Ch 18 Endocrine - Pt 2 Flashcards
Control of hormone secretion is regulated by whatever
Signals from nervous system, chemical change in the blood or by other hormones
Negative feedback control (most common) is what?
Decrease/ increase in blood level reversed
Body does opposite of what act is doing
Bodies response in direct opposition to stimulus
Positive feedback control is what?
Change produced by the hormone causes more hormone to be released
Stimulus and response enhance one another
Disorders involve…
Hyposecretion/hormone or hyper secretion/hormonal of a hormone
Hormone begins life where
On a gland
What is a hormones end destination
A target cell
We have to control amount of hormone
From secretion to target cell( by receptors)
3 mechanisms control hormone release
- Humoral
- capillary blood contains low concentration of Ca2 which stimulates
Secretion of parathyroid hormone (PTH) by parathyroid gland
Chemical content of bodily fluid
…mechanism to control hormone
- Neural
- preganglioinic SNS fibers stimulate adrenal medulla cells
To secrete epinephrine and norepinephrine
Neurological- reflex it
… mechanical control of hormone release
- Hormonal
- hypothalamus secretes hormones that…
Stimulate other endocrine glands to secrete hormones
Hormone controlling another hormone
3 mechanical controls of hormone release
All 3 aide in feedback control
Feedback control of hormone secretion - Negative feedback
Prevents over activity of hormone system
The control variable is often not the secretory rate of the hormone itself but the degree of activity of the target tissue
Feedback regulation of hormones can occur where
All levels- gene transcription and transplation steps involved in processing the hormone or releasing stored hormone
HPA axis ( hypothalamo-pituitary-adrenal axis) is equal to what
Complex negative feedback
Not every hormone is controlled by every feedback mechanism ( positive/negative)- true or false
True
Thyroid hormone uses what feedback control?
Negative
Oxytocin- labor
Utilizes positive feedback back response
Negative feedback control allows us to control what
Timing and quantity
By controlling production
We control the quantity produced
By controlling secretion we control
The amount that is released/ circulated
Each mechanism- humoral, neural, hormonal
Uses a feed back loop (positive/negative)
Factors affecting response of target cells to hormones
Concentration of the hormone
Number of receptors
Duration of exposure
Intracellular conditions such as conc. Of rate-limiting enzymes, substrate or cofactors
Antagonistic or synergistic hormones
Target cells
Carry out homeostatic process
By controlling receptors on targets cells we control
Intensity of hormonal action and biochemical reactivity within target cell
Receptor control is called
Receptor regulation
Up regulation ( receptor regulation)
Cell increase the quantity of cellular components
Down regulation ( receptor regulation)
Cell decrease the quantity of cellular component in response to external variables
Decrease cell sensitivity to a hormone
This regulation increase cell sensitivity
Up regulation
Increases cell sensitivity to hormone
Stimulus causes number of receptor for a hormone to increase within target cell
What cell produces hormone with in a cell
Secretory cells
More receptors available on a receptor cell means what
Hyper reaction, intent reaction
Are effects of hormones the exact same day to day or can they differ?
They can differ
Pituitary gland
Found in brain, projection off of hypothalamus
Within the pituitary ( hypothalamus $
Nervous system has direct control over endocrine system
Hypothalamus to pituitary gland interaction is called
Hypothalamic pituitary axis (HPA)
Pituitary gland is made of 2 parts
Anterior pituitary (adenohypothisis) - actual gland
Posterior pituitary ( neurohypothisis)- made of neurons
2 separate structures
How does hypothalamus communicate with pituitary
Posterior- impulses( action potential) originate in hypothalamus— travel down axon to posterior- triggers hormones to hormone be released — neurons travel— neurological
Hypothalamic pituitary tract
Group of axon (neuron)- begin in hypothalamus and end in posterior pituitary
How does hypothalamus communicate Anterior pituitary
Secretes hormone to blood stream, to anterior pituitary and cells are stimulated
Anterior and posterior communication
Requires vascular connections
Infundibulum
Where hypothalamus and pituitary connect— connection structure
Tracts travel through
Hypothalamic pituitary portal system
Vascular connection between anterior and posterior pituitary
What is a Portal system ( standard circulatory system)
Specialized vascular system
Standard ;Heart into arteries into capillaries into veins back to heart
Portal; heart to arteries to capillaries to veins to capillaries to second vein then back to heart— blood vessel that begins in capillaries and ends in capillaries
Capillaries start in and end in
Arteries , veins
Portal system is an open or closed system?
