THE ENDOCRINE SYSTEM Flashcards
The second messenger system of the body.
The Endocrine System
Other term for chemical messages
Hormones
Hormones control several major processes, what are they?
Reproduction, Growth and Development, Mobilization of body defenses, Maintenance of much of Homeostasis, Regulation of metabolism
Where do cells secrete hormones into?
Extracellular Fluid
What transfers hormones to target sites?
Blood
What are the acid-based hormones?
Proteins, Peptides, Amines
Steroids are made of?
Cholesterol
It is made from highly active lipids.
Prostaglandins
True or False. Hormones affect only certain tissues or organs (target cells or organs)
True
True or False. Hormone binding does not influence the working of cell.
False
Hormones can alter cellular activity by __________ and __________ the rate of a normal metabolic process rather than by stimulating of a new one.
Increasing and Decreasing
What maintains the hormone levels in the blood?
Negative Feedback
A stimulus or low hormone levels in the blood triggers the release of (more or less) hormone.
More
Will the hormone release stop if the appropriate level in the blood is reached?
Yes
What forms when hormone enters the cell and bind with the receptor?
Hormone-receptor complex
If the hormone-receptor complex binds to the DNA, what happens?
It triggers transcription of certain genes to mRNA.
True or False. Direct gene activation enables synthesis of a new protein.
True
What mechanism happens when a hormone binds to a receptor on cell’s surface, activating the G-protein?
Second-messenger system
The activated G-protein activates an enzyme that convert ATP to ___________, and is called the second messenger.
cAMP
Three stimuli of Endocrine Glands.
Hormonal stimuli, Humoral stimuli, Neural stimuli
Endocrine glands are activated by other hormones.
Hormonal stimuli
Changing blood levels of certain ions stimulate hormone release.
Humoral stimuli
Capillary blood contains (low or high) concentrations of CA2+, which stimulates secretion of ____________ (PTH).
low, parathyroid hormone
Nerve fibers stimulate hormone release.
Neural stimuli
Preganglionic sympathetic fiber stimulates adrenal medulla cells to secrete ___________________ (epinephrine and norepinephrine).
catecholamines
Major Endocrine Glands
Pineal Gland, hypothalamus, Pituitary gland, Thyroid gland, Parathyroid glands, Thymus gland, Adrenal gland, Pancreas, Ovary, Testis
Compared to a size of a grape that hangs by a stalk from the hypothalamus.
Pituitary Gland
What protects the pituitary gland?
Sphenoid bone
Two functional lobes of pituitary gland
Anterior and Posterior
Composed of glandular tissue.
Anterior Pituitary
Composed of Nervous tissue.
Posterior pituitary
Anterior pituitary has _____ hormones
Six
From six anterior pituitary hormones, ______ affect non-endocrine targets.
Two
From six anterior pituitary hormones, four stimulate other endocrine glands or _________.
Tropic hormones
Characteristics of all anterior pituitary hormones.
Proteins, Act thru second-messenger system, regulated by hormonal stimuli (mostly negative feedback)
The general metabolic hormone
Growth Hormone
Major effects are directed to growth of
skeletal muscles and long bones. Causes amino acids to be built into proteins. Causes fats to be broken down for a source of energy. The one being defined is __________
Growth Hormone
Different hormones of Anterior pituitary gland
Growth hormone, Prolactin, FSH and LH, Thyrotropic hormone, Adrenocorticotropic hormone
Stimulated and maintains milk production; its function for male remains vague.
Prolactin (PRL)
Regulates endocrine activity of the adrenal
cortex.
Adrenocorticotropic hormone (ACTH)
Influences growth and activity of the thyroid
Thyroid-stimulating hormone (TSH)
Regulate hormonal activity of the gonads
Gonadotropic hormones
Stimulates follicle development in
ovaries; stimulates sperm development in
testes
Follicle-stimulating hormones
Triggers ovulation; causes ruptured follicle to become the
corpus luteum
Luteinizing hormone (LH)
Stimulates testosterone production in
males
LH
Referred to as interstitial cell-stimulating
hormone (ICSH)
LH
Stimulates contractions of the uterus during
labor; Causes milk ejection
Oxytocin
Can inhibit urine production
Antidiuretic hormone (ADH)
ADH In large amounts, causes vasoconstriction
leading to increased blood pressure or ___________.
