THE ENDOCRINE SYSTEM
D. C. MIKULECKY
PROFESSOR OF PHYSIOLOGY
AND
FACULTY MENTORING PROGRAM
COMPARISON OF ENDOCRINE
AND NERVOUS SYSTEMS
• NERVOUS SYSTEM
• “WIRED”
• CHEMICAL SIGNAL
AT TARGET CELL
• RAPID
• BRIEF DURATION
• CLOSE ANATOMICAL
PROXIMITY
• ENDOCRINE SYSTEM
• “WIRELESS”
• CHEMICAL SIGNAL
AT TARGET CELL
• SLOW
• LONG DURATION
• SPECIFIC
RECEPTORS
CATEGORIES OF
HORMONES
• PEPTIDES
• AMINES
• STEROIDS
PEPTIDES
• HYDROPHILIC
• DISSOLVED IN PLASMA
• RECEPTOR ON CELL SURFACE
• cAMP OR CALCIUM AS SECOND
MESSENGERS
• ACTIVATE SPECIFIC GENES TO
INITIATE PROTEIN SYNTHESIS
PEPTIDE HORMONES
• HYPOTHALAMIC
• PITUITARY
• PANREATIC
• PARATHYROID
• GI
• KIDNEY
• LIVER
• HEART
AMINES
• THYROID HORMONE
• CATECHOLAMINES
• ALL DERIVED FROM AMINO ACID
TYROSINE
• UNIQUE SYNTHETIC AND
SECRETORY PATHWAYS
STEROIDS
• LIPOPHILIC
• RECEPTOR IN CYTOPLASM
• ACTIVATE SPECIFIC GENES TO
INITIATE PROTEIN SYNTHESIS
• ADRENAL CORTICAL
• GONADAL
• PLACENTAL
PLASMA CONCENTRATION
OF HORMONES
• DEPENDS ON RATE OF SECRETION
• NEGATIVE FEEDBACK
• NEUROENDOCRINE REFLEXES
• DIURNAL RHYTHMS
TYPES OF ENDOCRINE
DISORDERS
• HORMONE EXCESS
• HORMONE DEFICIENCY
• DECREASED RESPOSIVENESS OF
RECEPTORS
HYPOTHALAMUS AND POSTERIOR
PITUITARY
HYPOTHALAMUS
NEUROSECRETORY
NEURONS
ANTERIOR
PITUITARY
POSTERIOR
PITUITARY
SYSTEMIC
ARTERY
SYSTEMIC
VEIN
VASOPRESSIN
OXYTOCIN
HYPOTHALAMUS AND ANTERIOR
PITUITARY
HYPOTHALAMUS
NEUROSECRETORY
NEURONS
ANTERIOR
PITUITARY:
•TSH
•ACTH
•PROLACTIN
•GROWTH
HORMONE
•LH
•FSH
POSTERIOR
PITUITARY
HYPOTHALAMIC-HYPOPHYSEAL
PORTAL SYSTEM
• VESSELS PASS THROUGH STALK OF
PITUITARY FROM HYPOTHALAMUS
TO ANTERIOR PITUITARY
• CARRY HYPOTHALAMIC
REGULATORY HORMONES
HYPOTHALAMIC REGULATORY
HORMONES
• TROPIC HORMONES
• CONTROL THE SECRETION OF OTHER
HORMONES BY ACTING ON
ENDOCRINE TISSUE
HYPOTHALAMIC RELEASING AND
INHIBITING HORMONES
• CONTROL THE SECRETION OF ANTERIOR PITUITARY
TROPIC HORMONES
• TRH:THYROTROPIN-RELEASING HORMONE
• PRH:PROLACTIN RELEASING HORMONE
• PIH:PROLACTIN INHIBITING HORMONE
• GHRH:GROWTH HORMONE RELEASING HORMONE
• GHIH: GROWTH HORMONE INHIBITING HORMONE
• CRH:CORTICOTROPHIN RELEASING HORMONE
HIERARCHICAL CONTROL
INPUT
HORMONE 1 (RELEASING/INHIBITING)
HORMONE 2 (TROPIC)
HORMONE 3
TARGET
CELLS
SYSTEMIC CIRCULATION
SYSTEMIC CIRCULATION
