Endocrine System

Question 1

How hormones work

Answer 1

Hormones are secreted into the circulatory system

Hormones reach all parts of the body, but only affect cells that have a receptor for that hormone

Question 2

Nervous system vs. endocrine system

Answer 2

Nervous system: fast and wired (ex-muscle contraction)

Endocrine system: slower and wireless (ex- growth and reproduction)

Question 3

Endocrine signaling

Answer 3

Hormones are released into the blood and trigger signals anywhere

Question 4

Paracrine signaling

Answer 4

Molecules trigger cells nearby

Question 5

Autocrine signaling

Answer 5

Molecule triggers itself

Question 6

Synaptic signaling

Answer 6

Neurotransmitter released from synapse triggers cell

Question 7

Neuroendocrine signaling

Answer 7

Neurohormones released into blood from nerves trigger cells anywhere

Question 8

Difference between endocrine and exocrine glands

Answer 8

Endocrine: ductless organs, release into bloodstream
Exocrine: ducts, release into a lumen

Question 9

Tropic hormone

Answer 9

Causes release of other hormone

Question 10

Path of hormone secretion

Answer 10

1. Neurosecretory cells of hypothalamus secrete first hormone
2. First hormone travels down portal vessels to anterior pituitary gland
3. Endocrine cells of anterior pituitary gland release second hormone
4. Second hormone travels out of anterior pituitary and into general circulation
5. Second hormone triggers target cells to release their hormones
6. Hormones from target cells take effect

Question 11

3 major classes of hormones

Answer 11

Polypeptides and peptides (water soluble)
Amines (water soluble)
Steroids (lipid soluble)

Question 12

Water soluble secretion pathway

Answer 12

Hormone is released from cell by exocytosis -> travels through bloodstream on its own (no carrier needed) -> binds to signal receptor on outside of target cell -> cytoplasmic response or gene regulation

Question 13

Lipid soluble secretion pathway

Answer 13

Hormone diffuses through plasma membrane -> travels through bloodstream via protein carrier -> binds to signal receptor inside target cell -> gene regulation -> cytoplasmic response

Question 14

Positive feedback

Answer 14

Reinforces stimulus, but must have end point

Example: oxytocin causes stretching of cervix -> more oxytocin -> more cervix stretching (endpoint: baby born)

Question 15

Negative feedback

Answer 15

Decreases stimulus

Example: high glucose in blood causes release of insulin -> insulin causes decrease of glucose in blood

Question 16

Insulin

Answer 16

Decreases blood glucose (causes body cells to take up glucose and causes liver to store glucose as glycogen)
Produced in pancreatic beta cells
Peptide

Question 17

Glucagon

Answer 17

Increases blood glucose (causes liver to break down glycogen and release glucose into blood): opposite of insulin
Produced in pancreatic alpha cells
Peptide

Question 18

Diabetes mellitus

Answer 18

Caused by deficiency of insulin or a decreased response to insulin in target tissues
Problem: elevated blood glucose levels
Damage to capillaries in kidneys, eyes, and feet
Become dehydrated

Question 19

Type 1 diabetes mellitus

Answer 19

Autoimmune disorder: immune system destroys pancreatic beta cells
Juvenile onset
Treatment: insulin injections

Question 20

Type 2 diabetes mellitus

Answer 20

Insulin deficiency or reduced response of target cells due to change in insulin receptors
Adult onset
Obesity is common cause
Treatment: diet and exercise (cells take up glucose)

Question 21

Thyroid hormone

Answer 21

Pair of hormones: Triiodiothyronin (T3; 3 iodine atoms) and Thyroxine (T4; 4 iodine atoms)
Controls body metabolism
Steroid

Question 22

Thyroid hormone cascade

Answer 22

TRH (thyrotropin-releasing hormone; hypothalamus) -> TSH (thyroid stimulating hormone; anterior pituitary) -> TH (thyroid hormone)
TH inhibits TSH and TRH

Question 23

Hypothyroidism

Answer 23

Too little thyroid function

Symptoms: weight gain, lethargy, cold intolerance

Question 24

Hyperthyroidism

Answer 24

Excessive production of thyroid hormone

Symptoms: high temperature, sweating, weight loss, irritability, high blood pressure

Question 25

Graves’ Disease

Answer 25

Form of hypothyroidism caused by autoimmunity

Symptom: protruding eyes

Question 26

Goiter

Answer 26

Enlarged thyroid gland caused by insufficient dietary iodine