Transcript PowerPoint 17- Endocrine System

Endocrine System
A. Endocrine glands
B. Comparison of nervous and
endocrine
systems
C. Hormones
1. Hormone receptors
2. Circulating and local hormones
D. Mechanisms of hormone action
1. Activation of intracellular receptors
2. Activation of plasma membrane
receptors
E. Control of hormonal secretions
F. Hypothalamus and pituitary gland
(hypophysis)
1. Anterior pituitary gland
(adenohypophysis)
a. Human growth hormone
b. Thyroid-stimulating hormone
c. Follicle-stimulating hormone
d. Luteinizing hormone
e. Prolactin
f. Melanocyte-stimulating
hormone
g. Adrenocorticotropic hormone
2. Posterior pituitary gland
(neurohypophysis)
a. Oxytocin
b. Antidiuretic hormone
G. Thyroid gland
1. Formation, storage, and release of
thyroid hormones
2. Actions of thyroid hormones
3. Control of thyroid hormone
secretion
4. Calcitonin
H. Parathyroid glands
1. Parathyroid hormone
I. Adrenal (suprarenal) glands
1. Adrenal cortex
a. Mineralocorticoids
b. Glucocorticoids
c. Gonadocorticoids
2. Adrenal medulla
a. Epinephrine and norepinephrine
J. Pancreas
1. Glucagon
2. Insulin
K. General adaptation syndrome
Endocrine Glands
Endocrine vs. exocrine
Hormone
Endocrine gland
Nervous System Versus Endocrine System
Together, the nervous and endocrine systems coordinate
functions of all body systems.
NERVOUS
ENDOCRINE
neurotransmitters
hormones
muscle contractions and
glandular secretions
metabolic activities of cells
acts in milliseconds
acts in seconds to minutes to
hours to days to months
brief effects
long-lasting effects
Hormone Receptors
1.
2.
3.
4.
target cells
receptors
down-regulation
up-regulation
Hormone Interactions
1. synergistic effects
2. permissive effects
3. antagonistic effects
Types of Hormones
1. circulating -- hormones
2. local – paracrines, autocrines
Mechanisms of Hormone Action
1. lipid-soluble hormones
a. steroid and thyroid hormones
b. use intracellular receptors
2. water-soluble hormones
a. catecholamine, peptide, and
protein hormones
b. use membrane-bound receptors
c. and second messengers
Lipid Soluble Hormones
1. intracelluar receptors
2. hormone-receptor complex
3. altered gene expression
Steroid Hormone Action
Water Soluble Hormones
1. membrane-bound receptors
2. first messenger vs second
messenger
3. adenylate cyclase and cyclic
AMP
4. phosphodiesterase
Water soluble hormones and
Cyclin AMP as a 2nd Messenger
2nd Messenger Systems
Control of hormonal secretions =
negative feedback
hyperglycemia =
insulin secretion
110 mg%
[glucose]
steady state
90 mg%
hypoglycemia =
glucagon secretion
time
Hypothalamus and Pituitary
Gland
Hypothalamus
1. master control
2. major integrator
Pituitary gland (hypophysis)
1. infundibulum
2. sella turcica
hypothalamus
infundibulum
pituitary gland
sella turcica in
sphenoid bone
Hypothalamus-Master Controller
Pituitary Gland
1. anterior pituitary
a. derived from Rathke's pouch
b. connected to hypothalamus
by hypophyseal portal system
(Rathke’s pouch)
2. posterior pituitary
a. outgrowth of hypothalamus
b. contains pituicytes
c. connected to hypothalamus
by nerve tract
Anterior Pituitary
(adenohypophysis)
1. releasing vs inhibiting
factors
2. hypophyseal portal system
superior hypophyseal arteries
primary plexus of capillaries
hypophyseal veins
secondary plexus of
capillaries
anterior hypophyseal veins
The seven hormones secreted by
the anterior pituitary gland
growth hormone (GH)
thyroid-stimulating hormone (TSH)
follicle-stimulating hormone (FSH)
luteinizing hormone (LH)
adrenocorticotropic hormone (ACTH)
prolactin (PRL)
melanocyte-stimulating hormone (MSH)
Tropic Hormones
FSH
LH
TSH
ACTH
Growth Hormone
Promotion of secretion
Regulation of secretion
1. HYPOGLYCEMIA (low blood sugar)
2. decreased blood fatty acids
3. increased blood amino acids
4. deep sleep
hypoglycemia
hyperglycemia
inhibits GH-IF
secretion
Inhibits GH-RF
secretion
HYPOTHALAMUS
Inhibition of secretion
1. HYPERGLYCEMIA (high blood
sugar)
2.
