Study sets, textbooks, questions
Upgrade to remove ads
Physiology- Endocrine Control Mechanisms
Terms in this set (44)
How does the endocrine system compare to the nervous system in how it maintains homeostasis?
Slower to initiate a response (hormones vs action potentials), but effects last longer.
What 4 general body functions do hormones regulate?
1) Metabolic rate
2) Water and electrolyte balances
3) Cell proliferation
4) Reproductive organs
In general, what are hormones? Where are they made, transported, and received?
Hormones are chemicals secreted by specialized endocrine cells into the blood, and act on receptors of target cells.
What are the 4 types of hormones based on signalling pattern?
1) Endocrine (classical)
How do classical endocrine hormones signal?
Made by classical endocrine cells and travel via blood to the target tissue
How do neurocrine hormones signal?
Released by axonal ends of neurons into blood and travel to reach target tissue
How do paracrine hormones signal?
Diffusion to different local/neighboring cell types via ISF or gap junctions
How do autocrine hormones signal?
Acting back on the cell that produced them or other identical cells nearby via gap junctions
What is the usual sequence in negative feedback regulation of hormone release?
Change in parameter signals endocrine cells to release hormones, which activate effector cells and return parameter to normal conditions. This turns off hormone production.
What is chronotropic control of hormones? What gland regulates circadian rhythm, and with what substance?
Hormone release in phases based on rhythms. The pineal gland regulates circadian rhythm with melatonin.
What are the 4 types of chemicals that can act as hormones?
1) Amino acids
2) Proteins and peptides
What are amino acid hormones derived from? Are they water and/or lipid soluble?
Amino acids come from tyrosine or tryptophan. Melatonin and catecholamines are water soluble, but thyroid hormone is lipid soluble.
How are proteins and peptides made, stored, and secreted? Are they water and/or lipid soluble?
Synthesized as large precursor molecules, stored in vesicles, and secreted by exocytosis. They are water soluble.
Generally, which molecules require carriers in the blood?
Lipid soluble molecules usually require carriers, while water soluble molecules can travel freely in the blood
What are steroids derived from? Are they water and/or lipid soluble?
Made from cholesterol, they are lipid soluble and require a protein carrier in the blood
What are prostanoids derived from? How are they produced and stored? How do they act in comparison to other hormones?
Made from arachidonic acid, they are not stored but released immediately after synthesis. They act on membrane receptors coupled to G-proteins, but are chemically unstable and rapidly metabolized.
What is the half-life of a hormone? What are the 3 forms of transport that affect the half-life of a hormone?
The time required for concentration to decrease to 1/2 of initial concentration.
1) Free (active) hormone
3 Bound to carrier
How fast do free hormones act and how long is their half life? Why?
They are the fastest acting, already in active form, but have the shortest half-life because they are susceptible to enzymatic degradation
What are prohormones? How fast do they act, and how long is their half-life?
Inactive precursors of water-soluble hormones that must be cleaved for activation, they have longer half-lives and delayed effect compared to free hormones.
How does carrier binding affect response time and half-life? What produces the carrier proteins?
Slowest response time, longest half-life. Carrier globulins are synthesized by the liver.
What 3 mechanisms contribute to the irreversible removal of hormones from blood plasma? Which has the biggest effect?
1) Target cell uptake
2) Metabolic degradation
3) Urinary and biliary excretion- most effect
What lab value is the sum of the removal processes?
Metabolic clearance rate- plasma cleared per time (ml/min)
What 3 steps are required for a hormone to elicit cellular response?
1) Hormone must be bound by the specific receptor
2) Hormone-receptor complex coupled to signal-generating mechanism (or be one itself)
3) Generated signal (2nd messenger) changes intracellular processes
What are the 2 types of receptor systems? What characteristic differentiates them, and which is faster?
1) Plasma Membrane receptor systems (Rm), for non-lipid soluble hormones. Slightly faster, seconds to minutes for action
2) Intracellular receptor systems (Rc and Rn), for lipid-soluble hormones. Slower, minutes to hours for action
What are Rm receptors, and where are they found? How do they respond to hormone occupancy?
