Week 3 - cardiovascular 1

Question 1

ventricular structure

Answer 1

Right ventricle:
- supports short, low pressure pulmonary circ. → thinner wall, weaker pump, crescent shaped

Left ventricle:
- support high resistance systemic circuit →3x thicker wall, circular cavity, powerful pump - more pressure

Question 2

pulmonary

Answer 2

Right side of the heart, receives deoxygenated blood and pumps to lungs for gas exchanged.
- oxygenated blood returns to left of heart

Question 3

systemic

Answer 3

left side of the heart receives oxygenated blood from the lungs and pumps to body.
- deoxygenated blood returns to right of heart

Question 4

energy required

Answer 4

FATIGUE RESISTANT

• depends on AEROBIC RESPIRATION to make ATP →process of producing cellular energy by oxygen, rich in myoglobin (stored oxygen) & glycogen (stored glucose) while MITOCHONDRIA TAKES UP 30% of CELL VOL
• adaptable to all organic fuels, fatty acid(60%), glucose(35%), lactic acid & amino acid (5%)
• vunerale to oxygen deficiency → MYOCARDIAL INFARCTION

Question 5

cardiac muscle

Answer 5

cells are striated due to organised myofibrils
features:
- since, centrally located nucleus
- short, branched cells, specialised intercellular connections INTERCALATED DISCS

Question 6

Contractile Cell AP

Answer 6

CONTRACTICE CELL (99%) of cardiac muscle
- cardciac muscle cell contractions last longer than skeletal muscle cells due to the long refractory period (200-250m sec)

AP generated by:

• a neuron
• nearby cardiac muscle cell
• myogenic activity (specialised cardiomyocyte)
• cells can generate an AP themselves

Question 7

autonomic regulation

Answer 7

neurol control of heart comes from cardiovascular centre in medulla oblongata (brainstem) through ANS

SYMPATHETIC IMPULSES (FIGHT OR FLIGHT)
- though symp. chain~ cardiac plexus
- inc HR & force of contraction
- inc HR up to 230bpm
PARASYMPATHETIC IMPULSE (REST & RIGEST)
- through vagus nerve (10) 
- dec. HR & force of contraction
- sets HR at rest 70-80 bpm

Question 8

conduction system - sinoatrial node

Answer 8

• pacemaker, initiates heartbeat, sets HR, situated in right atrium, spread throughout atria

Question 9

conduction system - atrioventricular node

Answer 9

• electrical gateway to ventricles, located near right AV valve

Question 10

conduction system - AV bundle

Answer 10

• pathway for signals from AV node → right and left bindle branches divisions of AV bundle that enter interventricular septum

Question 11

Conduction system - perkinke fibres

Answer 11

• upwards from apex spreaj in ventricular myocardium, nerve like, distribute electrical signals

Question 12

Pacemaker cells

Answer 12

• make up 1% of total no. of cardiac muscle cells
• located in sinoatrial node
• responsible for rhythmic, spontaneous depolarisation →RHYTMIC CONTRACTION
• control rate of contraction of heart

Question 13

CV functions

Answer 13

TRANSPORT: O2, CO2, nutrients, metabolic waste, hormones, medication
PROTECTION: WBC, antibodies, platelets
REGULATION: pH, composition of intracellular fluid, temp

Question 14

Heart rate - affecting factors

Answer 14

• hormones: adrenaline & thyroid
• ions in blood: Na+, K+ & Ca2+
• age, gender + temperature
• physical fitness

Question 15

autonomic regulation - input and output

Answer 15

input to cardiovascular centre : from cerebral cortex, limbic sys. & hypothalamus
from sensory receptors:
- Proprioceptors: movement
- chemoreceptors: blood chem
- baro receptors: bP

Question 16

Cardiac cycle

Answer 16

1. all 4 chambers relaxed
2. arteriole systole (o.1 sec)
   - contracting atria fill relaxed ventricles w/ blood
   - heart sound S4 (rarely heard in adults)
3. atriole dystole (last until start of next cycle)
4. ventricular systole - 1st phase= isovolumetric contraction
   - contractive ventricles close AV valves but not enough pressure to open semilunar valves
   - hear sound S1 (lubb) heard when AV valves close
5. ventricular systole -2nd phase: ventricular ejection
   - as ventricular pressure rises, semilunar valves open & blood leaves ventricle
6. ventricular distole - early phase
   - ventricles relax & blood pressure dops & allows closure, S2 (dubb) - heard when semilunar valves vlose
7. ventricular diastole - isovolumetric relaxation
   - Av valves still colsed
   - ventricular diastole : late phase
   - all chambers relax, AV valve open, ventricles fill to 70%