3.
4.
5.
6.
increased blood fatty acids
decreased blood amino acids
REM sleep
obesity
severe emotional states
GH-RF
GH-IF
secretion on
ANTERIOR PITUITARY GLAND
growth hormone
Actions
1. increased cellular uptake of amino acids = increased protein synthesis = growth/maintenance
2. increased lipolysis and gluconeogenesis for energy, leading to hyperglycemia = diabetogenic effect
secretion off
Growth Hormone Acromegaly
Thyroid Stimulating Hormone
decreased basal metabolic rate (BMR)
( -)
increased hypothalamic TSH-RF secretion
negative
feedback
increased anterior pituitary TSH secretion
increased thyroid gland T3 and T4 secretion
increased basal metabolic rate
Follicle Stimulating Hormone - male
decreased inhibin secretion
( -)
increased hypothalamic Gonadotropin-RF secretion
negative
feedback
of inhibin
increased anterior pituitary FSH secretion
1. increased sperm formation (spermatogenesis)
2. increased activity of Sertoli cells (spermiogenesis)
3. increased inhibin secretion by Sertoli cells
Follicle Stimulating Hormone-Female
decreased estrogen secretion
( -)
negative
feedback
of rising
estrogen
increased hypothalamic Gonadotropin-RF secretion
increased anterior pituitary FSH secretion
1. directly stimulates egg formation by ovaries
2. as a result, ovaries produce estrogen
Luteinizing Hormone- male
decreased testosterone secretion
( -)
negative
feedback
of rising
estrogen
increased hypothalamic Gonadotropin-RF secretion
increased anterior pituitary LH secretion
stimulates testosterone secretion by
interstitial cells (of Leydig) in testes
Luteinizing Hormone- female
increased estrogen secretion
( -)
negative
feedback of
dropping
estrogen
increased hypothalamic Gonadotropin-RF secretion
increased anterior pituitary LH secretion
1. directly stimulates ovulation
2. as a result, estrogen levels drop
until corpus luteum is formed
Adrenocorticotropic Hormone
increased stress
increased hypothalamic Corticotropin-RF secretion
( -)
negative
feedback of
decreasing
stress
increased anterior pituitary ACTH secretion
1.
2.
3.
4.
increased alertness
increased blood pressure
increased blood glucose
anti-inflammatory actions
decreased stress
Prolactin-Female
inhibition pathway
increased blood estrogen
stimulation pathway
decreased blood estrogen
+
postpartum suckling reflex
hypothalamic PRL-IF secretion
hypothalamic PRL-RF secretion
decreased or no PRL secretion
from anterior pituitary gland
anterior pituitary gland
PRL secretion
milk synthesis by postpartum
mammary glands
Posterior Pituitary
(neurohypophysis)
1.
2.
3.
4.
not really endocrine
pituicytes
hypothalamic nuclei
hypothalamohypophyseal tract
5. hormones
a. oxytocin
b. antidiuretic hormone
Oxytocin
1. neuroendocrine reflex
2. uterine contractions
3. myoepithelial cells
of mammary glands
ANTI-DIURETIC HORMONE
1.
2.
3.
