Cardiovascular System

Question 1

Cardiac cycle

Answer 1

• Mechanical and electrical events that happen in 1 heart beat
• Diastole: relaxation - fill with blood and twice as long as systole
• Systole: contraction

Question 2

Heart rate regulation

Answer 2

Intrinsic:

• Spontaneous rhythmicity: Special heart cells generate and spread electrical signals
• SA node: pacemaker of heart
• AV node: delay to fill ventricles
• AV bundle: continues the stimulus
• Purkinje fibers: spread impulse rapidly through ventricles
• Intrinsic HR - 100 bpm

Extrinsic:
- Autonomic nervous system (sympathetic and parasympathetic ) and hormonal control

• Parasympathetic system controls heart rate at rest

Question 3

HR values

Answer 3

Rest: 60 to 100 bpm Exercise: Max 200 bpm Maximal heart rate: the max heart rate the heart can beat at. Impacted by age. 220-age= MAX HR

Question 4

Answer 4

Loose electrode

• Characterized by scribbles without distinguishable waves

Question 5

Answer 5

Atrial fibrillation

• Characterized by fluttering of P wave

Question 6

Answer 6

Ventricular fibrillation

• Characterized by small waves, no QRS

Question 7

Answer 7

Sinus/Normal rhythm

Question 8

Answer 8

Myocardial infarction

• Characterized by unfinished QRS

Question 9

Answer 9

Cardiac arrest/death

• Characterized by no waves

Question 10

Arrhythmias

Answer 10

Extrasystoles: extra beats

Premature atrial contraction (PAC): parts of the atria become prematurely electrically active and depolarization spontaneously prior to S-A node excitation

Premature ventricular contraction (PVC): premature excitation of ventricles. Ventricular fibrillation

Question 11

Fick’s Equation

Answer 11

VO₂ = Q (AO₂-VO₂)

AO2 = arterial oxygen

VO2 = venous O2

Importance: blood flow to an organ can be calculated and be diverted to active muscles

Question 12

Blood Pressure Responses

Answer 12

- Resting cardiac output: 5L/min

• Steady-state exercise: increases systolic pressure in first few mins and then levels off
• Resistance exercise: increases blood pressure dramatically
• Rest: 120/80 mmHg
• Endurance: 175/80 mmHg
• Bicep curl: 240/160 mmHg

- Leg press: 280/180 mmHg

Question 13

Stroke Volume

Answer 13

- Volume of blood pumped in one heartbeat

• Equation : EDV - ESV = SV
• Exercise increases stroke volume
• Training adaptation increases blood volume and reduces resistance to blood flow in peripheral tissues.
• Rest: 50-70 ml/beat
• Exercise: 110-130 ml/beat
• Elite athletes have higher amounts so that their heart can beat less often

Question 14

Frank Starling Mechanism

Answer 14

- SV increases in response to increased volume of blood in the heart

- Increased volume of blood stretches ventricular walls causing a more forceful contraction

Question 15

Cardiac Output

Answer 15

- Volume of blood pumped per minute

• total blood volume circulated about once every minute

- Equation: Q= HR x SV

• in L/min

- Resting - 4.2 - 5.6 L/min

• Increases with exercise
• Increases through endurance training due to increase in SV
• HR and SV are the factors that impact cardiac output

Question 16

Poiseuille’s Law

Answer 16

Flow = (pressure gradient x vessel radius) / (vessel length x fluid viscosity)

Question 17

Blood distribution

Answer 17

• Flows where its needed most (regions of increased metabolism; stomach after eating; peripheral for heat)

- Rest: Liver and kidneys 50% and muscles 20%

• Heavy exercise: skeletal muscle 80% due to vasodilatioin and liver and kidneys very little due to vasoconstriction

Question 18

3 mechanisms that facilitate blood flow back to the heart

Answer 18

1. 1-way venous valves - prevent backflow
2. Muscle pump - smooth muscle squeezes
3. Respiratory pump - changes in pressure

Question 19

Functions of blood

Answer 19

1. Transport
2. Temp regulation
3. Acid base balance

Question 20

Components of blood

Answer 20

• Whole blood: 55-60% plasma (mostly water, some protein) + 40-45% formed elements
• Formed elements: RBC; WBC; platelets
• Volume decreases 10% with dehydration
• Volume increases 10% with training
• Hematocrit: % of total blood volume composed of formed elements

Question 21

Blood doping

Answer 21

• Intravenous infusion of blood to increase blood’s oxygen carrying capacity
• Homologous: from donor
• Autologous: from self
• Benefits: increased lactate threshold, RBC count, endurance performance, VO2 max

Question 22

Regulation factors of blood flow during exercise

Answer 22

1. Local: increased temp, CO2, acidity
2. Neural: sympathetic and parasympathetic - overrides local factors
3. Hormonal - Epi and Norepi - constricts everywhere but muscles