H/H PORTAL SYSTEM
HYPOTHALAMUS
ANTERIOR PITUITARY
ENDOCRINE GLAND
NEGATIVE FEEDBACK
INPUT
HORMONE 1 (RELEASING/INHIBITING)
HORMONE 2 (TROPIC)
HORMONE 3
TARGET
CELLS
SYSTEMIC CIRCULATION
SYSTEMIC CIRCULATION
H/H PORTAL SYSTEM
HYPOTHALAMUS
ANTERIOR PITUITARY
ENDOCRINE GLAND
ANTERIOR PITUITARY HORMONES:TSH
• THYROID GLAND
• THYROID HORMONES (T3 & T4 )
ANTERIOR PITUITARY
HORMONES:ACTH
• ADRENAL CORTEX
• CORTISOL
ANTERIOR PITUITARY
HORMONES:PROLACTIN
• MAMMARY GLANDS
• BREAST GROWTH AND MILK
SECRETION
ANTERIOR PITUITARY HORMONES:
GROWTH HORMONE
• LIVER
• SOMATOMEDINS
• BONE
• SOFT TISSUE
• GROWTH
• MANY TISSUES
• INTERMEDIARY
METABOLISM
• INCREASE OR
DECREASE
ANTERIOR PITUITARY HORMONES:
LH & FSH: ACT ON GONADS
• LH:LETEINIZING
HORMONE
• SEX HORMONE
SECRETION
• F: ESTROGEN AND
PROGESTERONE
• M: TESTOSTERONE
• FSH:FOLLICLE
STIMULATING
HORMONE
• GAMETE
PRODUCTION
• OVA
• SPERM
CONTROL OF GROWTH
• GENETIC
• DIET
• DISEASE
• HORMONES
ANTERIOR PITUITARY HORMONES:
GROWTH HORMONE
• LIVER
• SOMATOMEDINS
• BONE
• SOFT TISSUE
• GROWTH
• MANY TISSUES
• INTERMEDIARY
METABOLISM
• INCREASE OR
DECREASE
METABOLIC ACTIONS OF GROWTH
HORMONE
• MOBILIZES TRIGLYCERIDE FAT
STORED IN ADIPOSE TISSUE
• CONSERVES GLUCOSE FOR BRAIN
GROWTH PROMOTING ACTIONS
OF GROWTH HORMONE
• SOFT TISSUES: STIMULATES CELL
DIVISION, INCREASES SIZE OF CELLS
• STIMULATES ALMOST ALL ASPECTS
OF PROTEIN SYNTHESIS
• INHIBITS PROTEIN DEGRADATION
• PROMOTES UPTAKE OF AMINO
ACIDS
GROWTH PROMOTING ACTIONS
OF GROWTH HORMONE
• BONE: PROMOTES GROWTH OF LONG
BONES
• THICKNESS
• LENGTH
• AT END OF ADOLESCENCE, SEX
HORMONES STOP THIS ACTION
GROWTH HORMONE ACTS
THROUGH SOMATOMEDINS
• PEPTIDE MEDIATORS
• PRODUCED IN LIVER AND OTHER
TISSUES
• ALSO PARACRINE EFFECTS
GHRH AND GHIH
• ANTAGONIST IN CONTROL OF
GROWTH HORMONE SECRETION
• NEGATIVE FEEDBACK
• DIURNAL RHYTHM: GH SECRETED
AT NIGHT
• EXERCISE, STRESS, HYPOGLYCEMIA
ABNORMAL GH SECRETION
• DEFICIENCY: DWARFISM, REDUCED
MUSCLE STRENGTH, DECREASED
BONE DENSITY
• EXCESS:GIGANTISM, ACROMEGLY
THE THYROID GLAND
• OVER TRACHEA
• THYROGLOBULIN
• TETRAIODOTHYRONINE
• TRIIODOTHYRONINE
• IODINE REQUIRED FROM DIETARY
INTAKE
THYROID HORMONE’S EFFECTS
• METABOLIC RATE: INCREASED BMR
• CALOROGENIC: INCREASED HEAT PRODUCTION
• SYMPATHOMIMETIC: FLIGHT OR FIGHT
