Endocrine System Flashcards
within the human body involves the transmission of signals to control and coordinate actions in an effort to maintain homeostasis.
communication
Communication within the human body involves the transmission of signals to control and coordinate actions in an effort to maintain
homeostasis
Two major organ systems are responsible for providing these communication pathways;
the nervous and endocrine systems
are sent viathe generation and propagation of action potentials which move along the membrane of a cell.
electrical signals
Once the action potential reaches the synaptic terminal;
the electrical signal is converted to a chemical signalas neurotransmitters are released into the synaptic cleft
When neurotransmittersbind with receptors on the receiving (post-synaptic) cell;
new electrical signal is generated and quickly continues to its destination
enables body functions that involve quick, brief actions, such as movement, sensation, and cognition
neural communication
primarily responsible for rapid communication throughout the body
nervous system
relies on only a single method of communication: chemical signaling
endocrine system
are the chemicals released byendocrine cells that regulateother cells in the body
hormones
are transported primarily via the bloodstream throughout the body, where they bind to receptors on target cells, triggering a response
hormones
chemical signal that elicits a response in the same cell that secreted it
autocrine
tissue or organ that secretes hormones into the blood and lymph without ducts such that they may be transported to organs distant from the site of secretion
endocrine gland
cells, tissues, and organs that secrete hormones as a primary or secondary function and play an integral role in normal bodily processes
endocrine system
cells, tissues, and organs that secrete substances directly to target tissues via glandular ducts
exocrine system
secretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body
hormone
chemical signal that elicits a response in neighboring cells; also called paracrine factor
paracrine system
involved in the information business.
endocrine system
carry essential messages that have far-reaching effects
hormones
control body processes at every level, from the energy uptake of a single cell to the whole body’s rate of growth and development.
endocrine system
sends hormones through the Circulatory system to control and coordinate body functions in much the same way as the nervous system uses tiny electrical signals
endocrine system
work together to integrate into the brain and complement each other, but they tend to work at different speeds.
endocrine and nervous system
respond within split-seconds but their action soon fades
nerves
Hormones regulate processes such as:
a. The breakdown of chemical substances in the metabolism of what we eat and drink
b. Fluid balance and urine production
c. The body’s growth and development
d. Sexual Reproduction
connects the nervous system to the endocrine system. It receives and processes signals from other brain regions and pathways and translates them into hormones, the chemical messengers of the endocrine system.
hypothalamus
released by the pituitary gland and the hypothalamus control the other endocrine glands and regulate all major internal functions
hormones
are a mixture of both endocrine (ductless, hormones are secreted into the blood) and exocrine (have ducts, hormones are secreted onto surfaces) glands
glandular tissue
examples of exocrine glands are:
sebaceous and sweat glands (in the skin), salivary glands (oral), Brunner’s glands.
This gland secretes thin watery secretions, which are rich in enzymes and antibodies, and the ducts open onto the surface of the oral mucosa
exocrine glands
do not have ducts. Their secretions (hormones) are secreted into the bloodstream.
endocrine glands
it is somewhat analogous to the coordinating activity of neurons
neuroendocrine
Some short-range endocrine activity also occurs in the digestive system
paracrine activity
released - hormones, are usually released by exocytosis, by the secretory cells, into the interstitial spaces and pass through fenestrated capillaries to enter the bloodstream and move to target organs.
signaling molecules
always found in close proximity to a capillary bed and have a rich network of blood vessels.
secretory cells of endocrine glands
The signaling molecules released - hormones, are usually released by
exocytosis
these include the pituitary (hypophysis), thyroid, parathyroid, adrenal, and pineal glands.
discrete endocrine glands
These include the kidney, pancreas, and gonads.
Endocrine component of Glands with both an Endocrine and an Exocrine Function
a small gland 6-8mm long is found in the brain, close to the hypothalamus, and is a photoreceptor organ, which is stimulated by information received via the retina, that secretes the hormone melatonin, which appears to regulate the circadian rhythms of the body
pineal gland
Also known as the hypophysis has a complex microanatomy and physical and functional interconnection with the hypothalamus.
pituitary gland
is a “master regulator” of sorts, playing essential roles in body homeostasis, including temperature regulation, behavior (including thirst, hunger, and sex), inherent body rhythms, and control of the pituitary gland which, in turn, bears an immense effect on endocrine organs elsewhere.
