Chapter 18 Flashcards
Endocrine System
Endocrine System
oordinates the function of body systems, along with the nervous system
Exocrine gland
discharge secretions (usually enzymes), viaducts, on to
epithelial surfaces, usually for digestion and lubrication
Endocrine gland
discharge secretions (hormones) into interstitial fluid (the
hormones then diffuse into the blood), for regulation of metabolism
Hormones
chemical messengers, produced in small amounts, transported in the
blood, then interact with specific cells, to stimulate physiologic changes
Target cell
cell that contains specific receptor sites for a specific hormone
(each hormone has a specific shape that matches the contour of the
receptor site)
Paracrine hormone
a type of local hormone that is secreted by cell(s), then
diffuse to nearby cells/tissues to stimulate physiological changes
True endocrine hormones
(in contrast to local hormones)travel away from
the site of release to stimulate other tissues.
Autocrine hormone
a type of local hormone that is secreted by cell(s), then
interact with receptors on the cell that release the hormone, to
simulate physiologic changes
Up-Regulation
when a cell increases the number of hormones
receptors becoming more sensitive to stimulation
Down-Regulation
when a cell reduces the number of receptors, becoming less
sensitive to stimulation
Synergistic effect
when two or more hormones(or any chemical)act together to
produce a greater effect than an individual hormone
Permissive effect
one hormone enhances the target cells response to a second
hormone that is secreted later
Antagonistic effect
when one hormone opposes the action of another hormone
Hydrophobic hormones are transported by various proteins in the blood.
ex. Albumins, Globulins
a. These hormones diffuse through the plasma membrane.
b. Once inside the cell, the hormone interacts with specific receptor
sites, this usually initiates transcription(initiating the process
to make new proteins)
c. The new proteins create a physiologic change.
Water soluble hormone (ex. amines, peptides and eicosanoids)
a. The hormone interacts with the receptor site on the outer surface of
the plasma membrane. The hormone is referred to as the Primary
Messenger.
b. The signal is relayed to the inner surface of the plasma membrane
(often via a G-protein).
c. The signal activates the enzyme Adenylate Cyclase.
d. Adenylate Cyclase converts ATP to cyclic AMP (cAMP). cAMP is
referred to as the Secondary Messenger.
e. cAMP activates enzymes (usually kinases)that activate physiologic
changes in the cell
f. cAMP is deactivated by Phosphodiesterase
Hypothalamus
- the primary control center for the Autonomic Nervous System
- the integrating link between the CNS and Endocrine systems
- controls the release of Anterior Pituitary Gland (Adenohypophysis)
hormones - produces the Posterior Pituitary Gland (Neurohypophysis)hormones
- attached to the Pituitary Gland by the Infundibulum
Anterior Pituitary Gland
- produces FSH, LH, TSH, ACTH, Prolactin and GH
rowth Hormone (GH)
- has wide spread effects on the body
- results of GH release (these cause the production of Insulin-like
Growth factors [IGFs] certain tissues, ie. Liver, Skeletal muscle,
bone, etc….):
(1) increases cellular uptake of amino acids, and protein
synthesis
(2) increases lipid catabolism - breaks down triglycerides to
produce energy
(3) increases glucose utilization
(4) stimulated Kidneys to resorb electrolytes
- overall GH increases bone and muscle growth
Anterior Pituitary Gland Disorders Giantism
overproduction of growth hormone prior to the closure
of growth plates
Anterior Pituitary Gland Disorders Dwarfism
underproduction of growth hormone
Anterior Pituitary Gland Disorders Acromegaly
overproduction of growth hormone after the closure of
the major growth plates
lies below the Larynx, covering the anterior and lateral Trachea
- has two lateral lobes connected by the isthmus
Thyroid Gland
- contains Follicular cells which produce two key hormones, T3
(Triiodothyronine) and T4 (Thyroxine). These hormones
require iodine and tyrosine for their production.
Thyroid Gland
also contains Parafollicular cells which produce calcitonin (see bone
metabolism)
- actions of T3 and T4
Thyroid Gland
increases oxygen use for cells which increases ATP production
(increases BMR)
Thyroid Gland
stimulation synthesis of ATPase Pumps, the increased use of ATP
leaks to an increase in heat production (i.e. Calorigenic Effect)
Thyroid Gland
increases the heart rate and force of contraction
Thyroid Gland
stimulates glucose and triglyceride breakdown to produce ATP
e. accelerates growth (along with GH and Insulin
Thyroid Gland
Cretinism = hyposecretion of T3 and T4 at birth
infant has cool, yellowish skin
- thick tongue
- if untreated, this can lead to mental retardation
Graves Disease
Hypersecretion
- autoimmune disorder in which antibodies are produced that mimic
the action of TSH, over-stimulating the production of T3 and T4
- signs include an enlarged Thyroid gland (goiter), exophthalmos
(bulging eyes), increased activity
Pancreas
a retroperitoneal organ that lies behind the Stomach
- contains several clusters of cells known as Pancreatic Islets (of
Langerhans) that produce endocrine hormones. These clusters make up
approximately two percent of the cells in the Pancreas.
Pancreas hormones
a. Insulin - produced by Beta cells
- stimulates cells to absorb glucose and amino acids, also
stimulates glycogen synthesis
b. Glucagon - produced by Alpha cell
- stimulates the breakdown of glycogen and triglycerides
which increases the blood glucose level
Diabetes Mellitus
the hyposecretion (or the production of inactive)Insulin
- i.e. the inability to produce or use Insulin)
- Classic Signs:
Polyuria - excessive urination
Polydipsia - excessive thirst
Polyphagia - excessive hunger
- also hyperglycemia, glucosuria, ketonuria
General Adaptive System (GAS) (The Stress Response)
Stressor = any stimulus that produces the Stress Response
Part 1 …..
- Alarm Reaction
a. Heart rate and contraction strength increased
b. Vessels of the skin and viscera constrict (to hunt blood to the
brain and muscles).
c. The Spleen contracts to discharge blood.
d. The Liver breaks down glycogen to glucose, for energy.
e. Respiration increases.
f. Decreased digestive tract activity
g. Stress hormones are released from the Adrenal Medulla.
General Adaptive System (GAS) (The Stress Response)
Stressor = any stimulus that produces the Stress Response
Part 2 …..
Resistance Reaction
- the body’s long term reaction to stress
a. The Adrenal Cortex is stimulated. Glucose production is stimulated.
b. Wound healing is slowed.
c. Increased catabolism.
d. Sodium retention increases, along with retention of water. (The
current text associates this activity with the Alarm Reaction.)
e. Blood chemistry appears normal.
General Adaptive System (GAS) (The Stress Response)
Stressor = any stimulus that produces the Stress Response
Part 3 …..
Exhaustion
- depletion of body reserves
a. Muscle wasting
b. Rapid degeneration in all body systems. eg. Decreased immune
response, ulceration of the GI Tract, and failure of Pancreatic Beta
Cells
c. Can lead to many chronic degenerative diseases._
