FINAL: Endocrine System

Question 1

What does regulation of homeostasis require

Answer 1

Sensory input, integration and communication between organs

Question 2

What is the nervous system

Answer 2

Made of nervous tissue
- electrical signals and chemical messages (neurotransmitters)
- fast, direct communication to target tissue

Question 3

What is the endocrine system

Answer 3

Made of glandular tissue (secretes something)
- chemical messages (hormones)
- slower, indirect communication to target tissue (must have receptors)

Question 4

Hormones are either….

Answer 4

Steroid or protein (non-steroid)

Question 5

What is a steroid

Answer 5

• Made from cholesterol (a type of lipid)
• Ex. Testoterone and estrogen

Question 6

What are protein hormones

Answer 6

• typically polar and/or negatively charged
• made from amino acids
• ex. Insulin

Question 7

How do hormones interact with target cells to alter the function of the cell (usually by making new proteins)

Answer 7

1. A hormone travels through the bloodstream
   - from source gland to target tissue
2. Target tissue is determined by receptors
   - receptors are proteins in the plasma membrane (for protein hormones) or cytoplasm (steroid hormones)
3. Receptors act like switches to turn on or off gene expression
   - causes molecular changes
   - primarily activation (or synthesis) of proteins
   Hormone/receptor complex must be terminated

Question 8

Example of steroid hormone action

Answer 8

Question 9

Where are the digestive endocrine glands located

Answer 9

Pancreas, liver

Question 10

Where are the reproductive endocrine glands located

Answer 10

Gonads (testes, ovaries)

Question 11

Where are the nervous endocrine glands located

Answer 11

Hypothalamus, pituitary gland, pineal gland

Question 12

What organs are unique to the endocrine system

Answer 12

Thyroid, parathyroid and adrenal glands

Question 13

Function of the anterior pituitary gland

Answer 13

Synthesize and secrete hormones (a true endocrine gland)

Question 14

Function of the posterior pituitary gland

Answer 14

Store and secrete hormones (extension of neural tissue, not an endocrine gland)

Question 15

Function of the pituitary gland

Answer 15

Regulate many endocrine organs throughout body ( regulation is called an axis )

Question 16

What does the hypothalamic-pituitary axis involve

Answer 16

It involves the hypothalamus, anterior pituitary, endocrine glands and target cells

Question 17

How does the hypothalamic -pituitary axis regulate

Answer 17

• hypothalamic neurons produce hormones (typically a releasing hormone (RH))
• RH triggers release of hormone from pituitary gland (hormone 1)
• Hormone 1 triggers release of hormone 2 from another endocrine gland
• hormone 2 causes change in target tissue
  (Also limited hypothalamic production of RH hormones = negative feedback)

Question 18

Example of growth hormone and growth hormone releasing hormone forming an negative feedback loop

Answer 18

Question 19

Effects of growth hormone

Answer 19

Wide ranging effects
- affects metabolism
- stimulates liver to produce insulin like growth factors (IGFs)

Question 20

What are IGFs

Answer 20

Hormones that stimulate growth
- increase division of chondrocytes
- increase activity of osteoblasts
- triggers hypothalamus to produce somatostatin (which inhibits GH)

Question 21

What is gigantism

Answer 21

In children an increase in height at epiphyseal plates, due to overproduction of growth hormone
- usually the result of a tumor on the pituitary gland

Question 22

What is acromegaly

Answer 22

In adults, the thickening of the bones (growth in width) due to overproduction of growth hormone
- usually the result of a tumor on the pituitary gland

Question 23

GH levels throughout a lifespan

Answer 23

Question 24

Why do we stop growing

Answer 24

• GH levels drop after puberty
• Sex hormone levels peak at puberty
  
  • Includes estrogen (produced by gonads: ovaries and testes)
  • Estrogen stimulates osteoblasts and inhibits osteoclasts

Question 25

How does the closure of epiphyseal plates occur

Answer 25

• during puberty high GH levels stimulate chondrocyte division
• at the same time, rising estrogen levels stimulate osteoblasts activity
• osteoblasts eventually “out-compete” chondrocytes and the epiphyseal plate completely ossifies = no more growth

Question 26

What is achrondroplastic dwarfish

Answer 26

Alteration in a gene that affects the epiphyseal plate
Limits the division of chondrocytes in epiphyseal plate
Mostly affects the limbs

Question 27

What is osteoporosis

Answer 27

When bone resporption outpaces bone deposition
Spongy bone is most vulnerable
It commonly occurs in older women as estrogen levels drop

Question 28

What is the parathyroid hormone

Answer 28

An important hormone that helps to regulate free calcium concentrations in our body
- secreted by the parathyroid glands located in the neck, closely associated with the thyroid gland

Question 29

What is hydroxyapatite

Answer 29

The mineralized ground substance found in osseous tissue

Question 30

What is hypocalcemia

Answer 30

Low blood calcium levels
- Parathyroid hormone is released to bring blood calcium back to ideal range by stimulating osteoclasts to release bone calcium into the blood stream

Question 31

What is hypercalcemia

Answer 31

High blood calcium levels
- calcitonin is released to inhibit osteoclasts and activate osteoblasts, returning blood calcium to ideal range