1) Homeostasis, PH, Core Body Temp And Body Fluids Flashcards
What is the normal range of temperatures in the body?
36.5 to 37.5 celcius
Define homeostasis
- 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
Explain, by example what a negative feedback loop is
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
Explain, by example, what a positive feedback loop is
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)
List the (5) methods of measuring core body temperature
- tympanic thermometer
- infra-red skin thermometer
- temporal film
- Oral/rectal/axillary thermometer
- traditional (mercury)
What temperature range is a fever? (Symptoms?)
When temp is above 38 (but below 40)
Pale sweaty skin, cramps in stomach, arms and legs
Temperature range for heat stroke (and symptoms)
Temp higher than 40 (but below 46)
Flushed dry skin, hot to the touch, strong bounding pulse
Temperature range for heat exhaustion (and symptoms)
Temp above 46
Unconsciousness/fitting/seizures, confused/restless, headache, dizzy, uncomfortable
Temp range for mild hypothermia and symptoms
32.1 to 35
Shivering, fatigue, slurred speech, confusion, forgetfulness, muscle stiffness
Temp range for severe hypothermia and symptoms
28 to 32
Shivering stops, muscles become rigid, very slow and weak pulse, noticeable drowsiness
What happens if temp drops below 28?
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
Normal pH range in tissues
7.35 to 7.45
What 2 major organs are responsible for maintaining acid-base balance?
Lungs - respiratory balance
Kidneys - metabolic balance
What test/analytical process can be used to look at pH
Arterial Blood Gas Analysis
What are temperature and pH regulation examples of?
Negative feedback loops
Name one pH buffering system in the Extracellular fluid
Carbonic acid - bicarbonate buffer system
Protein buffer systems - plasma protein buffers, amino acid buffers, haemoglobin buffers
Name one buffer system in the Intercellular fluid
Phosphate buffer system
Protein buffer systems - haemoglobin buffer system, amino acid buffers, plasma protein buffers
Give the proportions of water found in the body of the average 70kg man
- 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
How does water content change with body fat percentage?
The higher the percentage body fat, the lower the percentage of total body water
(Muscle has a higher water content than fat)
Define hyper, hypo and isotonic
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
What is osmolality?
Concentration of a solution expressed as the total number of solute particles per kilogram (milliolsmoles per kilogram (mOsm/kg))
Describe mechanism of oedema
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)
