The Hypothalamus
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Transcript of The Hypothalamus
The Hypothalamus
• Found in diencephalon – below the thalamus.
• Plays a key role in maintaining homeostasisRegulates and integrates the autonomic
nervous system [ANS]Primary neuroendocrine link –makes/secretes
regulating hormones – affect pituitary gland directly
Autonomic Nervous System
Sympathetic Nervous SystemSympathetic Nervous System
Concerned primarily with preparing the body for stressful or emergency situations.
‘fight or flight’ Increases breathing, heart
rate, & blood flow to skeletal muscles, pupils dilate, stimulates adrenal gland function
Parasympathetic Nervous Parasympathetic Nervous SystemSystem
Active under normal, relaxed conditions.
‘Rest and digest’Increases digestive system
activity, slows breathing & heart rate, pupils constrict
Endocrine System
Hormone from the Greek horman ‘to set in motion’
Defined as: a chemical messenger from one cell [or group of cells] to another.
All multicellular organisms [including plants] produce hormones
Types of Hormones
•Water Soluble – protein based hormones- use secondary messenger
•Fat Soluble – steroid hormones - able to enter cell
Control of Hormone levels
Feedback regulationFeedback regulation
Positive feedback Negative Feedback
Functional regulationFunctional regulation
Central Nervous System control
Hypothalamus
-- secretes regulator hormones – releasing hormone [RH] and inhibitory hormone [ IH]
-- contains autonomic centers and interacts when sympathetic nervous system is activated
Primary Endocrine Glands – adrenals, gonads, pancreas, parathyroid, pineal, pituitary & thyroid Secondary Endocrine Glands – heart, kidney, liver, placentas, thymus
Pituitary Gland‘master gland’ hypophysis
Anterior lobe – adenohypophysis
Posterior lobe – neurohypophysis
Anterior Lobe Produces 7 Hormones:
ACTH – adrenocorticotrophic hormone
GH – growth hormone – also known as somatotrophin
PRL - prolactin
FSH – follicle stimulating hormone
LH – luteninzing hormone - female / ICSH – interstitial cell stimulating hormone – male
TSH – thyroid stimulating hormone
MSH – melanocyte stimulating hormone
ACTH – adrenocorticotrophic hormone Works with sympathetic nervous system to stimulate adrenal cortex to produce glucocorticoids needed for stress response
As adrenaline/epinephrine are released into the blood stream, glucocorticoidsare also released, they stimulate the liver to release stored glycogen for use as energy, also breaks down proteins and fats for energy use.
MSH – melanocyte stimulating hormone
Stimulates melanocytes to produce melanin, and increase skin pigmentation
GH – growth hormone – also known as somatotrophin
Produced primarily while sleeping.
Effects all tissues of body – see results primarily on musculoskeletal system
In adult – responsible for repair of tissue
PRL – prolactinCauses milk production in lactating women
FSH – follicle stimulating hormone – in women starts maturation of ovum/ in men causes sperm production
LH – luteninzing hormone : causes ovulation and progesterone production
ICSH – interstitial cell stimulating hormone : stimulates testosterone production
TSH – thyroid stimulating hormone
Causes production of thyroid hormones [thyroxine T4 and triiodothyronine T3] that maintain metabolism
Pancreatic HormonesBoth an endocrine and exocrine gland
Exocrine secretions are digestive enzymes
Endocrine hormones monitor and maintain blood glucose levels: glucagon [alpha cells] and insulin [beta cells] and somatostatin [delta cells]
Blood glucose levels at fasting should be between 80-100 mg/dl
Parathyroid HormonesWork in conjunction with Calcitonin [ produced in thyroid gland – parafollicular cells] to maintain blood calcium levels
Parathyroid Hormone [PTH] is released when blood calcium levels are low
Causes: activation of Vitamin D: enhanced absorption of calcium from digestive tract, decreased excretion of calcium via kidneys. Osteoclasts increase activity
Calcitonin is released when blood calcium levels are too high
Causes: enhanced excretion of calcium via kidneys, decreased absorption of calcium in digestive tract. Slows osteoclastic activity – enhances osteoblastic activity