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Anatomy and Physiology Exam > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

What is homeostasis?

A

Automatic, dynamic, self regulating processes to maintain and balance the normal state of body’s environment

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2
Q

Is homeostasis achieved anatomically or physiological functions?

A

Both

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3
Q

What happens if homeostasis is not achieved?

A

Illness and death

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4
Q

What are the control systems involved in homeostasis?

A

The nervous and endocrine systems

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5
Q

What is negative feedback

A

A change is sensed which triggers

A REACTION TO OPPOSE OR CORRECT THE CHANGE

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6
Q

What is positive feedback

A

A change is sensed which triggers

A REACTION TO REINFORCE ( NOT CORRECT) THE CHANGE

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7
Q

Examples of negative feedback

A

Lowering of blood pressure

Lowering the increasing acidity of blood

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8
Q

Examples of positive feedback

A

Blood clotting

Contractions during childbirth

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9
Q

What will happen to RBC in a hypertonic sln

A

There is a higher concentration of SOLUTES outside the cell.

Therefore, water will move by osmosis out of the cell and the cells will shrivel

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10
Q

What will happen to RBC in an isotonic sln?

A

Concentration of solutes outside and inside the cell is the same.

Therefore, no net gain of water in either direction

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11
Q

What will happen to RBC in a hypotonic sln?

A

Concentration of solutes outside of cell is lower.

Therefore water will move into the cell by osmosis.

Cells may burst.

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12
Q

What is facilitated diffusion?

A

Diffusion via carrier proteins in membrane.

Example- amino acid and glucose

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13
Q

What are some examples of substances that move by active transport?

A

CA2+, Na+, K+

sodium potassium pump
Requires ATP

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14
Q

How do very large molecules move across the cell membrane?

A

Endocytosis
Exocytosis

Endocytosis- the plasma membrane surrounds a part of the exterior environment and buds off as a vesicle

Exocytosis- A vesicle fuses with the plasma membrane.
The contents of the vesicle are released and its membrane becomes part of the plasma membrane.

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15
Q

What are electrolytes?

A

Chemicals that can carry an electrical charge
Dissolved in body fluids
Fluid and electrolyte levels are interdependent.

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16
Q

What are some examples of important ions?

A 
Na+
K+
Cl-
ca2++
HCO3-
Mg ++
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17
Q

In which membrane does the sodium/potassium pump occur?

A

Nerve cells

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18
Q

How does the Na+ and K+ pump occur?

A

Pump moves 3 Na+ out of cell
Pump brings 2 K+ into cell

Requires ATP

Changes the potential (electrical charge) of the cell.

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19
Q

What are the main categories of fluid in the body?

A

Intracellular-25L
Extracellular-13L
Plasma- 3.5 L
Lymph- 1.5 L

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20
Q

What can the extracellular components of fluid be divided into?

A 
Plasma
Tissue fluid
Lymph
Serous fluid
Intraocular fluid
Synovial fluid
Secretions of .GI tract
CSF
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21
Q

How are fluid shifts maintained in the body?

A

Osmotic and/ or hydrostatic pressures

e.g hydrostatic pressures in the capillary drives water out into tissue spaces. At venule end of capillary the high concentrations of plasma protein in blood ( low concentration of water) pulls water back into tissue spaces by osmosis.

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22
Q

Water follows…

A

SALT

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23
Q

What is our usual output of water (ml)

A

Urine- 1500
Faeces- 150
Lungs and skin- 900

TOTAL: 2550

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24
Q

What is oedema?

