Cell signalling and hormones

Question 1

How can diurnal rhythms change?

Answer 1

Can gradually change in response to a change in lifestyle, such as when entering a different timezone or having night shifts

Question 2

What are hormones?

Answer 2

Chemicals released by glands to elicit a response, enhancing or inhibiting cellular reactions

Question 3

How is the endocrine and nervous systems related?

Answer 3

Operate in synchrony. Hormones act more slowly and have longer lasting effects (exception of adrenaline)

Question 4

What is information processing?

Answer 4

Half of the largest families of proteins deal with information processing. Process from nervous stimulation to muscular contraction

Question 5

What happens to a lipid insoluble molecule acting as a cell signal?

Answer 5

Forms a ligand-receptor complex and enters cell

Question 6

What are intracellular receptors?

Answer 6

Lipid soluble hormones; intracellular receptor binding; steroid hormones; thyroid hormones; vitamin D3; vitamin A; oestrogens; androgens; e.g. glucocorticoids

Question 7

What does the thyroid gland do?

Answer 7

Converts iodine to thyroid hormones, which are major metabolic hormones which all cells are dependent on

Question 8

What are thyroid hormones?

Answer 8

Thyroxine (T4), and triiodothyronine (T3)

Question 9

What are increased T3 and T4 associated with?

Answer 9

Increased oxidative substrate metabolism (mitochondrial enzyme activity)

Question 10

What physiological changes occur with hyperthyroidism (opposite changes to hypothyroidism)?

Answer 10

Increased metabolic rate = heat intolerance, protein catabolism (= muscle breakdown). Increased heart rate

Question 11

What do glucocorticoids do?

Answer 11

Affect mobilisation of GLUT-4 to cell membrane, increasing glucose uptake from blood; affect breakdown of proteins, producing free amino acids, to enable gluconeogenesis; block process of glycolysis when glycogen storage is too low

Question 12

How does glucocorticoids initiate responses?

Answer 12

Diffuses through phospholipid membrane (as is lipid soluble); bind with receptor; cause cascade of enzymatic event or bind to DNA and cause gene transcription

Question 13

What can cell signals be?

Answer 13

Hormones, chemical elements, light, heat, water

Question 14

What can the purposes of cell signalling be?

Answer 14

Warn off pathogens and/or infections; alter/regulate metabolic processes; switch genes on/off; cell division, differentiation, adaptation

Question 15

What are types of cell signalling?

Answer 15

Autocrine, paracrine, and endocrine

Question 16

What are the differences between auto-, para-, and endocrine?

Answer 16

Autocrine signal same cell as released from (by cytokines); paracrine signal nearby cells (by cytokines); endocrine signal far away cells in a multi-cellular organism (by hormones)

Question 17

What is signal transduction?

Answer 17

Cascade of events that mediates sensing and processing of signal (detect, reception, amplify, respond)

Question 18

What are different responses created by cell signals?

Answer 18

Change metabolism of cell (enzymatic activity changed); change electrical charge across membrane (ion channel activity); change gene expression

Question 19

What is universal to all receptors?

Answer 19

All are integral membrane proteins

Question 20

What are secondary messengers, and examples?

Answer 20

Relay signal from receptor-ligand complexes; cAMP, cGMP, Ca, IP3, DAG

Question 21

What are catecholamines?

Answer 21

Chemicals released from adrenal medulla and sympathetic nerve endings; augment sympathetic neural effects; PA directly governs the quantity of secretion

Question 22

What are two catecholamines?

Answer 22

Adrenaline and noradrenaline

Question 23

How does adrenaline affect CV system?

Answer 23

Increases CO; redistributes CO to muscular and hepatic circulation with only a small change in MAP

Question 24

How does adrenaline affect substrate metabolism during exercise?

Answer 24

Increases liver glycogenolysis; stimulates gluconeogenesis in prolonged exercise

Question 25

Where is cortisol released from?

Answer 25

Adrenal cortex

Question 26

What is cortisol released in response to?

Answer 26

Physical or emotional stress

Question 27

What are effects of cortisol?

Answer 27

Increases effectiveness of catecholamines; promotes carb, protein and fat catabolism (muscle pp breakdown = stimulation of aa’s for synth of glucose for gluconeogenesis); stimulated release of FAs from adipose

Question 28

What are growth factors?

Answer 28

Developmental regulatory factors; regulate cell growth, division, differentiation, and apoptosis

Question 29

What are DHEAs?

Answer 29

Precursors for sex hormones, so decrease with age; are released from adrenal gland

Question 30

How are DHEAs affected by PA?

Answer 30

Increase with increased intensity of PA

Question 31

How do kinases activate/inactivate proteins?

Answer 31

Transfer Pi to protein; Pi has -ve charge; changes conformation of protein; changes function of protein

Question 32

What do tyrosine kinases do?

Answer 32

Phosphorylate tyrosine amino acid

Question 33

How many genes code for tyrosine kinases?

Answer 33

> 200

Question 34

How many tyrosine kinases are there?

Answer 34

> 90

Question 35

What are responses/ receptors to tyrosine kinases?

Answer 35

Ras signal transduction pathway; PI3 kinase pathway; JAK/STAT protein receptors

Question 36

Why is the PI3 kinase pathway important?

Answer 36

Important in insulin response; insulin attaches to receptor; receptor autophosphorylated on tyrosine; IRS attaches to receptor and is phosphorylated - GLUT4 via Ras; produces secondary messenger; glycogen synthase is activated