L.E. Bio Topic 10 Regulation Part II. The Endocrine System

Made up of: –Endocrine Glands blood streamSend hormones directly into blood stream ductlessNo tubes ductless Exocrine glands have tubes or ducts much –Hyper secretion - too much of a hormone is secreted little –Hypo secretion – too little of a hormone is secreted

Human Endocrine Glands

Picture of the Endocrine System

Hypothalamus brainA small region of the brain Releases hormones that link the endocrine system with the nervous system Major link between the body's two Regulatory systems!Major link between the body's two Regulatory systems!

Pituitary Gland brainAt base of brain Master Gland“Master Gland” otherRegulates other endocrine glands hormonesMakes many hormones – –Direct –Direct, acts on effectors –Indirect –Indirect, acts on other glands

LDHB Pituitary Hormones LDHB GSH – Growth stimulating hormone - Direct growth of long bones –Stimulates growth of long bones Dwarfism –Hypo secretion – Dwarfism Giantism LDHB –Hyper secretion – Giantism LDHB

Pituitary Hormones TSH – Thyroid Stimulating Hormone - Indirect thyroid thyroxin –Stimulates the thyroid to stimulate thyroxin

Pituitary Hormones FSH – Follicle Stimulating Hormone - Indirect follicles (eggs) ovaries –Stimulates development of follicles (eggs) in ovaries (females) sperm –Influences sperm production (males)

Pituitary Hormones ACTH – Adrenocorticotropic Hormone - Indirect cortisone –Stimulates adrenal gland to secrete cortisone

Pituitary Hormones LH – Lutenizing Hormone - Indirect corpus lutetium –Stimulates formation of the corpus lutetium (ovary) testosterone –Stimulates secretion of testosterone (testies)

Pituitary Hormones Prolactin - Indirect –Milk secretion in females Vasopresin - Indirect –Controls reabsorption of water in kidneys Oxytocin - Indirect –Stimulates contraction of uterus during labor

Thyroid Gland neckIn neck ThyroxinSecrets Thyroxin metabolism –regulates rate of metabolism –Essential for normal physical and mental development IodineIodine needed -Goiter

Goiter Why we use iodized salt

Thyroid Gland (thyroxin) Hypo Secretion (too little) –Low metabolic rate –Person is tired and often over weight –Creationism Hyper Secretion (too much) –High metabolic rate –Person is “Hyper” and often thin

Parathyroid Gland Embedded in the thyroid gland parathormoneSecretes parathormone –Controls calcium (Ca) metabolism –Necessary for nerve and muscle function, blood clotting, growth of bone and teeth

Adrenal Glands Located on top of kidneys adrenalineSecrete adrenaline –Raises heart rate and blood pressure –Helps in times of stress Secretes cortisone joints –For healthy joints Secretes steroids –Converts fats and proteins to glucose

Islets of Langerhans (pancreas) Small groups of cells on the pancreas InsulinSecret Insulin –Lowers –Lowers blood sugar – promotes absorption into cells GlucagonSecretes Glucagon –Raises –Raises blood sugar – promotes the conversion of glycogen into glucose

The Gonads (Sex Glands) Ovaries- estrogen –Secrete estrogen Egg development secondary sex characteristicsDevelopment of secondary sex characteristics (list) progesterone –Secrete progesterone Promotes the thickening if the uterine lining Testis- testosterone –Secrets testosterone secondary sex characteristicsDevelopment of secondary sex characteristics (list) Sperm Production

Thymus Underneath the sternum Thymosin –Secretes Thymosin immune systemHelps to develop the immune system Shrinks with age.

Feedback A change in one quantity causes a change in a second quantity, which then in turn causes a change in the first quantity. Types escalate –Positive Feedback, Levels will continue to escalate Keeping up with the Jones’. A stabilizing effect –Negative Feedback, a type of feedback that opposes the initial change. A stabilizing effect

Maintaining homeostasis high low hormone 1 lowers body condition hormone 2 gland specific body condition raises body condition gland Feedback

Negative Feedback Level of one hormone stimulate or inhibit the production of a second hormone. The second hormone level in the blood then in turn stimulates or inhibits the production of the first hormone. See diagram and example

Negative Feedback Response to changed body condition –if body is high or low from normal level signal tells body to make changes that will bring body back to normal level –once body is back to normal level, signal is turned off high hormone 1 lowers body condition gland specific body condition

Negative Feedback Example TSH and Thyroxin When Thyroxin level drops below the homeostatic level, the pituitary is stimulated to secrete TSH. TSH then stimulates the thyroid gland to secrete thyroxin. When Thyroxin level rises to the homeostatic level, TSH secretion by the pituitary is inhibited.

Negative Feedback pict. TSH Thyroxin

liver pancreas liver Regulation of Blood Sugar blood sugar level (90mg/100ml) insulin body cells take up sugar from blood liver stores sugar reduces appetite glucagon pancreas liver releases sugar triggers hunger high low Feedback Endocrine System Control Diabetes: insulin deficiency- results in an elevated blood sugar level (glucose)

Cell Membrane Receptors receptor molecules Many cell membranes have receptor molecules on their surface. These receptor sites play an important role in allowing cells and organs to communicate with one another.

A Hormonal Feedback Mechanism The animation at the right illustrates how a hormone can bind to receptors on a cell membrane and trigger that cell to produce a needed compound.

Responding to hormones Lock and key system –hormone fits receptor on “target” cell target cell non- target cells secreting cell can’t read signal

Regulation by chemical messengers axon endocrine gland receptor proteins target cell Neurotransmitters released by neurons Hormones release by endocrine glands receptor proteins hormone carried by blood neurotransmitter