Chapter 18 Notes

Chapter 18 Notes
Endocrine Glands and their Hormones

1. Overview

Body is controlled via nerves and hormones
Purpose: Homeostasis
Endocrine glands are specialized epithelial cells
Ductless glands
Hormones secreted into blood stream

2. Characteristics

Functions:

- Kinetic: target certain body cells
- Metabolic: regulate chemical reactions in cells

Structure

- steroids: cholesterol derivatives
- amines: amino acid derivatives
- peptides and proteins: amino acid chains

3. Regulatory Mechanism

lipids pass through cell membranes and cause DNA to synthesize new protein

protein derivatives attach to receptors on cell membrane and use a second
messenger cyclic AMP which amplifies enzymes to produce hormone action inside the cell

4. Negative Feedback

a circuit where once the hormone activity increases, it is turned off

decreases secretions of hormone

3. Endocrine Glands

Hypothalamus

- secretes antidiuretic hormone and oxytocin for storage in posterior pituitary
- ADH: water retention
- OT: milk ejection and uterine contractions
- secretes Releasing Hormones which regulate the anterior pituitary

1. GHRH: stimulates production of human growth hormone
2. GHIH: inhibits the release of the growth hormone
3. TRH: stimulates the release of the thyroid stimulating hormone
4. GnRH: stimulates release of both gonadotropins, FSH and LH
5. PRH: stimulates release of prolactin
6. PIH: prolactin inhibiting hormone
7. CRH: stimulates the release of ACTH

Anterior Pituitary Gland

- human growth hormone (hGH): growth via mitosis and metabolism
- thyroid stimulating hormone (TSH): acts on thyroid gland
- follicle stimulating hormone (FSH): development of follicles in ovaries and sperm production
- leutinizing hormone (LH): ovulation, stimulates progesterone and testosterone secretion
- prolactin (PRL): milk secretion
- adrenocorticotropic hormone (ACTH): stimulates adrenal cortex production
- melanocyte-stimulating hormone (MSH): may cause the distibution of melanin

Thyroid

- thyroxine (T4): cell growth and metabolism
- triiodothyronine (T3): cell growth and metabolism
- calcitonin: bone uptake of calcium and phosphate

Parathyroid

- parathormone (PTH): bone release of calcium and phosphate

Adrenal Cortex

- cortisol: anti-inflammatory and stress reduction
- aldosterone: Na+, K+, and water balance

Adrenal Medulla

- epinephrine: mimics sympathetic nervous system

Pancreas

- insulin: decreases blood glucose levels
- glucagon: increases blood glucose levels

Testes and Ovaries

- testosterone: sperm production and male secondary sex characteristics
- estrogen and progesterone: ova maturation, uterine preparation for pregnancy,
and female secondary sex characteristics

Pineal gland

- melatonin: responsible for the onset of puberty and biological rhythms