Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
168 Cards in this Set
- Front
- Back
|
The endocrine glands secrete
|
hormones
|
|
|
Hormones diffuse from
|
interstitial fluids into the blood stream and eventually act on target cells
|
|
|
Paracrine secretions
|
are secretions that do not travel in the blood stream to their targets
|
|
|
Autocrine secretions
|
are secretions that affect the secreting cell itself
|
|
|
Exocrine glands
|
secrete substances into ducts
|
|
|
Endocrine hormones
|
also play vital roles in reproduction, development, and growth
|
|
|
The larger endocrine glands are
|
the pituitary, thyroid, parathyroids, adrenals, and pancreas
|
|
|
Hormones
|
are released into the extracellular spaces surrounding endocrine cells. They diffuse into the bloodstream and are carried to all parts of the body.
|
|
|
Most hormones are
|
either steroids or steroid like substances or nonsteroids
|
|
|
Nonsteroid hormones include
|
amines, peptides, proteins, and glycoproteins
|
|
|
Steroids are
|
lipids that include complex rings of carbon and hydrogen atoms
|
|
|
Examples of steroid hormones are
|
testosterone, estrogen, aldosterone, and cortisol
|
|
|
Examples of hormones called amines are
|
norepinephrine and epinephrine
|
|
|
Protein hormones are composed of
|
long chains of amino acids
|
|
|
Examples of protein hormones are
|
those secreted by the anterior pituitary and parathyroid glands
|
|
|
Hormones called glycoproteins are produced by
|
the anterior pituitary
|
|
|
Peptide hormones are
|
short chains of amino acids
|
|
|
Peptide hormones come from
|
the posterior pituitary and hypothalamus
|
|
|
Prostaglandins are
|
paracrine substances and are produced in a wide variety of cells
|
|
|
Hormones exert their effects by
|
altering metabolic processes
|
|
|
The more receptors the hormone binds on its target cell
|
the greater the response.
|
|
|
Up regulation
|
is an increase in the number of receptors on a target cell
|
|
|
Steroid and thyroid hormones are
|
insoluble in water but are soluble in lipids
|
|
|
Steroid and thyroid hormones can
|
diffuse into cells relatively easily
|
|
|
Once steroid and thyroid hormones are inside a cell
|
they combine with specific protein receptors located usually in the nucleus
|
|
|
The binding of these steroid and hormones to the receptor usually
|
activates or inhibits a gene |
|
|
Activated genes
|
code for specific proteins
|
|
|
The new proteins may be
|
enzymes, transport proteins, or hormone receptors and they bring about cellular changes
|
|
|
A nonsteroid hormone usually binds
|
with receptors located on the cell membrane
|
|
|
When a nonsteroid hormone binds to a membrane receptor
|
this causes the receptor’s activity site to interact with other membrane proteins
|
|
|
Receptor binding may alter
|
the function of enzymes or membrane transport mechanisms, changing the concentrations of still other cellular components
|
|
|
A first messenger is the hormone that
|
triggers a cascade of biochemical activity
|
|
|
Second messengers are the chemicals in the cell that
|
induce the changes that are recognized as responses to the hormone
|
|
|
Many hormones use _____ AMP as a second messenger
|
cyclic
|
|
|
proteins are activated by
|
the binding of a hormone to a membrane receptor
|
|
|
Adenylate cyclase is activated by
|
G proteins
|
|
|
Adenylate cyclase functions to form
|
cyclic AMP from ATP
|
|
|
Cyclic AMP activates another set of enzymes called
|
protein kinases
|
|
|
Protein kinases function
|
to transfer phosphate groups from ATP to proteins substrate molecules
|
|
|
Phosphorylated substrates may be
|
converted from inactive to active forms
|
|
|
Activated proteins then alter various cellular processes to
|
bring about the effect of that particular hormone
|
|
|
Cellular responses to second messenger activation include
|
altering membrane permeabilities, activating enzymes, promoting synthesis of certain proteins, stimulating or inhibiting metabolic pathways, promoting cellular movements, and initiating secretion of hormones and other substances
|
|
|
Hormones whose actions require cyclic AMP include
|
releasing hormones from the hypothalamus, TSH, ACTH, FSH, LH, ADH, PTH, norepinephrine, epinephrine, glucagon, and calcitonin.
