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Foundation to Bioscience 2 > Cardiorespiratory system > Flashcards

Cardiorespiratory system Flashcards

1
Q

What is homeostasis?

A

Homeostasis is the property of a system in which a variable is actively regulated to remain nearly constant. In the body it is the maintenance of the internal environment, faced with variation in the external environment, activity, and intake of nutrients

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2
Q

How is homeostasis maintained in the body?

A

The core mechanism is a negative feedback loop

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3
Q

What are the functions of the cardiovascular system?

A

Rapid transport & distribution of nutrients and waste products
Distribution of water, electrolytes & hormones
Exchange between blood vessels and interstitial fluid
Infrastructure of immune system
Temperature regulation

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4
Q

What is pulmonary circulation?

A

Blood going to the lungs under low resistance and pressure

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5
Q

What is systemic circulation?

A

Blood going to the rest of the body under high resistance and pressure

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6
Q

What is the arterial system?

A

Blood flowing away from the heat in arteries under high pressure

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7
Q

Why is venous return important?

A

The heart can only pump out blood that comes back

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8
Q

Define systolic blood pressure

A

Blood pressure when the heart contracts

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9
Q

Define diastolic blood pressure

A

Resting blood pressure when the heart isn’t contracting

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10
Q

Describe the atria

A

Thin-walled (compare with ventricles)
Receive venous blood (reservoir function)
Right atrium receives systemic venous blood, left atrium receives oxygenated venous blood
Act as pumps to fill ventricles at low pressures
Produce the hormone atrial natriuretic peptide (ANP)

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11
Q

Describe the ventricles

A

Eject blood into the arterial systems including to lungs
Left ventricle has a thicker wall than the right ventricle and generates higher pressures – blood to systemic circulation

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12
Q

What structure within the heart initiates the beat?

A

The sinoatrial node. It’s the physiological pacemaker, maintaining the heart’s rhythmicity.

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13
Q

What does the P wave of an ECG correspond to?

A

Atrial depolarisation

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14
Q

What does the QRS complex of an ECG correspond to?

A

Ventricular depolarisation

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15
Q

What does the T wave of an ECG correspond to?

A

Ventricular repolarisation

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16
Q

What does the PR interval of an ECG correspond to?

A

Atrioventricular conduction

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17
Q

What does the QT interval of an ECG correspond to?

A

Duration of ventricular activation

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18
Q

Define tachycardia

A

A fast resting heart rate (>100 bpm)

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19
Q

Define bradycardia

A

A slow resting heart rate (<60 bpm)

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20
Q

Cardiac output =

A

heart rate X stroke volume

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21
Q

What does cardiac output measure?

A

The volume of blood ejected from the heart per minute (litres per minute)

22
Q

What is stroke volume?

A

The volume of blood pumped from the left ventricle per beat.

23
Q

What factors influence stroke volume?

A

Intrinsic factors: preload (the initial stretching of the cardiomyocytes prior to contraction), afterload (the pressure against which the heart must work to eject blood during systole)
Extrinsic factor: contractility (via nerve input)

24
Q

Starling’s law of the heart

A

The energy of contraction of a cardiac muscle fibre, like that of a skeletal muscle fibre, is proportional to the fibre length at rest.

25
Q

Define the term ‘mean arterial pressure’

A

Average blood pressure at the tissues

26
Q

Mean arterial pressure=

A

(Cardiac output x total peripheral resistance) + central venous pressure

27
Q

Why is controlling blood pressure important?

A

BP too low: poor perfusion e.g. lack of blood to brain on standing up
BP too high: excessive pressure at the small vessels in tissues, loss of fluid to tissue; excessive afterload on heart

28
Q

What are the functions of the respiratory system?

A

Inhalation and exhalation

Exchange of gases between the lungs and the blood, and between the blood and body tissues

29
Q

What does respiration refer to?

A

All the processes involved in the exchange of O2 and CO2 between the cells and the external environment

30
Q

Regulatory mechanisms for the respiratory system ensure that…

A

Ventilation of the lungs is matched with its blood supply (perfusion)
The O2 supply and CO2 removal vary appropriately with activity eg. in exercise
The regulation of respiration another example of homeostasis

31
Q

Why do mammalian lungs have a large surface area?

A

Increased area for diffusion, making gas exchange efficient

32
Q

Describe the process of respiration

A

Ventilation –> gas exchange in the lungs –> gas exchange between capillaries and tissues –> metabolism –> bulk transport via circulation

33
Q

Pressure of a system=

A

The sum of the separate (partial) pressures that each gas would exert if it alone occupied the entire volume

34
Q

Define the term ‘physiological dead space’

A

The volume of air which is inhaled that does not take part in the gas exchange

35
Q

Why does some of the air inhaled not take part in gaseous exchange?

A

It remains in the conducting airways, or reaches alveoli that are not perfused or poorly perfused.

36
Q

What is anatomical dead space?

A

The portion of the airways (such as the mouth and trachea to the bronchioles) which conducts gas to the alveoli. No gas exchange is possible in these spaces.

37
Q

What is alveolar dead space?

A

Alveoli which have little or no blood flowing through their adjacent pulmonary capillaries, i.e., alveoli that are ventilated but not perfused, and where, as a result, no gas exchange can occur

38
Q

Which substances is blood specialised to transport?

A

Oxygen and carbon dioxide

39
Q

Give the equilibrium of carbon dioxide and bicarbonate in the blood

A

CO2 + H2O ⇌ H2CO3 ⇌ H+ + (HCO3)-

40
Q

Why does the formation of bicarbonate never get to equilibrium?

A

It never goes to equilibrium because the products are removed by two mechanisms:

1) chloride/ bicarbonate exchange (‘chloride shift’)
2) H+ buffering by haemoglobin

41
Q

Why is it important to regulate [CO2] in the blood?

A

If [CO2] gets too high, it could lead to the blood becoming too acidic. If the blood pH drops below 7.2, then very soon the brain won’t be able to function normally

42
Q

What is hyperventilation?

A

An increased ventilation rate

43
Q

What is hypoventilation?

A

A decreased ventilation rate

44
Q

What are chemoreceptors?

A

A chemoreceptor is a specialised sensory receptor cell which responds to a chemical substance and generates a biological signal

45
Q

What do the carotid and aortic bodies detect?

A

They detect changes primarily in oxygen. They also sense increases in CO2 partial pressure and decreases in arterial pH.

46
Q

What is the pulmonary circulation loop?

A

The pulmonary circulation loop is the part of the circulatory system which carries deoxygenated blood away from the right ventricle of the heart, to the lungs, and returns oxygenated blood to the left atrium

47
Q

What is the systemic loop?

A

A loop through the rest of the body to provide oxygenated blood, from the left ventricle to the right atrium.

48
Q

What is the main function of the heart?

A

The heart produces the force that causes blood to circulate

49
Q

What are baroreceptors?

A

They monitor blood pressure

50
Q

What do baroreceptors do in response to low blood pressure?

A

They increase sympathetic stimulation and decrease parasympathetic stimulation of the heart, resulting in an increase in heart rate and force of contraction

Foundation to Bioscience 2 (15 decks)

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