Chapter 18, part 3
The Endocrine System
SECTION 18-6 The Adrenal Glands
Adrenal cortex
Manufactures steroid hormones (corticosteroids)
Cortex divided into three layers
Zona glomerulosa (produces mineralocorticoids)
Zona fasciculate (produces glucocorticoids)
Zona reticularis (produces androgens)
Figure 18.16 The Adrenal Gland
Figure 18.17 Adrenal Abnormalities
Adrenal medulla
Produces epinephrine (~75 - 80%)
Produces norepinephrine (~25-30%)
SECTION 18-7 The Pineal Gland
Pineal gland
Contains pinealocytes
Synthesize melatonin
Suggested functions include inhibiting reproductive function, protecting against damage by free radicals, setting circadian rhythms
SECTION 18-1 The Pancreas
The pancreatic islets
Clusters of endocrine cells within the pancreas called Islets of Langerhans or pancreatic islets
Alpha cells secrete glucagons
Beta cells secrete insulin
Delta cells secrete GH-IH
F cells secrete pancreatic polypeptide
Figure 18.18 The Endocrine Pancreas
Insulin and glucagon
Insulin lowers blood glucose by increasing the rate of glucose uptake and utilization
Glucagon raises blood glucose by increasing the rates of glycogen breakdown and glucose manufacture by the liver
Figure 18.19 The Regulation of Blood Glucose Concentrations
SECTION 18-9 The Endocrine Tissues of Other Systems
The intestines
Produce hormones important to the coordination of digestive activities
The kidneys
Produce calcitriol and erythropoietin (EPO) and the enzyme rennin
Calcitriol = stimulates calcium and phosphate ion absorption along the digestive tract
EPO stimulates red blood cell production by bone marrow
Renin converts angiotensinogen to angiotensin I
Angiotensin I converted to angiotensin II in the lungs
Stimulates adrenal production of aldosterone
Stimulates pituitary gland release of ADH
Promotes thirst
Elevates blood pressure
Figure 18.20 Endocrine Functions of the Kidneys
Figure 18.20 Endocrine Functions of the Kidneys
The heart
Specialized muscle cells produce natriuretic peptides when blood pressure becomes excessive
Generally oppose actions of angiotensin II
The thymus
Produces thymosins
Help develop and maintain normal immune defenses
The gonads
Interstitial cells of the testes produce testosterone
Most important sex hormone in males
In females, oocytes develop in follicles
Follicle cells produce estrogens
After ovulation, the follicle cells form a corpus luteum that releases a mixture of estrogens and progesterone
Adipose tissues secrete
Leptin, a feedback control for appetite
Resistin, which reduces insulin sensitivity
SECTION 18-10 Patterns of Hormonal Interaction
Hormones often interact, producing
Antagonistic (opposing) effects
Synergistic (additive) effects
Permissive effects (one hormone is required for the other to produce its effect)
Integrative effects (hormones produce different but complimentary results)
Hormones and growth
Normal growth requires the interaction of several endocrine organs
Six hormones are important
GH
Thyroid hormones
Insulin
PTH
Calcitriol
Reproductive hormones
Hormones and stress
Stress = any condition that threatens homeostasis
GAS (General Adaptation Syndrome) is our bodies response to stress-causing factors
Three phases to GAS
Alarm phase (immediate, fight or flight, directed by the sympathetic nervous system)
Resistance phase (dominated by glucocorticoids)
Exhaustion phase (breakdown of homeostatic regulation and failure of one or more organ systems)
Figure 18.21 The General Adaptation Syndrome
Figure 18.21 The General Adaptation Syndrome
Figure 18.21 The General Adaptation Syndrome
Hormones and behavior
Many hormones affect the CNS
Changes in the normal mixture of hormones significantly alters intellectual capabilities, memory, learning and emotional states
SECTION 18-11 Aging and Hormone Production
Endocrine system
Few functional changes with age
Chief change is a decline in concentration of reproductive hormones
You should now be familiar with:
The major chemical classes and general mechanisms of hormones.
The location and structure of the pituitary gland, and its structural and functional relationships with the hypothalamus.
The location and structure of each of the endocrine glands.
The hormones produced by each of the endocrine glands, and the functions of those hormones.
You should now be familiar with:
The functions of the hormones produced by the kidneys, heart, thymus, testes, ovaries and adipose tissue.
How hormones interact to produce coordinated physiological responses.
