The Hypothalamus
• Found in diencephalon – below the
thalamus.
• Plays a key role in maintaining homeostasis
Regulates and integrates the autonomic
nervous system [ANS]
Primary neuroendocrine link –makes/secretes
regulating hormones – affect pituitary gland
directly
Autonomic Nervous System
Sympathetic 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
System
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 hormonesuse secondary messenger
•Fat Soluble – steroid hormones - able to
enter cell
Control of Hormone levels
Feedback regulation
Positive feedback
Negative Feedback
Functional 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, glucocorticoids
are 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 – prolactin
Causes 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 Hormones
Both 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 Hormones
Work 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