• CARDIOVASCULAR:INCREASES RESPONSIVENESS
OF HEART
• GROWTH: ESSENTIAL FOR NORMAL GROWTH
• NERVOUS SYSTEM:DEVELOPMENT AND ADULT
ACTIVITY
REGULATION OF THYROID
SECRETION
HYPOTHALAMUS
TRH
ANTERIOR PITUITARY
TSH
THYROID GLAND
TARGET ORGANS
THYROID HORMONE
STRESS
COLD IN
CHILDREN
- +
ABNORMALITIES OF THYROID
FUNCTION
• HYPO
• REDUCED BMR
• POOR TOLERANCE OF COLD
• GAIN OF WEIGHT
• FATIGUE
• SLOW, WEAK PULSE
• SLOW REFLEXES AND
MENTATION
• MYXEDEMA
• GOITER
• CRETINISM
• HYPER
• GRAVE’S
DISEASE:TSI
• EXOPHTALMOS
• GOITER
THE ADRENAL GLANDS
• CORTEX: STEROID HORMONES
SECRETED
• MEDULLA: CATECHOLAMINES
CORTEX: STEROID
HORMONES SECRETED
• MINERALOCORTICOIDS
• GLUCOCORTICOIDS
• SEX HOMONES
MINERALOCORTICOIDS
• ALDOSTERONE
• ELECTROLYTE BALANCE
• BLOOD PRESSURE
• RENIN-ANGIOTENSIN-ALDOSTERONE
SYSTEM
GLUCOCORTICOIDS
• CORTISOL
• GLOCONEOGENESIS
• PERMISSIVE ACTIONS
• STRESS ADAPTATION
• ANTI-INFLAMITORY AND
IMMUNOSUPPRESSANT
REGULATION OF CORTISOL
SECRETION
HYPOTHALAMUS
CRH
ANTERIOR PITUITARY
ACTH
ADRENAL CORTEX
TARGET ORGANS
CORTISOL
STRESS
DIURNAL
RHYTHM
+ +
-
-
INCREASED
BLOOD GLUCOSE
BLOOD AA
BLOOD FATTY ACIDS
SEX HOMONES
• ANDROGENS (TESTOSTERONE)
• ESTROGENS
• LESS THAN GONADS
ADRENAL OVERSECRETION
• MINERALCORTICOIDS: SODIUM
RETENTION, POTASSIUM DEPLETION
• CORTISOL:EXCESS GLUCONEOGENESIS-
EXCESS GLUCOSE DEPOSITED AS FAT
• ANDROGEN:MASCULINIZATION,
PSEUDOHERMAPHODITISM, PRECOCIOUS
PSEUDOPUBERTY, NO EFFECT IN
ADULT MALES
ADRENAL INSUFFICIENY
• CORTEX: ADDISON’S DISEASE
• POOR RESPONSE TO STRESS
• LACK OF PERMISSIVE ACTION
• POTASSIUM RETENTION
• HYPOTENSION
MEDULLA: CATECHOLAMINES
• A MODIFIED SYMPATHETIC POST
GANGLIONIC NEURON
• EPINEPHRINE
ACTIONS OF EPINEPHRINE
• MIMICS SYMPATHETIC NS
• MOBILIZES STORED FAT AND
CARBOHYDRATE
• HEART AND BLOOD VESSELS
GENERAL ADAPTATION
SYNDROME
• FLIGHT OR FIGHT
• EPINEPHRINE
• CRH-ACTH-CORTISOL
• RENIN-ANGIOTENSIN-ALDOSTERONE
• VASOPRESSIN
• COORDINATED BY HYPOTHALAMUS
• CAN BE INDUCED PSYCHOSOCIALLY
CONTROL OF FUEL
METABOLISM
• GLYCOGENESIS
• GLYCOGENOLYSIS
• GLUCONEOGENESIS
• PROTEIN SYNTHESIS
• PROTEIN DEGRADATION
• FAT SYNTHESIS
• FAT BREAKDOWN
ANABOLISM VS CATABOLISM
• BUILD UP VS BREAKDOWN OF
LARGE MOLECULES
• ANABOLISM REQUIRES ENERGY
(ATP)
• CATABOLISM:ENERGY PRODUCTION
PANCREATIC HORMONES
• INSULIN
