Introduction to circulation

Question 1

what is the function of circulation

Answer 1

supply oxygen and nutrients to tissues and remove waste (co2 and heat)
homeostasis of extracellular fluid (via kidneys)
distribute hormones
regulate temperature
infection defence

Question 2

how do circulatory pathologies arise

Answer 2

diminished oxygen and diminished perfusion (compelling symptoms derived from waste)

Question 3

what is the function go the cardiovascular system

Answer 3

perfusion (flow) which requires a pressure difference (pressure and resistance are closely linked)

Question 4

why must correct blood pressure be maintained

Answer 4

blood pressure too low then there’s insufficient delivery of blood and oxygen

Question 5

what does hypertension cause

Answer 5

vessel damage, heart damage and other pathologies

Question 6

what does hypotension cause

Answer 6

syncope (shock) via insufficient perfusion (common death in the critically ill)

Question 7

what are the two sides of the heart

Answer 7

right - pulmonary

left - systemic

Question 8

what are the principles of blood pressure and flow

Answer 8

determined by heart, blood volume and vessels

Question 9

how can BP be calculated

Answer 9

BP = cardiac output x peripheral resistance

Question 10

how can BP be measured

Answer 10

korotkoff sounds
via a blood pressure cuff
artery closed/ open = no sounds but at right pressure it opens and closes (systole then diastole) = sounds

Question 11

what is the function of the aorta and arterioles

Answer 11

aorta - stretch and recoil, store energy

arteries - distribute and adjust volume

Question 12

what is the function of the venules and veins

Answer 12

venules - collect blood, some exchange

veins - reservoir (2/3 blood in veins), muscle pump

Question 13

what is the structure of blood vessels

Answer 13

intima (endothelium, basement membrane and lamina propria)
internal elastic membrane
media (smooth muscle and some elastic fibres)
adventitia
vasa vasorum (VAN)

Question 14

how do arteries and arterioles compare

Answer 14

arteries - muscular and thick elastic walls

arterioles - muscular and little connective tissue

Question 15

how do veins and venules compare

Answer 15

veins - thin walls, smooth muscle, flacid

venules - thin walls with some smooth muscles

Question 16

how do systemic and pulmonary circulation compare

Answer 16

pulmonary - right ventricle, thin walled, crescent x section (lungs only, low pressure, high flow, low resistance)
Systemic - left ventricle, thick walled, circular x section (multiple organs, high pressure, variable flow, variable resistance)

Question 17

what is the apex beat

Answer 17

at systole, the apex of the heart moves forward to strike the chest wall

Question 18

what prevents valve prolapse

Answer 18

chordae tendinae attached to papillary muscles (2 mitral and 3 tricuspid)

Question 19

what is the function of the mitral and tricuspid (AV) valves

Answer 19

papillary fibres close in systole (S1 1st heart sound, Lub)

Question 20

What is the function of the aortic and pulmonary (semilunar) valves

Answer 20

close during diastole (longer than systole) (S2 2nd heart sound, dub)

Question 21

how does the heart muscle (cardiomyocytes) contract

Answer 21

by a conducting system
myocyte is electrically activated (Action potential, extra cell (negative) to intracell (positive) as free intracellular calcium increases
muscle contracts
calcium removed and muscle relaxes

Question 22

how is blood volume set

Answer 22

by the kidneys (water and sodium central to this as depends on water intake)

Question 23

do formed elements have any effect on blood pressure

Answer 23

not unless blocking entire vessels

Question 24

how is BP determined

Answer 24

balance between circulating blood volume and circulating capacity

Question 25

what do the kidneys control

Answer 25

blood volume and the concentration of salts, ions, electrolytes

Question 26

how is blood filtered in the kidney

Answer 26

small molecules (H20, glucose, ions) go through nephron (contains glomerulus) blood cells and protein can't pass desirable small molecules reabsorbed excess fluid and undesirables left in bladder and excreted

Question 27

what controls filtration in the kidney

Answer 27

endocrine system and autonomic nervous system

Question 28

how can the rate of filtration be changed

Answer 28

constrict afferent arteriole (decrease) | dilate afferent and constrict efferent arteriole (increase)

Question 29

what is the renal portal system (filtration, reabsorption, secretion, excretion)

Answer 29

``` afferent arteriole glomerulus bowman's capsule urinary excretion or continue to efferent arteriole to peritubular capillaries to the renal vein ```

Question 30

how many glomeruli are there

Answer 30

1 million in a kidney | one input via the afferent arteriole and two exits via bowman's capsule or via efferent arterioles

Question 31

what is the glomerular filtration rate

Answer 31

fluid entering all bowman's capsules in ml/min increasing GFR = fluid loss to urine increasing renal blood flow = increases GFR

Question 32

what is hypoxia/ anoxia/ hypoxaemia

Answer 32

insufficient O2 supply to region/ entire body | anoxia (complete deprivation)

Question 33

what causes insufficient O2 in tissues

Answer 33

``` low haemoglobin (anaemia) tissue consumption to much for flow lung - failure of gas exchange/ breathing ```

Question 34

what is ischaemia

Answer 34

insufficient blood flow to a region

Question 35

what causes ischaemia

Answer 35

vessels clogged, constricted or closed insufficient blood volume (eg haemorrhage) heart generates insufficient pressure

Question 36

What is angina pectoris

Answer 36

a symptom chest pain (overexertion of (damaged) heart tissue) with/without physical exertion

Question 37

how can angina pectoris be treated

Answer 37

nitrates for immediate relief | long term as per CHD

Question 38

what causes angina pectoris

Answer 38

ischaemia of the heart tissue due to obstruction/ spasm of coronary artery ultimately may be caused by coronary artery disease/ embolism

Question 39

what is myocardial infarction

Answer 39

death of one region of the heart

Question 40

what are signs of MI

Answer 40

sudden crushing chest pain from occlusion of coronary artery

Question 41

how can MI be treated

Answer 41

immediate reperfusion (morphine, nitrates, aspirin, oxygen)

Question 42

what is heart failure

Answer 42

pumps out insufficient blood resulting from previous MIs

Question 43

what are symptoms of heart failure

Answer 43

fatigue, dysponea, oedema

Question 44

what is shock

Answer 44

critically low perfusion eg haemorrhagic shock | affects cerebral and renal function

Question 45

what is syncope

Answer 45

loss of consciousness due to insufficient blood flow to the brain due to heart failure (shock, arrhythmia)