A

An excessive amount of tissue fluid

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25
What are some causes of oedema?
Plasma protein deficiency High venous pressure ( e.g venous thrombosis) Blocked lymphatics Sodium retention
26
What are some hormones involved in fluid balance?
ADH ( anti-diuretic hormone) Renin-angiotensin-aldosterone Aldosterone ANH ( atrial natriuretic hormone)
27
Where is ADH secreted from?
The pituitary gland
28
What is the function of ADH?
Increases renal tubule permeability This increases water reabsorption in nephrons and collecting duct.
29
When is ADH secreted?
In response to water deprivation ( concentration of solutes in plasma increases)
30
After ADH has been secreted- what happens to urine?
Smaller volumes and increasing concentration
31
Where is aldosterone secreted from?
Adrenal cortex
32
What is aldosterone made from?
Cholesterol in the adrenal cortex
33
What is the function of aldosterone?
Reduces excretion of sodium in DCT
34
How long does affect of aldosterone last?
20 minutes
35
What does ANH stand for?
Atrial natriuretic hormone
36
When does ANH get secreted?
When there is too much blood in the cardiovascular system Produced if the atria of the heart are stretched
37
What does ANH oppose?
The Renin angiotensin system and inhibits aldosterone
38
What does the renin-angiotensin system aim to do?
Increase cardiac output for a short time ONLY
39
How does the renin angiotensin system work?
Renin acts on angiotensinogen Angiotensinogen is then converted to angiotensin 1 Angiotensin 1 is converted to angiotensin 2 in the lungs This causes vasoconstriction Renin also causes the release of aldosterone
40
How is most heat lost from the body?
Mostly via the skin. | Some heat is also lost through faeces, urine and exhaled air.
41
How is heat lost through convection?
Involves warming of air next to skin. Warm air rises and is replaced by colder air. Warm air is rapidly removed by the wind. If this wind is cold it causes the body to chill quickly ( wind chill factor)
42
What is conduction?
The passage of heat from the skin into any cooler object by touching it
43
What is radiation?
Heat passes directly out from the skin into any objects it hits, warming that object
44
What is evaporation?
Heat transfer by means of a change in state ( from a liquid to a gas)
45
Which type of temperature is most indicative of core temp?
Rectal temperature Oral temp is 0.6 below rectal temp Different body parts- different body temps. E.G feet and hands can be 29
46
What is circadian body temperature?
Patterns for fluctuations e.g minimum temp is between 5-6 am. Maximum temp is between 5-7 pm Ovulation alters body temp ( up by 1 degree after ovulation)
47
How does the body gain heat?
Dietary induced thermogenesis Muscle action ( exercise, postural, shivering) Environment ( radiation, convection, conduction) Climate ( e.g the Artic increases BMR by 10-20%) Endocrine factors ( e.g androgens increase temp by 10-15%)
48
How does the body lose heat
To cooler environments ( convection, conduction and radiation) To warmer environments- evaporation, sweating, vasodilation, shunting, clothing adjustments)
49
Where is the thermoregulatory centre?
Hypothalamus (anterior and posterior)
50
How does the anterior hypothalamus promote heat loss?
Vasodilation and sweating
51
How does the posterior hypothalamus promote heat conservation?
decreases blood flow to skin Piloerection Shivering Promotes heat production- increase of thyroid hormone and increase of adrenaline secretion ( these increase BMR)
52
What does the anterior hypothalamus promote with regards to heat?
Heat loss
53
What does the posterior hypothalamus promote with regards to heat?
Heat gain
54
What is the hypothalamic temperature set point?
A group of neurones that respond to increases/ decreases in blood temperature relative to the hypothalmic 'set point' temp if set point exceeded- promotes heat loss and decrease heat conservation If set point below- promotes heat conversation and decreases heat loss
55
What does vasodilation achieve?
Increase in skin blood flow Decrease in renal blood flow Increase in vascular volume ( due to increase S.A) Therefore a decrease in Bp
56
What is the lethal limit of sweating?
15-25% loss of body weight
57
What can sweating lead to? ( in terms of blood volume and stroke volume)
Decreased blood volume ( and increased blood viscosity) Leads to increased heart rate Decreased stroke volume
58
What is cold vasodilation?
As temp of tissues drop close to freezing. Smooth muscle in vascular wall paralyses ( relaxes) This increases blood flow and increases tissue temp Protects against frostbite
59
Why is taking body temp in children problematic
Oral non compliance Axilla not accurate enough Rectal- risk of perforation Infrared- shape changes in external ear can affect use.
60
What temperature is a fever?
higher than 38
61
What temperature is pyrexia?
continous body temp above 37.5 up to 39.9
62
What temperature is hyperpyrexia?
Continous 40 or above.
63
What are some causes of high temperature?
``` Infection Toxins Drug reactions Prolonged exposure to hot environment Brain disorders Neoplasm ( tumour) Autoimmune disease Penguin effect ( crowds retaining heat when huddled together) ```
64
What is hyperthermia?
Heat stroke | Set point is exceeded, sweating fails to control temp and this leads to collapse
65
What is hypothermia?
General loss of body heat Frostbite- local heat loss Most cases are in the very young/old Increased risk following surgery due to inactivity, cold environment and low energy input.
66
What is the best treatment for hypothermia?
Warm environment Remove wet clothing Warm drinks Gradual warming ( 1 degree/ hour)
67
What is thermal injury?
Where frostbite ( vasoconstriction) leads to blood occlusion- anoxia and then necrosis. This can then lead to infection.
68
What is the main mechanism of heat loss?
Sweating
69
What is the main mechanism of heat gain?
Shivering

Anatomy and Physiology Exam (10 decks)

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