chp 16. Flashcards
Endocrine system
acts with nervous system to coordinate and integrate activity of body cells
Endocrine system responses are _____ than nervous system responses
slower but longer lasting than nervous system responses
Endocrinology
study of hormones and endocrine organs
Endocrine system controls and integrates:
- Reproduction
- Growth and development
- Maintenance of electrolyte, water, and nutrient balance of blood
- Regulation of cellular metabolism and energy balance
- Mobilization of body defenses
Exocrine glands
- Produce nonhormonal substances (examples: sweat, saliva)
- Have ducts to carry secretion to membrane surface
Endocrine glands
- Produce hormones
- Lack ducts
List the Endocrine glands
pituitary, thyroid, parathyroid, adrenal, and pineal glands
Hypothalamus is a
neuroendocrine organ
Some have exocrine and endocrine functions
Pancreas, gonads, placenta
Hormones
long-distance chemical signals; travel in blood or lymph
Autocrines:
chemicals that exert effects on same cells that secrete them
NOT hormones
Paracrines
ocally acting chemicals that affect cells other than those that secrete them
NOT hormones
Amino acid–based hormones
Amino acid derivatives, peptides, and proteins
-water-soluble
Steroids
Synthesized from cholesterol
Gonadal and adrenocortical hormones
-lipid-soluble
Target cells
tissues with receptors for a specific hormone
Hormone act on target cells any of the following:
- Alter plasma membrane permeability and/or membrane potential by opening or closing ion channels
- Stimulate synthesis of enzymes or other proteins
- Activate or deactivate enzymes
- Induce secretory activity
- Stimulate mitosis
Which hormone act on G protien?
Water-soluble hormones
Amino acid–based hormones, except thyroid hormone, exert effects through
second-messenger systems
Cyclic AMP (cAMP) signaling mechanism
- Hormone (first messenger) binds to receptor
- Receptor activates a G protein
- G protein activates or inhibits effector enzyme adenylate cyclase
- Adenylate cyclase then converts ATP to cAMP (second messenger)
- cAMP activates protein kinases that phosphorylate (add a phosphate) other proteins
PIP2-calcium signaling mechanism
Hormone-activated G protein activates a different effector enzyme: phospholipase C
-splits into two second messengers
- Diacygylcerol
- Inositol Trisphosphate
Lipid soluble hormone mechanism
- hormone diffuses through plasma membrane and binds to intracellular receptor
- Receptor-hormone complex enters the nuclues
- receptor-hormone complex binds to specific DNA region
- transcription of gene to mRNA
- mRNA directs protein synthesis
Blood levels of hormones controlled by
Controlled by negative feedback systems
Increased hormone effects on target organs can inhibit further hormone release
Hormone release is triggered by:
Endocrine gland stimuli
Nervous system modulation
Endocrine glands are stimulated to synthesize and release hormones in response to one of three stimuli:
Humoral stimuli-Changing blood levels of ions and nutrients directly stimulate secretion of hormones
Neural stimuli-Nerve fibers stimulate hormone release
Hormonal stimuli-Hormones stimulate other endocrine organs to release their hormones
Nervous System Modulation
Nervous system can override normal endocrine controls
Target cell activation depends on three factors:
1.Blood levels of hormone
2.Relative number of receptors on/in target cell
3.Affinity (strength) of binding between receptor
and hormone
Up-regulation
target cells form more receptors in response to low hormone levels
Down-regulation: target cells los
Down-regulation:
target cells lose receptors in response to high hormone levels
Desensitizes the target cells to prevent them from overreacting to persistently high levels of hormone
steriods and thyroid hormone attached to
plasma protien
Hormones can be removed from blood by:
Degrading enzymes or
Kidneys or
Liver
lipid soluble hormones come from where?
