circulatory systems

Question 1

What are functions of a circulatory system?

Answer 1

distribution of nutrients, support for metabolism, distribution of water and electrolytes, transportation of hormones

Question 2

What re the two types of circulatory system?

Answer 2

open and closed

Question 3

What are features of open systems?

Answer 3

fluid is open to body cavities and cells, lower pressure system, less efficient, incomplete system of vessels, haemolymph flows around the body

Question 4

What system do insects use?

Answer 4

open - they have a tracheal system to transport nutrients and CO2

Question 5

What are features of a close system?

Answer 5

complete system of blood vessels, intercellular spaces filled with interstitial fluid, lymph in lymphatic vessels

Question 6

What are requirements of an efficient circulation system?

Answer 6

efficient O2 carriers in blood, efficient gas exchange in respiratory system, efficient delivery of nutrients and O2, efficient gas exchange in tissues

Question 7

What is flow rate equation?

Answer 7

flow rate = ΔP/R

Question 8

What do P and R stand for?

Answer 8

P = driving force R = resistance

Question 9

What is the equation for R?

Answer 9

R = 8ηL/πr^4

Question 10

What is the ΔP and R in a closed system?

Answer 10

ΔP is high and R is high

Question 11

What is cardiac output?

Answer 11

the total volume of blood pumped by the heart in one minute

Question 12

What is the cardiac output equation + units?

Answer 12

CO (L/min) = HR (bpm) x SV (L/beat)

Question 13

What can we use to investigate cardiac function?

Answer 13

ultrasound, ECG, MRI, electrode monitoring

Question 14

How does the heart generate its own rhythm?

Answer 14

pacemaker cells set the pace of the heart rate and generate action potentials which are conducted around the rest of the heart

Question 15

On an ECG what do the P wave, QRS complex, and T wave correspond to?

Answer 15

P wave = atrial depolarisation. QRS = ventricular depolarisation. T wave = ventricular repolarisation

Question 16

What happens in the PR interval?

Answer 16

conduction of the AV node

Question 17

What is heart rate modified by?

Answer 17

autonomic nervous system and circulation hormones

Question 18

What cells make the heart contract?

Answer 18

cardiac myocytes

Question 19

What happens during EC coupling in cardiac myocytes?

Answer 19

an action potential occurs and calcium channels open and enter cell. causes more calcium ions to be released into the cardiac muscles so the calcium can bind to myofilaments and allow shortening of muscles to occur

Question 20

What are the phases of the cardiac cycle?

Answer 20

systole - contraction and ejection of blood. diastole - relaxation and filling

Question 21

What are the events of the cardiac cycle?

Answer 21

1. Atrial systole (ventricular diastole)
2. Isovolumic contraction of the ventricles (ventricular systole)
3. Ventricular ejection
4. Isovolumic relaxation of the ventricles
5. Passive ventricular refilling

Question 22

What is Starling’s law?

Answer 22

increased ventricular filling causes an increase in the forces of contraction of the ventricular muscle

Question 23

Where is in the heart?

Answer 23

in the chest cavity, behind the sternum. on top of the diaphragm and is between the lungs

Question 24

Why is the left lung smaller than the right lung?

Answer 24

the heart bulges into the left side

Question 25

What is the pericardium?

Answer 25

fibrous bag around the heart - serous (visceral and parietal) and fibrous

Question 26

What does the serous pericardium contain?

Answer 26

lubricating fluid

Question 27

What is the function of the pericardium?

Answer 27

free movement

Question 28

Which pericardium prevents the heart from over expansion?

Answer 28

fibrous pericardium

Question 29

What is the visceral layer attached to?

Answer 29

the heart

Question 30

What do the coronary arteries split into?

Answer 30

smaller vessels - anastomoses

Question 31

What is bypass surgery?

Answer 31

when the coronary arteries become blocked - harvest veins from lower leg and sew them in the aorta and coronary artery

Question 32

What are the heart chambers lined with?

