Endocrine System

Question 1

List one example of lipid soluble and water soluble hormones

Answer 1

lipid-soluble : cortisol

water-soluble : nor/epinephrine

Question 2

How are lipid soluble hormones transported in the blood?

Answer 2

via transport proteins

Question 3

How are water soluble hormones transported in the blood?

Answer 3

in the watery blood plasma, in a ‘free’ form

Question 4

Outline the action of a lipid soluble hormone.

Answer 4

1. hormone molecule diffuses through the cell membrane, into the target cell;
2. hormone bonds to and activates receptors within the cytosol or nucleus - activated receptor-hormone complex alters gene expression;
3. as the DNA is transcribed, new mRNA is formed, leaves nucleus and enters cytosol. Directs synthesis of new proteins;
4. new proteins alter cells activity relative to the hormones typical response

Question 5

Name the two types of hormone receptors and identify which class of hormone attaches to each.

Answer 5

transmembrane receptors : water-soluble

nuclear receptors : lipid-soluble

Question 6

List three hypothalamic hormones that regulate release of hormones from the anterior pituitary gland.

Answer 6

growth-hormone releasing hormone; prolactin-releasing hormone; prolactin-inhibiting hormone

Question 7

Describe how the hypothalamus regulates the anterior pituitary gland in relation to the hormone prolactin.

Answer 7

hypothalamus secretes prolactin-releasing hormone, travels through hypophyseal portal veins and diffuses into anterior pituitary;
PRH interacts with receptors in lactotroph cell membrane;
lactotrophs release prolactin which moves into anterior hypophyseal vein and into circulation

Question 8

List the two hypothalamic hormones that regulate release of hormones from the posterior pituitary gland.

Answer 8

antidiuretic and oxytocin

Question 9

Describe how the hypothalamus regulates the posterior pituitary gland in relation to the hormone oxytocin.

Answer 9

Oxytocin is produced in hypothalamic neurosecretory cells;
packaged into transport vesicles and moved to axon terminals in posterior pituitary;
stored in terminals until nerve impulse triggers exocytosis and release of hormone;
oxytocin diffuses into capillary plexus, posterior hypophyseal vein and then the target cell/organ (uterus / mammary glands)

Question 10

Name and describe the function of two cells found in the thyroid gland.

Answer 10

follicular cells - produce T3 and T4

parafollicular cells - produce calcitonin

Question 11

Describe hormones involved in metabolism are produced by the follicular cells.

Answer 11

iodine trapping;
synthesis of TGB;
oxidation of iodine;
coupling of T1 and T2 (forming T3 and T4); 
pinocytosis and excretion of colloid; 
secretion of T3 and T4 into blood

Question 12

What two glands and two hormones are involved in Ca+ regulation?

Answer 12

Thyroid (calcitonin)

Parathyroid (Parathyroid hormone)

Question 13

Describe the feedback loops depending on Calcium levels in blood.

Answer 13

High Ca+ stimulates parafollicular cells to release calcitonin;
calcitonin prohibits activity of osteoclasts, decreasing Ca+ levels in blood;
low Ca+ levels in blood stimulates chief cells of parathyroid to release Parathyroid hormone;
parathyroid hormone promotes reabsorption of bone extracellular matrix, Ca+ released into blood