Animal Hormones and Endocrine System

Question 1

What are animal hormones?

Answer 1

Chemical signals secreted into the circulatory system and reaches target cells with receptors for that hormone.

Question 2

What long-lasting responses does the Endocrine system affect?

Answer 2

1. Reproduction
2. Development
3. Energy Metabolism
4. growth
5. Behaviour

Question 3

How does the endocrine system and nervous system interact?

Answer 3

High speed electrochemical signals are conveyed along specialized cells called neurons that regulate other cells including other neurons, muscle cells and endocrine cells.

Question 4

How does endocrine signalling work? What does it do?

Answer 4

Hormones secreted from endocrine cells into extracellular fluids and reach their targets via the bloodstream. It maintains homeostasis, mediates responses to stimuli, and regulates growth and development.

Question 5

What are local regulators?

Answer 5

Molecules that act over short distances reaching target cells solely by diffusion.

Question 6

What is the difference between paracrine signalling and autocrine signalling?

Answer 6

Paracrine: target cells are near the secreting cells

Autocrine: target cell is also the secreting cell

Question 7

What are synapses?

Answer 7

specialized junctions formed from neurons and target cells. It is paracrine if the target is muscle, and autocrine if the target is another neuron.

Question 8

How does synaptic signalling work? What does it do?

Answer 8

Neurons at synapses secrete neurotransmitters that diffuse short distances and bind to target cell receptors. It triggers responses in cognition, movement, memory, and sensation.

Question 9

How does Neuroendocrine signalling work?

Answer 9

1. stimulus is received by sensory neuron, stimulating neurosecretory cell
2. neurosecretory cell secretes neurohormone which enters the bloodstream and travels to target cells.

Question 10

How does pheromone signalling work? What does it do?

Answer 10

Chemical signals are released into the external environment rather than the internal environment. It is used to mark trails leading to food, defining territories, warning predators, and attracting potential mates.

Question 11

What are the three major classes of hormones in vertebrates?

Answer 11

1. Polypeptides (proteins and peptides)
2. Amines derived from amino acids
3. Steroid hormones

Question 12

What is the difference between lipid-soluble hormones and water-soluble hormones in terms of their molecules, how they are secreted, travelling through bloodstream, and their receptors.

Answer 12

Lipid-soluble: steroid hormones that diffuse through cell membranes. Receptor is in cytoplasm or nucleus.

Water-soluble hormones: polypeptides and amine hormones that are secreted by exocytosis and travel freely in the blood stream. Receptor is on the membrane of the cell.

Question 13

How does gaseous signalling work? What is an example?

Answer 13

Cells produce gases that have local signalling effects due to their small size and lack of charge which gives them the ability to diffuse in lipid and water. (E.g. Nitric Oxide, gas that functions in the body as a local regulator and neurotransmitter.)

Question 14

How is insulin made and what does it do?

Answer 14

Produced as a long inactive prohormone polypeptide stored in beta-cells. They are then cleaved and secreted by vesicular trafficking when needed to reduce blood glucose.

Question 15

What are amide hormones? What are three examples?

Answer 15

Signalling factors produced from amino acids. (e.g. epinephrine made from tyrosine, thryoxine made from tryptophan, GABA made from glutamate)

Question 16

What is the response of a pathway of a water-soluble hormone?

Answer 16

Responses in the cytoskeleton, enzyme activation, or change in gene expression.

Question 17

What is the pathway of epinephrine?

Answer 17

1. Epinephrine is released by adrenal gland
2. Binds to receptors on the plasma membrane of liver cells
3. Binding triggers release of messenger molecules that activate enzymes
4. Messenger molecule activates enzyme that breakdowns glycogen to release glucose in the bloodstream

Question 18

what is the response of a pathway of a lipid-soluble hormone?

Answer 18

Change in gene expression

Question 19

What is the pathway for a steriod?

Answer 19

1. Steroid binds to cytosolic receptor
2. hormone-receptor complex moves into nucleus
3. in the nucleus, the receptor part of the complex acts as a transcription factor to regulate the transcription of specific target genes.