Vasopressin
Hormones of the Posterior pituitary
Oxytocin, Antidiuretic hormone (ADH)
Found at the base of the throat and is consists of two lobes and a connecting isthmus.
Thyroid Gland
Thyroid gland produces two hormones
Thyroid hormone, Calcitonin
It is the major metabolic hormone
Thyroid Hormone
Thyroid hormone composed of two active iodine-containing hormones
Thyroxine (T4), Triiodothyronine (T3)
It is secreted by the thyroid follicles
Thyroxine (T4)
Conversion of T4 at target tissues
Triiodothyronine (T3)
Decreases blood
calcium levels by
causing its
deposition on bone
Calcitonin
Antagonistic to parathyroid
hormone, and is produced by C (parafollicular) cells
Calcitonin
Tiny masses on the posterior of the
thyroid, which secrets PTH
Parathyroid Glands
Stimulate osterclasts to remove calcium
from bone; Stimulate the kidneys and intestine to
absorb more calcium; Raise calcium levels in the blood
Parathyroid hormone
Sits on top of the kidneys
Adrenal Glands
Two glands of Adrenal Gland
Cortex, Medulla
Outer glandular region in three
layers
Cortex
Inner neural tissue region
Medulla
Hormones of the Adrenal Cortex
Mineralocorticoids, Glucocorticoids, Sex Hormones (Androgens and some Estrogen)
Produced in outer adrenal cortex
Mineralocorticoids
It targets the kidney, which then regulates mineral content in blood, water and electrolyte balance.
Mineralocorticoids
Mineralocorticoids production is stimulated by _________ and _________.
Renin, Aldosterone
Mineralocorticoids production is inhibited by _____________.
Atrial natriuretic peptide
Low blood pressure stimulates the release of _________ from kidney, which produces Angiotensin II that increases the release of _____________.
renin, aldosterone
If aldosterone increases, the absorption of ______ and _______ will increase and the release of K+ will increase, too.
Na+, water
High blood pressure stimulates the release of _______________ from the heart, to inhibit aldosterone release.
Atrial natriuretic peptide
During stress, ____________ is released from the anterior pituitary to increase aldosterone release.
Adrenocorticotropic hormone
Produced in the middle layer of the adrenal
cortex; Promote normal cell metabolism; Help resist long-term stressors
Glucocorticoids
Released in response to increased blood
levels of ACTH
Glucocorticoids
Produced in the inner layer of the adrenal
cortex
Sex Hormones
Male: Androgens::Female:
Estrogen
Hormones of the Adrenal Medulla
Catecholamines (Epinephrine, Norepinephrine)
These hormones prepare the body to
deal with short-term stress
Epinephrine, Norepinephrine
The pancreas is a mixed gland
Pancreatic Islets
The islets of the pancreas produce
hormones:
Insulin, Glucagon
Allows glucose to cross plasma membranes into cells from beta cells
Insulin
Allows glucose to enter the blood from alpha cells
Glucagon
Found on the third ventricle of the brain, which secretes Melatonin
Pineal Gland
Helps establish the body’s wake and sleep cycles; May have other as-yet-unsubstantiated function
Melatonin
Located posterior to the sternum; Largest in infants and children; Produces thymosin
Thymus
Matures some types of white blood cells; Important in developing the immune system
Thymosin
Hormones of the ovaries
Estrogens, Progesterone
What produces Estrogen?
Graafian follicles or the placenta
True or False. Estrogens stimulates the development of secondary female characteristics
True
Matures female reproductive organs; Helps prepare the uterus to receive a fertilized egg; Helps maintain pregnancy; Prepares the breasts to produce milk
Estrogen
What produces progesterone?
Corpus luteum
Acts with estrogen to bring about the menstrual cycle; Helps in the implantation of an embryo in the uterus
Progesterone
Hormone of the testes that produce androgens
Interstitial cells
What is the most important androgen that is responsible for adult male secondary sex characteristics
Testosterone
Promotes growth and maturation of male
reproductive system
; Required for sperm cell production
Testosterone
Other Hormone-Producing Tissues
and Organs
Parts of the small intestine, Parts of the stomach, Kidneys, Heart, Many other areas have scattered
endocrine cells
Endocrine function of the placenta
Produces hormones that maintain the pregnancy
Some hormones play a part in the delivery of the baby
Produces HCG in addition to estrogen, progesterone, and other hormones
True or False. Menopause is brought about by lack of
efficiency of the ovaries
True
True or False. Growth hormone production does not decline with age
False