T1 Flashcards
What’s the endocrine system purpose? (3)
regulates and controls metabolic processes
- helps maintain body homeostasis
- serves as one of two MAJOR control systems of the body
The endocrine glands make and secrete what?
hormones
How are the hormones transported through the body?
released into the blood and transported through the body
What are target cells in the endocrine system?
cells with specific receptor for a hormone
Target cells are also called ______ which fxns as what?
bind hormone, initiates or inhibits selective cell activity
What features are different from the nervous system? (6)
– Hormones transported within blood to target cells
– Causes metabolic changes in target cells
– Target any cells with receptors
– Exhibit longer reaction times
– More widespread effects throughout the body
– Longer-lasting effects (minutes to days and weeks)
What are the 4 fxn of the endo system?
- maintaining homeostasis of blood composition and volume
- controlling reproductive activities
- Regulating development, growth and metabolism, controlling digestive progesses
What is the composition of endocrine cells?
- secretory endocrine cells
- derived from epithelium with connective tissue framework
- high extensive blood supply which helps with uptake of hormones
What are the two organizations of organs within the system?
single organ with endocrine function
- cells in small clusters in organs with another function
Endocrine organs (single) include?(5)
pituitary gland • pineal gland • thyroid gland • parathyroid glands • adrenal glands
Pineal gland secretes what hormone? which is responsible for what?
melatonin, circadian rhythm
Which other hormone does the pineal gland affect? what does that hormone effect?
the synthesis of the hypothalmic hormone
- responsible for synthesis of the hypothalmic hormone
- involved in regulation of the reproductive system
The parathyroid has which two cell types?
-cheif cells and oxphil cells
Chief cells do what 3 things?
– source of parathyroid hormone
– released in response to decreased blood calcium levels
– return blood calcium to normal levels
What’s the fxn of oxphil cells?
fxn unknown
Endocrine cells iwthin other organs include?
- hypothalamus, skin, thymus
- heart, liver, stomach
- pancreas, small intestine
- kidneys, gonads
What are the three types of stimulation for the endocrine reflexes?
hormonal, humoral or nervous
Hormonal stimulation is?
1 part of body releases one hormone that hormone stimulates another part of the body to release a specific hormone
Humoral stimulation?
release of a hormone in response to changes in level of nutrient or ion in the blood
Nervous stimulation is?
release of a hormone in respone to stimulation by the nervous system (ex: norepenephrine and epinephrine aka adrenaline)
Steroid hormones are (soluble wise)
lipid soluble molecules synthesized form clestrol
Protein hormones are (soluble wise)
water souble
How are water-soluble hormones transported?
they readily dissolve
How are lipid soluble hormones transported
they require carrier molecules “ferrys”
Some lipid soluble carrier molecules are selective which means
that they bind only one lipid soluble molecule
How are hormones regulated
between synthesis and elimination
Increased hormone synthesis occurs when
increased blood levels
What are the hormone elimination routes (4)
- enzymic degradation in livier cells
- removal from blood via kidneys
- removal of blood by uptake into target cells
- increased elimination leading to decreased blood levels
Half life:
time necessary to reduce concentration to half of original level (shorter half life more frequent replacement)
Do water soluble hormones or lipid soluble hormones have a longer half life?
lipid soluble hormones have a longer half life
lipid soluble hormones are what size and are polar or non polar?
small nonpolar
because lipid soluble hormones are non polar how do they get across the plasma membrane?
able to diffuse across the plasma memberane
When a lipid soluble binds to intracellular receptors in the cytosol or nucleus what does it form
hormone receptor complex
hormone response elements in lipid soluble hormones are
- regions of chromatin within nucleus
- areas wher complex binds
lipid soluble hormone i nteractions results in what
transcription of mRNA
- translation resulting in protein synthesis
- may result in alteration in cell structure
- may result in shift of target cells’ metabolic activity
b/c water soluble hormones are polar how do they cross the plasma membrane
- initatte a series of biochemical events , signal transduction pathway
the signal trandcution pathway is initated by what
the hormone, the first messenger
In the signal trandsduction pathway what results in the formation of the second molecule, what does this molecule do
docking, termed second messenger which modifies some cellular activity
What is a G protein? inactive/active states, what activates it?
