1 copyright © 2005 mosby, inc. all rights reserved. chapter 16 endocrine system
TRANSCRIPT
1Copyright © 2005 Mosby, Inc. All rights reserved.
Chapter 16
Endocrine System
2Copyright © 2005 Mosby, Inc. All rights reserved.
The Endocrine System
3Copyright © 2005 Mosby, Inc. All rights reserved.
Mechanisms ofHormone Action
Endocrine glands secrete chemicals (hormones) into the blood Hormones perform general functions of communication and control, but a slower, longer-lasting type of control than that provided by nerve impulsesCells acted on by hormones are called target organ cells
3
4Copyright © 2005 Mosby, Inc. All rights reserved. 4
5Copyright © 2005 Mosby, Inc. All rights reserved.
Regulation of Hormone Secretion
Hormone secretion is controlled by homeostatic feedback
Negative feedback—mechanisms that reverse the direction of a change in a physiological system
Positive feedback—(uncommon) mechanisms that amplify physiological changes
5
6Copyright © 2005 Mosby, Inc. All rights reserved. 6
7Copyright © 2005 Mosby, Inc. All rights reserved.
Mechanisms of Endocrine Disease
Hypersecretion—secretion of excess hormoneHyposecretion—insufficient hormone secretionPolyendocrine disorders—hyper- or hyposecretion of more than one hormone Target cell insensitivity produces results similar to hyposecretionEndocrinologists have developed many different strategies for treatment (e.g., surgery and hormone therapy)
7
8Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
Anterior pituitary gland Names of major hormones
Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Growth hormone (GH) Prolactin (lactogenic hormone)
8
9Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
Functions of major hormones TSH—stimulates growth of the thyroid gland; also
stimulates it to secrete thyroid hormone ACTH—stimulates growth of the adrenal cortex and
stimulates it to secrete glucocorticoids (mainly cortisol) FSH—initiates growth of ovarian follicles each month
in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation; FSH also stimulates estrogen secretion by developing follicles; stimulates sperm production in the male
9
10Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
Functions of major hormones LH—acts with FSH to stimulate estrogen
secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male
10
11Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
GH—stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)
Hypersecretion during childhood results in gigantism and during adulthood results in acromegaly
Hyposecretion during childhood results in pituitary dwarfism
Prolactin or lactogenic hormone—stimulates breast development during pregnancy and secretion of milk after the delivery of the baby
11
12Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
Posterior pituitary gland Names of hormones
Antidiuretic hormone (ADH) Hyposecretion causes diabetes insipidus,
characterized by excessive volume of urine
Oxytocin (OT)
12
13Copyright © 2005 Mosby, Inc. All rights reserved.
Pituitary Gland
Functions of hormones ADH—accelerates water reabsorption from
urine in the kidney tubules into the blood, thereby decreasing urine secretion
Oxytocin—stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts
13
14Copyright © 2005 Mosby, Inc. All rights reserved. 14
15Copyright © 2005 Mosby, Inc. All rights reserved.
Hypothalamus
Actual production of ADH and oxytocin occurs in the hypothalamusAfter production in the hypothalamus, hormones pass along axons into the pituitary glandThe secretion and release of posterior pituitary hormones is controlled by nervous stimulationThe hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst)
15
16Copyright © 2005 Mosby, Inc. All rights reserved.
Thyroid Gland
Names of hormones Thyroid hormone—thyroxine (T4) and
triiodothyronine (T3) Calcitonin (CT)
Functions of hormones Thyroid hormones—accelerate catabolism
(increase the body’s metabolic rate) Calcitonin—decreases the blood calcium
concentration by inhibiting breakdown of bone, which would release calcium into the blood
16
17Copyright © 2005 Mosby, Inc. All rights reserved.
Thyroid Gland
Hyperthyroidism (hypersecretion of thyroid hormones) increases metabolic rate Characterized by restlessness and
exophthalmos (protruding eyes)
17
18Copyright © 2005 Mosby, Inc. All rights reserved.
Thyroid Gland
Hypothyroidism (hyposecretion of thyroid hormones) May result from different conditions Simple goiter—painless enlargement of
thyroid caused by dietary deficiency of iodine Hyposecretion during early development may
result in cretinism (retardation) and during adulthood in myxedema (characterized by edema and sluggishness)
18
19Copyright © 2005 Mosby, Inc. All rights reserved. 19
20Copyright © 2005 Mosby, Inc. All rights reserved.
Parathyroid Glands
Name of hormone—parathyroid hormone (PTH)
Function of hormone—increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood
20
21Copyright © 2005 Mosby, Inc. All rights reserved.
Pancreatic Islets
Names of hormones Glucagon—secreted by alpha cells Insulin—secreted by beta cells
Functions of hormones Glucagon increases the blood glucose
level by accelerating liver glycogenolysis (conversion of glycogen to glucose)
21
22Copyright © 2005 Mosby, Inc. All rights reserved. 22
23Copyright © 2005 Mosby, Inc. All rights reserved.
Pancreatic Islets
Functions of hormones Insulin decreases the blood glucose by
accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells
23
24Copyright © 2005 Mosby, Inc. All rights reserved.
