Homeostasis, pH, core body temperature and body fluids

Question 1

Define the term ‘homeostasis’

Answer 1

homeo= sameness and stasis = standing still.

Question 2

what percentage of a normal adults weight is intracellular water?

Answer 2

40% which is 2/3 of the total water content.

Question 3

what percentage of a normal adults weight is extracellular water

Answer 3

20% of their body weight
1/3 of the total water content

Question 4

is interstitial fluid and plasma extra or intracellular and how much of a normal adults water content do they make up ?

Answer 4

They are extracellular fluid.
interstitial fluid makes up 15% of and plasma makes up 5% of the body mass.

Question 5

how much of the blood volume is plasma

Answer 5

60 % of total blood volume is plasma.

Question 6

when does positive feedback cease ( give an example)

Answer 6

it ceases when the stimulus stops e.g when a baby pushes on the cervix it stimulates the release of oxytocin which causes uterine contractions, this will only stop when the baby stops pushing on the cervix.

Question 7

when does negative feedback cease(give an example)

Answer 7

when the effector ceases e.g during temperature control the effectors are the blood vessels, sweat glands they cease to work as the hypothalamus detects that basal body temperature has retuned t the normal rate.

Question 8

what is pyrexia

Answer 8

pyrexia is a fever or high temperature of over 38 degrees celsius.

Question 9

what is rigor

Answer 9

rigor is a sudden feeling of cold shivering accompanied by raise in temp. it is caused by pyrogens(toxins) and is detected by the hypothalamus

Question 10

state the body compartments where body fluids accumulate

Question 11

what happens if you have too much water and what do we give to patients.

Answer 11

osmotic pressure is high, cells absorb the excess water and have the potential to burst, enzymes and protein stop working. brain swelling and cell and tissue death.

patients need physiological saline concentrations( 0.9% NaCl)

Question 12

what happens if there’s too little water

Answer 12

cells and tissues initially absorb water from the interstitial space, then cell sacrifice takes place. as tissues die water is absorbed from the organs, first the brain, then liver and lastly the kidney and the heart.

Question 13

describe oedema in terms of hydrostatic pressure and osmotic pressure

Answer 13

oedema is when the hydrostatic pressure is higher than the osmotic pressure.

increase HS pressure causes more water to be driven into the interstitial spaces. a common symptom of heart failure, liver cirrhosis and renal disease

Question 14

describe how the pressures change in normal blood capillaries

Answer 14

blood flows from the arterial end to the venous end. hydrostatic pressure comes from within the capillary. oncotic pressure acts from outside the capillary.
at the arterial end there is more interstitial oncotic pressure and less blood hydrostatic pressure, forcing more water into the capillaries. in the venous end there is less oncotic pressure and more interstitial hydrostatic pressure.

Question 15

what’s the protein that controls oncotic pressure?

Answer 15

albumin

Question 16

describe the process of oedema

Answer 16

oedema is fluid retention caused by the presence of plasma proteins in the interstitial space.
when body fluids are diluted hyponatriaemia (extracellular) causes a shift in osmotic pressure that leads to excess water expulsion from the cells to the interstitial space causing swelling.

Question 17

normal pH for tissues and blood

Answer 17

blood in the arteries is more basic with a pH off 7.45 and is more acidic in the vein with a pH of 7.35

Question 18

what pH does acidosis and alkalosis begin. include some symptoms

Answer 18

acidosis is a blood pH lower than 7.35. metabolic acidosis due to production of lactic acid and respiratory acidosis from excess CO2 due to hypoventilation causes diarrhoea , nausea , vomiting, headache, coma, confusion arrhythmia, shortness of breath, seizures and coughing.

and alkalosis is a blood pH higher than 7.45

Question 19

Compare and contrast water balance in males and females
[and in early life and in older populations]

Answer 19

generally, lean people have the highest TBW. then normal and then obese, the parameters generally decrease by 10%(8% less for obese women) .

a lean baby has the highest TBW with 80% a lean adult male is 70% and a lean woman is 60% . etc

Question 20

Outline the physiology of dehydration and the effect of that on osmolality

Answer 20

dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. when the free water loss excess the free water intake usually due to exercise, disease of high environmental temperature.
this increases osmolality

Question 21

water toxicity and the effect of that on osmolality

Answer 21

excessive increase in water volume dilutes the fluids surrounding the cell decreasing osmolality making cells and tissues swell. This is called oedema and it is particularly dangerous in the brain, where swelling can cause convulsions, coma and death.