4.
aka = vasopressin, ADH
hypothalamic osmoreceptors
water reabsorption by kidneys
diabetes insipidus
dehydration
increased interstitial fluid osmotic pressure
( -)
stimulation of hypothalamic
osmoreceptors
secretion of ADH from posterior pituitary gland
1. WATER REABSORPTION BY KIDNEYS
2. decreased perspiration
increased water in blood
increased interstitial fluid osmotic pressure
Also leads to increase in BP
ADH actions
Thyroid Gland
1.
2.
3.
4.
5.
location
follicles
follicular cells
triiodothyronine (T3)
tetraiodothyronine
(T4, thyroxine)
_____________________
6. parafollicular (C-) cells
7. calcitonin
Thyroid Hormone Secretion
1
tyrosine
1.
2.
3.
4.
5.
stores secretory product
captures iodide ions
thyroglobulin
tyrosine
colloid
thyroglobulin
colloid
blood
capillary
thyroid
follicle
follicle cell
2
colloid
I
I
parafollicular
cells
blood
capillary
3
I
I
I
I
I
iodinated tyrosines on
thyroglobulin (T3)
thyroid hormone secretion
I
colloid
T3
follicular cell
T3
I
cleavage
colloid
I
I
I
pinocytosis
I
Thyroid Hormone Synthesis,
Storage and Secretion
Endemic Goiter- Iodine deficiencylack of thryoid hormone
Thyroxine Actions and Control
1. TSH stimulation
2. actions
a. increased carbohydrate catabolism
b. increased fat catabolism
c. increased protein anabolism
d. net result = increased BMR
__________________________________
3. normal growth and development
(nervous system -- cretinism)
Thyroxine
decreased basal metabolic rate
increased TSH-RF secretion from hypothalamic neurons
( -)
secretion of TSH from anterior pituitary gland
( -)
secretion of T3 and T4 (thyroxine) from thyroid gland follicle cells
negative
feedback
Increased carbohydrate catabolism
Increased fat catabolism
Increased protein anabolism
T3 and T4 (thyroxine) secretion
increased basal metabolic rate
Negative Feedback Inhibition in
Pituitary Thryoid Axis
Calcitonin
1. parafollicular (C-) cells
2. hypercalcemia = CT secretion
3. actions
a. inhibits osteoclasts
b. stimulates osteogenesis
c. decreased Ca++ reabsorption
4. result = normocalcemia
CALCITONIN and BLOOD CALCIUM REGULATION
CONTROLLED CONDITION
Normocalcemia
(blood calcium = 9.5-10.5mg%)
A stress or stimulus causes an increase in
blood calcium
negative
feedback
RETURN TO HOMEOSTASIS
Increased bone formation results in
increased calcium deposition in bone –
Return to normocalcemia
RECEPTOR
Parafollicular cells of thyroid gland
recognize hypercalcemia
EFFECTORS
(blood calcium >10.5 mg%
Reduced osteoclast activity
Increased osteoblast activity
CONTROL CENTER
Parafollicular cells secrete calcitonin
Parathyroid Hormone
1.
2.
3.
4.
a.
b.
c.
5.
location
chief cells and oxyphil cells
hypocalcemia = PTH secretion
actions
activate osteoclasts
increased Ca++ absorption
increased Ca++ reabsorption
result = normocalcemia
PTH and BLOOD CALCIUM REGULATION
CONTROLLED CONDITION
Normocalcemia
(blood calcium = 9.5-10.5mg%)
A stress or stimulus causes a decrease in
blood calcium
negative
feedback
RETURN TO HOMEOSTASIS
Increased bone breakdown results in
increased calcium release to blood –
Return to normocalcemia
RECEPTOR
EFFECTORS
Chief cells of parathythyroid glands
recognize hypocalcemia
Increased osteoclast activity
(blood calcium <9.5 mg%
Decreased osteoblast activity
Increased urine phosphate output
Decreased urine calcium output
CONTROL CENTER
Chief cells secrete PTH
Adrenal (suprarenal) glands (2)
1.
