Lecture 1- Homeostasis

Question 1

Define homeostasis

Answer 1

• homeo = sameness , stasis = standing still

Question 2

What is an example of negative feedback loop?

Answer 2

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

Question 3

What is an example of a positive feedback loop?

Answer 3

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

Question 4

What is our core body temp?

Answer 4

37+-0.5

Question 5

At what temperature would someone would have a fever?

Answer 5

38 degrees.

Question 6

What are the symptoms of a fever ?

Answer 6

• pale , sweaty, cramps in limbs and stomach

Question 7

What temperature would someone be considered to have heat stroke ?

Answer 7

40 degrees +

Question 8

What are the symptoms of a heat stroke ?

Answer 8

• hot to touch of the skin

- bounding pulse

Question 9

What temperature would someone be considered to have heat exhaustion?

Answer 9

46 degrees

Question 10

What are symptoms of heat exhaustion?

Answer 10

• confusion , seizures , unconsciousness

Question 11

At what degrees Would someone be considered mild hypothermic ?

Answer 11

Below 36.5 degrees

Question 12

What are the symptoms for mild hypothermia ?

Answer 12

• shivering
  Confusion
  Slurred speech

Question 13

What degrees is someone considered severely hypothermic ?

Answer 13

32 degrees and be,ow

Question 14

What are the symptoms of someone severely hypothermic ?

Answer 14

• shivering stops , muscle become rigid , weak pulse

Question 15

What is the normal blood Ph ?

Answer 15

7.35-7.45

Question 16

Blood in the …. is more alkali..

Answer 16

Arteries (7.45)

Question 17

What helps to regulate blood Ph ?

Answer 17

• kidney metabolic balance and lungs respiratory balance.

Question 18

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

Answer 18

Acidosis - which is characterised by headaches , coma , tremors

Question 19

What could possibly be the cause of acidosis ?

Answer 19

• hyperventilating which increases co2 concentration.

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

Question 20

What is alkalosis ?

Answer 20

• when blood ph range is between 7.45-7.8

Question 21

What are two ways to try and treat acidosis ?

Answer 21

1) mechanical ventilation

2) bicarbonate solution infusion

Question 22

What is an explanation of heart burns ?

Answer 22

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.

Question 23

How to treat heart burns a?

Answer 23

• antacids

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

Question 24

t what ph can human tissue survive at ?

Answer 24

6.8-7.8

Question 25

What is % of a 70kg man is water?

Answer 25

60%

Question 26

What proportion of fluids makes up the ICF and ECF?

Answer 26

ICF - 2/3 | ECF : 1/3

Question 27

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

Answer 27

1/4 plasma | IF : 3/4

Question 28

What are the differences between dehydration and water toxicity?

Answer 28

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.

Question 29

Dehydration

Answer 29

- 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.

Question 30

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

Answer 30

- 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.

Question 31

what is the main cause of oedema ?

Answer 31

- 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.

Question 32

Define Pyrexia

Answer 32

Raised body temperature

Question 33

Is pyrexiananprotective or destructive instinct?

Answer 33

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.

Question 34

What is and aNd what causes a rigor?

Answer 34

- this occurs at a very high fever where an infection is detected. - often characterised by exaggerated shivering.

Question 35

What is | A febrile seizure?

Answer 35

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

Question 36

Define isotonic

Answer 36

Equal concentrations of solutes inside and outside the cell.

Question 37

Define hypotonic

Answer 37

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

Question 38

Definehypertonic solution

Answer 38

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

Question 39

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

Answer 39

- 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.

Question 40

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

Answer 40

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