circulatory system

Question 1

what are the 3 types of capillary

Answer 1

1. continuous - inter-endothelial junctions 10 - 15 nm wide allow the diffusion of substances trancellular, however at the blood brain barriers tight junction prevent the diffusion of molecules (such as amino acids that could act as NT) so molecules must be actively transported.
2. fenestrated - found in areas of extensive molecular exchange - small intestine, kidneys, endocrine glands - fenstra are windows covered by a thin diaphragm allowing larger molecules such as petides to pass
3. sinusoidal - liver and bone marrow - allow the blood cells to pass through large gaps and fenestrations in the cap wall.

Question 2

what is the functions of the circulatory system

Answer 2

1. distribution of gasses and molecular for nutrition growth and repair
2. hormal signalling
3. heat dissipation
4. mediates inflammatory and defence response

Question 3

what are the functions of lymph

Answer 3

1. drain excess interstitual fluid to maintain circulating volume - 3L and 150g protein/day
2. transport of dietary lipids are chylomicrons - trigylcerides
3. immune response

Question 4

arteries

Answer 4

elastic - muscular replaced by concentric layers of elastic tissue to withstand high pressure (high collagen also to prevent tear), recoil to ensure that blood flows in ventricular systole and the heart is fully empties as well as giving the walls high compliance so stretch easily under the high pressure.
medium musclular - thick layer of smooth muscle less collagen, allows control of flow and pressure by vasocontriction and dilation mediated by ANS na on aphla 1, vascular tone means always partically contracted to maintain high pressure and efficeient flow.
aterioloes - highest proportion of smooth muscle and thickest wall - control of blood flow into capilaries
pre cap spincter - local regulation by o2, co2, low PH controls flow of blood into capilaries allow ANS control

Question 5

veins

Answer 5

venuloles - only endothelial cells, porous to allow exchange
muscular venuloes - 3 or less layers, thin walls, compliance to allow to act as blood resevoirs.
veins - less muscular and elastic than ateries, still distensible enough to adapt to varitation in volume and pressure of blood, can act a stores
vena cave - more muscular than venolues, smaller vein, higher collagen and smooth muscle
valve are formed from folds in the tunica intima
longitudinal muscle contracts to widen the vein
defective and leaky veins leads to varicose veins

Question 6

what are the 3 layers in the hippocampus

Answer 6

• polymorphic
• pyramidal
• molecular
  differs from cortex as this has 6 layer
• external granular - ouput
  external pyrimidial - output
  internal granular - stallate inputs from thalamus
  internal pyridimal - 5 output motor
  fusiform
  white matter

Question 7

what are the layers of the cerebellum

Answer 7

• molecular
• perkinje
• granular
• white matter

Question 8

what are the 4 sections of the hippocampus1

Answer 8

1. dentate gryus
2. ammons horn
3. subiculum
4. parahippocampal gryus

Question 9

How are the neurons involved in motor control similar to that of the somatosensory system

Answer 9

somatopopy of motor cortex represents the topological (inrealtion eg, axial to proximal, lateral to mwedial) organisation of spinal motor neurones inovating muscle

Innovation for each muscle occupies a mediolateal position within the spinal cord ventral horn - eg. from upper to lower
motor pools are organised somatopically from proximal to distal - motor pools are all the neurones innovating one muslce, extend up serveal vertbrea in rod like clusters. - medialoateral position depending on where on the head to tail they are from

Question 10

where do axons motor come from

Answer 10

main inputs to the motor cortex e.g. from the BG are into stellate cells layer 4, meanin outputs are layer 3, 5 and 6, in the motor cortex most axons down the corticopsinal tract are from layer 5 of the pyramidial cells of the motor cortex

Question 11

convergence theory

Answer 11

integrated and plastic pattern of
that somatosenory inputs
convergence onto somatosenosry areas in a
distributed network in brain

Question 12

diencenphalon

Answer 12

thalamus - all special senses apart from smell, lesssions leads to sythesisa, motor, arousal and higher functions
pineal - at the end of the thalamus - endocrine gland of serotinin and melantonin
hypothalamus - eating drinking, sexual, inputs from sesnory centres, non linear feedback, hormonal control links nervous and endocrine

Question 13

basal ganglia

Answer 13

- 4 nuclei 
straitum 
GP 
sub thalamic
substania nigra

Question 14

limbic

Answer 14

memory, emotions, hippocampus, amgydala, reticular formation
- memory, formation, motivation

Question 15

higher centres

Answer 15

broca - expresive - motor program to speak - left frontal

wernickers - posteriol temporal - receptive - loss of finding the word to speak

Question 16

olfactory

Answer 16

primary and afferent neurone
thin unmylinated
cribiform plate
olfactory epithelium - cillia - high in nasal cavity near olfactory bulb used to smell

Question 17

sights

Answer 17

alpha sububit of ospin actiavtes PDE - breaks down cGMP