L5: Secretion, transport and clearance of hormones - Action of Hormones

Question 1

Two parts of the nervous system

Answer 1

peripheral and central (brain and spinal cord)

Question 2

Two parts of the peripheral system

Answer 2

autonomic system and somatic system

Question 3

Autonomic system

Answer 3

controls self-regulated action of internal organs and glands

Question 4

Somatic system

Answer 4

controls voluntary movements of skeletal muscles

Question 5

Two parts of autonomic system

Answer 5

sympathetic and parasympathetic

Question 6

Sympathetic

Answer 6

arousing

Question 7

Parasympathetic

Answer 7

calming

Question 8

three things that activation of SNS is responsible for

Answer 8

1. Increases in heart rate which leads to circulation of blood and delivering oxygen to tissues in need
2. increase in respiration rate which allows to have more oxygen to deliver
3. Cause peripheral vasoconstriction which will constrict vessels so blood will go to more important parts of the body

Question 9

Are polypeptides with 100+ amino acids called proteins or peptides?

Answer 9

proteins

Question 10

Are polypeptides with <100 amino acids called proteins or peptides?

Answer 10

Peptides

Question 11

Describe the protein and polypeptide hormone synthesis and release

Answer 11

1. mRNA is going to be converted into amino acid on the ribosome of the ER. This amino acid chain is called preprohormone, which is then directed into the ER lumen by a signal sequence of amino acids.
2. Enzymes in the ER chop off the signal sequence, creating an inactive prohormone.
3. Prohormone then passes from the ER through the golgi apparatus
4. Secretory vesicles containing the enzymes and prohormone bud off the golgi. The enzymes chop the prohormone into one or more active peptides plus other fragments.
5. Secretory vesicle releases its contents by exocytosis into extracellular space
6. The hormone moves into circulation for transport to its target.

Question 12

What causes vesicle secretion?

Answer 12

• increasing calcium concentration

- increasing CAMP and activation of protein kinases

Question 13

Steroid hormones are usually synthesized by ________.

Answer 13

cholesterol

Question 14

What are the advantages of steroid hormones being lipid soluble?

Answer 14

because once steroid hormones are synthesized they diffuse across cell membrane and enter the interestial fluid and then the blood. This is a quick process unlike proteins which use exo- and endo- cytosis.

Question 15

Where are the two different tyrosine derivative hormones from?

Answer 15

thyroid and adrenal medulla

Question 16

How is hormone concentration tightly regulated in blood?

Answer 16

through metabolism and excretion: liver, blood, sweat, kidneys
also through negative feedback loops

Question 17

Example of negative feedback loop

Answer 17

hypothalamus secretes thyroid releasing hormone (TRH). TRH then stimulates pituitary to release thyroid stimulating hormone (TSH). Thyroid will then be stimulated by TSH to release T3 & T4 (responsible for metabolism), which will travel through the body to search for receptors. Some receptors are in hypothalamus and pituitary, and when they bind to these receptors, they signal these glands to stop making these hormones.

Question 18

Difference between peptides and catecholamines, and steroid and thyroid hormones.

Answer 18

peptides and catecholamines are water soluble hormones which can easily dissolve within plasma and can easily be transported to their target organs, where they can diffuse out of the capillaries into IF and then the target tissue fairly quickly. Meanwhile, steroids and thyroid hormones are bound to plasma proteins preserving hormones for longer period of time.