STRUCTURAL AND FUNCTIONAL ORGANIZATION OF THE ENDOCRINE SYSTEM Flashcards
Major glands of the Endocrine system:
(1) Hypothalamus
(2) Pituitary
(3) Thyroid
(4) Parathyroid
(5) Pancreas
(6) Adrenals
(7) Ovaries and testes
(8) Pineal gland
What glands secrete hormones to regulate many bodily functions, including growth and metabolism?
Major glands of the Endocrine system
This defines what?
A specific cell with specific receptors that will respond to specific hormones
Target Cell
A target cell will have _____ to ________ receptors for a particular hormone.
2,000 to 100,000
Hormones are either ________-soluble or ______-soluble.
lipid or water
Lipid Soluble or Water soluble?
a) Steroid hormones
(b) Thyroid hormones
(c) Nitric Oxide
Lipid
Lipid Soluble or Water soluble?
Amino Acids
1) Short-chain; Antidiuretic hormone
2) Long-chain; Insulin
Water Soluble
Hormones influence their target cells by chemically binding to what?
specific protein receptors
__________ is known as the master switchboard because it’s the part of the brain that controls the endocrine system. Also acts as the major link between the endocrine system and the nervous system.
The hypothalamus
The_________, which hangs by a thin stalk from the hypothalamus, is called the master gland of the body because it regulates the activity of the endocrine glands.
pituitary gland
Hypothalamus secretes a total of how many hormones?
nine
pituitary gland secretes how many hormones?
seven
what is the stalk like structure that, attaches the pituitary gland to the hypothalamus?
the infundibulum
Within the infundibulum, blood vessels termed ___________ connect capillaries in the hypothalamus to capillaries in the anterior pituitary and carries hormones secreted by the hypothalamus to the anterior pituitary.
hypophyseal portal veins
Gonadotropin-releasing hormone – stimulates…
FSH & LH
Growth hormone-releasing hormone – stimulates
HGH & IGF
Growth hormone-inhibiting hormone does what?
inhibits HGH & IGF
Thyroid-releasing hormone does what?
stimulates TSH
Prolactin-releasing hormone does what?
stimulates PRL
Prolactin-inhibiting hormone does what?
inhibits PR
Corticotropin-releasing hormone does what?
stimulates ACTH
Hypothalamus secretes what hormones?
a. Gonadotropin-releasing hormone
b. Growth hormone-releasing hormone
c. Growth hormone-inhibiting hormone
d. Thyroid-releasing hormone
e. Prolactin-releasing hormone
f. Prolactin-inhibiting hormone
g. Corticotropin-releasing hormone
The pituitary gland it about the size of a small grape and has two lobes called what?
1) Anterior pituitary
2) Posterior pituitary
Both lobes of the pituitary rest in the _______, a cup shaped depression in the sphenoid bone.
hypophyseal fossa
What is a a hormone that stimulates an endocrine gland to grow and
secrete its hormones.
Tropic Hormones
Hormones of the Anterior pituitary:
- Human Growth Hormone (hGH)
- Thyroid-Stimulating Hormone (TSH)
- Follicle-Stimulation Hormone (FSH)
- Luteinizing Hormone (LH)
- Prolactin (PRL)
- Adrenocorticotropic Hormone (ACTH)
- Melanocyte-Stimulating Hormone (MSH)
What Hormone?
- Promote synthesis and secretion of Insulinlike Growth Factors (IGFs).
- Maintains blood concentration by means of a negative feedback loop
Human Growth Hormone (hGH)
________ are proteins secreted mainly by cells in the liver, but is also secreted by cells in the skeletal muscles, cartilage, bones, and other tissues in response to stimulation of hGH.
- -Stimulate protein synthesis, help maintain muscle and bone mass, and promote healing of injury and tissue repair.
- -Enhance breakdown of triglycerides, which release fatty acid into the blood, and breakdown of liver glycogen, which releases glucose into the blood.
Insulinlike growth Factors
What Two hypothalamic hormones control secretion of hGH.
1) _____ – Low blood glucose levels
2) _____ – Above normal blood glucose levels
1) Growth Hormone-Releasing Hormone (GHRH) – Low blood glucose levels
2) Growth Hormone- Inhibiting Hormone (GHIH) – Above normal blood glucose levels
What hormone?
