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MBCHB PRINCIPLES > Physiology > Flashcards

Physiology Flashcards

1
Q

features of a membrane

A

-phospholipid bilayer
-cholesterol
-

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2
Q

what appearance does the cell membrane have?

A

trilaminar

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3
Q

what effect does the cholesterol have on the cell membrane

A

stiffens the membrane contributing to fluidity and stability

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4
Q

what is the function of the lipid layer

A

responsible for membrane fluidity

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5
Q

what component of the lipid layer serves as a barrier

A

hydrophobic interior

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6
Q

what is homeostasis?

A

maintenance of steady states within our body’s coordinated physiological mechanisms

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7
Q

what may disruption of homeostasis result in?

A

death/disease

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8
Q

what are the intrinsic physiological controls?

A

local controls that are inherent in an organ

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9
Q

what are the extrinsic physiological controls

A
  • regulatory mechanisms

- nervous and endocrine systems

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10
Q

describe the term feedforward

A

term used for responses made in anticipation of a change

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11
Q

describe the term feedback

A

after change has been detected (positive and negative systems)

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12
Q

describe positive feedback control

A

amplifies an initial change (eg birthing contractions during labour)

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13
Q

describe negative feedback control

A

a control mechanism where the action of the effector (response) opposes a change in the regulated variable and returns it back toward the set point value

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14
Q

describe the negative feedback control system

A

sense deviations from normal
integrate this information
make appropriate adjustments to restore controlled variable to a desired variable

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15
Q

what 3 things does a negative feedback need

A

a sensor, a control centre and effectors

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16
Q

name examples of negative feedback VARIABLES

A 
mean arterial blood pressure
core body temp
blood glucose 
pH
blood gases
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17
Q

describe the systemic systolic arterial blood pressure

A

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart CONTRACTS

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18
Q

describe the systemic diastolic arterial blood pressure

A

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart RELAXES

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19
Q

what is normal blood pressure usually?

A

120/80 mm Hg

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20
Q

what blood pressure is hypertension classified as?

A

140/90 mm Hg / 125/85 day time average

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21
Q

what is the pulse pressure?

A

difference between systolic and diastolic ie between 30 and 50 mm Hg

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22
Q

what is mean arterial blood pressure (MAPs)?

A

the average arterial blood pressure during a single cardiac cycle which involves contraction and relaxation of heart

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23
Q

what are the 2 equations to estimate MAPs?

A 
MAP= [(2x diastolic) + systolic]/3
MAP= adding diastolic BP + 1/3 of pulse pressure
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24
Q

what is the normal MAPS range

A

70-105

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25
Q

what MAP is needed for perfusion into vital organs?

A

at least 60 mm Hg

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26
Q

what is the main receptor used in negative feedback control?

A

baroreceptors

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27
Q

where are baroreceptors located?

A

aortic arch and carotid sinus

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28
Q

what are baroreceptors?

A

Sensitive to stretch, firing rate increases when MAP increases and decreases when MAP decreases. They only respond to acute changes (firing decreases if high blood pressure is sustained)

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29
Q

MAP=

A

Cardiac output (CO) x total peripheral resistance (TPR)

30
Q

what is CO

A

cardiac output= the volume of blood pumped by each ventricle of the heart per minute

31
Q

equation CO=

A

stoke volume (SV) x heart rate (HR)

32
Q

what is systemic vascular resistance

A

the sum of resistance of all vasculature in the systemic circulation

33
Q

how is MAP regulated?

A

by regulating HR, stoke volume and total peripheral resistance

34
Q

what vessel are the major systemic vascular resistance vessels (SVR)

A

arterioles

35
Q

what is autorhythmicity

A

heart capable of beating rhythmically in the absence of external stimuli

36
Q

how can heart rate be modified

A

by the autonomic nervous system

37
Q

what is the sympathetic nervous system

A

a division of the autonomic ns

38
Q

What is the name used when the sympathetic nervous system stimulates the acceleration of the heart rate

A

TACHYCARDIA

39
Q

what effect does the parasympathetic division do

A

stimulation of the vagus nerve slows the heart BRADYCARDIA

40
Q

What is systemic vascular resistance (SVR)

A

resistance that must be overcome to push blood around the body

41
Q

where’s the control centre?

