Cell Signaling and the Hormonal Response to Exercise Flashcards
Neuroendocrine system:
Endocrine system releases hormones
Nervous system uses neurotransmitters
Endocrine glands =
Release hormones directly into the blood
Hormones =
Alter the activity of tissues that possess receptors to which the hormone can bind
Several classes based on chemical makeup
> Amino acid derivatives
> Peptides/protein
> Steroids
The effect of a hormone on a tissue is determined by:
Plasma concentration of hormone
Rate of secretion of hormone from endocrine gland
Rate of metabolism or excretion of hormone
Quantity of transport protein
Changes in plasma volume
Rate of secretion of hormone from endocrine gland =
Magnitude of input
Stimulatory versus inhibitory input
Rate of metabolism or excretion of hormone =
At the receptor and by the liver and kidneys
Incretin =
gut-derived peptide hormone that are rapidly secreted in response to a meal – stimulate B cells to postprandially secrete insulin
The overarching role of insulin in the body:
regulate the body’s energy supply or glucose by transporting glucose intracellularly to cells, tissue
To be used as energy and to maintain blood glucose levels at a ‘normal’ level which ideally is less than 100mg/DL of blood – over 126 is indicative of diabetes
Contributing factors to increase insulin secretion by the pancreas are:
increased plasma glucose levels
glucose circulating in the blood stream
increased amino acid
automonic nervous system adjustment from both SNS and PSNS
incretins
Hormone-Receptor Interactions
Hormones only affect tissue with specific receptors
Hormones have to be congruent with a receptor inorder to activate the cell
Magnitude of effect of Hormone-Receptor Interactions dependent on:
Concentration of the hormone
Number of receptors on the cell
Affinity of the receptor for the hormone
Speed with which hormone is metabolized
Downregulation =
Decrease in receptor number in response to high concentration of hormone
Upregulation =
Increase in receptor number in response to low concentration of hormone
Mechanisms of Hormone Action
Altering activity of DNA to modify protein synthesis
Activating second messengers via G protein
= Cascade of events leads to a second messenger = Cyclic AMP, Ca++
Altering membrane transport = Insulin via tyrosine kinase = large class of transmembrane receptors; play a key role in regulation of glucose homeostasis
Hormones are secreted from endocrine glands:
Hypothalamus and pituitary glands
Thyroid and parathyroid glands
Adrenal glands
Pancreas
Testes and ovaries
endocrine system is comprised of:
pineal gland
thymus
ovary
testicle
hypothalamus
pituitary gland
thyroid gland
parathyroid glands
pancreas
adrenal glands
placenta - during pregnancy
Hypothalamus =
Stimulates release of hormones from anterior pituitary gland
Provides hormones for release from posterior pituitary gland
Hypothalamus function:
Coordinates the endocrine system: main function is to keep body in homeostasis
Body Temperature
BP
Hunger and Thirst
Satiety
Mood
Libido
Sleep
Anterior Pituitary Gland
hormones released:
ACTH
FSH
LH
MSH
TSH
Prolactin
GH
Adrenocorticotropic hormone (ACTH)
Stimulates cortisol (stress = increased levels) release from adrenal glands
Follicle-stimulating hormone (FSH)
Sexual development & reproduction
Luteinizing hormone (LH)
Stimulates production of testosterone and estrogen
Melanocyte-stimulating hormone (MSH)
Stimulates production of melanin
Thyroid-stimulating hormone (TSH)
Controls thyroid hormone (growth, metabolism) release from thyroid gland
Prolactin
Stimulates release/production of breast milk
Growth hormone (GH)
Controls height, bone length, and muscle growth