Stimulates the synthesis and secretion of thyroid hormones by the thyroid gland.
Thyroid-Stimulating Hormone (TSH)
What hormone?
(a) Females
1) Initiates the development of ovarian follicles.
2) Stimulates follicular cells to excrete estrogen.
(b) Males
1) Stimulates sperm production in the testes
2) Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus controls the secretion of this hormone
Follicle-Stimulation Hormone (FSH)
What hormone?
(a) Female
- -1) Triggers ovulation.
- -2) Stimulates formation of the corpus luteum in the ovary and the secretion of progesterone by the corpus luteum.
- -3) Along with FSH stimulates follicular cells to secrete estrogen.
(b) Male
- -1) Stimulates the testes to secrete Testosterone.
- -2) Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus controls secretion of this hormone
Luteinizing Hormone (LH)
What hormone?
Initiates and maintains milk production by the mammary glands.
–During pregnancy, very high levels of estrogens promote secretion of this
Prolactin (PRL)
What hormone?
Controls the production and secretion of hormones called Glucocorticoids by the cortex (outer portion) of the adrenal gland.
Adrenocorticotropic Hormone (ACTH)
What hormone?
(a) Very little in humans.
(b) Excessive amount can cause darkening of the skin.
Melanocyte-Stimulating Hormone (MSH)
Does the posterior pituitary synthesize hormones?
No
What hormones are stored and released from the posterior pituitary gland?
Oxytocin Antidiuretic Hormone (ADH)
WHat Hormone?
1) Uterus
–a) Released in large quantities just prior to childbirth to enhance
contraction of smooth muscle cells in the wall of the uterus.
2) Breast
–a) Stimulates milk ejection from the mammary glands in
response to the suckling infant.
Oxytocin
What Hormone?
1) Decreases urine production.
2) Causes the kidneys to retain more water, thus decreasing urine volume.
3) Decreases water loss through sweating.
4) Causes constriction of arterioles, thus causing an increase in blood pressure.
Antidiuretic Hormone (ADH)
In the absence of ADH, an individual’s urine output will increase from 1-2 liters per day to what?
20 liters.
The ______ gland’s function is to run the basal metabolic rate (BMR).
thyroid gland’s
________ =the rate at which the body uses energy while at rest to keep vital functions going, such as breathing, keeping the heart beating, and keeping the body warm
basal metabolic rate (BMR).
Structure of the Thyroid Gland
Spherical sacs called ______ make up most of the gland.
thyroid follicles
The walls of each follicle consists of cells called follicular cells which produce what two thyroid hormones?
1) Thyroxine (T4)
2) Triiodothyronine (T3)
True/False
Most body cells have receptors for thyroid hormones
True
Thyroid hormones (decrease or increase) basal metabolic rate (BMR),
INCREASE
_________ hormones also stimulate protein synthesis, increase the use of glucose and fatty acid for ATP production, increase the breakdown of triglycerides, and enhance cholesterol excretion, thus reducing blood cholesterol.
The thyroid hormones
Together with _______ and ________, thyroid hormones stimulate body growth, particularly the nervous and skeletal systems.
human growth hormone and insulin
What hormone?
(1) Produced by the parafollicular cells of the thyroid gland.
(2) Decreases the level of calcium in the blood by inhibiting the action of osteoclasts, the cells that break down bone
Calcitonin (CT)
WHAT GLAND?
Small round masses of glandular tissue that are partially embedded in the posterior surface of the thyroid gland.
- contains called chief cells that release parathyroid hormone (PTH).
parathyroid gland.
What hormone?
-is the major regulator of the levels of calcium, magnesium, and
phosphate ions in the blood.
-increases the number and activity of osteoclasts, which break down bone extracellular matrix and release calcium and phosphate into the blood
parathyroid hormone (PTH)
PTH produces what three changes in the kidney?
1) Slows the rate at which calcium and magnesium are lost from blood into urine.
2) Increases loss of phosphate from blood to urine.
3) Promotes formation of the hormone Calcitrol,
- -the active form of vitamin D.
- -Calcitrol acts in the gut to increase the rate of calcium, magnesium, and phosphate absorption from food into the blood.
(ELEVATED OR DECREASED) levels of PTH can cause bone pain, kidney stones, headaches, and abdominal pain.
