1.4 Cell Physiology Flashcards
Which cells can release hormones that affect the parameter?
Only cells that monitor the parameter (ex: body temp, blood glucose, blood salinity)
What must cells have to react to hormonal signals?
Correct hormone receptors
Conceptual framework for Endocrine Control Systems
Sensor cells –> Integrator cells –> Effector cells–> Physiological parameter normalized
Sensor cells
Assess parameter
Integrator cells
Hi / lo?
Send out the messengers…
Effector Cells
Target tissue function altered
What do TRH neurons do?
Sense low body temp w/ thermoreceptors
What does TRH do?
Causes TSH and Thyroid (T3, T4) hormones to be released which increases metabolism to release heat
What do TRH neurons do if a high temp is sensed?
Suppress TRH
What are the 3 ways to stimulate or inhibit hormone release?
Hormonal stimulation
Humoral stimulation
Nervous system stimulation
Hormonal stimulation
Release of a hormone in response to another hormone (ex: TSH and TH)
Humoral Stimulation
Release of a hormone in response to changes in level of nutrients or ions in the blood (ex: blood glucose levels and insulin)
Nervous system stimulation
Release of a hormone in response to stimulation by the nervous system (ex: epinephrine and norepinephrine)
How are hormones typically turned off?
Downregulating / removing a stimulator
inhibition of hormone release by negative feedback on the stimulators occurs on what levels?
ALL possible anatomic levels
- Primary (gland releasing the effector hormone)
- Secondary (first order stimulating gland / hormone)
- Tertiary ( Second order stimulating gland / hormone)
What are two major types of cellular communication?
Intercellular and intracellular
Is endocrinology just about blood-bourns hormones?
No, it is a broadly applied term for any cell to cell or within cell communication outside the nervous system
Intercellular messengers
“Cell to cell”; between cells and between tissues.. hormones, growth factors, cytokines carried by blood and interstitial fluid
Intracellular messengers
“Within cell,” signal transduction within a single cell, all within the confines of the plasma membrane
3 modes of intercellular communication
Endocrine
Paracrine
Autocrine
Endocrine
Circulates via bloodstream, messenger “hormones”
Paracrine
Diffuses locally to target cells
Autocrine
Affects cell that releases it
What are autocrine and paracrine messengers usually called?
Growth factors
Another term for intracellular communication
Cell signaling pathways
2 modes of intracellular communication
1) Lipid soluble hormones
2) Water soluble hormones
Lipid soluble hormones
- Diffuse through plasma membrane into the CYTOPLASM
- Interact with specific hormone receptor proteins inside the cell
What are two main groups / hormones that are lipid soluble?
Steroids and thyroid hormones
Process of estrogen and estrogen receptor
- ER binds to E, ER+E complex changes configuration to reveal a nuclear localization signal and shuttles to nucleus
- ER + E complex behaves as a transcription factor… Find specific ERE DNA sequences to turn on
Water soluble Hormones
- Insoluble in membranes, must bind extracellular domain of hormone receptors embedded in plasma membrane
- Hormone receptors activate signal transduction pathway
What do signal transduction pathways rely on
All rely on second messenger molecules or enzymes within the cell
Protein Kinase A (PKA) Pathway
- Activated G protein causes activation of adenylate cyclase
- Adenylate cyclase converts ATP molecules to cAMP
- cAMP serves as “second messenger” by activating protein kinase A
ADH is what kind of hormone?
Water soluble, peptide hormone
LOOK AT ADH & PKC PATHWAY
SLIDES 16 17 18
What does a PKA do?
It is a kinase that adds phosphate groups to activate proteins
Hypothalamus
Homeostatic control center of the brain
