endocrine system

Endocrine System

The ductless, hormone secreting glands of the body

A. Nervous vs endocrine system

B. The effects of hormones

1. Regulate chemical composition/volume of internal environment

2. Regulate metabolism/energy

3. Regulate contraction of smooth/cardiac muscles and glands

4. Maintain homeostasis

5. Immune system

6. Growth/development

7. Reproduction influence

C. Hormone chemistry

Lipid derivative
	Steroid	Aldosterone
		Testosterone
		Estrogen
		Progesterone
	Eicosanoids	Prostoglandins
Amino acid derivatives		T₃ and T₄
		Epinephrine/norepinephrine
Peptides and Proteins		OT, ADH,
		Anterior pituitary hormones
		Insulin/glucagon

D. How they work

1. Lipid soluble hormones bind to receptors inside target cells. These

activate a hormone complex that alters gene expression to make

certain proteins.

2. Water soluble hormones bind to receptors in the plasma

membrane of the cell and use a 2^ndmessenger called cAMP to

activate certain enzymes. These enzymes cause the needed

physiological reactions

E. How control –

1. Generally a negative feedback system

a. Levels of a chemical in the blood – EX calcium ions

b. Nerve impulses - ANS inhibiting hormones

c. Hypothalamus secretions

F. Glands

Gland	Hormone(s) Secreted	Chief Action(s) Of Hormone(s)
Pituitary gland	By the anterior pituitary: Growth Hormone (HGH) Prolactin (PRL) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle - stimulating hormone (FSH) Luteinizing hormone (LH) Melanocyte stimulating hormone (MSH) By the posterior pituitary: Oxytocin (OT) Antidiuretic hormone (ADH)	Promotes growth of skeletal muscles and long bones. Stimulates milk production Stimulates thyroid gland Stimulates adrenal cortex Stimulates ovarian follicles Triggers release of egg in females; stimulates testosterone production in males MSH increases, melanin increases, skin darkness increases Stimulates uterine contractions in labor; produces “let-down” reflex to cause milk ejection Decrease in urine to retain water
Pineal Gland	Melatonin	Sleep / wake cycle
Thyroid Gland	Thyroid Hormone (T3, T4) Calcitonin (CT)	Controls rate of metabolism needed for normal tissue growth and development ↓ in blood calcium → ↑ in bone
Parathyroid Glands	Parathyroid hormone (PTH)	↑ in blood calcium → decrease in bone
Thymus	Thymosin	Turns white blood cells into antibodies
Pancreas	Insulin Glucagon	Stores glucose from blood to cells - ↓ blood sugar Releases glycogen stored in liver - ↑ blood sugar
Adrenal (Suprenal) Glands	By the adrenal medulla: Nor/epinephrine By the adrenal cortex: Aldosterone Cortisol Androgens	Fight or flight Response (Short-Term Stress) Regulate blood salts; retains salt to retain H₂O Breaks down fats, proteins, sugar for energy Contribute to onset of puberty - mostly male
Testes	Testosterone	Stimulates development of male reproductive system and secondary sexual characteristics (muscles, aggression, facial/pit/leg hair, etc); promotes sperm production
Ovaries	Estrogen Progesterone Relaxin Inhibin	Maturation of female reproductive system and development of secondary sexual characteristics in females, act with progesterone to produce menstrual cycle Acts on uterus in pregnancy to keep uterine lining blood rich; acts with estrogen to produce menstrual cycle Relaxes cervix during birth During pregnancy it inhibits FSH → no eggs

G. Organs that produce hormones, but are not endocrine glands

GI tract
	Gastrin	↑ gastric juices
	Gastric inhibitory peptide	↓ gastric juices
	Secretin	↑ pancreatic juice/bile
	CCK	↑ gastric juices/fullness
Placenta
	HCG	↑ estrogen/progesterone
	Estrogen/progesterone	Maintain pregnancy/preps mammary glands
	HGS	Preps mammary glands
Kidney
	Erythropeitin	↑ RBCs
Skin
	Vitamin D	↑ absorption Ca/P
Heart
	ANP	↓ BP

H. Stress and G.A.S.

1. Stress – physical or psychological

2. G.A.S (general adaptation syndrome)

a. Controlled by hypothalamus

b. Alarm and resistance reactions

c. G.A.S stress levels rise above syndrome the reaction of the

body when "normal" bounds