|
|
|
An example of another second messenger is
|
DAG
|
|
|
In another mechanism, a hormone binding its receptor increases
|
calcium, ion concentration within the target cell
|
|
|
Calcium ions bind
|
to the protein calmodulin to activate it
|
|
|
Activated calmodulin functions
|
to interact with enzymes, altering their activities
|
|
|
Cells are highly sensitive to
|
changes in concentration of nonsteroid hormones because responses to them is greatly amplified through second messengers
|
|
|
Prostaglandins
|
are paracrine substances that act locally
|
|
|
Some prostaglandins regulate
|
cellular responses to hormone
|
|
|
The variety of effects prostaglandins can produce
|
relaxation of smooth muscle in airway and blood vessels, contraction of smooth muscle in the uterus, stimulation of secretion of various hormones, and promotion of inflammation
|
|
|
Hormones with short half lives
|
control body functions that turn on and off quickly
|
|
|
Hormones
|
are continually excreted in urine and broken down by enzymes in the liver
|
|
|
Increasing or decreasing blood levels of hormones requires
|
increased or decreased secretion
|
|
|
Control of hormone secretion is essential to
|
maintaining the internal environment
|
|
|
The hypothalamus controls
|
the anterior pituitary gland’s release of tropic hormones
|
|
|
Tropic hormones stimulate
|
other endocrine glands to release hormones
|
|
|
An example of an endocrine organ directly stimulated by the nervous system is
|
the adrenal medulla
|
|
|
Some endocrine glands respond
|
to changes in the composition of the internal environment
|
|
|
As a result of negative feedback mechanisms
|
hormone levels remain relatively stable
|
|
|
The pituitary gland is located
|
at the base of the brain
|
|
|
The infundibulum
|
is a stalk that attaches the pituitary gland to the hypothalamus
|
|
|
The two portions of the pituitary are
|
anterior and posterior
|
|
|
The anterior lobe secretes
|
the following hormones: GH, TSH, ACTH, FSH, LH, PRL
|
|
|
The posterior pituitary secretes the following hormones
|
OT and ADH
|
|
|
The hypothalamus controls
|
most of the pituitary gland’s activities
|
|
|
The posterior pituitary receives impulses from
|
the hypothalamus
|
|
|
Releasing hormones from the hypothalamus
|
controls the anterior pituitary
|
|
|
The hypophyseal portal veins
|
are vessels that pass downward along the pituitary stalk from the hypothalamus and give rise to a capillary bed in the anterior lobe of the pituitary
|
|
|
Somatotropes secrete
|
GH
|
|
|
Mammotropes secrete
|
PRL
|
|
|
Thyrotropes secrete
|
TSH
|
|
|
Corticotropes secrete
|
ACTH
|
|
|
Gonadotropes secrete
|
FSH and LH
|
|
|
Actions of growth hormone are
|
stimulation of cells to enlarge and more rapidly divide, enhance movement of amino acids through the cell membranes, and increases the rate of protein synthesis
|
|
|
GH also decreases
|
the rate as which cells utilize carbohydrates and increases the rate at which cells use fats
|
|
|
The secretion of GH is controlled by
|
somatostatin and GHRH
|
|
|
Actions of prolactin are to
|
sustain mild production after birth and to amplify effect of LH in males
|
|
|
The secretion of PRL is under inhibitory control by
|
PIH and PRF
|
|
|
Actions of thyroid stimulating hormone are
|
to stimulate the thyroid gland to release its hormones
|
|
|
The secretion of TSH is controlled by
|
TRH
|
|
|
The actions of adrenocorticotropic hormone
|
are to control secretion of certain hormone from the adrenal cortex
|
|
|
The secretion of ACTH is controlled by
|
CRH
|
|
|
Gonadotropins
|
are LH and FSH
|
|
|
The actions of follicle stimulating hormone
|
are to promote development of egg containing follicles in ovaries, to stimulate follicular cells to release estrogen, and in males, to stimulate production of sperm cells
|
|
|
The actions of luteinizing hormone
|
are to promote secretion of sex hormones and to promote the release egg cells in females
|
|
|
The secretion of FSH and LH is controlled by
|
GnRH.
