Cardiovascular System

Question 1

Circulation time

Answer 1

Time for a drop to pass: R atrium -> pulmonary circulation -> L atrium -> systemic circulation -> R atrium

At rest = 1 min

Question 2

Pericardium

Answer 2

Doubled walled sac enclosing the heart

Isolate + give room for expansion, resists compression

Visceral - covers heart
Outer = parietal pericardium

Pericadial cavity - with fluid, lubricates beat without friction

Question 3

Cardiac tamponade

Answer 3

=compression of heart by abnormal accumulation of fluid on pericardial cavity

Pericarditis - viral infection, cancer

Question 4

Heart wall

3 layers

Answer 4

1. Outer = epicardium
   - visceral pericardium
2. Middle = myocardium
   - thickest layer, cardiac muscle
3. Inner = endocardium
   - next to blood, forms inner lining of chamber

Question 5

Fibrous skeleton
surrounds…
prevents…
…

Answer 5

Dense connective tissue of heart
Surrounds valves
Prevents outstretching of valves
Electrical insulator

Question 6

Right atrium

Receives blood from:

Answer 6

3 veins

• superior vena cava
• inferior vena cava
• coronary sinus

Question 7

Interatrial septum/wall
Separates….
Small depression…

Answer 7

Seperates RA and LA

Has small depression (fossa ovalis)
- remnant of foetal opening

Question 8

Fossa ovalis - after birth

Answer 8

Allows blood flow RA -> LA to bypass pulmonary circulation

Normally closes after birth
- if fails = patent foramen ovale

Question 9

Blood flow through heart

Answer 9

3 veins -> RA -(tricuspid valve)> RV -(S.L valve)> pulmonary trunk -> L + R pulmonary arteries

4 pulmonary veins -> LA - (AV valve)> LV -(S.L valve)> aorta -> coronary arteries + arch of aorta

Question 10

Valves
Prevent….
2 types…

Answer 10

Prevent backflow/ensure 1-way flow

AV valves - chordae tendinea, papillary muscle

SL valves - pocket-like cusps

Question 11

Coronary circulation
Supply….
Uses….
Arteries…

Answer 11

Hearts own blood vessels
Supply nutrients to heart tissue
Uses 5% circulating blood
Arteries encircle heart

Question 12

Myocardial infarction
Cause…
Solved by..

Answer 12

Fatty deposit or blood clot

Sudden death of patch of tissue - deprived of blood flow

Heart bypass - reroute blood using vein graft

Question 13

Anastomoses

Answer 13

Union of 2< arteries/veins supplying same region
Defence for MI
Alternative route if blockage

Question 14

Conduction system

APs

Answer 14

1. SA node
2. AV node
3. AV bundle (His)
4. R+L bundle branches
5. Purkinjie fibres
   Specific location

Various hormones can increase or decrease pace of heart

Question 15

Ectopic pacemaker site

Answer 15

Excitable cells cause premature heartbeat outside normally functioning SA node

Extra beats or pace heart

Triggers - caffeine, electrolyte imbalance, hypoxia, drugs

Question 16

Artificial pacemaker implanted

Answer 16

If bundle of His/R+L bundle/Purkinjie fibres initiates AP
Slow AP
Only creates 20-40bpm

Question 17

Contraction: ventricular AP

Answer 17

1. Rapid depolarisation
2. Contraction/plateau
3. Repolarisation

Question 18

Refractory period

Answer 18

= time interval when 2nd contraction cannot be triggered

Longer than contraction itself

Question 19

Ventricular AP

Membrane permeability changes

Answer 19

Due to voltage-gated ion channels
Cells at rest: inside - and outside +

Depolarisation = inside +
Repolarisation = inside -

Question 20

ECG

Answer 20

Recording of electrical changes + AP propagation detected at body surface
Electrodes: arms, legs, 6x heart
Produces 12 different tracings

Determine
- abnormal conduction pathway, heart enlarged, damaged regions

Question 21

P wave

Answer 21

Atrial depolarisation/contraction

Question 22

QRS complex

Answer 22

Ventricular depolarisation/contraction

Question 23

T wave

Answer 23

Ventricular repolarisation (before relaxation)

Question 24

Abnormalities of heart beat

Answer 24

Large P = enlarged atrium
Large Q = MI
Large R = enlarged ventricles
Flat T = insufficient 02
Long P-Q interval = scar tissue

Question 25

Long Q-T syndrome

Answer 25

Rare, genetic Repolarisation abnormality Prone to very rapid heartbeats => poor supply to brain Treatment - b-blockers, defibrillator

Question 26

Arrhythmia

Answer 26

Irregular heart rhythm defect in conduction system of heart Causes - anxiety, drugs, hyperthyroidism Heart blocker Atrial flutter Atrial fibrillation Ventricular fibrillation

Question 27

Cardiac cycle

Answer 27

All events associated with 1 heartbeat ``` systole = contract Diastole = relax ```

Question 28

Cardiac cycle | 3 phases

Answer 28

1. Relaxation period occurs after T-wave 2. After P-wave 3. After QRS

Question 29

Cardiac cycle | Divisions

Answer 29

1. Atrial systole 2. Early ventricular systole 3. Late ventricular systole 4. Early ventricular diastole 5. Late ventricular diastole

Question 30

Heart sounds

Answer 30

From blood turbulence caused by closing of heart valves ``` S1= lubb = louder,longer, AV closing S2= dup = quieter, shorter, SL closing ```

Question 31

Heart murmurs

Answer 31

Abnormal sounds | Indicate valve disorder

Question 32

Cardiac output

Answer 32

= volume blood ejected from L/R ventricle into aorta each min = stroke vol x heart rate

Question 33

Cardiac reserve

Answer 33

Ratio between max cardiac output and rest cardiac output

Question 34

Regulation of stroke volume

Answer 34

Preload = degree of stretch Contractility = forcefulness of contraction of individual ventricular muscle fibres After load = pressure to exceed to eject ventricular blood

Question 35

Regulation of heart rate

Answer 35

1. Autonomic NS; increased depolarisation SA node increases HR 2. Chemical; hormones, ions 3. Other factors; age, gender, body temp

Question 36

Shock

Answer 36

Failure of CV system to deliver enough O2 + nutrients to meet cellular metabolic needs Cells aerobic -> anaerobic => lactic acid -> organ failure

Question 37

Types of shock (4)

Answer 37

1. Hypovolumic - decreased blood vol, diabetes 2. Cardiogenic - poor heart function 3. Vascular - blood vessels dilate 4. Obstructive - block blood flow

Question 38

Homeostatic response to shock

Answer 38

1. Activation of renin-angiotensin-aldosterone system so increased blood vol + BP 2. ADH secretion; increases blood vol + BP 3. Activation of sympathetic ANS; E and norE 4. Release of local vasodilators

Question 39

Pulse

Answer 39

Heart rate ``` Tachycardia = rapid resting pulse Bradycardia = slow resting pulse ```

Question 40

Blood pressure

Answer 40

120/80 | = hydrostatic pressure exerted by blood on walls of vessels

Question 41

Blood flow

Answer 41

From high to low pressure Resistance = friction between blood vessel walls + blood Pumps to boost venous return - heart, skeletal muscle, valves Low o2 - systemic circ DILATE - pulmonary circ CONSTRICT

Question 42

Capillary exchange

Answer 42

Movement by - diffusion - transcytosis - bulk flow