Endocrine System

Some Review First 4 types of cell signal mechamisms  Direct Contact- see table and page 127  Paracrine Signaling, message transmitted to neighboring cells  Synaptic signaling — neurotransmitters carry messages between nerve cells  *Endocrine signaling —hormones travel through circ system  Focus of this presentation

Hormones-4 groups  Polypeptides-short chains of aa’s- insulin and ADH (anti-diuretic hormone)  Glycoproteins-longer chains of aa’- FSH and LH (from reproductive system)  Amines-from tyrosine and tryptophan-melanin and epinephrine  Steroids- derived from cholesterol (inc. ring shape)-testosterone and progesterone

2 Hormone Mechanisms  Lipid or steroid hormones—diffuse into cell and trigger response  Protein or peptide hormones– use a second messenger system Hormone binds (1 st messenger) Triggers intracellular response via a G protein  c AMP (second messenger)

ANTERIOR PITUITARY HORMONES  Growth Hormone (GH) – Stimulates bone growth  Luteinizing Hormone (LH) – Stimulates ovaries and testes  Named for corpus luteum  Follicle Stimulating Hormone(FSH)- stimulates gonads to produce sperm and ova  Named for follicle  Thyroid Stimulating Hormone (TSH)- Stimulates thyroid gland

Gigantism

Posterior Pituitary Hormones  Oxytocin – Stimulates contractions of uterus and mammary glands, associated with love and bonding.  Antidiuretic hormone (ADH) – retention of water by kidneys

GONADS AS GLANDS  Ovaries Estrogen – stimulates uterine lining, development of primary and secondary female characteristics Progesterone – Uterine lining growth, helps maintain pregnancy  Testes Androgens (testosterone) – sperm production (after stimulation by FSH), secondary sex characteristics

Thyroid  Thyroxine– controls metabolic rate  Calcitonin– lowers blood calcium levels (deposits Ca++ in bone)  Hypothyroidism may lead to goiter  Hyperthyroidism may lead to protrusion of the eyes (bulging) and Grave’s Disease Both problems make it difficult to control metabolic rate

Cretinism Hyposecretion of thyroxine in childhood

Parathyroid  Parathyroid Hormone (PTH) Raises blood calcium level (removes Ca ++ from bone) Hypoparathyroidism - Bones become weakened  Osteoporosis—same outcome, but for a variety of reasons

Osteoporosis

PANCREAS- Islets of Langerhans  Insulin – β cells – lowers blood glucose levels  Glucagon – α cells -raises blood glucose levels Read Analyzing Functions of Pancreas (Dog Studies)

Diabetes  Type 1 – Hyposecretion of Insulin, Insulin Dependent diabetes  Type 2 – Cellular response to insulin is decreased Associated with obesity, strong diet correlation

Diabetes Uncontrolled diabetes can lead to damage of many systems. Some problems may be kidney disease, nervous system problems, blindness, peripheral vascular disease.

Adrenal Glands  Adrenal Medulla – Catecholamines Epinephrine and Norepinephrine raises blood sugar by incr. breakdown of glycogen in liver, short term stress response  Adrenal Cortex --Glucocorticoids -- raise blood sugar levels, long term stress response Overproduction—Cushing’s Disease (breakdown of proteins and unusual fat distribution) Long term stress has adverse effects on many systems

THYMUS  Thymosin– Stimulates T lymphocytes

Pineal  Melatonin - Biorhythms –Day and Night Cycles

Homeostasis  Homeostasis may be thought of as a see-saw  (Look at anatomy transparency 14.20)  Negative feedback--Return to baseline- balance see-saw  Positive feedback--Continued unbalance

ANTAGONISTS  Antagonistic hormones have opposite effects. They work together to maintain homeostasis.  Ex: Insulin and Glucagon, PTH and Calcitonin

GLAND INTERACTIONS  Glands may stimulate (or inhibit) other glands See Thyroxine secretion page 1004 See testes and anterior pituitary page 1071

CASE STUDIES  See page 102 in ABLE