- internal plasma membrane protein complex
inactive = GDP
active = GTP - activated by binding of hormone
Adenylate Cyclase is
a plasma membrane protein bound and activated by g protein, increases formation of second messenger cAMP from ATP
- cAMP activates protein kinase which results in activation or inhibition of molecules
What are the actions of water-soluble hormones
multiple results possible from hormone activation
ex: activation or inhibition of enxymatic pathways- stimulation of growth through cellular reproduction
- results dependend on hormone, messenger types and enzymes phosphorylated
The water soluble hormone glucagon is
released from pancreatic cells in response to low blood glucose leveles
- glucose released from liver cells
The water soluble hormone oxytocin is
released from posterior pituitary during childbirth
- causes stronger uterine muscle contractions to expel baybay
What are the three types of interactions with receptor cells
synergistic, permissive, antagonistic
Synergistic reactions are
activity of one hormone reinforcing activity of another hormone
Permissive interactions are
activity of one hormone requiring second hormone
Antagonistic interactions are
activity of one homrone opposing effects of another
Steps of nutrient metabolism
Glucose, fatty acids, and some amino acids
• “nutrients”
• oxidized by cells to provide energy to form ATP
• circulate in the blood in their simple form
• glucose stored within glycogen
• fatty acids stored within triglycerides
• liver, adipose tissue, and skeletal muscle
– nutrients “deposited” and “withdrawn” here
Nutrient processing in the liver includes (3 things)
– Glycogenesis
– Glycogenolysis
– Gluconeogenesis
Glycogenesis
synthesis of glycogen from blood glucose
• also active in muscle cell
Glycogenolysis
- breakdown of stored glycogen into glucose
* also in muscle cells, but used locall
Gluconeogenesis
production of glucose from noncarbohydrate molecules
• Nutrient processing in adipose tissue include
– Lipogenesis
– Lipolysis
Lipogenesis
synthesis of triglycerides from blood fatty acids and glycerol
• for storage
Lipolysis
- breakdown of triglycerides into glycerol and fatty acids
* released into blood
Nutrient processing in all cells, especially muscle include
- Protein anabolism
– Protein catabolism
Protein anabolism
protein synthesis
• stimulated with increased uptake of amino acids from blood
Protein catabolism
- protein degradation
- not generally broken down for fuel
- may be broken down during stress or starvation
In the endocrine system the hypothalmus does what
Influences or controls many endocrine glands
– Has direct control over hormone release from pituitary gland
– Has indirect control over hormone release from:
• thyroid and adrenal glands
• liver, testes, and ovaries
In the endocrine system the pituitary gland does what
Lies inferior to the hypothalamus
– Approximately the size of a pea
– Housed within sella turcica of sphenoid bone
– Connected to hypothalamus by thin stalk, infundibulum
– Partitioned into anterior and posterior pituitary
Posterior Pituitary
– Neural part of pituitary gland
– Grows from developing hypothalamus
Cell bodies and dendrites within hypothalamus
• axons extending from hypothalamus to pars nervosa
• termed hypothalmo-hypophyseal tract
Anterior Pituitary
– Develops beginning of third week of development
• develops as invagination of ectoderm in developing oral cavity
Hormones stored in posterior pituitary
Synthesized in hypothalamus by neurosecretory cells
• packed within secretory vesicles
• transported by fast axonal transport
• released from synaptic knobs of neurons
- oxytocin, antidiuretic hormone
Oxytocin
• produced by paraventricular nucleus
Antidiuretic hormone (ADH)
produced by supraoptic nucleus
Hormone release from anterior pituitary
– Specific hormones within hypothalamus released
– Travel through from primary plexus to secondary plexus
– Hormones released from anterior pituitary
• reach target cells through the bloodstream
Hormones of the Hypothalamus tract
– Termed regulatory hormones (Tropic)
• secreted into blood to regulate anterior pituitary hormones
releasing hormones, inhibiting hormones
– Releasing hormones
stimulate secretion of specific anterior pituitary hormones
Inhibiting hormones
• deter secretion of specific anterior pituitary hormones
Hormones of the Hypothalamus