Pancreatic Islets
Diabetes mellitus Type 1 results from hyposecretion of
insulin Type 2 results from target cell insensitivity
to insulin Glucose cannot enter cells and thus blood
glucose levels rise, producing glycosuria (glucose in the urine)
24
25Copyright © 2005 Mosby, Inc. All rights reserved.
Female Sex Glands
The ovaries contain two structures that secrete hormones—the ovarian follicles and the corpus luteum
Effects of estrogen (feminizing hormone) Development and maturation of breasts and
external genitals Development of adult female body contours Initiation of menstrual cycle
25
26Copyright © 2005 Mosby, Inc. All rights reserved.
Male Sex Glands
The interstitial cells of testes secrete the male hormone testosterone
Effects of testosterone (masculinizing hormone) Maturation of external genitals Beard growth
26
27Copyright © 2005 Mosby, Inc. All rights reserved.
Male Sex Glands
Effects of testosterone Voice changes at puberty Development of musculature and body
contours typical of the male
27
28Copyright © 2005 Mosby, Inc. All rights reserved.
Thymus
Name of hormone—thymosin
Function of hormone—plays an important role in the development and function of the body’s immune system
28
29Copyright © 2005 Mosby, Inc. All rights reserved.
Other Endocrine Structures
Many organs (e.g., the stomach, intestines, and kidney) produce endocrine hormones
The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys
Fat-storing cells secrete leptin, which controls how full or hungry we feel
29
30Copyright © 2005 Mosby, Inc. All rights reserved.
Endocrine Glands (cont’d)
pituitary (cont’d) anterior lobe produces hormones (cont’d)
antidiuretic hormone (ADH) oxytocin
hypothalamus: located near the pituitary gland in the brain; which secretes “releasing” hormone that functions to stimulate or inhibit the release of pituitary gland hormones
31Copyright © 2005 Mosby, Inc. All rights reserved.
Endocrine Glands (cont’d)
thyroid: largest endocrine gland located in the neck below the larynx produces hormones
triiodothyronine (T3)
thyroxine (T4)
parathyroid: four small bodies lying directly behind the thyroid produces hormone
parathormone (PTH)
32Copyright © 2005 Mosby, Inc. All rights reserved.
Endocrine Glands (cont’d)
islets of Langerhans: clusters of endocrine tissue found throughout the pancreas produces hormones
insulin glucagon
33Copyright © 2005 Mosby, Inc. All rights reserved.
Endocrine Glands (cont’d)
adrenal glands: paired glands, one above each kidney. The outer portion is called the cortex, and the inner portion is called the medulla. produces hormones
cortisol (hydrocortisone) Aldosterone epinephrine (adrenaline)
34Copyright © 2005 Mosby, Inc. All rights reserved.
Combining Forms for the Endocrine System
aden/o
adren/o, adrenal/o
cortic/o
endocrin/o
parathyroid/o
thyroid/o, thyr/o
35Copyright © 2005 Mosby, Inc. All rights reserved.
Combining Forms Commonly for the Endocrine System (cont’d)
acr/o
calc/i
dips/o
kal/i
natr/o
36Copyright © 2005 Mosby, Inc. All rights reserved.
Suffix
-drome
37Copyright © 2005 Mosby, Inc. All rights reserved.
Disease and Disorder Terms Built from Word Parts
acromegaly adenomalacia adenomegaly adrenalitis adrenomegaly
calcipenia
hypercalcemia
hyperglycemia
hyperkalemia
hypocalcemia
38Copyright © 2005 Mosby, Inc. All rights reserved.
Helpful Information
hypocalcemia and calcipenia both mean a deficiency of calcium
39Copyright © 2005 Mosby, Inc. All rights reserved.
Disease and Disorder Terms Not Built from Word Parts
acidosis Addison’s disease cretinism Cushing’s syndrome diabetes insipidus (DI) diabetes mellitus (DM) gigantism goiter Graves’ disease
40Copyright © 2005 Mosby, Inc. All rights reserved.
Cushing Syndrome
41Copyright © 2005 Mosby, Inc. All rights reserved.
Goiter
42Copyright © 2005 Mosby, Inc. All rights reserved.
Surgical Terms Built from Word Parts
adenectomy
adrenalectomy
parathyroidectomy
thyroidectomy
thyroidotomy
thyroparathyroidectomy
43Copyright © 2005 Mosby, Inc. All rights reserved.
Diagnostic Not Built from Word Parts
Diagnostic imaging radioactive iodine uptake test (RAIU) thyroid scan
Laboratory fasting blood sugar (FBS) thyroxine level (T4) thyroid-stimulating hormone level (TSH)
44Copyright © 2005 Mosby, Inc. All rights reserved.
Complementary Terms Built from Word Parts
adrenopathy calcipenia cortical endocrinologist endocrinology endocrinopathy polydipsia syndrome
45Copyright © 2005 Mosby, Inc. All rights reserved.
Complementary Terms Not Built from Word Parts
exophthalmos
hormone
metabolism
46Copyright © 2005 Mosby, Inc. All rights reserved.
Abbreviations
DI
DM
FBS
RAIU
T4