The Endocrine System Chapter 18
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. What would you like to do?
- ex. sweat, sebaceous, mucous, salivary, digestive
- Always secrete hormones that travel through bloodstream
What are the 5 actions of hormones?
- Regulate internal environment, ex. antidiuretic hormone
- Respond to stress, ex. epinephrine
- Integrate growth and development, ex. Human Growth Hormone
- Contribute to reproductive processes, ex. gonadotrophic hormones
- Help control organic metabolism and energy balance, ex. thyroxin
Glands that have both exocrine and endocrine functions
- heterocrine glands
- ex. pancreas and gonads
Chemically, how are hormones classified?
As amines, peptides, proteins, and steroids
What are the simplest hormones structurally?
- modified from amino acids
- ex. Tyrosine
What do proteins and peptide hormones consist of?
Chains of amino acids
Proteins are longer chains, peptides are shorter chains
ex. most pituitary hormones
What hormones are derived from cholesterol which has 4 carbon rings?
ex sex hormones & cortisol
What is one thing all hormones have in common?
They all have the function of maintaining homeostasis by changing the rate of the physiological activities of cells.
What determines the amount of hormone released?
The body's need for the hormone at any given time.
What are the cells that respond to the effects of hormones called?
All cells are target cells for one or more hormones.
Where are receptors found in the target cell?
the plasma membrane, cytoplasm, and nucleus.
Receptors are specific in that they recognize only certain hormones.
Are hormones released continuously or in short bursts?
Short bursts, with little or no release in between.
What mechanism prevents overproduction or underproduction of a hormone?
Negative feedback control
How are hormone secretions controlled?
By biological sensing mechanisms in the blood, by nerve impulses, and by regulating hormones (regulating factors).
What is a regulating factor?
A hormone that controls another hormone.
Where is the pituitary located?
At the base of the brain within the sella turcica of the sphenoid bone under the hypothalamus
What is the pituitary connected to? By what?
Connected to the hypothalamus by a stalk-like structure called the infundibulum.
- connects the hypothalamus to the pituitary
- stalk-like structure
How many parts is the pituitary divided into?
What are the 2 parts of the pituitary?
what is another name for the adenohypophysis?
the anterior lobe of the pituitary
what is another name of the neurohypophysis
the posterior lobe of the pituitary
How may hormones does the hypothalamus release?
9 regulating hormones
How many hormones does the pituitary release?
- 7 from the anterior lobe
- 2 from the posterior lobe
These hormones are released or inhibited by 9 (different) regulating hormones produced in the hypothalamus
What are the 7 hormones released by the anterior lobe of the pituitary?
- Thyroid Stimulating Hormone (TSH)
- Melanocyte Stimulating Hormone (MSH)
- Adrenocorticotropic Hormone (ACTH)
- Prolactin (PRL) or lactogenic hormone (LTH)
- Human Growth Hormone (HGH)
- Follicle Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
What are the 2 hormones released by the posterior lobe of the pituitary?
- Antidiuretic Hormone (ADH)
- Oxytocin (OT)
Where does the posterior lobe of the pituitary receive it's stimulation from?
By way of a nerve tract from the hypothalamus.
Where does the anterior lobe of the pituitary (adenohypophysis) get its blood supply from?
From the superior hypophyseal arteries which transport regulating hormones from the hypothalamus to the anterior lobe.
Which is larger? The adenohypophysis or the neurohypophysis?
What releases TSH -Thyroid stimulating hormone? What does it do?
- Anterior lobe of the the pituitary
- TSH stimulates the thyroid gland to release it's hormone thyroxin
What releases MSH - Melanocyte stimulating hormone? What does it do?
- The anterior pituitary
- Increases skin color
What is (ACTH) - Adrenocorticotropic hormone? Where is it secreted from?
Secreted from the anterior lobe of the pituitary it stimulates the cortex of the adrenal gland to secrete it's hormones (corticosteroids).
What is prolactin and where is it secreted form?
Prolactin (PRL) is also known as lactogenic hormone (LTH)
is secreted from the anterior pituitary and helps initiate milk production in the breasts
What does Human Growth Hormone do and here is it secreted from? What cells in the pancreas produce hormones that counteract HGH?
HGH is secreted by that anterior pituitary. It stimulates growth. Delta cells in the pancreas secrete HGIH which inhibit growth.
What does FSH do? and where is it secreted from?
Follicle stimulating hormone is secreted from the anterior pituitary. It regulates the activities of the gonads.
Luteinizing hormone (LH) regulates what? where is it secreted from?
Luteinizing hormone is secreted from the anterior pituitary and regulates the activities of the gonads (along with FSH)
What term is 2 hormones are often termed gonadotropic hormones? Why?
FSH and LH because they regulate the activities of the gonads (testes and ovaries)
What are the two hormones released by the posterior pituitary? What are they stimulated by?
Antidiuretic hormone (ADH)
they are stimulated by the nerve tract from the hypothalamus
What is antidiuretic hormone and what secretes it?
Produced by the posterior pituitary, antidiuretic hormone stimulates water reabsorption by the kidneys. Makes you retain water. It is released when the body is dehydrated and causes the kidneys to conserve water.
Little water intake = lots of ADH released = retaining of water by kidneys
What is Oxytocin (OT)? Where is it secreted from?
