Transcript A View of Life

Chapter 14
Endocrine System
1
Outline
•
•
•
•
•
•
•
•
Endocrine Glands
Hypothalamus and Pituitary
– Posterior vs. Anterior
Thyroid Gland
Parathyroid Glands
Adrenal Glands
Pancreas
Other Endocrine Glands
Homeostasis
2
Endocrine Glands
•
Endocrine glands are ductless glands and
tissues that secrete hormones directly into
the bloodstream.
– Hormone secretion by an endocrine gland
is often controlled by negative feedback.
– Actions of a hormone can also be
controlled by the presence of an
antagonistic hormone.
3
Endocrine System
4
Hypothalamus and Pituitary Gland
•
Hypothalamus regulates the internal
environment through the autonomic system.
– Also controls glandular secretions of the
pituitary gland.
5
Posterior Pituitary
•
•
•
Posterior pituitary releases two hormones
produced by the hypothalamus.
Antidiuretic hormone (ADH).
– Causes water to be reabsorbed into
kidney capillaries.
 Negative feedback control.
Oxytocin.
– Causes uterine contraction during
childbirth and milk letdown.
 Positive feedback control.
6
Anterior Pituitary
•
Hypothalamus controls the anterior pituitary
by producing hypothalamic-releasing and
-inhibiting hormones.
– Anterior pituitary also produces:
 Thyroid Stimulating Hormone (TSH).
 Adrenocorticotropic Hormone (ACTH).
 Gonadotropic Hormones (FSH and LH).
 Prolactin (PRL).
 Growth Hormone (GH).
7
Effects of Growth Hormone
•
Growth hormone is produced in greater
quantities during childhood and
adolescence.
– Too little GH produced during childhood
may lead to pituitary dwarfism.
– Too much GH produced during childhood
may lead to giantism.
– Too much GH produced as an adult may
lead to acromegaly.
8
Thyroid Gland
•
The thyroid gland actively acquires iodine to
produce triiodothyronine and thyroxine.
– A diet lacking iodine cannot produce
thyroid hormones, and the thyroid may
enlarge resulting in a simple goiter.
 Cretinism may result if the thyroid fails
to develop properly.
9
Thyroid Gland
Hypothyroidism in adults produces the
condition of myxedema.
– Hyperthyroidism (Graves Disease) may
cause an exophthalmic goiter to form due
to an overactive thyroid.
Blood calcium level is regulated in part by
calcitonin.
– Hormone secreted by the thyroid gland
when the blood calcium level rises.
–
•
10
Parathyroid Glands
•
Parathyroid hormone is produced by the
parathyroid glands and causes the blood
phosphate level to decrease and the blood
calcium to increase.
– Antagonistic action of calcitonin and
parathyroid hormone maintain blood
calcium levels within normal limits.
11
Adrenal Glands
•
Each adrenal gland consists of an adrenal
medulla and an adrenal cortex.
– Epinephrine and norepinephrine are
produced by the adrenal medulla and
rapidly bring about bodily changes when
an individual reacts to an emergency.
 Mineralocorticoids regulate salt and
water balance and glucocorticoids
regulate metabolism.
12
Malfunction of the Adrenal Cortex
•
•
When the level of the adrenal cortex
hormones is low due to hyposecretion, a
person develops Addison disease.
When the level is high due to
hypersecretion, a person develops Cushing
syndrome.
13
Addison Disease and Cushing Syndrome
14
Pancreas
•
The pancreas is composed of two tissue
types.
– Exocrine tissue produces and secretes
digestive juices.
– Endocrine tissue, pancreatic islets,
produces and secretes insulin and
glucagon directly into the blood.
 Antagonistic.
15
Diabetes Mellitus
•
Diabetes mellitus is a hormonal disease in
which liver cells and other body cells are
unable to take up and/or metabolize
glucose.
– Type I - Pancreas is not producing insulin.
– Type II - Pancreas produces insulin, but
the liver and muscle cells do not respond
in the normal fashion.
16
Other Endocrine Glands
•
Testes and Ovaries.
– The testes produce androgens
(testosterone) and the ovaries produce
estrogens and progesterone.
 Puberty.
 Secondary sexual characteristics.
17
Other Endocrine Glands
•
•
Thymus Gland.
– Secretes thymosins that aid in the
differentiation of lymphocytes inside the
lobules of the thymus.
Pineal Gland.
– Secretes melatonin that is involved in
regulating daily sleep-wake cycle.
18
Hormones from Other Tissues
•
•
Growth Factors.
– Stimulate cell division and mitosis.
Prostaglandins.
– Chemical signals produced within cells
from fatty acid.
 Act locally.
19
Homeostasis
•
•
•
•
Hypothalamus produces ADH and thus
regulates blood water balance.
Endocrine system controls secretion of
epinephrine and norepinephrine and thus
controls fight or flight responses.
Controls blood calcium levels.
– Muscle contraction.
Insulin encourages uptake of glucose by
cells and storage of glucose as glycogen in
the liver and muscles.
20
Review
•
•
•
•
•
•
•
•
Endocrine Glands
Hypothalamus and Pituitary
– Posterior vs. Anterior
Thyroid Gland
Parathyroid Glands
Adrenal Glands
Pancreas
Other Endocrine Glands
Homeostasis
21
22