A

medulla

42
Q

where are the effectors?

A

heart and blood vessels

43
Q

what is core body temperature? and what is the temperature of human body?

A

temperature of structures deep within the body.

homeostatically maintained at 37.8

44
Q

what type of control system is the maintenance of core body temperature

A

negative feedback

45
Q

where is the site for the control of core body temp/bodys thermostat?

A

hypothalamus (posterior=cold, anterior=hot)

46
Q

describe the function of the posterior hypothalamic centre

A

for cold

vasoconstriction -> increased muscle tone -> shivering

47
Q

describe the function of the anterior hypothalamic centre

A

for warmth
vasodilation
sweating
decreased muscle tone

48
Q

what stimulates sweating

A

sympathetic nervous system

49
Q

describe the process in maintaining core body temp

A

sensor detects change in controlled variable
sends signal to hypothalamus
effectors (ie skeletal muscles/skin arterioles/sweat glands) triggered to respond and restore variable to normal

50
Q

name for normal body temperature

A

normothermia - optimum for cellular metabolism and function

51
Q

2 sites for monitoring body temperature

A
  1. ear drum (indirect tympanic thermometer) 36-37.5

2. rectal (higher than tympanic more accurate) 36.7 – 37.5

52
Q

name the 5 ways to gain heat in the body

A
  1. basal metabolic rate - basic level of heat production (can be increased by hormones ie adrenaline)
  2. muscle activity (shivering)
  3. radiation (emission of heat energy in EM waves)
  4. convection (transfer of heat by air waves)
  5. conduction (transfer between objects in contact)
53
Q

name the 4 types of heat loss

A

convection (Air next to the skin warmed by conduction, warmed air becomes less dense and rises while cooler air moves in next to skin)
conduction
radiation
evaporation (passive/active)

54
Q

where are the central thermoreceptors

A

hypothalamus/abdominal organs

55
Q

where are the peripheral thermoreceptors

A

skin

56
Q

what happens to the arterioles in response to heat exposure

A

vasodilation -relaxation of the arterioles smooth muscles

-blood flow to the skin surface increased

57
Q

name the processes in changing the set point in fever

A
  1. infection
  2. chemicals released from macrophages which act as an endogenous pyrogen
  3. stimulates hypothalamus to realise prostaglandins in the hypothalamus
  4. this resets the thermostat to higher temp
  5. hypothalamus initiate mechanisms to heat the body ie cold response
  6. body temp increases to reach new set point resulting in fever
58
Q

temp for fever

A

38-40

59
Q

temp for hyperthermia

A

over 40

60
Q

temp for hypothermia

A

35 or below

61
Q

when is the thermostat reset to normal?

A

if pyrogen release is reduced or stopped

62
Q

where does excitation of the heart normally originate?

A

pacemaker cells in the Sino-atrial node

63
Q

what is the name for when the heart is able to beat rhymically in the absence of external stimuli

A

autorhythmicity

64
Q

heart rate can be modified by…

A

the autonomic nervous system

65
Q

what are the two branches of ANS

A

sympathetic and parasympathetic

66
Q

what does the sympathetic division do

A

stimulation accelerates the heart rate
TACHYCARDIA
noradrenaline acts on beta1 receptors

67
Q

what does the parasympathetic division do

A

stimulation of vagus nerve slows down the heart rate
BRADYCARDIA
acetylcholine acts on muscarinic receptors

68
Q

where in the heart does the excitation normally originate?

A

SA node

cluster of the specialised pacemaker cells in the SA node initiate the heart excitation

69
Q

where is the SA node located

A

in the upper right atrium close to where the superior vena cava enters the right atrium

70
Q

a heart controlled by SA node is said to be …

A

sinus rhythm

71
Q

what do cells in the SA node have?

A

no stable resting membrane potential

MBCHB PRINCIPLES (6 decks)

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