Homeostasis

Question 1

Which type of communication involves chemicals being released from the cell into extracellular fluid and then acting on the same cell itself?

Answer 1

Autocrine

Question 2

Which type of communication involves chemical messengers between cells - short distances?

Answer 2

Paracrine

Question 3

Which type of communication involves hormones travelling long distances between cells?

Answer 3

Endocrine

Question 4

What is exocrine communication?

Answer 4

Hormones are secreted into ducts then into the organ.

Question 5

What is the key difference between endocrine and paracrine communication?

Answer 5

Hormones travel in the blood when endocrine and in extracellular fluid when paracrine.

Question 6

What is a positive feedback loop?

Answer 6

Amplification of a signal.

Question 7

Give an example of a positive feedback loop.

Answer 7

Oxytocin release in childbirth.

Clotting cascade

Question 8

What is a negative feedback loop?

Answer 8

When a high levels of an output are fed back to the hypothalamus/pituitary gland to reduce the output itself.

Question 9

Which organ causes primary hypothyroidism?

Answer 9

Thyroid - produces little thyroxine so TSH levels keep increasing as pituitary doesn’t think there is enough thyroxine in the blood.

Question 10

Which organ causes secondary hypothyroidism?

Answer 10

Pituitary/hypothalamus - pituitary is not producing enough TSH so there is little thyroxine.

Question 11

Name 3 types of hormone.

Answer 11

Peptide
Steroid
Amino-acid derivative

Question 12

What are peptide hormones made of?

Answer 12

Short chain amino acids. Fast acting.

Question 13

How do peptide hormones enter the cell?

Answer 13

Cannot diffuse across so have to bind to receptors on membrane and 2nd messenger is released.

Question 14

Name a peptide hormone.

Answer 14

Insulin, ADH, GH

Question 15

What are steroid hormones made of?

Answer 15

Cholesterol. Slow acting as directly affects DNA.

Question 16

How do steroid hormones enter the cell?

Answer 16

They diffuse into the cell

Question 17

Name a steroid hormone.

Answer 17

Testosterone, cortisol, oestrogen

Question 18

What are amino acid hormones made of?

Answer 18

Derived from tyrosine

Question 19

Name an amino acid derivative hormone.

Answer 19

Adrenaline, T4, T3

Question 20

What is the predominant electrolyte in ICF?

Answer 20

K+

Question 21

What are the predominant electrolytes in ECF?

Answer 21

Na+, Cl-, CO3, Ca2+

Question 22

Which fluid surrounds cells but does not circulate?

Answer 22

Interstitial fluid

Question 23

What is the total body water volume? How much is ICF and ECF?

Answer 23

Total = 42L, 60% of body weight 
ICF = 28L, 40% of body weight
ECF = 14L, 20% of body weight

Question 24

Of ECF, how much is interstitial fluid, plasma and transcellular fluid?

Answer 24

Interstitial fluid = 10L
Plasma = 3L
Transcellular = 1L

Question 25

Name insensible losses of water.

Answer 25

Sweat, breath, vomiting, faeces

Question 26

What is osmosis?

Answer 26

Net movement of water through a semipermeable membrane from an area of high water potential to an area of low water potential.

Question 27

What is osmolality?

Answer 27

Number of solutes per kg of fluid

Question 28

What is osmolarity?

Answer 28

Number of solutes per L of fluid

Question 29

What is osmotic pressure?

Answer 29

Pressure applied to a solution by pure solvent

Question 30

What is oncotic pressure?

Answer 30

Pressure exerted by protein

Question 31

What is hydrostatic pressure?

Answer 31

Pressure difference between capillary and interstitial fluid.

Question 32

Which receptors detect water potential of ECF?

Answer 32

Osmoreceptors in hypothalamus

Question 33

Which hormone is released in response to decreased water in ECF?

Answer 33

Renin from juxtaglomerular cells in kidney. Converts angiotensinogen to angiotensin I. This is converted to angiotensin II by ACE, triggering release of aldosterone from adrenal cortex. Aldosterone increases Na+ reabsorption which pulls water into ECF.

Question 34

List causes of dehydration.

Answer 34

Vomiting, diarrhoea, sweating, diabetes insipidus (too little ADH produced).

Question 35

What is oedema?

Answer 35

Excess water in intercellular tissue space.

Question 36

Name the 3 causes of oedema.

Answer 36

Inflammatory Venous Lymphatic

Question 37

Describe inflammatory oedema.

Answer 37

Proteins leak out due to increased permeability, pulling in water.

Question 38

How is venous oedema caused?

Answer 38

Due to increased venous pressure or venous obstruction from a thrombus.

Question 39

How is lymphatic oedema caused?

Answer 39

Obstructions from a tumour/parasite.

Question 40

What is the clinical term for high sodium?

Answer 40

Hypernatraemia

Question 41

What are the consequences of hypernatraemia?

Answer 41

Cerebral intracellular dehydration. Water moves from intra-cell to extra-cell

Question 42

What is the clinical term for low sodium?

Answer 42

Hyponatraemia

Question 43

What are the consequences of hyponatraemia?

Answer 43

Intracellular over hydration

Question 44

What is the clinical term for high potassium?

Answer 44

Hyperkalaemia

Question 45

What are the consequences of hyperkalaemia?

Answer 45

Risk of myocardial infarction as high K+ disrupt resting potential generated for heart contraction

Question 46

What is the clinical term for low potassium?

Answer 46

Hypokalaemia

Question 47

What are the consequences of hypokalaemia?

Answer 47

Weakness and cardiac dysrhythmia (abnormal heat beat)

Question 48

What is the clinical term for high calcium?

Answer 48

Hypercalcaemia

Question 49

What are the consequences of hypercalcaemia?

Answer 49

Metastatic calcification i.e. stones and kidney stones

Question 50

What is the clinical term for low calcium?

Answer 50

Hypocalcaemia

Question 51

What are the consequences of hypocalcaemia?

Answer 51

Tetany (spasms of the hands and feet)