• GLUCAGON
INSULIN: ACTION ON BLOOD
SUGAR
• BETA CELLS IN ISLETS OF
LANGERHANS: INSULIN
• FACILITIES GLUCOSE ENTRY INTO
CELLS
• STIMULATES GLYCOGENESIS
• INHIBITS GLYCOGENOLYSIS
• INHIBITS GLUCONEOGENESIS
INSULIN: ACTION ON FAT
• INCREASES TRANSPORT INTO
ADIPOSE CELLS
• PROMTES TRIGLYCERIDE SYNTHESIS
• INHIBITS LIPOLYSIS
INSULIN: ACTION ON PROTEIN
• PROMOTES UPTAKE OF AA BY
MUSCLE AND OTHER TISSUE
• PROMOTES PROTEIN SYNTHESIS
• INHIBITS PROTEIN DEGRADATION
CONTROL OF INSULIN SECRETION
• NEGATIVE FEEDBACK: BLOOD
SUGAR
• BLOOD AA
• GI HORMONES
• PARASYMPATHETIC ACTIVITY
TWO TYPES OF DIABETES
MELLITUS
• TYPE I: AUTOIMMUNE
DESTRUCTION OF BETA CELLS,
LACK OF INSULIN SECRETION
• TYPE II: REDUCED SENSITIVITY OF
INSULIN RECEPTORS
ACUTE EFFECTS OF DIABETES
MELLITUS
• EXTRACELLULAR GLUCOSE EXCESS
• GLUCOSE IN URINE
• EXCESS FLUID LOSS
• CIRCULATORY FAILURE
• RENAL FAILURE
• NERVOUS SYSTEM MALFUNCTION DUE TO DEHYDRATION
• EXCESSIVE FOOD INTAKE
• PROGRESSIVE WEIGHT LOSS
• MOBILIZTION OF FAT
• KETOSIS
• ACIDOSIS
• COMA AND DEATH
GLUCAGON
• PANCREATIC ALPHA CELLS
• GENERALLY OPPOSES ACTIONS OF
INSULIN
• DECREASE GLYCOGEN SYNTHESIS
• PROMOTE GLYCOGENOLYSIS
• STIMULATE GLUCONEOGENESIS
• PROMOTES FAT BREAKDOWN
• ONLY IN LIVER: PROTEIN CATABOLISM
EPINEPHRINE, CORTISOL, AND
GROWTH HORMONE
• ALL INCREASE BLOOD GLUCOSE
AND FATTY ACIDS
• CORTISOL INCREASES BLOOD AA
AND DECREASES MUSCLE PROTEIN
• GH DECREASES BLOOD AA AND
INCREASES MUSCLE PROTEIN
CONTROL OF CALCIUM
METABOLISM
• PARATHYROID HORMONE
• CALCITONIN
• VITAMIN D
PARATHYROID HORMONE
• RAISES FREE PLASMA CALCIUM
• FROM BONE
• CONSERVATION IN KIDNEYS
• INCREASES INTESTINAL ABSORPTION (VIA
VITAMIN D ACTIVATION)
• REGULATED BY FREE CALCIUM IN
PLASMA (NEGATIVE FEEDBACK)
CALCITONIN
• C CELLS OF THYROID GLAND
• DECREASE IN CA MOBILIZATION
FROM BONE
• NOT AS IMPORTANT AS PTH AND
VITAMIN D
VITAMIN D
• ACTUALLY A HORMONE
• RELEASED FROM SKIN BY SUNLIGHT
• TWO STEP ACTIVATION: LIVER AND
KIDNEYS
• INCREASES CALCIUM ABSORPTION
IN INTESTINE
PTH HYPOSECRETION
• LOW CALCIUM AND HIGH
PHOSPHATE
• MUSCLE SPASMS
• MENTAL CHANGES
VITAMIN D DEFICIENCY
• IMPARED ABSORPTION OF CALCIUM
• PTH MAINTAINS PLASMA LEVEL AT
EXPENSE OF BONES
• RICKETS IN CHILDREN
• OSTEOMALACIA IN ADULTS

LECTURE 9C ENDOCRINE SYSTEM physiology.ppt