Endocrine Ch 16 Flashcards
Endocrine glands
Ductless glands, release hormones into surrounding tissue fluid.
Endocrine glands include:
pituitary thyroid parathyroid adrenal pineal
Neuroendocrine
Hypothalamus alsong with its neural functions produces and releases hormones.
Contain endocrine tieeus and proform other functions
Hypothalamus
Placenta
Gonads
Pancreas
Autocrines
Chemicals that exert their effects on the same cells that secrete them.
Paracrine
Also act locally (with in the same tissue) but affect cells other than the cells releasing the chemicals.
2 classes of hormones
Amino acid based
Steroids
Amino acid based hormones
Most hormones
widely varries size
Steroids
Synthesized from cholesterol
Include gonadal and adrenocortical
Hormone changes typically protuces
One or more of the following:
Alters plasma membrane permiability or membrane potential
Stimulates synthesis or enzymes and other proteins within the cell
Activates or deactivates enzymes
Induces secretory activity
Stimulates mitosis
How do hormones act on receptors
- Water soluable: act on receptors in the plasma membrane. Usually use second messangers
- Lipid soluable: Act on receptors inside the cell, directly activates genes.
Cyclic AMP signaling
- Hormone binds receptors (first messanger)
- Receptor activates G protein
- G protein activates adenylate cyclase
- Adenylate cyclase converts ATP to cyclic AMP
- Cyclic AMP activates protein kinases
Phosphodiesterase
Enzyme that degrades cAMP
3 factors that target cell activation depends on
- Blood levels of the hormone
- Number of receptors of the hormone on the target cells
- Affinity of binding between hormone and receptor
Up-regulation
When persistantly low levels of a hormone cause a target cell to form additional receptors
Down-regulation
High hormone concentrations decrease the number of target cells for that hormone to prevent it from over reacting to the hormone
Direct gene activation mechanism of lipid-soluable hormone
- Steroid diffuses through membrane and bindes to intracellula receptor
- Receptor-hormone complex enters the nucleus
- Then binds to DNA
- Binding initiates transcription of mRNA
- mRNA directs protein synthesis
3 hormone stimuli
Humoral
Neural
Hormonal
Humoral Stimuli
Glands that secrete their hormones in responce to certian ion and nuetriant levels in the blood
Neural Stimuli
In few cases nerve fibers stimulate hormone release, example: adrenal medulla
Hormonal Stimuli
Many glands release their hormons in responce to other hormones
3 types of hormone interaction
Permissive
Synergism
Antagonism
Permissive
One hormone can not exert its full effects with out another hormone being present.
Synergism
One or more hormones produce the same effect on a target but their combined effects are amplified
Antagonism
When one hormone opposes that action of another
Posterior Pituitary lobe
Composed largely of neural tissue
Stores hormones made in the hypothalamus
not a true endocrine gland.
Actually part of the brain
Anterior Pituitary lobe
Composed of granular tissue
Manufactures and releases a number of hormones
Hypothalamis-hypophyseal tract
Consisds of:
Paraventricular neuron: makes oxytocin
Supraotic neurons: produce antidiuretic hormone
Primary capillary plexus
Vascular connection between the anterior ptiuitary and hypothalamus
Portal system
Unusual arrangement of blood in which capillary bed feeds into veins which feeds into a second capillary bed
Posterior pituitary and hypothalamiv hormones
Oxytocin Antidiuretic hormone (ADH)
Oxytocin
Stong stimulant for uterine contractions, released during chilbirth and nursing, acts as a hormonal trigger for milk ejection (positive feed back mechanisms)
Cuddle hormone
Antidiuretic hormone ADH
Inhibits urine formation, prevents water imballances and helps the body avoid dehydration.
Vassopression
Osmoreceptors
Hypothalamic neurons that monitor solute concentration of the blood.
Anterior putuitary hormone
Growth Hormone Thyroid-STimulating Hormone Adrenocortopic Hormone Follicle-Stimulating Hormone Luteinizing Hormone Prolactin
GH
Growth Hormone Produces by somatotropic cells Stimulates: Liver, muscle, bone, and other tissues Anabolic (tissue building) hormone Anti-insulin affects (glucose sparing)
GHRH
Growth hormone releasing hormone
released by the hypothalamus
Stimulates the Anterior Pituitary gland to release GH.
GHIH
Growth hormone inhibiting hormone
Produced in various locations in the gut
triggered by negitive feed back of rising GH and inhibits release of GH.
Oxytocin
From posterior pituitary
Stimulated by uterine contraction and breast feeding.
Acts on uterus to contract and breast to eject milk
Positive feed back
ADH
Antidiutetic hormone
Released by posterior pituitary
Acts on the kidneys tubule cells to reabsorb water.
Stimulated by increased blood solute concentration or decreased blood volume.