|
|
|
The posterior pituitary consists of
|
nerve fibers and neuroglial cells
|
|
|
Specialized neurons in the hypothalamus produce
|
two hormones called OT and ADH
|
|
|
The hormones produced in the hypothalamus travel
|
down axons through the pituitary stalk to the posterior pituitary
|
|
|
The actions of antidiuretic hormone are
|
to cause a reduction in water excretion, and to raise blood pressure
|
|
|
The secretion of ADH is controlled by
|
blood water concentration and blood volume
|
|
|
The actions of oxytocin
|
are to contact muscles in uterine wall and to contract muscles associated with milk secreting cells
|
|
|
The secretion of oxytocin is controlled by
|
uterine stretch and stimulation of breasts
|
|
|
The thyroid gland consists of
|
two lobes
|
|
|
The thyroid gland is located
|
just below the larynx on either side and anterior to the trachea
|
|
|
Follicles
|
are secretory parts of the thyroid gland
|
|
|
Colloid
|
is a viscous fluid that fills follicles and contains thyroglobulin.
|
|
|
Thyroglobulin
|
is a glycoprotein
|
|
|
Extrafollicular cells are located
|
outside of follicles
|
|
|
The follicular cells produce
|
hormones
|
|
|
The three hormones produced by the thyroid gland are
|
T4, T3, and calcitonin
|
|
|
The actions of thyroxine and triiodothyronine are
|
to regulate metabolism of carbohydrates, lipids, and proteins
|
|
|
The secretion of T3 and T4 are controlled by
|
TSH
|
|
|
Follicular cells require ____ to produce T3 and T4
|
iodine
|
|
|
The actions of calcitonin
|
are to lower blood calcium levels
|
|
|
The secretion of calcitonin is controlled by
|
blood calcium levels. It is released in response to high blood calcium levels.
|
|
|
Parathyroid glands are located
|
embedded in the thyroid gland
|
|
|
Usually a person has ___ parathyroid glands
|
four
|
|
|
Each parathyroid gland is covered by
|
a thin capsule
|
|
|
The body of a parathyroid gland consists of
|
many tightly packed secretory cells
|
|
|
The actions of PTH are to
|
raise blood calcium levels
|
|
|
The secretion of PTH is controlled by
|
blood calcium levels
|
|
|
It is released in response to
|
low blood calcium levels
|
|
|
The adrenal glands are shaped like
|
pyramids
|
|
|
The two parts of an adrenal gland are
|
the cortex and medulla
|
|
|
The adrenal medulla consists of
|
irregularly shaped cells grouped around blood vessels
|
|
|
The adrenal cortex is composed of
|
closely packed masses of epithelial layers
|
|
|
The three layers of the adrenal cortex are
|
the outer zona glomerulosa, the middle zona fasciculata, and the inner zona reticularis.
|
|
|
The two hormones released by the adrenal medulla are
|
epinephrine and norepinephrine.
