Transcript Endocrine System - HCC Learning Web

Endocrine System
Function
• Maintain Homeostasis (Balance)
– Communicates and coordinates physiological
responses
• Example of Imbalance?
Hormones
• Chemical messengers
– Stimulate physiological responses in other cells
– Target Cells
• How do hormones travel?
Hormone Production and
Distribution
• Production
– Endocrine Glands
– Gland: an organ specialized to produce
secretions
• Distribution
– Relies on blood circulatory system
• How does this compare to nervous system?
Endocrine Glands
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Hypothalamus
Pituitary
Thyroid
Parathyroid
Pancreas
Adrenal
Gonads
Hypothalamus
• Location- Base of brain
case
• Functions- Regulation
of Primitive or Basal
activities such as sex
drive and water balance
• 9 hormones– 7 act on anterior lobe of
pituitary gland (Tropic)
– 2 stored in posterior
lobe
Hypothalamo-hypophyseal
portal system
• What type of vessels comprise a portal
system?
• What is unique about a portal system?
Hypothalamo-hypophyseal
portal system and tract
• Location– Pituitary Stalk
(Infundibulum)
• Link the hypothalmus
to the pituitary gland
• Portal- Capillary beds
connect to anterior
lobe
• Tract- Neurons connect
to posterior lobe
Pituitary gland
• Location- Sphenoid
bone of the skull
• Anterior Lobe
– Produces Six hormones
that Regulate
• Reproduction
• Growth
• Activity of the
Thyroid Gland
• Posterior Lobe
– No hormone production
only storage of
hypothalamic hormones
Thyroid
• Largest endocrine gland
• Location- Wrapped around
anterior and lateral sides of
Trachea, just below Larynx
• Hormone- Thyroid Hormone
• Function- Increases Metabolic
Rate
Parathroid Glands
• Location- Four glands
imbedded on posterior
surface of Thyroid
• Hormone- Parathyroid
Hormone
• Function- Calcium
Regulation
Adrenal Glands
• Location- 2 glands one
superior to each Kidney.
• Cortex
– Zona Glomerulosa:
Outer layer
– Zona Fasciculata:
Middle Layer
– Zona ReticularisInner Layer
• Medulla
Adrenal Glands
• Medulla- (Fight or
Flight Response)
Epinepherine and
Norepinephrine
• Cortex– Zona Glomerulosa
• MineralocorticoidsRegulate Kidney Na+ and
K+ excretion
– Zona Fasiculata
• Glucocorticoids- Stress
and immune supression
– Zona Reticulata• Sex steroids- androgens
precursor to sex hormones
Pancreas
• Location- Inferior
and posterior to
Stomach
• Pancreatic Islets
– Clusters of
endocrine cells
• FunctionGlucose Regulation
Gonads
• Male- Testes
– Secrete Androgens such as Testosterone
• Female- Ovary
– Secrete Estrogen and Progesterone
Homeostatic Control
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Metabolic Rate
Growth Hormone
Blood Glucose Levels
Blood Calcium Levels
Water Retention
Stress
Metabolic Rate
Gland
Hormones
Hypothalamus
Thyrotropin
Releasing Hormone
(TRH)
Thyroid
Stimulatory
Hormone (TSH)
Thyroxine (T4) and
Triiodothyronine
(T3)
Pituitary Gland
Thyroid
Interactions between Metabolic
Hormones
T4 & T3
Metabolic Rate
• Hormones released in response to a
decrease in T3 blood levels
• Affects: All cells in the body except brain,
spleen, testes, uterus and the thyroid gland
• Results: Increase in basal metabolic rate,
oxygen consumption and heat production
Disorders
• Hypothyroidism
(Creatinism)
– Children: mental
retardation,
development
abnormalities
– Adults: lethargy,
obesity
• Goiter
• Hyperthyroidism
(Graves’ Disease)
– Weight loss, sweating,
nervousness,
sleeplessness
• Goiter
-----a hypertrophy of the
thyroid gland resulting
from iodine deficiency
Growth
• Gland- Pituitary Gland
• Hormone– Growth Hormone: increases mitosis and
cellular differentiation.
– Secreted in response to Sleep, Trauma,
Exercise, High protein meals, and Low blood
sugar
• Effects
– Directly: Liver
– Indirectly: Bone, Muscle, and Cartilage
Disorders
• Pituitary Dwarfism• Gigantism- OverInsufficient secretion of
secretion of Growth
Growth Hormone
Hormone
Blood Glucose Levels
• Gland- Pancreas
• Hormones
– Insulin- increases uptake of glucose by cells
– Glucagon- increases release of glucose by cells
and increases liver glucose production
• Released in response to…
– Insulin: high blood glucose levels
– Glucagon: low blood glucose levels
• Effects– Systemic
– Liver
Disorders
• Diabetes Mellitus- Disruption of Metabolism due
to lack of insulin or lack of response to insulin.
• Symptoms- Excessive Urine, Intense Thirst, and
Ravenous Hunger
• Type I- (Juvenile of Insulin Dependant)
Destruction of Insulin Producing Cells
• Type II- (Adult or Noninsulin Dependant)
Target cells resistant to Insulin
Blood Calcium Levels
• Gland- Parathyroid
• Hormone- Parathyroid hormone
– Released in response to low calcium levels
• Effects
– Kidneys- Retain Calcium
– Bones- Release Calcium
Disorders
• Hyper- or Hypo-parathyroidism
– Hyper-parathyroidism: Over Secretion
• Soft, Fragile Bones
• Kidney stones
– Hypo-parathyroidism: Under Secretion
• Rapid Decline of Blood Calcium
• Fatal
Water Retention
• Gland- Hypothalamus
– Stored and released by posterior pituitary
• Hormone- ADH
– Released in response to Dehydration and High
Osmolarity (thickening) of blood
• Effects?
Disorders????
Stress
• Gland- Adrenal Cortex
• Hormones
– Glucocorticoids
• Effect- Systemic
Disorders
• Cushing Syndrome
– Cause: Excess
Glucocorticoids
– Disrupts Protein and Fat
Metabolism
– Symptom is abnormal fat
deposits, fatigue and
exhaustion
Cushing Syndrome (cont.)
After Surgery