Endocrine Flashcards
A ductless gland whose secretion is released directly into the bloodstream
Endocrine gland
What are the glands making up the endocrine system
Pituitary, thyroid, adrenal, parathyroid, pineal
Other organs contain cells that secrete hormones but are part of other bodily systems, what are they?
- hypothalamus
- thymus
- pancreas
- ovaries
- testes
- kidneys
- stomach
- liver
- small intestine
- skin
- heart
- adipose tissue
A gland who’s secretion is drained by ducts onto the body surface or into a body cavity; hence the label, ducted glands
Exocrine glands
Examples of exocrine glands
- sebaceous glands
- sudiferous glands
- mammary glands
Usually drain onto the surface of the body
Substances produced in one part of the body and transported to another part of the body where they affect chemical actions or the secretion of other hormones. Chemical messengers
Hormones
__________ is controlled by the nervous system though nerve impulses.
Homeostasis
Nerve impulses and homeostasis
Impulses cause muscles to contract and glands to secrete. The secretions, usually hormones, affect virtually all systems of the body.
What virtually maintains homeostasis?
Hormones
The body’s natural method of maintaining its internal environment within certain a physiological limits
Homeostasis
Hormones affect only specific cells called __________
Target cells
Hormones circulate freely or _____?
Travel bound to special carrier proteins
Target cells have ______ within their cell membranes that bind (or recognize) a given hormone
Receptors
Hormones that enter the bloodstream to reach distant target cells are called _____________.
Circulating hormones
How long do circulating hormones usually remain in the blood?
Few minutes to a few hours
How are the circulating hormones eventually inactivated?
By the liver and excreted by the kidneys
What happens in patients with kidney or liver failure?
They have excess hormone build up
Hormones that do not enter the bloodstream to reach target cells are called _________
Local hormones
Local hormones acting on neighboring cells. Ex. Histamine
Paracrine
Local hormones acting on the same cell that secreted it
Autocrine
Ex. Interleukin-2
How are local hormones inactivated?
Quickly by enzymes in the interstitial fluid which surrounds cells
The effect of one hormone on a target cell requires previous or simultaneous exposure to another hormone(s) to enhance the target cell response or increase activity of another hormone.
Permissive effect
In order for one hormone to work, another hormone had to be there before the first one or there at the same time
The sum effects of two or more hormones acting together is greater or more extensive than of each hormone acting alone
Synergistic effect
The effect of one hormone on a target cell is opposed by another hormone
Antagonistic effect
The synthesis and release of most hormones are through a _______________
Negative feedback system
A _________________ is a corrective mechanism (maintaining homeostasis) that opposes a variation from normal limits thus minimizing change.
Negative feedback system
What stimulates or inhibits hormonal secretions: humoral stimuli
Changing levels of ions and nutrients in the bloodstream
What inhibits or stimulates hormonal secretions: hormonal stimuli
The release of other hormones
What stimulates or inhibits hormonal secretions: neural stimuli
Signals from the nervous system
What is the master endocrine gland?
Pituitary gland (hypophysis)
How many hormones does the pituitary gland secrete?
7
________ is the major link bringing together the nervous and endocrine systems.
Hypothalamus
What hormones does the hypothalamus synthesize?
Oxytocin
Antidieuretic hormone
Regulatory hormones
Together the __________ and ____________ regulate practically all aspects of growth, development, metabolism, and homeostasis.
Pituitary gland
Hypothalamus
Location of the hypothalamus **
Inferior to the two lobes of the thalamus
Location of the pituitary gland **
About 1/2” circular gland sitting in the sella turcica of the sphenoid bone, Has a short stalk called the infundibulum which attaches the pituitary to the superiorly located hypothalamus
What connects the pituitary gland to the superior located hypothalamus?
Infundibulum
What are the two lobes of the pituitary gland?
Anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis)
What is the anterior lobe of the pituitary gland called
The adenohypophysis
What is the posterior lobe of the pituitary gland called
The neurohypophysis
The synthesis and release of hormones from the anterior lobe is stimulated by ________________
Releasing hormones (RH) from the hypothalamus
The synthesis and release of hormones from the anterior lobe of the pituitary gland is suppressed by ___________
Inhibiting hormones (IH) from the hypothalamus
What are the 5 principle cell types of the anterior lobe?
- Somatotrophs
- thyrothophs
- gonadotrophs
- lactotrophs
- corticotrophs
How many hormones does the 5 principle cell types of the anterior lobe of the pituitary gland secrete?
7
What do somatotrophs produce and what does that hormone do?
Human growth hormone. Stimulates general body growth and regulates aspects of metabolism
What do thyrotrophs secrete and what does that hormone do?
Thyroid stimulating hormone. Controls secretions and other activities of the thyroid gland
What hormones do the gonadotrophs secrete and what do those hormones do?
- follicle stimulating hormone
- leutinizing hormone
Together LH and FSH stimulate secretion of estrogen and progesterone, and maturation of oocytes in the ovaries and secretion of testosterone and production of sperm in the testes
What hormones do lactotrophs produce and what does that hormone do?
Prolactin which initiates milk production
What hormones do corticotrophs secrete and what do they do?
- adrenocorticotropic hormone (ACTH)
- they stimulate the cortex of the adrenal glands to secrete glucocorticoids.
-Melanocyte-stimulating hormone (MSH) which affects skin pigment
What do glucocorticoids do?
Inhibit functions of some WBC. Antiinflammatory, used in creams for rashes
What dictates the secretion of all of the hormones that are secreted by the pituitary gland (anterior lobe)?
