Final Endocrine system Flashcards
Endocrine system composed of two parts
endocrine orgaans
hormones
pure endocrine organs
a) Pituitary gland: base of the brain
b) Pineal gland: roof of the diencephalon
c) Thyroid and parathyroid glands: neck
d) Adrenal glands: superior kidney
endocrine organs cntained within orgains of other body systems
a) Pancreas
b) Thymus
c) Gonads
d) Hypothalmus
hypothalmus
considered a
“neuroendocrine” organ because it
produces hormones in addition to
performing its nervous functions
what is the origin of most endocrine glands?
epithelium cells
endocrine glands are richly supplied with?
blood and lymphatic vessels
endocrine cells are typically arranged in ? and why?
small clusters, cords, or
branching networks
- greater surface area
most hormones belong to one of two broad molecular categories, what are they?
amino-based molecules
steroid molecules
amino based molecules
Modified amino acids, peptides, and
proteins (e.g. insuli
steroid molecules
: Lipid molecules derived from cholesterol (e.g.
testosterone).
basic hormone a ttion
Circulate → Leave the bloodstream @ the capillaries → Encounters all tissues
a given hormone influences only specific tissue cells, called
target cells
targe cells have
e receptor molecules in or on target cells to which that
particular hormone can bind. Once binding has occurred, the target cell reacts in
a preprogrammed way
hormones are just
molecular triggers–they do not carry any coded
information (the same hormone can have different effects on different target
cells).
pituitary gland
- hypophysis
- Sits in the hypophyseal fossa of the sphenoid bone and secretes at
least nine major hormones
infundibulum
funnel-shaped stalk
connecting the pituitary gland to the hypothalamus
the basic divisions of the pituitary gland
adenohypophysis
neurohypophysis
adenohypophysis
: anterior division made up of glandular tissue
neurohypophsis
: posterior division made up of neural tissue
adenohypophysis
- pars distalis
- contains five different types of endocrine cells that make and secrete protein hormones:: somatrotrophic cells mammotropic cells thyroptropic cells corticotropic cells gonqadrotropic cells
somatotropic cells
secretes growth hormone (GH), which stimulates the
growth of the entire bod
mammotropic cells
secretes prolactin (PRL), which stimulates the manufacture of milk by the breasts.
thyrotropic cells
secretes thyroid-stimulating hormone (TSH), which prompts
the thyroid gland to secrete thyroid hormone, ultimately controlling metabolic rate.
corticotropic cells
secretes adrenocorticotropic hormone (ACTH), which
stimulates the adrenal cortex to secrete hormones that help people cope with stress
and melanocyte-stimulating hormone (MSH), which stimulates melanocytes to
produce melanin
gonadotropic cells
secretes follicle-stimulating hormone (FSH) and
luteinizing hormone (LH). FSH and LH (gonadotropins) act on the gonads,
stimulating the maturation of sex cells
adenohypophysis
- hypothalmus of the brain secretes
releasing hormones (releasing factors) inhibiting hormones
releasing hormones (releasing factors)
prompt the cells in the
adenohypophysis to release their hormones
inhibiting hormones
t turn off the secretion of hormones of the
adenohypophysis.
there are distinct releasing and inhibiting hormones released by the hypothalmus for
for almost
every adenohypophyseal
hormone
the brain controls:
the large
and important endocrine glands via two pathwyas
the hypothalmus controls the secretion of hormones by?
the adenohypophysis.
they adenohypophysis controls the secretion of homones by?
by the thyroid
gland, the adrenal cortex, and the gonads.
the neurohypophysis has three subdivions
inf -> sup
a) Pars nervosa (posterior lobe)
b) Infundibular stalk
c) Median eminence - cone shaped
The neurohypophysis is structurally
part of the brain and consists of
nervous tissue that contains unmyelinated axons and neuroglial cells
function of neurophypohysis
stores and
releases two peptide hormones
produced in the hypothalamus:
antidiuretic hormone ADH and oxytocin
antidiuretic hormone ADH
targets the collecting ducts and distal
tubules in the kidney, which reabsorb
more water from the urine
oxytocin
induces contraction of
the smooth musculature of reproductive
organs in males and females (uterus
during childbirth)
both antidiuretic hormone and oxytocin cause a desire to?
o cuddle, groom and bond with a mate.
thyroid gland location
located anterior to the trachea just inferior to the
larynx; the largest endocrine gland
thyroid gland has
two lateral lobes connected by a median bridge called the
isthmus.
thyroid gland produces two hormones
thyroid hormone TH and calcitonin
thyroid hormone TH
: affects many target
cells throughout the body; increases the basal
metabolic rate (the rate at which the body uses
oxygen to transform nutrients into energy) of
cells.
what releases TsH and it results in?
