session 6

Question 1

factors affecting blood flow

Answer 1

• vascular resistance
• venous return (how much blood is returning to heart)
• speed of blood flow
• blood pressure

Question 2

Blood pressure is

Answer 2

hydrostatic pressure exerted by blood on walls of blood vessels

Caused by ventricle contraction

Question 3

components of blood pressure

Answer 3

• systolic blood pressure
  
  • highest artery pressure during systole
• diastolic blood pressure
  
  • lowest artery pressure during diastole

Question 4

mean arterial pressure (MAP)

Answer 4

• average blood pressure in arteries
• MAP = diastolic BP + 1/3(systolic - diastolic BP)

Question 5

factors affecting blood pressure

Answer 5

• cardiac output
  
  • dependent on HR and SV
• blood volume
• vascular resistance
  
  • opposition to blood flow
  • caused by lumen size, thickness of blood and length of the vessel
• elasticity of arteries

Question 6

systemic vascular resistance (SVR)/ total peripheral resistance (TPR)

Answer 6

all vascular resistances offered by systemic blood vessels

*

Question 7

what is venous return and how is it achieved

Answer 7

• volume of blood flowing back to heart through systemic veins
• depends on
  
  • pressure difference in venules and right atrium
  • skeletal msucle pump
    
    • ​contraction/relaxation of skeletal muscles
    • opens and closes venous valves
  • respiratory pump
    
    • ​diaphragm movement changing abdominal pressure

Question 8

velocity of blood flow

Answer 8

• velocity inversely related to cross sectional area of blood vessels
  
  • blow flows slowly whre cross sectional area is greatest
• Blood flow decreases from aorta to arteries, is slowest in capillaries

Question 9

circulation time

Answer 9

time for blood drop to pass from right atrium through pulmonary circulation, back to left atrium, through systemic circulation down to foot and back to right atrium

usually 1 min in resting person

Question 10

blood pressure and blood volume are controlled by adjusting heart rate, stroke volume, blood volume and vascular resistance.

This is done thorugh several negative feedback mechanisms….

Answer 10

• cardiovascular centre
• nervous system
• hormones
• auto regulation

Question 11

cardiovascular centre for blood flow and pressure control

Answer 11

• group of neurons in medulla oblongata that regulate HR, contraction and vessel diameter
  
  • output from CV centre through
    
    • sympathetic impulses incresae HR and contractility
    • parasympathetic impulses along vagus nerves decrease heart rate

Question 12

nervous system control of blood flow and pressure

Answer 12

• nervous system regulated BP by
  
  • baroreceptor reflex
    
    • ​pressure sensitive neurons in aorta, carotid arteries
    • monitor stretch of wall
    • low BP -> low baroreceptor feedback -> CV centre increases sympahtetic stimulation -> increases HR and contractility
  • chemoreceptro reflex
    
    • ​monitor chemical composotion of blood ie o2, co2 and H+
    • located in carotid sinus and aortic arch
    • eg hypoxia or acidosis -> chemoreceptor stimulation -> increased sympathetic stimulation -> vasoconstriction and increased BP

Question 13

hormonal control of BP and blood flow

Answer 13

• renin-angiotenisin-aldosterone system
  
  • changes blood volume and therefore BP
• epinephrine and norepinephrine
  
  • (adrenaline and noradrenaline)
  • released from adrenal medulla
• antidiuretic hormone (ADH)
  
  • ​from posterior pituitary
  • causes vasoconstriction
• atrial natriuretic peptide
  
  • ​released by cells in atria of heart when BP rises
  • causes vasodilation

Question 14

autoregulation of BP

Answer 14

• automatic adjustment to meet metabolic demands
• physical changes
  
  • ​warming = vasodilation
  • cooling = vasoconstriction
• vasodilating and vasoconstricting chemicals
  
  • ​vasodilators being H+, lactic acid, histamine and NO
  • vasoconstrictors being thromboxane, serotonin, endothelins
• changes in o2 levels
  
  • ​systemic vessels dilate with low o2 while pulmonary vessels constrict

Question 15

methods of checking circulation

Answer 15

• pulse
  
  • created by pressure in elastic artery caused by left ventricle systole
• blood pressure
  
  • measured with a sphygmomanometer
  • determines systolic and diastolic pressure
  • can hear heart sounds (korotkoff sounds)

Question 16

what is pulse pressure

Answer 16

The difference between systolic and diastolic

Question 17

define shock

Answer 17

failure of CV system to deliver o2 and nutrients

• negative feedback systems attempt to fix
  
  • eg ADH, vasodilators, renin-angiotensin-aldosterone

Question 18

disorders of homeostatic imbalance

Answer 18

• hypertension
  
  • systolic above 140
  • diastolic above 90
• results in damage to blood vessels, heart, brain and kidneys
• managed with lifestyle changes and various drugs

Question 19

primary hypertension

Answer 19

90-95% of all hypertension cases

No known/obvious cause for persistent hypertension

Question 20

secondary hypertension

Answer 20

has a known underlying cuase

eg. obstruction of renal blood flow or damaged renal tissue

Question 21

aging and the CV system

Answer 21

• general changes in CVS associated with aging
  
  • decreasled compliance of aorta
  • lowered CO and max HR
  • incresed systolic pressure
  • HDL decreases and LDL increases

Question 22

circulatory routes

Answer 22

• systemic circulation
  
  • from left side of heart to rest of body and back to right side
    
    • coronary circ
    • cerebral circ
    • hepatic portal circ
• pulmonary circulation
  
  • ​from right side of heart to lungs and back to left side
• foetal circulation
  
  • ​from foetal heart through umbilical cord and back

Question 24

oxygenated and deoxygenated blood

Answer 24

• oxygenated blood
  
  • flows through systmeic arteries
• deoxygenated blood
  
  • returns to heart through systemic veins that drain blood into superior or inferior vena cava -> right atrium

Question 25

aorta and its regions

Answer 25

* Aorta is largest artery of the body * branches are * **ascending aorta** * **arch of aorta** * **descending aorta**

Question 26

branches of ascending aorta and arch of aorta

Answer 26

* ascending = right and left coronary arteries * arch = * brachiocephalic trunk -\> * right common carotid * right subclavian * left common carotid * left subclavian artery

Question 27

subclavian branches

Answer 27

* vertebral artery * axillary artery * brachial artery * radial and ulnar branches

Question 28

common carotid branches

Answer 28

* external carotid arteries * fro external skull structure * internal carotid arteries * for eyeballs and brain

Question 29

descending aorta composed of

Answer 29

* **Thoracic aorta** * **​**having visceral and parietal branches * **Abdominal aorta** * **​**continuation of thoracic aorta after it passes diaphragm * visceral branches * coeliac artery * mesenteric arteries * parietal branches

Question 30

abdominal aorta segments to become

Answer 30

left and right common iliac arteries * these divide again into left/right external/internal iliac

Question 31

external iliac artery becomes..

Answer 31

femoral artery -\> popliteal artery

Question 32

Veins can be deep or superficial. All drain blood to

Answer 32

* superior vena cava * drains head and upper extremities * inferior vena cava * drains abdomen, pelvis and lower limbs * coronary sinus * drains heart muscle

Question 33

hepatic portal circulatio

Answer 33

* carries blood between two capillary networks * Veins of pancreas, spleen, stomach, intestines and gallbladder -\> direct blood into hepatic portal vein of liver before -\> heart * *enables nutrient utilisation and blood detoxification*