Thyrotropin-releasing hormone – Prolactin-releasing hormone – Gonadotropin-releasing hormone – Corticotropin-releasing hormone – Growth hormone-releasing hormone
Thyrotropin-releasing hormone
• increases secretion of thyroid-stimulating hormone
Prolactin-releasing hormone
• increases secretion of prolactin
Gonadotropin-releasing hormone
ncreases secretion of follicle-stimulating hormone and luteinizing
hormone
Corticotropin-releasing hormone
• increases secretion of adrenocorticotropic hormone
Growth hormone-releasing hormone
• increases secretion of growth hormone
Hormones of the Anterior Pituitary
– Six major hormones
– Most tropic hormones
• stimulated cells to secrete hormones
• exception prolactin
Six major hormones of the Anterior Pituitary
– Thyroid-stimulating hormone (TSH) – Prolactin – Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) – Adrenocorticotropic hormone (ACTH) – Growth hormone
Thyroid-stimulating hormone (TSH)
regulates release of thyroid hormone from thyroid gland
Prolactin
- regulates mammary growth and breast milk production
* may help androgen production in males
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- collectively called gonadotropins
- regulate hormone synthesis by the gonads
- regulate production and maturation of gamete
Adrenocorticotropic hormone (ACTH)
stimulates adrenal cortex to produce and secrete glucocorticoids
Growth hormone
stimulates cell growth and cell division
• affects most body cells
• particularly affects skeletal and muscular system
• stimulates liver to release insulin-like growth factor 1 and 2
– have overlapping function with growth hormone
Growth hormone characteristics
Functions include:
• stimulation of linear growth at epiphyseal plate
• hypertrophy of muscle
Anatomy of the Thyroid Gland
Largest structure in body devoted to endocrine activities
– Immediately inferior to thyroid cartilage of larynx
– Anterior to trachea
– Covered by connective tissue capsule
– Has left and right lobes
• connected at midline by narrow isthmus
– Highly vascularized by superior and inferior thyroid arteries
– Composed of microscopic spherical structures
• termed thyroid follicles
– Follicular cells
• form wall of follicles
• surround central lumen
• houses protein-rich fluid, colloid
– Thyroid hormone
• produced and released by follicular cells
Action of Thyroid Hormone
– Thyrotropin-releasing hormone (TRH) released by hypothalamus
• enters in response to decreased in blood levels of thyroid hormone
• also stimulated by:
– cold weather, pregnancy, high altitude, and hypoglycemia
– TRH binding to cells of anterior pituitary
• stimulates anterior pituitary to release thyroid-stimulating hormone (TSH)
– Increased thyroid hormone
inhibits release of TRH from hypothalamus
• inhibits release of TSH from anterior pituitary
• causes release of growth inhibiting hormone
– further inhibits release of TSH from anterior pituitary
– Hyperthyroidism
result from excessive production of TH
• increased metabolic rate, weight loss, hyperactivity, and heat intolerance
• treated by removing the thyroid (with daily hormone supplements)
– Hypothyroidism
results from decreased production of thyroid hormone
• low metabolic rate, lethargy
• cold intolerance, weight gain, and photophobia
• caused by decreased iodine intake, loss of pituitary stimulation of thyroid,
postsurgical, or immune system destruction of thyroid
• treated with thyroid hormone replacement
– Goiter
• enlargement of thyroid
• typically due to insufficient dietary iodine
• lack of dietary iodine preventing thyroid from producing thyroid hormone
• once relatively common in United States
– now iodine added to table salt
Adrenal cortex
- synthesizes more than 25 corticosteroids
- yellow color due to lipids within cells
- three regions producing different steroid hormones
– Pancreatic islet cells
small clusters of endocrine cells scattered among acini • 1% of total pancreatic volume • composed of two primary cell types: – alpha cells secreting glucagon – beta cells secreting insulin
• Blood glucose concentration
Pancreatic endocrine function
• maintaining normal blood glucose
– Normal range 70 to 110 mg of glucose/deciliter*
– Chronically high levels damaging to blood vessels and kidneys
– Low levels resulting in lethargy, mental and physical impairment, and
death (if too low)