Question 20

What is the hormone that regulates metabolism in vertebrates, as well as the metamorphosis of a frog?

Answer 20

Thyroid hormone

Question 21

What are endocrine glands?

Answer 21

Ductless organs that secret hormones directly into a surrounding fluid (e.g. thyroid, parathyroid, testes, ovaries)

Question 22

What is the difference between an endocrine gland and an exocrine gland?

Answer 22

endocrine: secretions enter surrounding fluid direcetly

exocrine: secretions enter body cavities or go onto body surfaces.

Question 23

What is a simple hormone pathway?

Answer 23

1. Stimulus triggers release of hormones from an endocrine cell
2. hormones travel through the bloodstream, and interact with specific receptors within a target cell
3. Binding to receptors causes a physiological response

Question 24

What parts of the brain regulates the coordination of endocrine and nervous systems? How does it do it?

Answer 24

hypothalamus receives information from nervous system and initiates responses through endocrine signalling.

Question 25

whats the difference between posterior and anterior pituitary gland?

Answer 25

posterior: extension of hypothalamus that stores and secretes HYPOTHALAMUS hormones

anterior: releases ITS OWN hormones, controlled by releasing/inhibiting hypothalamus hormones

Question 26

What are tropic hormones?

Answer 26

Hormones that regulate the function of other endocrine cells or glands

Question 27

What is the negative feedback loop of thyroid hormone?

Answer 27

1. thyroid level drops in blood
2. hypothalamus senses this and secretes TRH from posterior pituitary
3. release of TRH causes anterior pituitary to secrete TSH
4. TSH stimulates release of thyroid hormone from the thyroid gland

Question 28

What is hypothyroidism and hyperthyroidism?

Answer 28

hypothyroidism: too little thyroid function, leads to weight gain, fatigue, cold intolerance. may be caused by malnutrition

hyperthyroidism: excessive thyroid production, leads to high temperature, sweating, weight loss, irritability, and high blood pressure

Question 29

What is the growth hormone? What does it do?

Answer 29

GH is secreted by anterior pituriatry and has both nontropic and tropic effects. It protmotes growth directly by stimulating production of growth factors

Question 30

What is the negative feedback loop for Ca2+

Answer 30

Insufficient calcium:
PTH from parathyroid glands releases CA2+ from bone and stimulates reabsorption of Ca2+ from kidneys. Stimulates kidneys to activate vitamin D which promotes intestinal uptake of Ca2+

Excessive calcium:
Calcitonin from thyroid gland stimulates Ca2+ deposition in bones and secretion by kidneys.

Question 31

Where are the adrenal glands? What do they do?

Answer 31

Found on each kidney, consists of the adrenal medulla (inner portion) and adrenal cortex. Adrenal glands secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) as a response to stress-activated impulses from the nervous system

Question 32

What do epinephrine and norepinephrine do?

Answer 32

Trigger release of glucose and fatty acids into the blood, increase oxygen delivery to the body cells, and direct blood toward the heart, brain, and skeletal muscles, and away from skin, digestive system and kidneys.

Question 33

What are corticosteroids?

Answer 33

Family of steroids that are triggered by a hormone cascade via hypothalamus and anterior pituitary. Can be glucocorticoids (influence glucose metabolism and immune system), or mineralocorticoids (influence salt and water balance)

Question 34

What are the hormones produced in the gonads? What do they do?

Answer 34

Androgens: i.e. testosterone, stimulate development and maintenance of the male reproductive system. causes an increase in muscle and bone mass.

Estrogens: i.e. estradiol, responsible for maintenance of femal reproductive system and development of female secondary sex characteristics

Progestins: i.e. progesterone, involved in preparing and maintaining the uterus for growth and development of an embry.

Question 35

What controls the synthesis of sex hormones?

Answer 35

Controlled by hormones of the anterior pituitary.

Question 36

What is the pineal gland? What does it do?

Answer 36

Pineal gland is located in the brain and secretes melatonin. Secretion of melatonin is controlled by group of neurons in the suprachiasmatic nucleus (SCN) that sense light and dark cycles