TSH
Tyroid-stimulating hormone
Released: Anterior Pituitary
Stimulated by TRH
Target: Thyroid gland stimulates release of tyroid hormone
ACTH
Adrenocortropic hormone
Released: anterior pituitary
Target: Adrenal Cortex, promotes release of gluccorticoids and androgens
Stimulated by CRH
FSH
Folicle-stimulating hormone
Released by anteroir pituitary
Target: Ovaries and Testies
Stimulated by GnRH
LH
Luteinizing hormone
Released by anterior pituitary
Stimulated by GnRH
Target:Ovaries and testies
PRL
Prolactin
Target: breast, promotes lactation
inhibited my PIH(dopamine)
Hypothalamic releasing and inhibiting hormones
GHRH : Stimulate GH GHIH : Inhibits GH TRH : Thyrotropin-releasing hormone CRH : Corticotropin-releasing hormone GnRH : Gonadotropin-releasing hormone PIH: Prolactin-inhibiting hormone
Gonadotropins
FSH and LH
TH
Tyroid hormone T3 and T4 Uses intracellular receptors Major metabolic hormone Effects almost evey body system Can be stored extracellularly Increases metabolic rate,Regulateds growth and development, maintains BP
T3 & T4
T3: Triiodothyronine (3 bound iodineatoms) forms at target tissues by converting from T4
T4: Thyroxine (4 bound iodine atams) Major hormone secretes by thyroid folicles
Graves disease
Most common hyperthyroid pathology
autoimmune condition where the person makes abnormal antibodies directed against the thyroid folicular cells
S/S: elevated metabolic rate, sweating rapid irregular HR, weightless bulging eyes.
Calcitonin
Released by parafollicular or C cells of the thyroid.
Targets bones and inhibits osteoclasts and stimulates Ca+ uptake into the bone.
Parathyroid hormone
Most important in controlling Ca+
Falling blood Ca+ levels trigger its release
Stimulates osteoclasts, enhances reabsorbtion of Ca+, Promoted Vit D activation,
Adrenal glands
On top od the kidneys
2 parts: Adrenal medula and Adrenal cortex
Helps cope with stressful situations.
Adrenal Cortex
Synthesizes over 12 steroid hormones called corticosteroids.
Not stored in cells so thier rate of release depends on rate of wynthesis
3 layers of the adrenal cortex.
From outside in:
Zona glomerulosa: Cell clusters, Help control balance of minerals and water in blood
Zona fasciculata: Linear cordes, mainly produce glucocorticoids.
Zona reticularis: Netlike arrangement, small amounds of adrenal sex hormones and gonadocorticoids.
Aldosterone
Mineralocorticoids, regulate electrolyte concentrations in extracellular fluids.
Stimulates Na+ reabsorbtion.
Targets distal kidney tubules
Na+ K regulation
Renin-Angiotensin-Aldosterone Mechanism
Regulates blood volume and BP
1. BP falls, specialized cells of the juxtaglomerular complex in the kidneys are excited
2. They release Renin into the blood
3. Renin cleaves off part of the plasma protein angiotensiogen, triggering and enzymatic cascade that forma angiotensin II, which stimulates the release or aldosterone.
Altimatly rises BP
ANP
Atrial Natriuretic Peptide
Secreted by the heart when BP rises, fine tunes BP and sodium/water balance
Inhibits renin-angiotensin-aldosterone mechanism and decreases BP by allowing Na+ and Water to flow out as urine.
Cortisol
Glucocorticoids Influence the energy metabolism of most cells, and help resist stressors. Keep Blood glucose levels constant Modify gene activity Negitive feed back regulation
Cushing’s Syndrome
Excess Glucocorticoid
Persistand hyperglycemia, HTN and edema
Addison’s Disease
Hyposecretory disorder of the adrenal cortex. Deficiencies in glucocorticoids and mineralocorticoids. Weight loss low Na+ high K
Adrenal Medulla
Synthesize catecholamines Epi and N Epi
Mobilize when sympatheic nervous system is activated 80% Epi 20% N Epi
Epinephrine
More potent, stimulator of metabolic activities: bronchial dilation, increased blood flow to skeletal muscles and heart
Norepinephrine
Greater influence on PVC and BP
Pineal Gland
Hangs fron the roof of the 3rd ventricle in the diencephalon.
Secretes pinealocytes
Secretes Melatonin
Melatonin
Amine hormone derived from serotonin. Peak levels occure at night and make us drowsy.
Pancreas
Has both endocrine and exocrine cells
Hormone producing cells:
glucogon-synthesizing: alpha
insulin-synthesizing: beta
Glucogon
Secreted from pancreas
Targets the Liver
Synthesizes glucose fron lactic acid and raises blood glucose
Insulin
Small amino acid protein
Lowers blood glucose in 3 ways:
1. Enhances membrane transport of glucose
2. Inhibits the breakdown of glycogen to glucose
3. Inhibits the breakdown of amino acids and fats to glucose.
Also promotes protein synthesis and fat storage
Gonads Produce 3 sex hormones
Estrogen
Progesterone
Testosterone
Erythropoetin
Secreted from interstitial cells in the kidneys, glygoprotein hormone that signals bone marrow cells to increase production of red blood cells
Leptin
Secreted by adipose tissue to tell your body how much stored fat you have.
Cholecalciferol
Inactive form od vitamin D3 produced by the skin. Modified in the liver and fully activates in the kidneys
Thymus hormones
Developr T Lymphocytes
Thymulin
Thymopoietins
Thymosins
