Topic 7 - Endocrine system I

Question 1

What are hydrophilic hormones?

Answer 1

• Made in advance (stored in secretory vesicles)
• Short lifespan (usually)
• travel individually bloodstream
• Need to bind to receptor on membrane & activate 2nd messenger to initiate signal transduction for response in cell

Question 2

What are hydrophobic hormones?

Answer 2

• Made on demand
• long life span (usually)
• travel w/ carrier molecule in bloodstream
• penetrate membrane & bind receptor in cytosol to initiate signal transduction for response in cell

Question 3

What do the exocrine glands do?

Answer 3

• They secret their products into ducts/free surfaces
• under control of autonomic nerves
• e.g sweat, sebacious, mucous & digestive glands

Question 4

What do the endocrine glands do?

Answer 4

• They secrete their products (hormones) into extracellular space to go into bloodstream
• e.g pancreas, gonads, pituitary, pineal, thyroid, parathyroid & adrenal glands

Question 5

What are the 3 types of hormones?

Answer 5

• Amines = modified from aa tyrosine (e.g T3 & T4 from thyroid gland)
• Steroids = derived from cholesterol (e.g testosterone from testis)
• Proteins & peptides = aa chains (e.g oxytocin from posterior pituitary & insulin from pancreas)

Question 6

What are the 2 types of hormone interactions?

Answer 6

• Direct effects = binding of hormone w/ receptor to initiate activity change of target tissue (e.g insulin on liver cells)
• Permissive effects = 2nd hormone’s presence require to permit 1st hormone to exert full effect (e.g oestrogen from uterus)

Question 7

Where are hormone receptors for a cell & roughly how many are there?

Answer 7

• 2000-100000 per cell
• located in/on cell membrane, in cytoplasm or in cell nucleus

*Note: receptors are large proteins & specific

Question 8

How does 2nd messenger system for hormones work?

Answer 8

• used for hormones binding to plasma mem. as X physically enter intercellular processes
  1. 1st hormone binds to receptor
  2. This promotes production of 2nd messenger
  3. This then mediates 2nd messengers effects,
  4. This leads to cell response
• NOTE: hormones e.g catecholamines (NA, ADR), thyroid-stimulating hormone (TSH) & oxytocin

Question 9

What are the major organs/systems that remove hormones?

Answer 9

• Liver & kidney = remove hormones from plasma through metabolism/excretion

*Note: Peptide hormones & catecholamines rapid removal from blood vs steroid & thyroid hormones slow removal

Question 10

What is the pituitary?

Answer 10

• It’s at the base of the brain below the hypothalamus, in sella turcica
• It has consists of 2 things; anterior pituitary & posterior pituitary

Question 11

What is the hormones secreted by posterior pituitary?

Answer 11

• Oxytocin
• ADH/Vasopressin (ADH = antidiuretic hormones)

Question 12

What are the hormones secreted by the anterior pituitary gland?

Answer 12

• ACTH (adrenocorticotrophic hormone)
• TSH (thyroid-stimulating hormone)
• GH (growth hormone)
• FSH (follicle-stimulating hormone)
• LH (luteinizing hormone)
• PRL (prolactin)