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

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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