Physiology 2058 CVS

Question 1

Organisation of ANS

Answer 1

Involuntary, 2 neurone system - preganglionic neurones that synapse on post ganglionic
Neurotrasnmitters are ACh and noradrenaline
Sympathetic and para sympathetic
Regulates cardiac muscle, smooth and glands

Question 2

SNS

Answer 2

thoraco-lumbar division, innervates almost every organ in the body, fight or flight

Question 3

PNS

Answer 3

cranio-sacral division, maintain and restore body energy

Question 4

Adrenal medulla

Answer 4

innervated by pre-ganglionic sympathetic nerves, modified ganglion cells, release adrenaline - 80% adrenaline, 20% noradrenaline, regulates metabolic events

Question 5

Hypothalamus

Answer 5

regulates activity of ANS with brainstem, regulates reproduction, hunger, reaction to stress, control of emotions, sleep/wake cycle, circadian rhythms

Question 6

Heart

Answer 6

Outside to in
pericardium - epicardium - myocardium - endocardium

Question 7

Blood flow through heart

Answer 7

RA - tricuspid valve - RV - plumonary valve - pulmonary trunk and arteries - pulmonary capillaries - pulmonary veins - LA - bicuspid valve - LV - aortic valve - aorta and systemic arteries - systemic capillaries - SVC, IVC and coronary sinus

Question 8

Heart valves

Answer 8

AV - atria and ventricles
Semi lunar - lungs and aorta

Question 9

Cardiac AP

Answer 9

After depolarization - plateau phase due to movement of EC calcium 250-300msec
longer refractory period - relaxation has started by the time refractory period is over
tetany can’t occur

Question 10

Generation of heart beat

Answer 10

conduction system - right atrium , sino-atrial node, generates more AP

Question 11

Conduction system

Answer 11

AP originate in SA node
AP reach AV node - pause
AP conducted through AV bundle
Into ventricles via bundle branches
Through musculature via purkinje fibers

Question 12

ECG

Answer 12

Record of electrical events occurring in heart, electrodes on body
P wave- atrial depolarization
QRS complex- ventricular depolarization
T wave - ventricular repolarization

Question 13

ANS effect on heart

Answer 13

SA node innervated by PNS (vagus nerve) - increased parasympathetic nerve activity decreases HR
Muscle of heart (ventricular myocardium) - innervated by SNS - increased sympathetic nerve activity increases cardiac contractility

Question 14

Cardiac cycle of a beat

Answer 14

Relaxation - diastole
Contractions - systole
Blood flow to heart muscle via coronary arteries and most occurs during diastole

Question 15

Events of cardiac cycle

Answer 15

Ventricular diastole- relax and pressure within falls
AV valves open blood flows from atria into ventricles
As V fills, pressure rises, AV valves snap shut- sound 1
V pressure rises higher than pulmonary or aortic valves the semi lunar valves open silently and blood ejected into 2 arteries - ventricular systole
Semi lunar valves snap shut - sound 2
Cycle typically 0.8 seconds
Sounds caused by closing of valves

Question 16

Cardiac output

Answer 16

HR v SV
Greater volume of blood in heart during diastole (EDV) end diastolic volume , greater next contraction = stroke volume

Question 17

SNS on SV and CO

Answer 17

For any EDV, increase in SNS will increase SV- increased contractility
Increased SNS will increase HR
Hormones increase CO

Question 18

Vascular system

Answer 18

Closed system of arteries, veins and capillaries into R and L of heart
Blood flow around body - pressure and resistance - Ohm’s law

Question 19

Ohm’s law

Answer 19

Q=P/R
Blood flow around body - pressure gradient, high to low
Related to resistance in the circulation - vascular resistance of total peripheral resistance

Question 20

Pressure in circulation

Answer 20

Starts at aorta high pressure left side
Ends at vena cavae - empty into lower pressure right side
Greatest pressure in arteries, greatest drop in arterioles - major resistance vessels in circulation

Question 21

What determines VR/ TPR

Answer 21

Size of blood vessel- diameter
SNS innervates blood vessels - increased SNS - vasoconstriction - increase resistance
Decreased SNS - vasodilation- decrease resistance
Blood viscosity - cellular components
Length of vessels - constant

Question 22

Capillaries

Answer 22

Exchange vessels of circulation, vast SA, one cell thick- endothelial cells, no smooth muscle, exchange driven by force/ pressure gradients between inside capillary and surrounding IF, selectively permeable

Question 23

Osmotic pressure

Answer 23

Pressure in blood due to its solute conc, more solute higher osmotic pressure, fluid more concentrated than plasma is hypertonic, reverse is hypotonic, bloods large plasma protein molecules contribute to blood colloid osmotic pressure

Question 24

Forces acting on capillary walls/ exchange

Answer 24

Solutes by diffusion, water by osmosis
Capillary blood/ hydrostatic pressure forces fluid out of capillaries into IF at arterial end of capillary - filtration
At venous end fluid is reabsorbed back into capillary
BCOP- pulls fluid into capillaries from IF
Lymphatic vessels mop up excess IF but if IF cuilds up - oedema

Question 25

Short term regulation of BP

Answer 25

Barorecptor receptor - arch of aorta and coronary sinus, pressure detecting BP falls, less stretch on receptors, reflex inhibited -> increase in BP, effects of ANS on heart and circulation Negative feedback BP increases- stretch on receptors, increased nerve impulses to CV in medulla, decreased SN activity, decreased CO, decreased peripheral resistance

Question 26

Renin Angiotensin Aldosterone System

Answer 26

longer term regulation of BP, involves variety of hormones e.g. RAAS, w kidneys Kidneys directly affected by BP anf flow to them through juxtaglomerular apparatus If BP falls, antidiuretic hormone released from posterior pituitary, causes water retention by kidneys, expand blood volume, increase bp ADH - vasopressin- vasoconstrictor

Question 27

Atrial Natriuretic Peptide

Answer 27

salt losing hormone, counteracts affect of aldosterone, if BP is too hgh can be released, in health balance between ANP and aldosterone

Question 28

Regulation of CO/ blood flow

Answer 28

Increase in blood flow to muscle during exercise up to 80-85%

Question 29

Organ metabolism

Answer 29

important factor in regulation of blood flow, greater metabolism in organ, greater demand for blood supply

Question 30

Regulation blood flow in exercise

Answer 30

Muscle metabolism increases, blood temporarily shunted from other regions of body to muscles - by vasodilation of the arterioles that feed muscle and vasoconstriction of arterioles that supply other organs, supply to meet demand

Question 31

Ischemia

Answer 31

obstructed blood supply to organ, eg skin- moving patients, induces reactive hyperaemia, prevents skin ulceration Skin blood flow goes up during exercise to allow heat loss to regulate body temp

Question 32

Autoregulation

Answer 32

Ability of tissues to automatically adjust their blood supply to meet demands

Question 33

Foetal circulation

Answer 33

Umbilical Vein and ductus venosus, Ductus arteriosus, umbilical arteries

Question 34

Umbilical vein and ductus venosus

Answer 34

oxygenated blood returning from the placenta is carried in the umbilical vein, empties into ductus venosus, empties into IVC

Question 35

Ductus arteriosus

Answer 35

allows blood to pass from pulmonary trunk directly into aorta, onwards to systemic circulation

Question 36

Umbilical arteries

Answer 36

transport foetal deoxygenated blood to placenta, foramen ovale opening between right and left atrium by pass the lings