Hypothalamus
What does the posterior lobe of the pituitary gland do?
It does not synthesize hormones, it stores and releases 1 hormones made by the hypothalamus
What two hormones does the posterior lobe of the pituitary gland store and secrete?
Oxytocin (OT) and antidieureitc hormone (ADH)
What are oxytocin and antidiuretic synthesized by?
The neurosecretory cells in the hypothalamus
What does oxytocin do?
Stimulates contraction of the uterus and release of milk
What does ADH do?
Decrease water loss by the kidneys and stimulates arteriole constriction
A butterfly shaped gland weighing about one ounce
Thyroid gland
What are the right and left lobes of the thyroid joined together by?
Isthmus
Location of the thyroid gland
Right and left lobes lie one either side of the trachea. The isthmus lies anterior to the trachea
The thyroid gland consists of _________
Thyroid follicles
The wall of each thyroid follicle consists of these two types of cells
- follicular cells
- parafollicular cells (C cells)
What do the follicular cells of the thyroid follicles do?
Secrete T3 and T4, which are THE thyroid hormones
What do the parafollicular cells (C cells) of the thyroid follicles do?
Produce calcitonin
The thyroids storage of its secretory products
Stores them in large quantities; enough to last 100 days
What is the primary important of the T3 and T4 hormones?
Increase in BMR which is important in maintaining a normal body temperature
What are some other functions of T3 and T4
- Increase triglyceride breakdown and enhance cholesterol elimination in the bile, thus reducing blood cholesterol levels
- increase nervous tissue growth
- regulates (lowers) calcium ions in the blood
Two pairs of very small, coal shaped glands embedded in the posterior surface of the thyroid gland. A superior gland and an inferior gland are on each thyroid gland lobe
Parathyroid gland
Wha are the two types of cells that the parathyroid glands consist of?
- principal/chief cells
- oxyphil cells
Principal/chief cells
From the parathyroid gland
-produce parathyroid hormone (PTH) which raises the calcium levels in blood
Oxyphil cells
In the parathyroid glands
-function not known
Location of the adrenal glands (suprarenal)
Paired; one i located on the superior pole of each kidney
What is each adrenal gland made up of?
Capsule of connective tissue, then the adrenal cortex, and the innermost adrenal medulla
Functions of the adrenal glands
The cortex and medulla secrete different hormones
What are the 3 different zones of the adrenal cortex
- zone glomerulosa
- zone fasciculata
- zone reticularis
What do the cells of the zona glomerulosa of the adrenal cortex do?
Control water and electrolyte balance
What do the cells of the zona fasciculata of the adrenal cortex do?
Cells increase fat and protein breakdown, synthesize glucose, provide resistance to stress, act as anti inflammatory hormones, amd in high doses, depress the immune response
What do the cells of the zona reticularis of the adrenal cortex do?
Produce male sex hormone in small amounts, the effect is insignificant
The adrenal medulla consists of the __________ which secrete hormones responsible for the fight or flight response
Chromaffin cells
What are the fight or flight hormones?
Epinephrine/ adrenaline, and norepinephrine/noradrenaline
Also called catecholamines
Location of the pineal gland
Inferior to the posterior portion of the brains corpus callosum.
What are pinealocytes
Secretory cells of the pineal gland that form melatonin
An antioxidant protecting the CNS from free radical damage. Also, maintains circadian rhythms
Melatonin
Location of the pancreas
Stretches across the posterior abdominal wall from duodenum to the spleen, posterior to the stomach
Parts of the pancreas
Head, neck, body, tail
Exocrine function of the pancreas
Produce digestive enzymes
Endocrine function of the pancreas
Produce hormones to raise and lower blood glucose levels
What kind of gland is hte pancreas
Exocrine and endocrine
The ________ portion makes up 99% of the pancreatic cells
Exocrine
Clusters of exocrine cells that produce digestive enzymes which flow into the gastrointestinal tract through a network of ducts
Acini
Scattered among the exocrine acini are 1-2 million clusters of endocrine tissue called ______________
Islets of Langerhans
What are the 4 cells types of the islet of Langerhans?
- alpha cells (A)
- beta cells (B)
- delta cells (D)
- F-cells
What do the alpha cells of the islet of langerhans do?
Produce the hormones glucagon which erases blood glucose levels
20%
What do the beta cells of the islets of langerhans do?
Produce the hormones insulin which lowers blood glucose levels
70%
What do the D cells of the islet of langerhans do?
Inhibit HGH
5%
What do the F cells of the islets of langerhans do?
Inhibit gall bladder contraction
5%
The level of blood glucose controls glucagon and insulin via __________
Negative feedback system
Paired solid glands resembling unshelled almonds in size and shape
Ovaries
Location of ovaries
One on each side of the uterus
Function of ovaries
- produce the ovum
- produce estrogen and progesterone
Regulates development and maintainence of female sex organs and secondary characteristics
Estrogen
Prepares uterus for pregnancy
Progesterone
What is the ovary homologous to?
Testes
Where are the testes located?
Scrotum/scrotal sac
Septa from a dense fibrous capsule divide each testi into a series of internal compartment called _____
Lobules
Each of he 200-300 lobules of the teste contains 1-4 tightly coiled tubules called ___________
Seminiferous tubules
What is the site of sperm production?
Seminiferous tubules
What hormone do the testes produce?
Testosterone
Function of testosterone
- normal growth, development, and function of the male reproductive organs
- necessary for the development and maintainence of secondary sex characteristics
