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Physiology Flashcards

1
Q

Organs are made up of how many types of primary tissues that function together to form a particular function?

A

Two or more types of primary tissue

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2
Q

What is a body system?

A

A group of organs that perform related functions and work together to achieve common goals

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3
Q

What is essential for normal cell and body function?

A

A stable internal environment called ‘homeostasis’

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4
Q

What type of homeostatic mechanisms cause disease?

A

Deficient, inappropriate or excessive homeostatic mechanisms

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5
Q

In order to maintain homeostasis, a control system must be able to:

A
  • sense deviations from normal in the internal environment that need to be held within narrow limits
  • integrate this information with other relevant information
  • make appropriate adjustments in order to restore a controlled variable to its desired value
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6
Q

Homeostatic control systems are grouped into two classes:

A

Intrinsic controls and extrinsic controls

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7
Q

Intrinsic controls

A

Local controls that are inherent in an organ

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8
Q

Extrinsic controls

A

Regulatory mechanisms initiated outside an organ and are accomplished by nervous and endocrine systems

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9
Q

Feedforward

A

A term used for responses made in anticipation of a change. It usually acts in combination with negative feedback

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10
Q

Feedback

A

Refers to responses made after a change has been detected

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11
Q

Positive feedback

A

Amplifies an initial change (uterine contractions during labour become increasingly stronger until the birth of a baby)

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12
Q

Negative feedback systems

A

Oppose an initial change

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13
Q

Negative feedback promotes..?

A

Stability by regulation of a controlled variable through flow of information along a closed loop

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14
Q

What is blood pressure?

A

The outwards pressure exerted by the blood vessel walls

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15
Q

How can systemic arterial blood pressure be expressed?

A

By systolic and diastolic blood pressures

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16
Q

What is arterial blood pressure?

A

The pressure exerted on the walls of the aorta and systemic arteries when the heart contracts. Usually under 140

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17
Q

What is the diastolic arterial blood pressure?

A

The pressure exerted by the blood on the walls of the aorta and systemic arterial when the heart relaxes. Normally under 90mmHg

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18
Q

Hypertension

A

A clinical blood pressure of over 140/90 and a day time average of over 135/85

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19
Q

Pulse pressure

A

The difference between the systolic and diastolic blood pressure. Normally between 30 and 50mmHg

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20
Q

Mean Arterial blood pressure

A

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

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21
Q

Why is the MAP not obtained by averaging the systolic and diastolic pressures?

A

Because the diastolic portion of the cardiac cycle is twice as long as the systolic portion of the cardiac cycle

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22
Q

How to calculate MAP (more complicated)

A

MAP = (2x diastolic +systolic) divided by three

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23
Q

How to calculate the MAP (easier)