Answer 32

the endocardium

Question 33

Where is the tricuspid valve?

Answer 33

between right atrium and ventricle

Question 34

What is the foramen ovale?

Answer 34

site of a flap-like valve between R and L atria

Question 35

Why was the foramen ovale needed?

Answer 35

in the foetus blood O2/CO2 exchange occurred in the placenta. therefore, most blood bypassed the lungs by going through the foramen ovale

Question 36

Where was the ductus arteriosus?

Answer 36

between pulmonary trunk and aorta

Question 37

When does the foramen ovale close?

Answer 37

closes when baby takes first breath and then seals permanently

Question 38

What is another name for the bicuspid valve?

Answer 38

mitral valve

Question 39

What do the chorda tendinae do?

Answer 39

prevent valves inverting

Question 40

What are the three layers of the heart?

Answer 40

endocardium (lining), myocardium (muscle layer), epicardium (visceral pericardium)

Question 41

What is the structure of the endocardium?

Answer 41

appears ridged (trabeculae carnae) - underlying bundes of muscle fibres. made up of endothelium + underlying connective tissues

Question 42

What makes up the myocardium?

Answer 42

cardiac muscle fibres + connective tissue

Question 43

What are the three types of cell-cell junctions that link the heart muscle cells?

Answer 43

adherens junction links the actin cytoskeleton, desmosomes link intermediate filaments, gap junctions link cytosol

Question 44

What are the components of blood vessels?

Answer 44

endothelium, smooth muscle, connective tissue

Question 45

What does the endothelium do?

Answer 45

allows transfer between vessels and surroundings, keeps blood in system

Question 46

What are the endothelium cells like?

Answer 46

thin and flat

Question 47

What is the junctional complex?

Answer 47

bridge between cells

Question 48

What are the three layers of blood vessels?

Answer 48

tunica intima, tunica media, tunica adventitia

Question 49

What makes up the tunica intima?

Answer 49

endothelium + connective tissue

Question 50

What makes up the tunica media?

Answer 50

smooth muscle and connective tissue

Question 51

What makes up the tunica adventitia?

Answer 51

connective tissue

Question 52

What surrounds the tunica media?

Answer 52

external elastic lamina

Question 53

What surrounds the tunica intima?

Answer 53

internal elastic lamina

Question 54

What is the arrangement of smooth muscle?

Answer 54

circular

Question 55

What are vasa vasora?

Answer 55

little blood vessels in the walls of large arteries

Question 56

What controls blood flow to capillary beds?

Answer 56

terminal arterioles

Question 57

What are the three types of endothelium?

Answer 57

continuous (in most capillaries), fenestrated (in endocrine glands - exchanges hormones), discontinuous (found in sinusoids - exchanges whole cells)

Question 58

What does the walls of a vein contain?

Answer 58

small tunica media, substantial tunica adventitia

Question 59

What are valves?

Answer 59

folds on tunica intima for one way flow

Question 60

What is blood pressure?

Answer 60

difference between pressure in the system and the ambient pressure (surrounding air, gas or liquid)

Question 61

What are two components of blood or haemolymph pressure?

Answer 61

dynamic pressure produced by the pump, hydrostatic pressure of the fluid

Question 62

What do changes in smooth muscle tone lead to?

Answer 62

vasoconstriction (higher resistance) and vasodilation (lower resistance)

Question 63

What can smooth muscle tone be altered by extrinsically?

Answer 63

neurotransmitters, hormones

Question 64

What can smooth muscle be altered by intrinsically?

Answer 64

endothelium-derived substances, metabolites, other locally-produced factors

Question 65

What is total fluid energy?

Answer 65

potential energy acquired from the beating of the heart, kinetic energy of the fluid itself, potential energy of the fluid that it possesses because of its position in the gravitational field

Question 66

What is the effect of gravity above the heart?

Answer 66

arteriole pressure increases with height