2.
3.
4.
a.
b.
c.
location
cortex vs medulla
cortex = steroids
medulla = catecholamines
sympathetic NS
NE and EPI
fight-or-flight
Adrenal cortex (zona
glomerulosa)
1. mineralocorticoids (aldosterone)
2. electrolyte and fluid balance
3. high [K+] = aldosterone secretion
or
renin-angiotensin system
4. actions
a. decreased K+ reabsorption
b. increased Na+ reabsorption
Aldosterone
control via potassium
control via renin-angiotensin system
hyperkalemia
( -)
negative
feedback
dehydration, Na+ deficiency, hemorrhage
aldosterone secretion from
zona glomerulosa cells
decreased blood volume
decreased blood pressure
decreased K+ reabsorption by kidneys
( -)
renin secretion by kidneys
normokalemia
negative
feedback
activation of angiotensin II
aldosterone secretion
ADH secretion
increased thirst
increased vasoconstriction
increased blood pressure
Adrenal cortex (zona fasciculata)
1. glucocorticoids (hydrocortisone, cortisone)
2. stress > C-RF > ACTH > glucocorticoids
3. actions
a. promote normal metabolism (glucose
availability)
b. resistance to stress (alertness, energy,
blood pressure)
c. anti-inflammatory (stabilizes
membranes)
Glucocorticoids
increased stress or decreased blood levels of glucocorticoids
( -)
increased hypothalamic corticotropin-RF secretion
( -)
increased anterior pituitary ACTH secretion
negative
feedback
increased adrenal secretion of glucocorticoids
promote normal metabolism and ensure glucose availability by:
increasing protein catabolism
increasing gluconeogenesis
increased lipolysis
Provide resistance to stress by:
increased mental alertness
increased energy
increased blood pressure
Increasing anti-inflammatory activity by:
stabilizing cell membranes
depressing phagocyte activity
decreased capillary permeability (decreased swelling)
decreased stress
negative
feedback
Adrenal cortex (zona reticularis)
1. gonadocorticoids
a. androgens
b. estrogens
2. important in development
Endocrine (pancreas)
1. location
2. islets of Langerhans
3. cell types
a. alpha cells = glucagon
b. beta cells = insulin
c. delta cells =
somatostatin (GH-IF)
d. F cells = digestion
Glucagon
1. alpha cells
2. hypoglycemia >
glucagon secretion
3. actions
a. glycogenolysis
b. gluconeogenesis
4. result = normoglycemia
hypoglycemia (<90mg%)
alpha cells secrete glucagon
( -)
negative
feedback
liver cells:
increase glycogenolysis
increased gluconeogenesis
increased blood glucose
normoglycemia (>90mg%)
Insulin
1. beta cells
2. hyperglycemia >
insulin secretion
3. activities
a. glucose uptake
b. glycogenesis
c. glycogenolysis
d. gluconeogenesis
e. lipogenesis
4. result = normoglycemia
______________________
diabetes mellitus
hyperglycemia (<110mg%)
beta cells secrete insulin
( -)
negative
feedback
increased glucose uptake into body cells
increase glycogenesis
(skeletal muscle, liver)
increased lipogenesis
decreased blood glucose
normoglycemia (<110mg%)
GENERAL ADAPTATION SYNDROME
STRESS
ALARM
hypothalamus
C-RF secretion
increased sympathetic activity
ACTH
increased blood pressure
norepinephrine
epinephrine
----------------------------------------------------------------------------------------------------------------------------- ---RESISTANCE
glucocorticoids
increased blood pressure continued
decreased inflammatory response
increased blood glucose
altered protein and fat metaoblism
----------------------------------------------------------------------------------------------------------------------------- ---EXHAUSTION
decreased immune response + decreased energy reserves
decreased resistance to disease
hypertension
cardiac failure and renal failure
DEATH