A

MAP = DBP + 1/3 pulse pressure

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24
Q

Normal range of MAP

A

Between 70 and 105 mmHg

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25
What are baroreceptors?
They are receptors sensitive to changes in pressure and stretch
26
What are the sensors in the baroreceptor reflex?
Baroreceptor afferent neurons
27
What are afferent neurons?
Sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system and brain
28
Firing rate in baroreceptor afferent neurons...
Increases when the mean arterial blood pressure increases | Decreases when the mean arterial blood pressure decreases
29
what does the CV control centre do?
it receives CVS afferent information, generates vagal outflow to heart and regulates spinal sympathetic neurones
30
MAP calculation using cardiac output and SVR
MAP = CO x SVR
31
What is the cardiac output?
The volume of blood pumped by each ventricle of the heart per minute
32
How to calculate cardiac output
CO = SV x HR
33
What is the stroke volume?
He volume of blood pumped by each ventricle of the heart per heart beat
34
What is the systemic vascular resistance?
The sum of resistance in all vasculature in the systemic circulation. Regulated by vascular smooth muscle
35
Vasomotor tome meaning
Vascular smooth muscles are partially constricted at rest
36
What is the vasomotor tone caused by?
Tonic discharge of sympathetic nerves resulting in a continuous release of noradrenaline
37
Autothythmicity
The heart can beat rhythmically in the absence of the external stimuli
38
Why should vital signs be recorded?
They can be valuable when assessing parents and monitoring their deterioration
39
What depends on the need and frequency to monitor vital signs?
The individual patient presentation
40
What can supplement clinical vital signs?
Special investigations such as blood tests and x-rays
41
Clinical vital signs commonly assessed and recorded?
Pulse, blood pressure, temperature, respiratory rate, capillary refill time, oxygen saturation and consciousness
42
Why might a patient with blood loss feel dizzy?
Low arterial blood pressure prevents brain from getting normal perfusion and oxygenation which can progress to confusion, lethargy and loss of consciousness with more blood loss
43
Why might a patient with blood loss be breathless?
The body is trying to supply more oxygen to tissues
44
Why might a patient with blood loss look pale and have cool, clammy skin?
Arterial blood pressure has decreased. Low arterial blood pressure is detected by baroreceptors resulting in sympathetic stimulation and peripheral vasoconstriction. This helps raise SVR and hence right the drop in blood pressure.
45
Why might a patient with blood loss have a fast, regular, but weak pulse?
Arterial blood pressure decreases. Low blood pressure is detected by baroreceptors, resulting in increased sympathetic and decreased parasympathetic activity to the heart - both increase heart rate. The pulse is weak due to the loss of blood resulting in low stroke volume
46
What is laminar flow?
The flow of fluid when each particle follows a smooth path. The velocity of the fluid is constant at any point in the fluid.
47
Instruments used to estimate arterial blood pressure?
Cuff Sphygmomanometer and stethoscope
48
Core body temperature
The temperature of structures deep within the body
49
Normothermia
The normal core body temperature and is optimum for cellular metabolism and function
50
Increased body temperature
Speed up cellular metabolism
51
What does overheating cause?
Protein denaturation, nerve malfunction, convulsions and death
52
What does decreased body temperature cause?
A slow down in cellular reactions, and may fatally slow down the metabolism
53
Normal range for tympanic temperature (ear temperature)
35.5-37.5 degrees Celsius
54
Why not use oral temperature?
Affected by consumption of food and drink
55
Heat gain from internal environment?
Metabolic heat
56
Heat gain from external environment?
Radiation, convection and conduction
57
Heat loss to external environment
Convection, conduction, radiation and evaporation
58
What is basal metabolic heat?
The minimum amount of energy required to sustain vital body functions and leads to basic level of heat production
59
What hormones can increase the BMR?
Adrenaline, thyroxine and noradrenaline
60
What is conduction?
Transfer of heat between objects in contact
61
In what way does heat move?
From a warmer to a cooler object
62
What does heat conduction depend on?
The temperature gradient and thermal conductivity
63
How does the human body maintain its core temperature at a set point?
By homeostatic mechanisms involving a negative feedback control system
64
what are neural inputs to the hypothalamus
Those from the negative feedback receptors for temperature regulation
65
The hypothalamus role
Acts as the body’s thermostat (maintains the temperature at a set point)
66
Anterior hypothalamic centre is activated by what?
Activated by warmth
67
where are the central thermoreceptors?
in the hypothalamus, abdominal organs, elsewhere
68
where are the peripheral thermoreceptors?
in the skin
69
what are the three effectors for the negative feedback: temperature control?
skeletal muscles, skin arterioles and sweat glands
70
what is the posterior hypothalamic centre activated by?
cold
71
where are endogenous pyrogens released from?
from macrophages
72
what are macrophages?
a type of phagocytic white blood cell
73
what do endogenous pyrogens stimulate the release of?
prostaglandins in the hypothalamus
74
what effect do prostaglandins acting on the hypothalamic thermo-regulatory centre have?
they reset the thermostat
75
what will happen to the hypothalamic temperature set point if there is a fever?
the set point is raised
76
what effect does raising the set point temperature have?
it initiates mechanisms to heat the body to raise the body to the new set point
77
what happens when the body temperature increases to reach the new set point?
fever
78
How can the hypothalamic set point be restored to normal?
if the pyrogen release is reduced/stopped or the prostaglandin production is decreased/ceased
79
how does the body temperature return to the normal hypothalamic set point?
the hypothalamus initiates mechanisms to cool the body (sweating, vasodilation)
80
fever is a result in temperature set point being said to around?
38-40 degrees Celsius
81
hyperthermia
extreme uncontrolled increase in body temperature due to failure of heat regulating mechanisms
82
hypothermia
a drop in body temperature below the required value for cellular metabolism (below 35 degrees)

Principles (11 decks)

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