Closed- blood within portal system doesn’t circulate into body- direct vascular communication between hypothalamus to anterior pituitary. Target cells go direct
Hypothalamus acts like what with the anterior pituitary
Endocrine gland
Hypothalamus produces hormones true or false
True- they control anterior pituitary, that also produces hormones
Tropic hormones- produced by hypothalamus
Stimulate or inhibit hormone secretion
Tropic hormone- Releasing hormones
Those that stimulate
Tropic hormone- inhibiting hormone
Those that slow secretion
At least ______tropic hormones are made by hypothalamus
9- these controlTSH, FH, LH, FSH, ACTH, and prolactin
Anterior is made up of ___types of cells
5
Cells within anterior pituitary
Trophic cells
5 groups of trophs
1 somatotroph- growth hormone- bones,muscles
- Lactotroph - PRL- mammory
- Corticotrophs - ACTH- adrenal cortex
- Thyrotroph- TSH- thyroid
- Gonadotroph- gonads- FSH, LH
Growth hormone
Primary job is to grow Lean tissue
Effects: stimulates epiphyseal plates in bones
Causes muscles to enlarge
Tiggers growth factors— thee trigger the growth plates
Prolactin
Job is to travel to mammory glands, causing them to produce milk
ACTH
Works on adrenal cortex( outer layers)release cortisol and aldosterone (steroids)— releases from anterior pituitary- glands on top kidneys- controls levels of steroids
TSH
Stimulates thyroid gland, releasing thyroid hormone-t3 and t4 ( numbers indicate iodine molecules)
FSH, LH
Gonads
Work on testes and ovaries. FSH targets follicles in ovary- triggers maturation steps
LH triggers- releasing process (ovulation)
LH and FSH in male
FSH- testes- works on cells ( sertoli)— spermatogenisis- producing sperm ( reproductive cell)
LH- leydig cell- testosterone synthesis- this gives bigger stature, deep voice etc
All trophs
Do not release hormones unless signaled by hypothalamus
Anterior pituitary _____ do anything unless hypothalamus tells it to
Doesn’t
Hypothalamus hav_____ that produce and release hormones much like NT are released
Neurons
Releasing and inhibiting ____ the anterior pituitary
Control
How growth hormone release
In hypothalamus releases growth hormone releasing hormone—- goes to to anterior pituitary— somatotroph releases growth hormone- triggering growth of bone (spurt) —- after spurt hypothalamus releases growth hormone inhibiting hormone (shuts off anterior pituitary)
Prolactin
Hypothalamus received signal of pregnancy and releases prolactin releasing hormone- activates mammory glands (milk production)
Turned off/on- hypothalamus releases prolactin inhibiting hormone, shuts off production in anterior pituitary
Gonadotroph
Hypothalamus- produce- gonadotroph releasing— LH and FSH-
TRH- hypothalamus releases
Anterior pituitary releases TSH- thyroid gland—- releases TSH
Adrenal gland
Hypothalamus—- CRH —- anterior pituitary— releases ACTH- finds adrenal cortex- release of corticosteroids
Control secretion
Control effects- target cells control receptor available
Posterior pituitary produces hormones
- ADH- anti diuretic
- Oxytocin- pregnancy
Produced and released in anterior pituitary
Tracts
Begin in thalamus, end in posterior pituitary
How do you shut off anterior pituitary
Neuronal impulse
ADH
Anti diuretic hormone- anti water loss-
Kidneys and skin- tells kidneys to produce less urine, retaining water
Skin- sweat glands — decreases sweat gland activity
Also targets blood vessels- water loss in blood, blood volume drops- leads to decrease in BP— vessels constrict — increasing BP
Oxytocin - works through positive feedback
1 uterus
2 mammory glands
Looking for smooth muscle contraction (positive feedback)
Mammory cells produce milk - smooth muscle wraps around - when oxytocin finds smooth muscle is will cause construction - squeeze gland- forces milk out(milk let down reflex)