hypothalamus
hypothalamus is a “master regulator” of sorts, playing essential roles in body homeostasis, including
temperature regulation, behavior (including thirst, hunger, and sex), inherent body rhythms, and control of the pituitary gland
The pituitary gland is generally divided into two components with developmental and functional differences;
the anterior pituitary (adenohypophysis)and theposterior pituitary (neurohypophysis)
formed from adowngrowthof the diencephalon that forms the floor of the third ventricle.
posterior part
derived from anupgrowthfrom theoral ectodermof the primitive oral cavity calledRathke’s pouch.
anterior part
anterior pituitary (adenohypophysis) is composed of two histologically and functionally distinct regions;
the pars distalis and the pars intermedia.
Along the posterior part of the anterior lobe there is a narrow region called
the pars intermedia
is the largest component of the anterior pituitary gland, and is comprised of cords and trabeculae of polygonal cells arranged on a vascular stroma.
pars distalis
there are three
morphologically distinct cells within the
pars distalis:
acidophils,basophils,
andchromophobes.
There are two types of chromophils (cells which take u p stain) called?
acidophilsandbasophils
cells that produce growth hormone are called
somatotrophs
cells producing ACTH
corticotrophs
is distinguished histologically by cords of polygonal cells with occasional formation of luminal structures lined by polygonal to cuboidal epithelial cells and containing central pink, homogeneous fluid (colloid)
pars intermedia
develops from the brain and grows ventrally to interact with and abut the anterior pituitary during development.
posterior pituitary (neurohypophysis)
distinct in that it lacks the secretory polygonal cells characteristic of the anterior pituitary.
posterior pituitary, orpars nervosa
These hypothalamic neurons are responsible for the production. Which are then transported along the axons into the pars nervosa where they are secreted and enter the bloodstream.
anti-diuretic hormone (ADH; also referred to as vasopressin)andoxytocin
specialized supporting cells (glial cells) of the pars nervosa that surround the axons and facilitate secretion of ADH and oxytocin
pituicytes
It is also a part of the digestive system. It excretes pancreatic juice into the small intestine via the pancreatic duct.
pancreas
In domestic species such as dogs and cats, the pancreas is a discrete organ directly adjacent to the duodenum, containing a right (proximal to the duodenum) and left limb
In large animals such as horses and cattle, the pancreas has more of a diffuse distribution within the mesentery adjacent to the duodenum
comprises the majority cell population and volume of the pancreas
exocrine pancreas
the production and secretion of diverse digestive enzymes and an alkaline fluid that neutralizes the acidic secretions of the stomach
exocrine pancreas
specialized cytoplasmic organelles that function in the sorting and secretion of pancreatic proenzymes, such asprolipase, pepsinogen and trypsinogen.
zymogen granules
secreted into the lumina which coalesce into a progressively enlarging system of ducts.
zymogens
endocrine pancreatic tissue consists of small, discrete clusters of cells, called
islets of Langerhans
which secrete into a ductular system, cells of the islets of Langerhans secrete directly into small fenestrated capillaries that are integrated within the islets, allowing for systemic distribution of their hormones
exocrine pancreatic acini
The primary hormones secreted by cells of the islets of Langerhans are;
insulin (β-(beta) cells) glucagon (α-(alpha) cells)
Additional hormones produced and secreted
amylin, somatostatin, pancreatic polypeptide and ghrelin
that release hormones into the bloodstream.
pancreatic islets
pancreatic islets make up less than 2% of pancreatic tissue, but their specialized cells regulate blood glucose levels (or blood sugar).
When blood sugar is low, alpha cells in the islets release glucagon. Glucagon spurs the liver to break down glycogen and release more glucose into the blood
When blood sugar is high, beta cells in the islets release insulin, which increases glucose reuptake.
are pyramid-shaped organs that sit at the top of each kidney.
adrenal glands
Each adrenal gland consists of two structures:
an outer adrenal cortex
an inner adrenal medulla.
is a network of fine connective tissues that makes up most of the gland. It secretes a range of steroid hormones.
adrenal cortex
which manages protein and glucose levels
cortisol
which adjusts our levels of water and salt.
aldosterone
are secreted by the adrenal cortex in small amounts by both sexes
androgens and estrogens
produces epinephrine and nor-epinephrine (NE). These chemicals promote “fight-or-flight,” the body’s initial response to stress.
adrenal medulla
In avian species, cells of the adrenal cortex and medulla are intermingled, although the cytologic features of the cells are similar to that of mammalian adrenal cells.
