Notes 18

Question 1

What are hormones?

Answer 1

Signalling molecules that regulate different body
functions. “Horman” == Greek “to excite”

Question 2

What is the endocrine system?

Answer 2

communicating and regulating system

Question 3

What are the types of signalling?

Answer 3

Endocrine signalling and paracrine signalling. There are also synaptic and neuroendocrine signalling (different systems)

Question 4

What is endocrine signalling?

Answer 4

Hormones released into interstitial fluid travel via bloodstream to distant targets

Question 5

What is paracrine signalling?

Answer 5

Signals only travel to nearby cells
Autocrine signalling: The target cell is the same as the one sending the signal

Question 6

What is synapic signalling?

Answer 6

Uses the nervous system (next unit): signal molecules are neurotransmitters (not hormones)

Question 7

What is neuroendorine signalling?

Answer 7

Uses the nervous system working together with the endocrine system

Question 8

How can you classify hormones?

Answer 8

Hydrophilic or hydrophobic

Question 9

How do hydrophobic and hydrophilic hormones differ?

Answer 9

Water soluble (hydrophilic) hormones is actively secreted from the cell, but then freely diffuses into blood. To enter target cell, it needs a receptor protein.
Lipid soluble (hydrophobic) hormones is diffuses freely in and out of secretory and target cell. To enter blood vessel, it needs a transport protein.

Question 10

How does signal transduction happen for water-soluble hormones?

Answer 10

When a hormone binds to a receptor protein at the
membrane, it triggers a cellular response.
This could be:
- enzyme activation
- change in uptake of a
specific molecule
- rearrangement of the
cytoskeleton
- proteins moving into nucleus
and altering gene transcription

Question 11

How does signal transduction happen for lipid-soluble hormones?

Answer 11

When a hormone binds to a receptor protein in the
cytoplasm, it triggers a cellular response. This is usually a change in gene expression.

Question 12

What is epinephrine?

Answer 12

Epinephrine == adrenaline (“fight or flight” hormone)
Increasing blood glucose → Energy for escape
Increase blood flow to skeletal muscles → brings more oxygen to those muscles about to get moving. Has alpha and beta forms which when added to different target tissue (same form) that does different things and takes on different forms. When alpha and beta forms go on the same tissue, they have opposite reactions (one contracts, one relaxes).

Question 13

How do simple endocrine pathways work?

Answer 13

Cells respond directly to an internal (e.g., changing pH) or external (e.g., scary predator) stimulus by secreting a hormone. The hormone travels in the bloodstream to the target cell. Target cell brings a physiological response

Question 14

How do simple neuroendocrine pathways work?

Answer 14

Stimulus is received by a sensory neuron, which stimulates a neurosecretory cell. The neurosecretory cell then secretes a hormone. The hormone travels in the bloodstream to the target cell. Target cell brings a physiological response

Question 15

Whats the difference in postibe and negative feedback?

Answer 15

The key difference between positive and negative feedback is their response to change: positive feedback amplifies change while negative feedback reduces change. This means that positive feedback will result in more of a product: more apples, more contractions, or more clotting platelet

Question 16

What does the hypothalamus do in the endocrine system?

Answer 16

The hypothalamus plays a central role in regulating the
endocrine and nervous systems. The hypothalamus signalsto the pituitary. The pineal gland helps regulate biorhythm

Question 17

What does the pituitary gland do in the endocrine system?

Answer 17

The posterior pituitary is an extension of the hypothalamus. The axons from the brain secrete neurohormones. The anterior pituitary is a gland in the
synthesis and secretes hormones in response to signals from the hypothalamus. Many anterior pituitary hormones are tropic hormones → regulate other endocrine cells/glands

Question 18

What are the hormones in the posterior pituitary?

Answer 18

ADH – regulates kidney function
Oxytocin – mammary glands (lactation, uterine contractions in childbirth, also brain function)

Question 19

What are the hormones in the anterior pituitary?

Answer 19

FSH (testes or ovaries), TSH (thyroid gland), ACTH (adenal cortex, Prolactin (mammary glands), MSH (melanocytes), and GH (liver,bones, tissues).
Can have:
Tropic effects – regulate other endocrine cells/glands
Non-tropic effects –direct action

Question 20

How do thyroid hormones respond to a drop?

Answer 20

Thyroid levels drop. The hypothalamus secretes TRH into the blood. portal vessels carry TRH to the anterior pituitary. TRH causes the anterior pituitary to secrete TSH. TSH stimulates endocrine cells in the thyroid gland to secrete T3 and T4. Thyroid hormones block TRH release and TSH release preventing overproduction of thyroid hormones. Thyroid hormone levels return to normal range.

Question 21

What are some thyroid disorders?

Answer 21

Hypothyroidism: too little thyroid hormone produced (Weight gain, lethargy, cold intolerance)
Hyperthyroidism: too much thyroid hormone produced (Grave’s disease (autoimmune disease))
Malnutrition (low Iodine in diet) inhibits synthesis of T3
and T4; this triggers the pituitary to continue to secrete
TSH

Question 22

What do parathyroid hormones do in the parathyroid glands?

Answer 22

Regulate blood Calcium levels. Ca2+ ions are essential for normal function of cells. PTH raises blood Ca2+ directly and indirectly.

Question 23

How does blood calcium regulation work in mammals?

Answer 23

The stimulus is the falling blood Ca2+ level, the parathyroid gland (behind the thyroid) produces PTH, which stimulates Ca2+ uptake in the kidneys, which creates active vitamin D leading to increased Ca2+ in the intestines and blood Ca2+ level rises.

Question 24

How do growth hormes affect people?

Answer 24

Too much causes gigantism. Too little causes
dwarfism

Question 25

What is the adrenal gland?

Answer 25

Like the pituitary; this is a fused endocrine
and neuroendocrine gland. The cortex consists of
true endocrine cells; the medulla derives from neural tissue.

Question 26

What happens in a short-term stress response to adrenal hormones? Long term?

Answer 26

Short term: The effects of epinephrine and norepinephrine:
-Glycogen is broken down into glucose which leads to increased blood glucose.
-Increases blood pressure
-Increases breathing rate
-Increases metabolic rate
-Change in blood flow patterns leading to increases alertness and decreased digestive and kidney activity.

Question 27

What happens in a long-term stress response to adrenal hormones?

Answer 27

The effects of mineralocorticoids
-Retention of sodium ions and water by kidneys
-Increased blood volume and blood pressure

The effects of glucocorticoids
-Proteins and fats broken down and converted into glucose, leading to increased blood glucose.
-Immune system may be suppressed.

Question 28

What are sex hormones?

Answer 28

Both sexes in humans have glands that produce testosterone, progesterone and estrogen, however testosterone is higher in males and estrogen/progesterone is higher in females. Sex hormones trigger puberty development, regulation
of the reproductive system

Question 29

What are sources of endocrine distruptors?

Answer 29

Dioxins, flame retardants, phthalate’s, pesticides, phytoestrogens, PFAS, and bisphenol A (BPA).