W18 Cardiorespiratory system

Question 1

Define:

• cardiac output
• stroke volume

How are they measured?
What is the normal value for each?

Answer 1

Cardiac output: Rate of blood leaving heart into systemic circulation, measured in lit/min (normal ~5l)

Stroke volume: the volume of blood leaving the heart every time it beats, measured in ml (normal is ~60ml)

Question 2

What happens in
- systole
-diastole
?

Answer 2

Systole: ventricles contract, blood leaves the heart via the aorta into systemic circulation

Diastole: heart fills with blood from the venous system

Question 3

Define:

• heart rate
• blood pressure

How are they measured?
What is the normal value for each?

Answer 3

Heart rate: how many times the heart contracts per minute, measured in bpm (normal ~70)

Blood pressure: self explanatory, normal 120/80 mmHg (systolic/diastolic)

Question 4

Heart rate: how many times the heart contracts per minute, measured in bpm (normal ~70)

Blood pressure: self explanatory, normal 120/80 mmHg (systolic/diastolic)

Answer 4

Diastole: the heart relaxes, atria is filled with blood, AV-valves open and blood flows into ventricles, pumped put thorugh the aorta (systemic circ) and pulmonary vein (to lungs)

Question 5

What is the Mean Arterial Pressure?
How is it calculated?
Which is a controlled variable, which is an effector?

Answer 5

The mean pressure of all arteries and veins
MAP = CO x TPR
(cardiac output x total peripheral resistance)

MAP - controlled
TPR - effector

Question 6

What is the annulus fibrosus?

Why is it important?

Answer 6

Insulating tissue between atria and ventricles (incl. valves). Important because it doesn’t conduct electricity hence allows the action potential to travel through the heart properly.

Question 7

How do you calculate cardiac output?

Answer 7

CO = heart rate X stroke volume

Question 8

What happens if your BP si too low?

Too high?

Answer 8

Perfusion - lac of blood to the brain = fianting

Excessive pressure - on small blood vessels = loss of fluid to tissues and lungs = swelling in extremitiesW

Question 9

Blood pressure is a _____ variable and TPR is an ______ mechanisms which can be changed

Answer 9

controlled variable

effector mechanism

Question 10

What are the receptors called detecting BP? Where are they detected?

Answer 10

Baroreceptors

in CNS

Question 11

What is it called when blood vessels contract?
Expand?
Which variable do they affect?

Answer 11

Vasorestriction
Vasodilation
They affect the TPR

Question 12

Describe the different parts of an ECG representing a cardiac cycle

Answer 12

R-R = one cardiac cycle
P wave = atrial depolarisation (contraction)
QRS complex = ventricular depolarisation (contraction)
PR interval = AV conduction (action potential down fibres)
T wave = Ventricular repolarisation (relaxes)

Question 13

Which part of the nervous system controls the cardiovascular systmem?

Answer 13

Autonomic , para + sympa

Question 14

What are the 2 main functions of the respiratory system?

Answer 14

Gas exchange

Ventilation of the lungs

Question 15

What is dead space?

Answer 15

A collapsed alveolus that has no blood supply OR is fluid filled (pneumonia)
hence CANNOT facilitate gas exchange

Question 16

Gas exchange occurs between alveoli and the blood due to the ____ _____ between the air in the lungs and gases in the blood

Answer 16

concentration gradient

Question 17

What is the chloride shift, what happens during it?

Answer 17

CO2 + H20 -> H + HCO3-

That acidic bicarbonate is swapped for a chlorine and removed from the blood :)

Question 18

How does the blood detect a change in pH?

Answer 18

Chemoreceptors!

Question 19

What are the effects of exercise on the cardio-respiratory system?

Answer 19

Increase in blood flow due
Vasodilation
Increase in ventilation and oxygen consumption
A vasodilator: nitric oxide