1 Homeostasis

Question 1

Definition

Answer 1

Homeo is defined as sameness and stasis as standing still

Question 2

Definition 2

Answer 2

The process whereby cells, tissues and organisms maintain the status quo

Question 3

Disrupters

Answer 3

Changes a homeostatic parameter (running, on a hot day)

Question 4

Detectors

Answer 4

Detect disruption

Question 5

Control system and effectors

Answer 5

Bring it back into homeostatic range

Question 6

Things needed for chemical reactions in cells

Answer 6

Correct pH
Correct temp
Sufficient glucose and O2 
Volume and pressure
Amino acids, fats, vitamins, minerals
Correct amount of hormones
Correct amount of water
Correct amount of electrolytes (Na, K, Cl)

Question 7

Cells produce

Answer 7

CO2

NH3

Question 8

Negative feedback when hot

Answer 8

Vasodilation
Sweating
Pilorelaxation
Stretching out

Question 9

Negative feedback when cold

Answer 9

Vasoconstriction
Shivering
Piloerection
Curling up

Question 10

Negative feedback blood glucose

Answer 10

Blood glucose rises, detected by insulin-secreting cells of pancreas, pancreases secretes insulin, liver takes up glucose, blood glucose levels decrease, insulin release stops

Question 11

Positive feedback

Answer 11

Output enhances or exaggerates original stimulus

Stops when initiator ceases

Question 12

Positive feedback blood clotting

Answer 12

Break in blood vessel wall, clothing occurs as platelets adhere to site and release chemicals, released chemicals attract more platelets, clotting proceeds, newly forming clot grows, feedback cycle ends after clot seals break

Question 13

Positive feedback childbirth

Answer 13

Baby pushes against cervix causing it to stretch, causes nerve impulses sent to brain, brain stimulates pituitary it release oxytocin, oxytocin causes uterus to contract

Question 14

Negative feedback

Answer 14

When conditions change from ideal or set point and returns conditions to this set point
Stops when effector ceases

Question 15

Core body temp

Answer 15

36.5-37.5 degrees
Older people have lower temp, athletes have even lower temp
Immune system works more effectively at higher temp

Question 16

Increased body temp

Answer 16

Hypothalamus activates cooling mechanisms, skin blood vessels dilate, sweat glands activated, body temp decreases, thermostat shuts of cooling mechanisms

Question 17

Decreased body temp

Answer 17

Hypothalamus activates warming mechanisms, skin blood vessels constrict, skeletal muscles activated (shivering), body temp increases, thermostat shuts off warming mechanisms

Question 18

> 46.5 degrees

Answer 18

Heat exhaustion

Unconsciousness, fitting, confused, headache, dizzy

Question 19

40.5-46.5 degrees

Answer 19

Heat stroke

Flushed dry skin, hot to the touch, strong pulse

Question 20

37.5-40.5 degrees

Answer 20

Fever/pyrexia

Pale sweaty skin, cramps in stomach, arms, legs

Question 21

36.5-37.5 degrees

Answer 21

Normal

Question 22

32-36.5 degrees

Answer 22

Mild hypothermia

Shivering, fatigue, slurred speech, confusion

Question 23

28-32 degrees

Answer 23

Severe hypothermia

Shivering stops, muscles become rigid, slow weak pulse, sever reduction in response levels

Question 24

<28 degrees

Answer 24

No vital signs
Unconsciousness, dilated pupils, pulse undetectable, appearance of death
Not dead until warm and dead

Question 25

Acid-base balance

Answer 25

Normal pH 7.35-7.45
2 major organs responsible for maintaining balance are lungs and kidneys
pH 6.8 = disease symptoms begin
pH 5.8 = cancer cells begin to form
pH 3.5 = human body cannot sustain life

Question 26

Acidosis

Answer 26

6.8-7.35 pH

Question 27

Alkalosis

Answer 27

7.45-7.8 pH

Question 28

[H+]

Answer 28

Change in [H+] by factor 2 causes pH change of 0.3

Question 29

Buffer systems

Answer 29

Intracellular fluid (ICF) include phosphate and protein
(Haemoglobin, amino acid, plasma) buffer systems
Carbonic acid is important in blood for erythrocytes
Other cells use sodium phosphate buffering system
All systems regulate water
Antacids (Al(OH)3) neutralise acids

Question 30

Blood gas analysis

Answer 30

Arterial blood gas analyses pH and gases

Shows metabolite values

Question 31

Fluid balance

Answer 31

2.5l per day
Intake: metabolism, food, drinking
Output: faeces, skin, breathing, urine

Question 32

Total body water

Answer 32

60% normal male
50% normal female 
70% normal infant
Higher % body fat, lower % water
2/3 is ICF, 1/3 is ECF
80% of ECF is interstitial, 20% is plasma

Question 33

Isotonic

Answer 33

Same amount of water on both sides of plasma membrane

Question 34

Hypertonic

Answer 34

Solute concentration inside cell lower than outside so water moves out (shrinks)

Question 35

Hypotonic

Answer 35

Solute concentration inside cell higher than outside so water moves in (swells)

Question 36

If not enough water in cells

Answer 36

Cells and tissues initially absorb water from interstitial space
Then absorb water from each other
Then as tissues die, water absorbed from organs
As organs die, water absorbed from brain, liver and lastly kidney and heart

Question 37

Aquaporins

Answer 37

Control amount of after that moves in and out of cells
Integral membrane proteins
Different aquaporins have different affinities for water
Regulated by amount of glycerol in cell

Question 38

If too much water

Answer 38

Osmotic pressure high
Cells absorb water and swell
Enzymes and proteins stop working as they can’t meet each other
Cells keep swelling until burst
Patient needs isotonic solutions, IV drips need saline concentrations (0.9% NaCl)

Question 39

Dehydration

Answer 39

Water loss
Thirst/dryness, decrease in plasma volume, increase in osmolarity
Increase in ADH
Oliguria (less urine output)

Question 40

Osmolality

Answer 40

Concentration of all solutes in a given weight of water

mOsm/kg

Question 41

Oedema

Answer 41

Fluid retention 
Peripheral oedema
Hydrostatic pressure>osmotic pressure
Lymphatics blocked or damaged
Presence of plasma proteins in interstitial space