Adrenal cortex, gonads, and thyroid gland*
Water-soluble hormones come from where
all other hormones
half-life of lipid soluble hormones
long
half-life of water soluble hormones
short
location of receptors for lipid soluble hormones
inside cell
Location of receptors for water-soluble hormones
on plasma membrane
Permissiveness
one hormone cannot exert its effects without another hormone being present
Synergism
more than one hormone produces same effects on target cell, causing amplification
Antagonism
one or more hormones oppose(s) action of another hormone
Hypothalamus is connected to pituitary gland (hypophysis) via stalk called
infundibulum
Posterior pituitary: composed of ____ that secretes ___
Neural issue, neurohormones
Posterior lobe, along with infundibulum make up the
neurohypophysis
Anterior pituitary: consits of
consists of glandular tissue
Posterior lobe Maintains neural connection to hypothalamus via
hypothalamic-hypophyseal tract
posterior lobe secretes
oxytocin-birth contractions, breast milk-> positive feedback
ADH-antideretic, absorbs water from kidneys, causes vasoconstriction
anterior lobe consists of
Hyposphyseal portal system
Primary capillary plexus
Hypophyseal portal veins
Secondary capillary plexus
Hypothalamus secretes releasing and inhibiting hormones to
anterior pituitary to regulate hormone secretion
Diabetes insipidus
ADH deficiency,
loose fluids, vasodilation
Syndrome of inappropriate ADH secretion (SIADH
ADH hyper secretion, retention of fluids
Anterior pituitary hormones, which ones are tropic and which ones are not
- Growth hormone (GH)
- Prolactin (PRL)
tropic:
Thyroid-stimulating hormone (TSH) (tropic)
Adrenocorticotropic hormone (ACTH) (tropic)
Follicle-stimulating hormone (FSH) (tropic)
Luteinizing hormone (LH) (tropic)
Growth hormone
Produced by
Direct actions on
Dont take in
- produced by somatotropin cells
- direct actions of metabolism
- don’t take in glucose, use fatty acids
hyper secretion of GH
gigantism in children- 8ft tall
acromegaly-overgrowth of hands, feet, and face
hyposecrection of GH
Adults vs. Children
children-pituitary dwarfism-4ft
in adults no problem
thyroid-stimulating hormone
stimulates normal development and secretory activity of thyroid
hypothalamus, anterior pituitary gland, target cells
releasing, stimulation, hormone
Adrenocorticotropic hormone
stimulates adrenal cortex to release corticosteroids
Gonadotropins (FSH and LH)
FSH stimulates production of gametes (egg or sperm)
LH promotes production of gonadal hormones
testosterone, estrogen, progesterone
Prolactin (PRL)
-stimulates milk production
thyroid gland shape
butterfly shaped gland
Isthmus
median mass connecting two lateral lobes of thyroid
Follicles:
hollow sphere of epithelial follicular cells that produce glycoprotein thyroglobulin
Colloid
fluid of follicle lumen (middle portion_ contains thyoglobulime
Thyroid produces hormones called:
t4 (thyroxine)-two tyrosine, 4 iodine
t3-(triiodothyronine)-two tyrosine’s, 3 iodine
thyroid hormone effects
basal metabolic rate and heat production, tissue and growth development, maintains blood pressure
thyroid hormone synthesis 7 steps
- thyroglobulin is made
- iodine goes into cell and put into lumen (colloid)
- iodine becomes oxidized
- iodine attaches to tyrosine to form DIT and MIT
- DIT and MIT join to make T3 and T4
- thyroglobulin endocytose and joined with lysosome
- lysosome cleave t3 and t4 and form the thryogobuline and hormones diffuse into blood stream
myxedema
hypo secretion of TH, low metabolic rate, puffy eyes, constipation, lethargy
goiter
lack of iodine, decreases TH levels
cretinism
hyposecretion of TH in infants, intellectual disabilities and short body size
Graves disease
hyper secretion of TH, elevated metabolic rate, eyes protrude
calcitonin
antagonist to parathyroid hormone, inhibits osteoclast activity
parathyroid hormone
4-8 yellow-brown glands embedded in posterior aspect of thyroid
parathyroid hormone function
stimulate osteoclasts to digest bone matrix and release Calcium into blood.