-The pituitary gland releases TSH which
ultimately results in the release of TH.
calcitonin
lowers calcium blood levels by a)
slowing the calcium-releasing activity of
osteoclasts in bones and b) increasing the calcium
secretion by the kidney
calcitinon function in adults
-No function in adults; acts mostly during
childhood when the skeleton grows quickly
parathyroid gland
distinct glands that lie on the posterior surface
of the thyroid gland
- - Most people have two pairs; varies among individuals
parathyroid gland contains
thick, branching cords composed of
two types of endocrine cells:
chief cells
oxyphil cells
chief cells of parathyroid gland
small and abundant; produce a hormone called parathyroid hormone (PTH),
PTH increases the blood calcium concentration by?
TH increases the blood calcium concentration by the following:
a) Stimulating osteoclasts to release Ca2+ from bone
b) Decreasing the secretion of Ca2+ by the kidney
c) Activating vitamin D (uptake of Ca2+ by the intestine)
oxyphil cells
rare; function unknown
adrenal (suprarenal) glands
perched on the superior surface of
the kidneys
each adrenal gland is two endocrine glands in one
adrenal medulla
adrenal cortex
adrenal medulla
nervous tissue that acts as part of the
sympathetic division of the ANS.
adrenal cortex
: surrounds the medulla; forms the bulk of the gland
adrenal medulla contains
contains the chromaffin cells (neurons) that secrete
the hormones epinephrine and norepinephrine into the blood to
enhance the “fight or flight” response.
adrenal cortex secretes
a variety of steroid hormones; contains three distinct layers (external → internal):
adrenal cortex: the three distinct layer
zona glomerulosa
zona fasciculatata
zona reticularis
zona glomerulosa
contains cells
arranged in spherical clusters
zona fasciculata
contains cells
arranged in parallel cords and an
abundance of lipid droplets
zona reticularis
contains cells that are
arranged in a branching network
The adrenal cortex secretes two main classes of corticosteroid
hormones:
mineralocorticoids
glocucorticoids
mineralocorticoids
The main example is aldosterone, which is secreted by the zona glomerulosa in response to a decline in either blood pressure or blood volume
Aldosterone prompts the
distal and collecting tubules
in the kidney to
reabsorb
more sodium into the blood.
glucocorticoids
The main type is cortisol, which is secreted by the zona fasciculata and zona reticularis to help the body deal with stressful situations (fasting, anxiety, trauma, crowding, and infection).
glucocorticoids keeps the blood glucose level? and?
the blood glucose levels high enough to support the brain’s activities. - and Redirect circulating lymphocytes to lymphoid and peripheral tissues.
pineal gland (pineal body)
: small, pine cone-shaped structure
The Pineal Gland
- Contains endocrine cells called pinealocytes that secrete the
hormone melatonin, which helps regulate circadian rhythms (a 24-hr
cycle in biochemical, physiological, or behavioral processes).
pancreas
: contains both exocrine (acinar cells) and endocrine cells.
islets of langerhans
~1 million; spherical bodies that contain the
endocrine cells of the pancreas
in each islet..
the endocrine cells are arranged in twisted, branching
cords separated by capillaries.
• Alpha (α) cells (A cells): secrete
glucagon, a hormone that signals liver
cells to release glucose from their liver stores thus raising blood sugar levels
when they fall too low.
• Beta (β) cells (B cells): secrete
insulin, a hormone that signals most cells
of the body to take up glucose from the blood and promotes the storage of
glucose as glycogen in the liver thus lowering blood sugar levels
thymus
Located in the lower neck and anterior thorax.
-Immune system organ where T
lymphocytes arise from
lymphocyte-precursor cells
thymic hormones
ssecreted by reticular cells; peptide hormones (examples: thymopoietin and thymosin); T lymphocytes gain their immunocompetence.
gonads
testes and ovaries; the main source of the steroid sex hormones
testes
\: interstitial cells secrete androgens (primarily testosterone), which maintain the reproductive organs, the male sex characteristics, and promotes the formation of sperm
ovaries
follicular granulosa cells and the corpus luteum secrete estrogens (maintains the reproductive organs and the female sex characteristics) and progesterone (signals the uterus to prepare for pregnancy).
heart
produces atrial natriuretic peptide (ANP), which reduces blood
pressure, blood volume, and blood sodium concentration
gastrointestinal tract
enteroendrocrine cells release local-acting digestive
hormones
placenta
: releases hormones that influence the coarse of pregnancy
kidneys
secrete erthropoietin (EPO), which signals the production of red blood cells
skin
: produces cholecalciferol, the precursor of vitamin D
adipose tissue
: releases leptin, which is involved in the sensation of
satiety, and stimulates increased energy expenditure.
