lymph and picked up by lymphatic system
what is the circulatory systems main roled
carry blood
exchange of gasses
transport of other substances
regulate blood pressure
direct blood flow for homeostasis
what are the three layers of a blood vessel and what are they made of
Tunica interna - thin layer which continues from basement membrane
Tunica media - smooth muscle and elastic fibres which changes size the most
tunica externa- made up of elastin and collagen and nerves which anchor the vessel to surrounding tissue
what are the two types of artery
elastic- carry blood from heart initially with larger diameter
muscular- distribute blood
what is the structure of an arteriole like
thin tunica interna with fenestrated elastic lamina
tunica media is made of 2 layers of smooth muscle
what is the terminal end of an arteriole called
metarteriole
junction is called precapillary sphincter
types of capillary
continuous
fenestrated
sinusoids
structure of venules
thin walls allows stretching to allow increase in volume up to 360%
structure of veins
think tunica externa with collagen and elastic fibres
tunica interna folds inwards
what is vasomotion
the contraction and relaxing of smooth muscle to move blood along the metarterioles and sphincters
what are the receptors of cardiovascular system
proprireceptors - joint movement
baroreceptors
chemoreceptors
what are the three functions of the nervous system
detecting stimuli
interpreting stimuli
initiating response
what are the three parts of a neurone and what they do
cell body- contains organelles
dendrites- receive signals from other neurones
axon- transmits signal to end of neurone
what is a bundle of neurones called
a nerve
what cell insulates the neurones and with what
scwann cells, produce myelin
how is the ion concentration gradient maintained
sodium potassium pump which pumps out 3 Na for every 2 K in
outline how a neurone transmits a signal across a synapse
depolarisation of presynaptic terminal causes ca ion channels to open, ca 2+ moves in and causes vesicles to fuse with membrane to secrete neurotransmitter
this binds to a receptor
define action potential
a sequence of rapidly occurring events which results in depolarisation and then repolarisation
how is the vertebrate brain regionally organised
forebrain - olfactory bulb and cerebrum- smell and sleep
midbrain- routing sensory input to appropriate area
hindbrain- cerebellum - involuntary activities
what does the human brain form out of
the neural tube
what is the cerebrum responsible for
contains the cerebral cortex
language
cognition
memory
awareness
how is cerebrum regionally specialised
cognitive functions in cortex and outer layer of cerebrum
how is a stimuli dealt with
input to hypothalamus where it is organised into sensory areas. prefrontal cortex plans movement
cerebral cortex generates motor command where the cerebrum controls the skeletal muscle
what are the main functions of the brain stem
signal from brain for movement
sends information to brain
and a reflex response
