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