Endocrine Flashcards
Types of chemical messengers
Autocrine
Paracrine
Neurotransmitter
Endocrine
Autocrine
Secreted by cells in local area
Influences the activity of the same cell or cell type from which it was secreted
Ex: Eicosanoids (prostaglandins, thromboxanes, prostacyclins, leukotrienes)
Paracrine
Produced by wide variety of tissues
Secreted into extracellular fluid
Has localized effect on other tissues
Ex: somatostatin, histamine, eicosanoids
Neurotransmitter
Produced by neurons Secreted into synaptic cleft by presynaptic nerve terminals Travels short distances Influences postsynaptic cells Ex: acetylcholine, epinephrine
Endocrine
Secreted into blood by specialized cells
Travels some distance to target tissues
Results in coordinated regulation of cell function
Ex: Thyroid hormones, growth hormone, insulin, epinephrine, estrogen, progesterone, testosterone, prostaglandins
Exocrine vs endocrine glands
Exocrine=have ducts that carry secretions to outside of body or into hollow organ like intestine or stomach
Endocrine=secretes messengers into the bloodstream
Humoral stimuli
Blood-borne chemicals that stimulate the release of hormones
Neuropeptide
Chemical messenger that is secreted directly into the blood by a neuron which causes it to become a hormone
Releasing hormones
Released by hypothalamus and acts on anterior pituitary gland and stimulate the release of hormones from there
They are released into blood to travel to target cells
Tropic hormones
Secreted by anterior pituitary gland
Hormonal stimuli-a hormone that stimulates the release of other hormones
Inhibiting hormones
Hormones from the hypothalamus that prevents secretion of tropic hormones from the anterior pituitary gland
Negative feedback
Hormone’s secretion is inhibited by the hormone itself one blood levels reach a certain point
most hormones are regulated by this
SELF-LIMITING
Positive feedback
Some hormones (when stimulated by a tropic hormone) promote the synthesis and secretion of the tropic hormone in addition to stimulating the target cell
This stimulates further secretion of the original hormone
SELF-PROPAGATING
G protein complex
Complex of proteins that when activated they alter the activity of other enzyme
When hormone binds to membrane bound receptor it changes the shape of G protein complex exposing active sites which lead to a change in another molecule
Alpha, beta and gamma subunits
Water soluble hormone
Membrane bound receptor
Lipid soluble hormone
Nuclear receptors
Pituitary gland
Master gland
Controlled by hypothalamus
Anterior=adenohypophysis
Posterior=neurohypophysis
Sella turcica
Houses the pituitary
ADH
Anti-diuretic hormone
Same as vasopressin
HPP
Hypothalamic Pituitary Portal System
Portal system
Going from capillary bed directly to another capillary bed without passing through heart
Protein kinases
Enzymes that regulate the action of other enzymes after binding to cAMP (activated by cAMP)
Adenylate cyclase
Enzyme that catalyzes the formation of cAMP
Examples of lipid soluble hormones
Thyroid hormones
Steroid hormones
Two chemical categories of ENDOCRINE hormones
Lipid-solube
Water-soluble
Sequence of events of a lipid soluble hormone binding to its receptor
1) Hormone diffuses across plasma membrane
2) Hormone binds to receptro
3) Hormone-receptor complex binds to a hormone response element on DNA
4) Transcription factor is formed
5) mRNA is produced
6) Proteins are synthesized
Androgens
Class of steroid hormone
Secreted by adrenal cortex
Effects of adrenal medullary hormones
Increased blood flow to skeletal muscle and heart
Increased release of fatty acids from adipose tissue
Increased glucose release from the liver
Classes of hormones secreted by the adrenal cortex
Androgens
Mineralocorticoids
Glucocorticoids
Oxytocin
Posterior pituitary hormone that targets the uterus and mammary glands
What effect does PTH have on the bones
Increased osteoclast activity
Increased bone reabsorption
Nuclear receptors can be found where
Nucleus
Cytoplasm
Glucagon
Pancreatic hormone
Increases rate of glucose synthesis from fats and amino acids
Increases breakdown of glycogen in the liver
