Biology 212 Anatomy & Physiology Dr. Thompson Endocrine System

Hormones: Three major chemical groups: 1)

Hormones: Three major chemical groups: 2)

Hormones: Three major chemical groups: 3)

Endocrine System

Hormones can produce a variety of changes in their target cells: -

A specific hormone can only affect cells which have specific receptors for it on their plasma membranes.

Any single hormone can have only one effect on any specific target cells, but it may affect different types of target cells in different ways. For example, epinephrine can: Stimulate contraction of smooth muscle cells in arterioles of intestines Inhibit contraction of smooth muscle cells in arterioles of leg muscles Stimulate cardiac muscle cells to contract more quickly Stimulate sweat glands to secrete sweat Stimulate liver cells to release glucose into the blood Stimulate fat cells to break down and release fats into the blood

The effect of a hormone on its target cells can be changed (increased or decreased) by: - Changing Upregulation Downregulation

Pituitary Gland

Anterior pituitary

1) Growth Hormone 2) Thyroid Stimulating Hormone 3)Adrenocorticotropic Hormone 4) Prolactin 5) Follicle Stimulating Hormone 6) Luteinizing Hormone

Posterior pituitary

1) Oxytocin 2) Antidiuretic Hormone

Thyroid Gland:

Triiodothyronine & tetraiodothyronine Calcitonin

Parathyroid Glands:

Adrenal Glands:

Adrenal Medulla:

Adrenal Cortex: Secretes more than twenty different steroid hormones, collectively called the Secretory cells arranged in three concentric layers, each of which secretes a specific group of corticosteroids. From superficial to deep: -

Cells in zona glomerulosa

Cells in zona fasciculata

Cells in zona reticularis

Pancreas:

Primarily an exocrine gland 99% of cells secretes digestive enzymes into small intestine

Pancreas: Primarily an exocrine gland 99% of cells secretes digestive enzymes into small intestine

Pancreatic Islets: Alpha cells Beta cells

Diabetes Mellitus Two forms: INSULIN DEPENDENT (Type I; Juvenile-onset) NON-INSULIN DEPENDENT (Type II; Adult-onset)

Gonads:

Produce most of the steroid sex hormones Testes:

Gonads: Produce most of the steroid sex hormones Ovaries:

Many other organs also contain cells & tissues which secrete hormones. Examples: Kidney: Renin (blood pressure) Erythropoietin (erythrocyte development) Calciferol (blood calcium) Heart: Atrial natriuretic hormone (blood sodium) Liver: Angiotensin (blood pressure) Thymus: Thymopoietin (lymphocyte development) Stomach: Cholecystokinin (gall bladder contraction) & Secretin (pancreas secretion) Intestine: Gastrin (stomach function)