- enhances reabsorption of calcium and secretion of phosphate by kidneys
- increase activation of vitamin D in kidney
Hyperparathyroidism
due to parathyroid gland tumor
Calcium leaches from bones, causing them to soften and deform
Osteitis fibrosa cystica
severe form resulting in easily fractured bones,
to much parathyroid hormone
Hypoparathyroidism
following gland trauma or removal can cause hypocalcemia
Results in tetany (muscles contract and can’t reverse, respiratory paralysis, and death
adrenal gland
-pyramid shaped on top kidneys
-adrenal cortex- three layers
adrenal medulla-nervous
adrenal cortex produces
corticosteroids
Zona glomerulosa
Zona fasciculata
Zona reticularis
Zona glomerulosa
Mineralocorticoids-aldosterone-stimulates Na+ reabsorption and K+ elimination in kidneys
Zona fasciculata
Glucocorticoids-cortisol
Zona reticularis
Gonadocorticoids-androgens
adrenal medula releases
epinephrine and norepinephrine
aldosteron regulators
Renin-angiotensin-aldosterone mechanism- kindey-relases renin, produces, angiotensin II stimulates aldosterone release
Plasma concentration of K+- K+ in blood increases stimulates release of aldosterone
ACTH (adrenocorticotropic hormone)-stress, anterior pituitary releases ACTH, stimulates release of aldosterone
Atrial Natriuretic peptide-increase blood pressure and/or blood volume, releases ANP, releases aldosterone
Aldosteronism
hypersecretion usually due to adrenal tumors, hypertension
Glucocorticoids function
Increase blood glucose during lonterrm stress
Influence metabolism of most cells and help us resist stressors
Keep blood glucose levels relatively constant
-cortisonl causes increase in blood levels of glucose
Cushing’s syndrome/disease
hyper secretion of glucocorticoids, cortisol
depresses cartilage/bone formation, immune system
moon face, buffalo hump
Addison’s disease
hypo secretion of mineralocorticoids
decrease in glucose, weight loos, sever dehydration
Gonadocorticoids
weak androgens
Adrenogenital syndrome
masculinization
- Not noticeable in adult males
- females and prepubertal males
- boys- reproductive organs mature
females: beard clitoris resembles small penis
Catecholamines: epinephrine, norepinephrine effects
-vasoconstriction
increase heart rate and blood glucose levels
Hyposecretion and Hypersecretion
of catecholamines
Hyposecretion
-no problems
Hypersecretion
hyperglycemia, increased metabolic rate, rapid heart beats
Pineal gland
melatonin,
- Timing of sexual maturation and puberty
- Day/night cycles
- Physiological processes that show rhythmic variations (body temperature, sleep, appetite)
- Production of antioxidant and detoxification molecules in cells
Pancreas has both
exocrine and endocrine cells Acinar cells(exocrine) Pancreatic islets (edoncrine0 -alpha -beta
Acinar cells
produce enzyme-rich juice for digestion
Pancreatic islets
alpa and beta
- Alpha (α) cells produce glucagon (hyperglycemic hormone)
- Beta (β) cells produce insulin (hypoglycemic hormone)
Glucagon
Glycogenolysis
Glucogenesis
Extremely potent hyperglycemic agent
Glycogenolysis-break down gylogen to glucose
Glucogenesis -sythesize glucose
Insulin
Secreted when blood glucose levels increase
-lowers blood glucose
Diabetes mellitus (DM) can be due to:
Hyposecretion of insulin: Type 1
Hypoactivity of insulin: Type 2
Glycosuria
excess glucose is spilled into urine
polyuria
polydispia
polyphagia
ketonuria
Polyuria: huge urine output
Glucose acts as osmotic diuretic
Polydipsia: excessive thirst
From water loss due to polyuria
Polyphagia: excessive hunger and food consumption
Cells cannot take up glucose and are “starving”
ketonuria: ketone bodies in urine
Hyperinsulinism
Excessive insulin secretion
Causes hypoglycemia: low blood glucose levels
Symptoms: anxiety, nervousness, disorientation, unconsciousness, even death
Treatment: sugar ingestion
Gonads produce same steroid sex hormones as those of adrenal cortex, just
more amounts than adrenal cortex
Ovaries produce
estrogens and progesterone
Estrogen
Maturation of reproductive organs
Appearance of secondary sexual characteristics
With progesterone, causes breast development and cyclic changes in uterine mucosa
Testes produce
testosterone
- Initiates maturation of male reproductive organs
- Causes appearance of male secondary sexual characteristics and sex drive
- Necessary for normal sperm production
- Maintains reproductive organs in functional state
Placenta
secretes estrogens, progesterone, and human chorionic gonadotropin (hCG)