The layers, from outermost to innermost, are: adrenal cortex
zona glomerulosa
zona fasciculata
zona reticularis.
the outermost layer, is composed of trabecular arrangements of polygonal cells with moderate amounts of eosinophilic, slightly vacuolated cytoplasm, and round nuclei
zona glomerulosa
responsible for production of mineralocorticoid hormones, primarily aldosterone, which exerts its effect on the kidneys to increase sodium retention
cells of the zona glomerulosa
composed of irregular cords of polygonal epithelial cells with small to moderate amounts of eosinophilic cytoplasm, with few clear cytoplasmic vacuoles. These cells are primarily responsible for the secretion of the androgen sex hormones.
zona reticularis
Control of hormone secretion of the adrenal cortical layers
complex
The secretion of aldosterone by cells of the zona glomerulosa is controlled by the kidneys, via the renin-angiotensin system
regulated by the pituitary gland via ACTH
zona fasciculata and zona reticularis
The primary hormones secreted by the adrenal medulla are?
norepinephrine and epinephrine (also known as adrenaline)
the regulation of secretion in the adrenal cortex, secretion of these hormones is regulated by the
sympathetic nervous system
owing to the brown staining of cytoplasmic granules when stained with chromium salts
chromaffin cells
There are 2 hormones made by the kidneys
vitamin D and erythropoietin
essential for a number of different functions in the body
vitamin D
Most of the vitamin D that is in the blood is inactive and it is modified by the kidney and other tissues to activate it
active vitamin D
stimulates the uptake of calcium from food, is important for the maintenance of healthy bones, and also helps to regulate the response of the immune system to infection
produced when oxygen levels in the blood are low. It acts in the bone marrow to stimulate the production of mature red blood cells and to maintain healthy oxygen levels in our tissues
erythropoietin
major role of the parathyroid gland
regulating serum calcium and phosphorus homeostasis via the production of parathyroid hormone (PTH)
the parathyroid glands have an interconnected relationship with other tissues and organ systems: namely,
bone, the kidneys, and the intestine.
indirectlyfaciliates intestinal calcium absorption by inducing production of vitamin D3 (1,25 hydroxycholecalciferol) by renal tubular epithelium
parathyroid hormone
acts on intestinal epithelium (enterocytes) to induce transport of calcium from the intestinal lumen into the blood.
vitamin D3
are responsible for the production and secretion of parathyroid hormone, which is stimulated by low blood calcium levels
chief cells
single organ present in both mammalian and non-mammalian species but with some variation in gross anatomy.
thyroid gland
Pigs have a very little lobar distinction in their thyroid gland. Regardless of the anatomic features, the organ serves the same major functions in all species: the production of THYROID HORMONE and CALCITONIN
most prominent architectural feature of the thyroid gland
thyroid follicles
stored hormone is bound to a glycoprotein, and this stored hormone is called
colloid
normally cuboidal, with moderate amounts of eosinophilic cytoplasm and round, hyperchromatic nuclei.
Thyroid follicular epithelial cells
protein rich fluid containing thyroid hormones produced by the thyroid follicular epithelium
colloid
essentially act as a storage vat for thyroid hormone, which may then be transported across the follicular epithelium and released into capillaries adjacent to the epithelium.
thyroid follicle lumina
gland secretes iodine containing hormones called
Tri-iodo thyronine(T3) andthyroxine(T4)
It regulates the basal metabolic rate, and it is regulated by the pituitary hormone TSH. It also secretescalcitonin- which regulates blood calcium levels. Secretion of calcitonin causes blood calcium levels to drop, and its secretion is directly dependent on blood calcium levels
Tri-iodo thyronine(T3)
These cells secretecalcitoninin response to increased levels of blood calcium.
clear cells
the thyroid becomes enlarged, and hyperactive, and the follicles look smaller.
hyperthyroidism
produce and secrete calcitonin (see below), a hormone that regulates calcium
/phosphate levels within the body.
C cells
endocrine system, hormones are secreted into the interstitial fluid and then diffuse into the blood or lymph for circulation throughout the body to reach target tissues.
a signaling molecule released in an inflammatory response that binds to receptors located on the surface of the cell releasing the molecule.
interleukin-1
