Lecture 1- Homeostasis Flashcards Preview

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Flashcards in Lecture 1- Homeostasis Deck (40)
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1
Q

Define homeostasis

A
  • homeo = sameness , stasis = standing still
2
Q

What is an example of negative feedback loop?

A
  • blood glucose concentration - for example insulin secreting cells detect high blood glucose conc
3
Q

What is an example of a positive feedback loop?

A

Blood clotting :

1) tear in a blood vessel which activates platelets at the site of the wound which release chemicals.
2) these chemicals attract more platelets at the site of the wound.
3) clotting occurs - after clot seals the break positive feedback ends

4
Q

What is our core body temp?

A

37+-0.5

5
Q

At what temperature would someone would have a fever?

A

38 degrees.

6
Q

What are the symptoms of a fever ?

A
  • pale , sweaty, cramps in limbs and stomach
7
Q

What temperature would someone be considered to have heat stroke ?

A

40 degrees +

8
Q

What are the symptoms of a heat stroke ?

A
  • hot to touch of the skin

- bounding pulse

9
Q

What temperature would someone be considered to have heat exhaustion?

A

46 degrees

10
Q

What are symptoms of heat exhaustion?

A
  • confusion , seizures , unconsciousness
11
Q

At what degrees Would someone be considered mild hypothermic ?

A

Below 36.5 degrees

12
Q

What are the symptoms for mild hypothermia ?

A
  • shivering
    Confusion
    Slurred speech
13
Q

What degrees is someone considered severely hypothermic ?

A

32 degrees and be,ow

14
Q

What are the symptoms of someone severely hypothermic ?

A
  • shivering stops , muscle become rigid , weak pulse
15
Q

What is the normal blood Ph ?

A

7.35-7.45

16
Q

Blood in the …. is more alkali..

A

Arteries (7.45)

17
Q

What helps to regulate blood Ph ?

A
  • kidney metabolic balance and lungs respiratory balance.
18
Q

What happens when someone has a blood Ph in a range of 7-7.35?

A

Acidosis - which is characterised by headaches , coma , tremors

19
Q

What could possibly be the cause of acidosis ?

A
  • hyperventilating which increases co2 concentration.

And build up of lactic acid or poor excretion by the kidneys

20
Q

What is alkalosis ?

A
  • when blood ph range is between 7.45-7.8
21
Q

What are two ways to try and treat acidosis ?

A

1) mechanical ventilation

2) bicarbonate solution infusion

22
Q

What is an explanation of heart burns ?

A

Vomiting - which causes gastric juice which is acidic from the stomach to reach the pharynx/ oesophagus.

  • pharynx/ oseophagus does not have goblet cells so acid reflux damages epithelium which causes the heart burn.
23
Q

How to treat heart burns a?

A
  • antacids

- aluminium hydroxide is the best one to use as it has fewer side effects as it is insoluble.

24
Q

t what ph can human tissue survive at ?

A

6.8-7.8

25
Q

What is % of a 70kg man is water?

A

60%

26
Q

What proportion of fluids makes up the ICF and ECF?

A

ICF - 2/3

ECF : 1/3

27
Q

What is the promotion of fluid that makes up IF and plasma from ECF?

A

1/4 plasma

IF : 3/4

28
Q

What are the differences between dehydration and water toxicity?

A

Water toxicity is when you drink too much water. This can lead to hyponatraemia where the Serum Na+ is below/equal to 135 mol/L.

This is where water from outside cells enters cells causing them to swell and burst.

In the brain this could lead to brain oedema which causes seizures , brain damage , coma and even death.

29
Q

Dehydration

A
  • tissue and cells become dehydrated where the cells give up their water to the intertestial fluid where the cells shrink.
  • this can cause thirsty ness , dry mouth , low urine output volume.

This can lead to dizziness , confusion , weight loss.

30
Q

As a result of dehydration , what happens when there is a reduction in blood plasma volume ?

A
  • this could lead to an increased haematocrit , which in turns increases blood viscosity where as a result increases workload of the heart because of the increased viscosity which again may even cause blood clots because the blood is stickier.
31
Q

what is the main cause of oedema ?

A
  • when water is consumed too quickly or there is a blockage in urine production , body fluids become too diluted and there is a reduction in sodium concentration in the ECF which causes a shift in osmotic pressure.
32
Q

Define Pyrexia

A

Raised body temperature

33
Q

Is pyrexiananprotective or destructive instinct?

A

Protective? When there is an infection chemicals called pyrogens are released into the bloodstream - even by pathogens sometimes. The pyrogens bind to receptors in the hypothalamus which causes an increase in temperature.

34
Q

What is and aNd what causes a rigor?

A
  • this occurs at a very high fever where an infection is detected.
  • often characterised by exaggerated shivering.
35
Q

What is

A febrile seizure?

A
  • occurs in a child.
  • child loses consciousness and both their arms and legs shake uncontrollably.
  • happens at fevers above 38 degrees.
36
Q

Define isotonic

A

Equal concentrations of solutes inside and outside the cell.

37
Q

Define hypotonic

A

Lower water potential inside the cell than outside the cell so water enters a cell from surrounding solution causing lysis of a cell.

38
Q

Definehypertonic solution

A

Water potential inside cell is greater than outside cell so water moves out of the cell causing cell to become flaccid

39
Q

What is another cause of oedema in relation to hydrostatic pressure ?

A
  • raised hydrostatic pressure in the capillary which causes more fluid to enter the intertestial fluid. This can result from congestion eg heart failure. Or vasodilation during inflammation.
40
Q

What is another cause of oedema in relation go oncotic pressure ?

A
  • decreases omcotic pressure in the capillary which could be due to liver disease as less albumin is produced.