Large glycoproteins with extracellular binding sites, they are within the plasma membrane of target cells. Hormones cause conformation changes like endocytosis where complex is brought into the cell.
How saturated do target cell receptors need to be for maximal response?
5-10% usually, target cells are very responsive to hormone binding
What is up-regulation? How can this occur?
Increasing number of Rm. It occurs with infrequent exposure to submaximal hormone concentrations, with hormones recruiting their own receptor and enhancing cell sensitivity
What is down-regulation? What nervous system effect is it analogous to? How can this occur?
Decreasing number of Rm, endocrine adaptation. Occurs with sustained presence of excess hormone, lessening effect of chronic signalling
What is K in relation to Rm, and what factors can alter it?
The affinity of receptors for hormones, it can be affected by changes in phosphorylation, pH, osmolarity, ion concentrations, and substrate levels
What are G-proteins composed of?
An alpha subunit and a beta-gamma dimer subunit
What is the function of the alpha sub-unit of G-proteins?
Dissociates from the G-protein and receptor, simulating/inhibiting an enzyme to open/close ion channel
What are examples of 2nd messengers, and what is their function?
cAMP, cGMP, DAG, IP3, Ca2+ can activate protein kinases that activate/deactivate enzymes in metabolic pathways and cascade effects
What is the function of phosphodiesterases?
Hydrolyze the 2nd messengers cAMP, cGMP into their inactive straight 5' form
What is autohydrolysis?
G-protein subunits terminate their own activity by reassociating with G-protein
What is the non-G-protein signaling mechanism? What are 2 major types?
Rm with a single transmembrane portion
1) Mitogen-activated protein kinases (MAPK)
2) Tyrosine kinases
What is the function of tyrosine kinases?
Autophosphorylation of intracellular portion of receptor, and modulation of gene transcription
Where are intracellular receptors found for lipid-soluble hormones? What does the receptor-hormone complex target, and to what effect?
In the nucleus (Rn) and cytoplasm (Rc). Complex interacts with DNA in the nucleus to alter gene transcription
What 6 factors determine target cell responsiveness to hormones?
1) Hormone concentration
2) Number of receptors
3) Chronotropic factors
4) Intracellular conditions
5) Other hormones
6) Number of target cells
Why is hormone concentration usually very small?
Energy inefficient to regularly produce large amounts, and takes more time to clear.
What are chronotropic factors involved in target cell responsiveness?
Duration of exposure, interval between consecutive exposures
What are intracellular conditions that affect target cell responsiveness?
Rate limiting enzymes, co-factors, or substrates
Why does the presence of other hormones affect cell responsiveness to a specific hormone?
Concurrent affects of either antagonistic or synergistic hormones can occur.
What is permissive action?
When one hormone increases target cell responsiveness to another hormone or signalling molecule
What two ways can hormones increase the number of target cells?
1) Stimulating movement through mitotic cycle
2) Inhibiting apoptosis
Recommended textbook explanations
Anh-Hue Thi Tu, Brian M. Forster, Mark Schneegurt, Nina Parker, Philip Lister
Elevate Middle Grade Science 2019 Earth Digital Courseware 6 Year License
Biology: The Dynamics of Life (California)
Sets found in the same folder
Physiology- Thyroid Hormones
Physiology- Hypophyseal-Hypothalamic Hormones
Physiology- Adrenal Glands
Physiology- Endocrine Pancreas
Sets with similar terms
Chapter 16 The Endocrine System
Ch. 17 A&P
Other sets by this creator
DLBCL regimens and agents
Maryland Law- Drug Therapy Management
Maryland Law- Specialty Pharmacy
Maryland Law- Misbranding/Adulteration
Other Quizlet sets
PersonalityTheories Humanists 2014
Selection and Eval. Reining
Bio 1421 Exam 2 Chapters 16-20 BERGH
MEDICAL TERM CHAP 6 & 7
Why does the FVC and FEV1 increase with the use of a bronchodilator inhaler medication in the asthmatic patient?
what do conducting arteries do ?
43) High fructose drinks are theorized to be beneficial to sport performance because they have a minimal impact on what hormone specifically?
What are the two stages of the Cell Life Cycle?