ELEVATED
Cells of the pancreatic islets
1) Alpha cells secrete the hormone _______. Release is stimulated by the sympathetic division of the autonomic nervous system (ANS).
2) Beta cells secrete the hormone _______. Release is stimulated by the parasympathetic division of the ANS.
1) glucagon
2) insulin
The main action of glucagon is……
to increase blood glucose level when it falls below
normal.
the hormone ________ helps glucose move into cells, especially muscle fibers, which lower blood glucose level when it is too high.
insulin
The level of blood glucose controls secretion of both glucagon and insulin via (NEGATIVE/POSITIVE) feedback
NEGATIVE feedback
What promotes uptake of amino acids into the body cells and increases the synthesis of protein and fatty acid within the cells.
Insulin
Adrenal Cortex – Consists of three zones, each of which synthesizes and secretes different _____ hormones
steroid
What are the three zones of the Adrenal cortex?
- Outer Zone (Zona Glomerulosa)
- Middle Zone (Zona Fasciculata)
- Inner Zone (Zona Reticularis)
What zone of the adrenal cortex?
releases androgens. (male & female sex hormones)
The Inner Zone (Zona Reticularis)
What zone of the adrenal cortex?
releases hormones called glucocorticoids because they affect glucose homeostasis
(1 Cortisol
The Middle Zone (Zona Fasciculata)
What zone of the adrenal cortex?
releases hormones called mineral corticoids because of their effect on mineral homeostasis.
(1 Aldosterone
The Outer Zone (Zona Glomerulosa)
What is this?
Inner most region of the adrenal gland. Consists of
sympathetic postganglionic cells of the autonomic nervous system (ANS) that are specialized to secrete hormones known as catecholamines
Adrenal Medulla
What are the catecholamine hormones?
a) Epinephrine
b) Norepinephrine
What Hormone?
Regulates homeostasis of two mineral ions, sodium ions (Na+) and potassium ions (K+).
a) Increases reabsorption of Na+ from the urine into the blood.
b) Stimulates excretion of K+ into urine.
-Helps adjust blood pressure and blood volume and promotes excretion of H+ in the urine. Such removal of acids from the body can help prevent metabolic acidosis
Aldosterone
Aldosterone is made where?
Adrenal Cortex – Zona Glomerulosa
The most abundant glucocorticoid is _____
cortisol
What class of hormones has these functions? -Protein breakdown -Glucose formation -Breakdown of triglycerides -Anti-inflammatory effects [Depression of immune response
Glucocorticoids
True/False
Thus the amount of androgens secreted by the adrenal cortex in males is usually so low that their effects are insignificant.
TRUE
What hormones stimulate axillary and pubic hair in boys and girls and contribute to the growth spurt before puberty.
Androgens
Impulses from the hypothalamus stimulate the sympathetic preganglionic neurons, which in turn stimulate the cells of the adrenal medulla to secrete what?
epinephrine and norepinephrine
epinephrine and norepinephrine greatly augment what response?
the fight-or-flight response
1) By increasing heart rate and force of contraction, epinephrine and
norepinephrine increase the pumping output of the heart, which (increases or decreases) blood pressure.
2) They also (increase or decrease) blood flow to the heart, liver, skeletal muscle, and adipose tissue; dilate airways to the lungs; and increase blood levels of glucose and fatty acid.
3) Epinephrine and norepinephrine also help the body resist _____
1) Increase
2) Increase
3) Stress
A small endocrine glad attached to the roof of the third ventricle of the brain at the midline
-One hormone secreted by this gland is melatonin.
pineal gland
What hormone contributes to setting the body’s biological clock. (circadian rhythm).
Melatonin
Aging of the Endocrine System
As we age:
(a) Human growth hormone ______ - one cause of muscle atrophy
(b) Thyroid hormones (T3, T4, and calcitonin) _______ - causing decreased metabolic rate, increased body fat, and hypothyroidism.
(c) Parathyroid hormone ______- the rise in PTH and the fall in calcitonin decrease bone mass leading to osteoporosis.
(d) Insulin is released more ______ - causing blood glucose levels to increase faster.
(e) Estrogen ______- as the ovaries decrease in size, they no longer respond to gonadotropins. This leads to conditions such as osteoporosis, high blood cholesterol, and atherosclerosis.
a) decreases
b) decrease
c) rises
d) slowly
e) decrease