Secreted by the posterior pituitary, Oxytocin stimulates the contraction of the uterus (positive feedback). Also stimulates the contractile cells of the mammary glands for milk ejection.
Where is the thyroid located?
Just below the larynx
What does the thyroid look like?
It has right and left lateral lobes which look like wings. It is shaped like a butterfly.
What connects the right and left lobes (wings) of the thyroid gland?
What two types of cells does the thyroid gland consist of ?
follicular and parafollicular
What do the follicular cells of the thyroid gland secrete?
thyroxine (T4) and triiodothyronine(T3)
What do the parafollicular cells of the the thyroid secrete?
What do the thyroid hormones T3 and T4 regulate?
Metabolism, energy balance, growth, and development, and influence the activity of the nervous system.
T3 has 3 atoms of iodine. T4 has 4.
Where is most of the body's iodine stored?
What are enlarged thyroid glands called? And what are they caused by?
Goiters. They are caused by tumors of the thyroid, lack of iodine, or autoimmune conditions such as Grave's disease.
What are the symptoms of Grave's Disease and what is it an autoimmune disease of?
exophthalmos, high metabolic rate, heat intolerance, nervous energy, generally thin.
Autoimmune disease of the thyroid
What is exophthalmos?
Bulging of the eye anteriorly out of the orbit. Often seen in Grave's disease.
Where is Calcitonin (CT) produced and what does it do?
Calcitonin is produced in the parafollicular cells of the thyroid
It helps maintain homeostasis of calcium and phosphates in the blood
Deposition of calcium IN THE BONE
Where are the parathyroids located? How many are their?
They are embedded on the posterior surfaces of the lateral lobes of the thyroid. There is usually a pair on either side.
What hormone do the parathyroids release? What does it do?
Parathyroid hormone (PTH) or parathormone
It acts with calcitonin to regulate the homeostasis of calcium and phosphate
Parathyroid hormone (parathormone) RELEASES calcium from bone.
Where are the adrenal glands located?
In the fat pads superior to the kidneys.
What 2 parts make up the adrenal glands?
Outer cortex and inner medulla
What 3 hormones are produced by the adrenal cortex (outside of adrenal glands)
Gonadocorticoids (sex hormones)
What do mineralocorticoids do and where are they produced? give and example
They are produced in the cortex of the adrenal glands.
They regulate water and sodium and ptassium levels in the body by way of the kidneys.
What do Glucocorticoids do? where are they produced? give an example
They promote resistance to stress and serve as anti-inflammitories
produced in the cortex of adrenal glands
What are gonadocorticoids? where are they produced? give an example
They are male and female hormones produced by the adrenal cortex. Have minimal effect until old age.
example testosterone and estrogen
What are the hormones produced in the medulla of the adrenal gland?
Epinephrine and Norepinephrine
The effects of the hormones epinephrine and norepinephrine from the adrenal medulla produce a response similar to the sympathetic nerve response (fight or flight). What is this referred to as?
Where does the pancreas lie?
Underneath the stomach
What special kind of gland is the pancreas? Name another one of the these special glands.
A heterocrine gland. It's both a endocrine and exocrine gland.
Gonads are also heterocrine glands.
What are the endocrine cells of the pancreas called?
islets of Langerhans
What are the exocrine cells of the pancreas? What do they produce?
produce pancreatic juice
What are the 3 types of cells within the islets of Langerhans?
What do Alpha cells secrete?
Glucagon, which increases blood glucose levels
What do Beta cells secrete?
Insulin, which decreases blood glucose levels
What do Delta cells do? What are they?
Delta cells secrete growth inhibiting hormone (GHIH) which decreases production of HGH. Stress and hypoglcemia stimulate its release. They are endocrine cells of the pancreas
Where are the ovaries located? What do they produce?
pelvic cavity of females
Produce estrogen, progesterone
Where are the testes located. What do they produce?
inside the scrotum and produce androgenic sex hormones (primarily testosterone)
refers to male characteristics
refers to mixed mail and female characteristics
Where is the pineal gland located?
third (central) ventricle of the brain and is shaped like a pine cone
What does the pineal gland secrete and when does it secrete it?
secretes melatonin during darkness
retinal stimulation stopes the production of melatonin (paradoxical)
believed to play a part in circadian rhythms
Where is the thymus located and who is it most conspicuous in?
bilobed structure located in the superior mediastinum immediately behind the sternum
very conspicuous in infants and young children. Shrinks as people age.
What does the thymus secrete? Why are these important?
thymic femoral factor (THF) and thymic factor (TF)
Important in cellular immunity by promoting the development of T lymphocytes
What disorders are associated with the anterior pituitary?
Those that affect human growth including dwarfism, giantism, acromegaly.
Most common disorder of the posterior pituitary?
undersecretion of antidiuretic hormone causes polyuria and severe dehydration
caused by inability of pancreatic beta cells to produce insulin
caused by undersecretion of thryoxin by the thyroid gland during infancy.
characterized by dwarfism and mental retardation.
caused by undersecretion of thyroid hormones during adulthood.
lethargy, dry skin, puffy face
treated with Synthroid
Over secretion of cortisone by the adrenal cortex
spindly legs, moon face, buffalo hump, pendulous abdomen, striae (stretch marks)
What would you like to do?
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