1) Homeostasis, PH, Core Body Temp And Body Fluids

Question 1

What is the normal range of temperatures in the body?

Answer 1

36.5 to 37.5 celcius

Question 2

Define homeostasis

Answer 2

• the ability or tendency of a living organism, cell or tissue to keep the conditions inside it the same despite any changes in the conditions around it
  OR
• maintaining s state of internal balance
  OR
• Homeo = sameness and stasis = standing still

Question 3

Explain, by example what a negative feedback loop is

Answer 3

Stimulus e.g. rising blood glucose -> detected by insulin-secreting cells of pancreas -> pancreas secretes insulin, so liver cells take up glucose and store it as glycogen; most body cells also take up more glucose -> as glucose is take up, blood glucose levels decline -> pancreas senses this and halts insulin secretion -> return to homeostasis

Question 4

Explain, by example, what a positive feedback loop is

Answer 4

Childbirth: baby pushes against the cervix, causing it to stretch -> stretching of cervix causes nerve impulses to be sent to the brain -> brain stimulates the pituitary to release oxytocin -> oxytocin causes uterus to contract -> pushes baby further into cervix -> …

(The output enhances or exaggerates the original stimulus)

Question 5

List the (5) methods of measuring core body temperature

Answer 5

• tympanic thermometer
• infra-red skin thermometer
• temporal film
• Oral/rectal/axillary thermometer
• traditional (mercury)

Question 6

What temperature range is a fever? (Symptoms?)

Answer 6

When temp is above 38 (but below 40)

Pale sweaty skin, cramps in stomach, arms and legs

Question 7

Temperature range for heat stroke (and symptoms)

Answer 7

Temp higher than 40 (but below 46)

Flushed dry skin, hot to the touch, strong bounding pulse

Question 8

Temperature range for heat exhaustion (and symptoms)

Answer 8

Temp above 46

Unconsciousness/fitting/seizures, confused/restless, headache, dizzy, uncomfortable

Question 9

Temp range for mild hypothermia and symptoms

Answer 9

32.1 to 35

Shivering, fatigue, slurred speech, confusion, forgetfulness, muscle stiffness

Question 10

Temp range for severe hypothermia and symptoms

Answer 10

28 to 32

Shivering stops, muscles become rigid, very slow and weak pulse, noticeable drowsiness

Question 11

What happens if temp drops below 28?

Answer 11

No vital signs, severe reduction in response levels, unconsciousness, dilated pupils, pulse undetectable, appearance of death
HOWEVER: NOT DEAD UNTIL WARM AND DEAD i.e. above 28

Question 12

Normal pH range in tissues

Answer 12

7.35 to 7.45

Question 13

What 2 major organs are responsible for maintaining acid-base balance?

Answer 13

Lungs - respiratory balance
Kidneys - metabolic balance

Question 14

What test/analytical process can be used to look at pH

Answer 14

Arterial Blood Gas Analysis

Question 15

What are temperature and pH regulation examples of?

Answer 15

Negative feedback loops

Question 16

Name one pH buffering system in the Extracellular fluid

Answer 16

Carbonic acid - bicarbonate buffer system

Protein buffer systems - plasma protein buffers, amino acid buffers, haemoglobin buffers

Question 17

Name one buffer system in the Intercellular fluid

Answer 17

Phosphate buffer system

Protein buffer systems - haemoglobin buffer system, amino acid buffers, plasma protein buffers

Question 18

Give the proportions of water found in the body of the average 70kg man

Answer 18

• 60% total mass made up of water
  
  • 2/3 total water is intracellular
  • 1/3 total water is extracellular
    
    • 3/4 extracellular is interstitial
    • 1/4 extracellular is in the blood
      
      • 3 litres plasma, 2 litres red cells

Question 19

How does water content change with body fat percentage?

Answer 19

The higher the percentage body fat, the lower the percentage of total body water

(Muscle has a higher water content than fat)

Question 20

Define hyper, hypo and isotonic

Answer 20

Hypertonic - “hyper = higher, tonic = solute” higher solute outside the cell

Hypotonic - “hypo = lower, tonic = solute” lower solute outside the cell

Isotonic - “iso = equal, tonic = solute” same solute concentration on both sides of the cell membrane

Water moves from a hypotonic to a hypertonic solution

Question 21

What is osmolality?

Answer 21

Concentration of a solution expressed as the total number of solute particles per kilogram (milliolsmoles per kilogram (mOsm/kg))

Question 22

Describe mechanism of oedema

Answer 22

Oedema is fluid retention
Hydrostatic pressure > osmotic pressure

Often due to presence of plasma proteins in the interstitial space, or the lymphatics being blocked or damaged

(Hydrostatic pressure = force exerted by the fluid on the vessel wall)
(osmotic pressure = force applied by the solute/colloid to prevent osmotic movement across the membrane)