Endocrine System
Endocrine System
• Regulates overall metabolism, homeostasis, growth and reproduction
• Glands – are ductless (tubeless) organs that specialize in the secretion of substances needed by an organism directly into the bloodstream.
• Hormones – chemical substances that are produced in glands and help regulate your body’s functions. The secretions produced by the endocrine glands
- released into the bloodstream
Endocrine Glands• Hypothalamus – part of the
CNS, but it produces hormones that influence the pituitary gland
• Pituitary Gland – the “master gland” – regulates and controls the activities of all of the other endocrine glands. - Located at the base of the
brain- Secretes growth hormone
which affects growth of bone and cartilage
Why is the Hypothalamus so Important?
• Secretes regulatory homones• RH• RIH
• "Directs" pituitary
Pituitary
Pituitary
The pituitary gland produces a growth hormone which controls growth and homeostasis.
Endocrine Glands (continued)
• Thyroid Gland- Located in the neck- Secretes thyroxine which regulates the
rate of metabolism in the body
• Parathyroid Gland- Embedded in the back of the thyroid- Secretes parathormone which controls
metabolism of calcium and phosphate
Thyroid
Thyroid
The thyroid gland produces thyroxin to regulate metabolism.
Parathyroid
Parathyroid
The parathyroid gland produces parathormone which controls calcium levels in the body.
Endocrine Glands (continued)• Adrenal Glands
- Located on top of the kidneys- Secrete adrenaline which helps deal
with stress and accelerates the heart and breathing rates
- Fight or Flight
• Islets of Langerhans – specialized cells- Located in the pancreas- Secrete insulin and glucagon- Insulin lowers blood sugar- Glucagon raises blood sugar
Adrenal Insufficiency
• Addison’s disease--hyposecretion of cortisol
• JFK• Darkened skin (ACTH mimics MSH)• Weight loss, hypoglycemia• Find the anomaly in the feedback loop.• Inability to handle stress
Adrenals
Adrenals AdrenalsThe adrenal glands produce adrenaline in response to physical and emotional stress.
Adrenal gland
Adrenal Problems
Liver and Pancreas
Pancreas
Pancreas
The pancreas produces insulin which controls sugar levels in the blood.
Endocrine Glands (continued)
• Gonads – sex glands- Male gonads are called testes- Located in the scrotum - Secrete testosterone which regulates
male secondary sex characteristics
- Female gonads are called ovaries- Located in the pelvic region- Secrete estrogen and progesterone
which regulate female secondary sex characteristics
Testes (in males)
Testes
The testes produce testosterone used in sperm production and the development of male traits.
Ovaries (in Females)
Ovaries
The ovaries produce estrogen used in egg production and the development of female traits.
Feedback Mechanisms
• Negative Feedback – is when an activity alters a condition in the body, and this triggers a series of events that reverses the altered condition
Ex. Body temperature- When body temp. goes up, we sweat- When body temp. goes down, we
shiver
Ex. Blood sugar levels- When blood sugar goes up, insulin
lowers blood sugar- When blood sugar goes down,
glucagon raises blood sugar
A. Positive Feedback
• Not common• Classic example:
Action of OXYTOCIN on uterine muscle during birth.
Disorders
• Diabetes – is a disease where a person cannot produce insulin- Inability of the body to store sugar as
glycogen
• Goiter – is enlargement of the thyroid gland caused by iodine deficiency
DIABETES
DIABETES
Goiter
Other Disorders
• Grave’s Disease: hyperthyroidism, an autoimmune disorder in which an overactive and enlarged thyroid gland produces excessive amounts of thyroxine.
• Cushing’s Disease: overproduction of adrenal hormones.
• Growth Disorders: abnormal amounts of growth hormone.
GH as Juvenile (Gigantism)
GH = pituitary dwarfism
GH as an Adult
