lecture 3 - cardiovascular physiology

Question 1

where does gas exchange take place?

Answer 1

between the blood and tissues

Question 2

what are the functions of the cv system?

Answer 2

circulate o2 and co2, provides cells with nutrients, removes waste products of metabolism, clotting, regulate body temp, transport hormones, protect body against disease and infection

Question 3

what happens in the heart?

Answer 3

blood flows from the right atrium to the right ventricle - deoxuygenated blood - then pumped to the lungs where it receives o2 - flows into the left atrium to the left ventricle where its then pumped around the body
blood goes from atrium - ventricle, separated by a septum
muscle tissue which allows the heart to contact
atria contracts, blood leaves the ventricles through the pulmonary aorta

Question 4

what blood does the right side of the heart receive?

Answer 4

deoxygenated

Question 5

what blood does the left side of the heart receive?

Answer 5

oxygenated

Question 6

what does the bicuspid valve do?

Answer 6

causes a one way blood flow

Question 7

what does the aortic valve do?

Answer 7

prevents blood flowing back into the heart between contractions

Question 8

what does the superior vena cava do?

Answer 8

transports deoxygenated blood from upper body to right atrium

Question 9

what does the inferior vena cava do?

Answer 9

transports deoxygenated blood from tissues below the heart to the right atrium

Question 10

what are arterioles?

Answer 10

“resistance vessels” containing circular layers of smooth muscle, which can either constrict or relax to regulate blood flow to the periphery which allows redistribution of blood

Question 11

what is blood pressure and what does it do?

Answer 11

cardiac output x total peripheral resistance - propells more blood out and increases output on the arterial walls

Question 12

what is total peripheral resistance?

Answer 12

vessel diameter, vessel length, blood viscosity

Question 13

what does the venus system do?

Answer 13

deoxygenated blood returns to the heart via the superior and inferior vena cava

Question 14

why do arteries have thicker walls than veins?

Answer 14

more difficult for blood to be propelled through veins

Question 15

what is myosin?

Answer 15

has myosin heads which bind to actin and pull it to the middle of the sarcomere which causes it to shorten and causes force to be generated

Question 16

what is cardiac cellular structure and function?

Answer 16

During contraction of a cardiac muscle cell (cardiomyocyte), myosin heads pull actin towards the centre of the sarcomere, generating the force for contraction of the heart

Question 17

what is depolarisation?

Answer 17

excitable cells - heart muscle cells can be activated, measure charge in the interior of the cell, due to diffs in the intracellular and extracellular concentrations of ions
pos ions flow into the cell so that it is less polarised

Question 18

what is repolarisation?

Answer 18

pos ions flow out of the cell

Question 19

what do action potentials mean?

Answer 19

causes an alteration in this permeability, sodium and ca cant enter the cell, permeability of this outcome changes, causes an influx of pos charged ions

Question 20

what does the sinonatrial node do?

Answer 20

Specialised muscle tissue located in the top right of the right atrium which spontaneously depolarises and repolarises, which spreads throughout the right atrium to the atrioventricular node

Question 21

what does the AV node do?

Answer 21

Specialised muscle tissue located near the interatrial septum which receives signals from the SA node and, following a brief delay, transmits them to the ventricles

Question 22

what is step 1?

Answer 22

The SA node transmits a wave a depolarisation which begins to spread across the right and left atria

Question 23

what is step 2?

Answer 23

Depolarisation is complete, and the atria contract, pumping blood into the ventricles.

When the depolarisation reaches the AV node, the impulse is delayed

Question 24

what is step 3?

Answer 24

Ventricular depolarisation begins, traveling through the Bundle of His and onto the right and left ventricles (in orange in the image)

Simultaneously, there is repolarisation (relaxation) of the atria (in red in the image)

Question 25

what is step 4?

Answer 25

Ventricle depolarisation is complete, and ventricles contract.

Question 26

what is step 5?

Answer 26

ventricular repolarisation

Question 27

what is the P wave?

Answer 27

atrial depolarisation

Question 28

what is the QRS wave?

Answer 28

ventricular depolarisation

Question 29

what is the T wave?

Answer 29

ventricular repolarisation

Question 30

what is step 1 of the Wiggers diagram?

Answer 30

atrial depolarisation, which initiates atrial systole

Question 31

what is step 2 of the Wiggers diagram?

Answer 31

With blood leaving the left atrium, the pressure drops to below that of the left ventricle, this causes the mitral/bicuspid valve to close.
- This represents the end of ventricular diastole. The volume of blood remaining in the left ventricle is the end-diastolic volume

Question 32

what is step 3 of the wiggers diagram?

Answer 32

valves remain closed - isovolumetric contraction which causes pressure to rapidly increase

Question 33

what is step 4 of the wiggers diagram?

Answer 33

Once ventricular pressure exceeds aortic pressure, the aortic valve opens and blood leaves the left ventricle.

Question 34

what is step 5 of the wiggers diagram?

Answer 34

With blood leaving the left ventricle, the pressure within the left ventricle eventually drops to below that of the aorta, causing the aortic valve to close.
The volume of blood left in the ventricle following systole is the end systolic volume

Question 34

what is step 6 of the wiggers diagram?

Answer 34

The t-wave represents ventricular repolarisation, causing ventricular diastole.
Pressure within the left ventricle continues to drop, causing it to fall below left atrial pressure, which in turn causes the mitral valve to open

Question 35

what is step 7 of the wiggers diagram?

Answer 35

With the mitral valve open, blood passively flows into the left ventricle from the left atria, causing left ventricular volume to increase

Question 36

what mechanisms regulate cardiac output?

Answer 36

SV, HR

Question 37

what is the preload influence on SV?

Answer 37

ventricles stretched, blood leaves aorta

Question 38

what is the afterload influence on SV?

Answer 38

resistance of lv must overcome to circulate blood through the aorta

Question 39

what do resistance vessels do?

Answer 39

constrict and dilate to alter the amount of blood flow going to each of the things

Question 40

what is the vascular network?

Answer 40

distribution/resistance, exchange, capacitance

Question 41

what is functional anatomy?

Answer 41

an artery can contain smooth muscle and elastin - elastic tissue which gives it this compliance and allows the walls to stretch

Question 42

why do venules and veins have thin walls?

Answer 42

more stretchy so hold more blood

Question 43

what does arterial blood pressure mean?

Answer 43

Blood pressure is the pressure of circulating blood against the walls of blood vessels. In order to maintain blood flow to tissues and organs, blood pressure must be regulated within narrow limits

Question 44

what do baroreceptors do?

Answer 44

detect a decrease in pressure, there is a reduction in the number/frequency of signals sent from the baroreceptors to the cardiovascular control centre in the medulla