APH CH 11 endocrine system

Nervous

Cells

Neurons

Endocrine

Cells

Glandular epithelium

Nervous

Chemical

Neurotransmitters

Endocrine

Chemical

Hormones

Nervous

Response

Receptors on postsynaptic cell

Endocrine

Response

Receptors on target cell

Nervous

Speed

Seconds

Endocrine

Speed

Seconds to hours

Nervous

Duration

Very brief unless neuronal activity continues

Endocrine

Duration

May be brief or last for days - years even if secretion ceases

Endocrine system

Includes cells, tissues, and organs collectively called endocrine glands that secrete hormones

2 main types of glands

Exocrine and Endocrine

Exocrine Glands

Secrete fluid to the outside of the body

Ex: Sweat glands, salivary glands, mammary glands and sebaceous glands

Endocrine glands

release hormones into the bloodstream

Ex: pituitary gland, thyroid gland, parathyroid gland, adrenal gland and pancreas, pineal gland, thymus gland, testis, and ovary

Functions of glands and their hormones

a) Regulate metabolic processes

b) Control rates of certain chemical reactions

c) Aid in transport of substances across the membrane

d) Regulates water and electrolyte balance

e) Reproduction, development, and growth

Endocrine glands secrete substances called _______ into the internal environment

hormones

Hormones diffuse from the interstitial fluid into the blood stream, and act on cells called

target cells

Only target cells with specific protein or __________ binding sites can respond to a hormone

glycoprotein

Hormones and target cells are like

“locks and keys” or “puzzle pieces”

Steroids -

made from cholesterol (lipids); water insoluble

Anabolic steroids -

synthetic substances related to the male sex hormones (androgens)

Ex: estrogen, and testosterone

Corticosteroids -

drugs closely related to cortisol, a hormone which is naturally produced in the adrenal gland. Act on the immune system by blocking the production of substances that trigger allergic and inflammatory actions

Non- steroids -

made from amino acids

Ex: insulin, Growth hormone, epinephrine

Negative Feedback Loop

Mechanism used by the Endocrine System that is activated to correct an imbalance in order to correct itself

Negative Feedback Loop

Excess of a particular hormone may shut off its production

Negative Feedback Loop

Excess or lack of a hormone may signal the production of another

Negative Feedback Loop

Ex: Blood Sugar Regulation

Pancreas (insulin, glucagons)

Increased sugar levels stimulates the beta cells to produce insulin and inhibits production of glucagons

Low sugar levels stimulates glucagons to be release from the alpha cell which increase sugar level in the body

Positive Feedback Loop

Process by which changes cause additional similar changes; moving away from “normal”

Positive Feedback Loop

Ex: Stretching of the uterine tissue causes the hypothalamus to signal the posterior pituitary gland to release oxytocin. Oxytocin stimulates uterine contractions. Uterine contractions stimulates more powerful contractions stimulating the release of more oxytocin... Etc...

Positive Feedback Loop

Ex: Blood clotting to minimize bleeding