|
|
|
The actions of epinephrine and norepinephrine are
|
increased heart rate, increased force of cardiac muscle contraction, elevated blood pressure, increased breathing rate and decreased activity of the digestive system
|
|
|
The secretion of epinephrine and norepinephrine are controlled by
|
the sympathetic nervous system
|
|
|
The adrenal cortex produces
|
more than 30 different steroids
|
|
|
The most important adrenal cortical hormones are
|
aldosterone, cortisol, and certain sex hormones
|
|
|
Aldosterone is secreted
|
by the zona glomerulosa and is called a mineralocorticoid because it helps regulate the concentration of mineral electrolytes
|
|
|
The actions of aldosterone are
|
regulation of concentration of extracellular electrolytes by conserving sodium ions and excreting potassium ions
|
|
|
The secretion of aldosterone is controlled by
|
electrolyte concentrations in body fluids and the renin angiotensin mechanism
|
|
|
Cortisol is secreted by
|
the zona fasciculata
|
|
|
Cortisol is called
|
a glucocorticoid because it affects glucose metabolism
|
|
|
The actions of cortisol are
|
to decrease protein synthesis, increase fatty acid release, and simulate glucose synthesis from noncarbohydrates
|
|
|
The secretion of cortisol is controlled by
|
CRH
|
|
|
The sex hormones are secreted by the
|
zona reticularis
|
|
|
The actions of the sex hormones are
|
to supplement sex hormones from the gonads
|
|
|
Examples of sex hormones are
|
androgens such as testosterone
|
|
|
The pancreas is located
|
posterior to the stomach
|
|
|
The endocrine portion of the pancreas consists of
|
islets of Langerhans which are also called pancreatic islets
|
|
|
Three cell types of the pancreatic islets are
|
alpha, beta, and delta
|
|
|
Alpha cells secrete
|
glucagon
|
|
|
Beta cells secrete
|
insulin
|
|
|
Delta cells secrets
|
somatostatin
|
|
|
The actions of glucagon are
|
to stimulate the liver to break down glycogen and to convert noncarbohydrates into glucose. It also simulates the breakdown of fats
|
|
|
The secretion of glucagon is controlled by
|
blood glucose concentrations
|
|
|
The actions of insulin are
|
to promote the formation of glycogen from glucose, to inhibit conversion of noncarbohydrates into glucose, and to enhance movement of glucose through adipose and muscle cell membranes
|
|
|
Insulin also
|
decreases blood glucose concentrations, promotes transport of amino acids into cells, and enhances synthesis of proteins and fats
|
|
|
The secretion of insulin is controlled by
|
blood glucose concentrations
|
|
|
The function of somatostatin
|
is to help regulate carbohydrates
|
|
|
The pineal gland
|
is located near the roof of the third ventricle deep in the cerebral hemispheres.
|
|
|
The pineal gland produces
|
the hormone melatonin
|
|
|
The functions of melatonin
|
are to help regulate circadian rhythms and to inhibit secretion of
gonadotropins.
|
|
|
The thymus gland is located
|
between the lungs
|
|
|
The thymus gland secretes
|
a group of hormones called thymosins
|
|
|
The function of thymosin is to promote
|
the maturation of T lymphocytes.
|
|
|
Reproductive organs that secrete hormones are
|
ovaries and testes
|
|
|
Examples of hormones produced by reproductive organs are
|
estrogen, progesterone, and testosterone
|
|
|
The hormone produced by the heart is
|
ANP
|
|
|
The hormone produced by the kidneys is
|
erythropoietin
|
|
|
A stressor
|
is a factor capable of producing stress
|
|
|
Stress
|
is a protective response produced by the body in response to stress factors
|
|
|
Types of Stress
|
physical stress, psychological stress
|
|
|
Examples of physical stress include
|
extreme cold or heat, decreases oxygen concentrations, infection, injuries, heavy exercise and loud sounds
|
|
|
Examples of psychological stress are
|
imagined dangers, personal losses, unpleasant social interaction or any factor that threatens a person
|
|
|
The general stress syndrome
|
is a group of symptoms produced by the hypothalamus in response to stress
|
|
|
Major events of the general stress syndrome are
|
increased blood glucose levels, increased heart rate and breathing rate, dilation of airways, and shunting of blood into muscles
|
|
|
Life span changes of the endocrine system
|
are a decrease in size and increase in the proportion of each gland that is fibrous in nature
|
|
|
Treatments for endocrine disorders include
|
supplements of hormones or removing part of an overactive gland or using drugs to block the action of an overabundant hormone
|
|
|
Levels of ADH with age
|
increase with age and as a result, the kidneys reabsorb more water
|
|
|
calcitonin levels with age
|
decrease and this increases the risk of osteoporosis
|
|
|
The most obvious changes in endocrine function involve
|
blood glucose regulation
|
