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Bioscience 2 > Cardiovascular + Respiratory System 1 > Flashcards

Cardiovascular + Respiratory System 1 Flashcards

1
Q

What is the role of the cardiovascular system?

A

A transport system for getting the right amount of blood to the right place at the right time and back again.

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2
Q

What are 5 key functions of the cardiovascular system?

A
  • rapid transport and distribution of nutrients e.g glucose and O2 and waste products e.g. urea and CO2
  • distribution of water
  • infrastructure of immune system
  • temperature regulation
  • exchange between blood vessels and interestrial fluid
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3
Q

What is the key principle in physiology

A

= homeostasis

–> the maintenance of the internal environment, faced with variation in the external environment, activity and intake of nutrients.

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4
Q

What is the negative feedback loop in homeostasis?

A

= Core mechanism

Controller –> Effector –> Variable –> Receptor

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5
Q

What are the three ways that blood can circulate?

A

Pulmonary circulation –> lungs (lower resistance, lower pressure)

Systemic Circulation –> body (higher restance, higher pressure)

Arterial System and Venous system –> distribution of blood, venous return

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6
Q

Definition of systole:

A

= phase of heartbeat where muscle contracts and pumps blood from chambers into the arteries.

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7
Q

Definition of diastole:

A

= Phase of heartbeat where heart muscle relaxes and allows chambers to fill with blood.

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8
Q

Definition of stroke volume:

A

= how much blood is in the left ventricle each time it contracts

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9
Q

Definition of cardiac output:

A

= amount of blood that leaves the heart in L / min

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10
Q

What does pressure (P) mean?

A

= force per unit area (heart generates a ‘head of pressure’)

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11
Q

What does Resistance (R) mean?

A

how hard it is for flow (Q) to occur

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12
Q

What is normal arterial blood pressure?

A

= systolic / diastolic: very variable

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13
Q

What is the controlled variable in the Central Nervous System (CNS)

A

= mean arterial pressure

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14
Q

What is myocardium?

A

= heart muscle

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15
Q

What is endocardium?

A

The innermost layer of the heart. It lines the chambers and extends over structures such as the valves.

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16
Q

What is epicardium?

A

The outermost layer of the heart.

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17
Q

What is pericardium?

A

a fibrous sac that encloses the heart and great vessels.

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18
Q

What muscle is the heart made up of?

A

Cardiac (striated) muscle

19
Q

What is annulus fibrousus?

A

a fibrocartilaginous tissue consisting of layers of lamellae with highly cross linked collagen fibrils.

20
Q

What is the structure of the Atria?

A
  • thin walled (compared to ventricles)
  • Located above the ventricles
  • receive venous blood
  • right atrium receives systemic venous blood
  • left atrium receives oxygenated venous blood
21
Q

What is the function of the Atria?

A

acts a a pump to fill or ‘prime’ ventricles at low pressures

produces the hormone atrial natriuretic peptide (ANP)

22
Q

What is the function of ventricles?

A

eject blood into the arterial systems including the lungs

Left ventricle has a thicker wall than the right ventricle which helps generate higher pressure - blood to systemic circulation

23
Q

What initiates the heartbeat?

A

the sinoatrial node (SAN)

24
Q

What is the sinoatrial node (SAN)

A

the physiological pacemaker

25
Q

How does the sinoatrial node (SAN) function?

A

excitable cells generate action potentials

automaticity - (spontaneous)
rhythmicity - (regular)

dominance over other potential pacemakers

Causes cardiac muscle contraction

26
Q

What is the electrophysiology of the Sinoatrial node (SAN) ?

A

Several ion currents are involved

No ‘fast’ outward sodium currents

Unstable resting membrane potential

27
Q

How is a heart contraction stimulated by the sinoatrial node (SAN) ?

A

SAN sends signals to AVN
Signals sent to bundle of His
Travel down left and right bundle branches to purkinje fibres
Cause heart muscle to contract.

28
Q

What is the resting membrane potential of the heart (myocardial cell)?

A

~ 90 mV

29
Q

What are the components of an ECG and what do they mean?

A

P wave - atrial depolarisation
QRS complex (<0.10s) - Ventricular depolarisation
T wave - Ventricular repolarisation (some cells still depolarised)
PR interval (0.12 - 0.2s) - Atrioventricular conduction
QT interval (QTc < 0.44s) - Duration of ventricular activation

30
Q

What is cardiac output?

A

the volume of blood ejected from the heart per minute

31
Q

What is the equation for cardiac output?

A

Cardiac output = heart rate x stroke volume

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

resting adult ~ 5 L/min
exercising adult ~ 20 L/min

32
Q

What system controls the heart and blood vessels?

A

The Autonomic Nervous System

33
Q

What controls the heart rate?

A

Parasympathetic nerves
Vagus nerve
Sympathetic nerves

34
Q

What is the difference between a normal and intrinsic heart rate?

A
  • at rest both parasympathetic and sympathetic systems are active
  • pharmacological block of both systems causes a 50% increase in heart rate. At rest the parasympathetic effects are dominant.
35
Q

What is the heart rate known a tachycardia and bradycardia?

A

tachycardia = >100/min

bradycardia = < 60 /min

36
Q

What is the mean arterial pressure? (MAP)

A

the average blood pressure of the tissues that the heart has perfused blood to

37
Q

What is the equation for Mean Arterial Pressure?

A

MAP = (CO x TPR) + CVP

TPR is the total peripheral resistance
CVP (central venous pressure) is very small (often ignored in the calculation)

38
Q

What is the key controlled variable via cardiac output?

A

Blood pressure

39
Q

What happens when blood pressure is too low or too high?

A

Too low blood pressure = poor perfusion e.g lack of blood to brain when you stand up

Too high bp = excessive afterload on heart and excessive pressure at small vessels in tissues - loss of fluid to tissue e.g. legs and lungs

40
Q

What is the controlled variable for blood pressure?

A

Mean arterial pressure

Blood Pressure is critical for correct perfustion

41
Q

What do baroreceptors measure?

A

Mean Arterial Pressure

42
Q

What would happen if a sudden fall in blood pressure was detected?

A
  • arterial pressure => - MAP => Baroreceptor firing –> - –> CNS –> + sympathetic TPR –> parasympathetic + –> CO
43
Q

Why do arterioles change diameter (volume) ?

A

arterioles are the ‘taps’ of tissue perfusion
respond to local tissue factors
innervated by sympathetic system (alpha receptors)

= Vasoconstriction
= Vasodilation —> bring about changes in TPR

Bioscience 2 (21 decks)

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