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Control of Anterior Pituitary
Hypothalmic Neurosecretory cells
Negative feedback
Releasing and release-inhibiting hormones
Anterior pituitary gland
Growth hormone
Non-endocrine Tissue
Metabolic response
ACTH
Thyroid Stimulating Hormone
Other Endocrine Tissue
Posterior Pituitary
•
•
Neurosecretory cells secrete hormones
directly onto capillaries
Only 2 hormones:
1. Antidiuretic hormone (ADH, also called
vasopressin)
•
Water retention by the kidney
2. Oxytocin
•
•
Uterine contractions during childbirth
Milk ejection during breast feeding
The Adrenal Glands
• An example of Pituitary control over other
endocrine tissue
• One gland attached to the top of each
kidney
Adrenal Medulla
Adrenal Cortex
Fig 9-32
Kidney
Adrenal Cortex
• Steroid hormones
– Aldosterone
– Cortisol
– Small amounts of
testosterone,
progesterone
Adrenal Medulla
• Catecholamine
– Epinipherine (adrenalin)
– Norepinipherine
(noradrenalin)
Control of Adrenal Cortex
Stress, circadian rhythm
and other neural input
Hypothalamic neurons
Corticotropin releasing hormone (CRH)
Anterior Pituitary
Adrenocorticotropic hormone (ACTH)
Adrenal cortex
Release of steroid hormones
Adrenal Cortical Steroids
• Mineralocorticoids
– eg. aldosterone
– Controls ion transport
in the kidney function
– Regulates expression
of a Na channel
– Important for water
reabsorption
• Glucocorticoids
– eg. cortisol
– Important for
metabolism esp. glucose
– Activate enzymes (in
liver) that increase
glucose production
–  blood glucose
Adrenal Medulla
• Catecholamines stored in large vesicles within
chromaffin cells of the adrenal medulla
• Chromaffin cells innervated by neurons of the
sympathetic nervous system
• ‘Fight or flight’ response
Sympathetic nerve terminal
Acetycholine synapse
Ca++
Adrenal medulla
Catecholamine
containing vesicles
Chromaffin cell
Blood vessel
• Ach depolarizes chromaffin cell by
activating nicotinic Ach receptors
• Opens voltage-gated Ca++ channels
• Ca++ causes fusion of vesicles
• Release of catecholamine into blood
stream
• Catecholamines released by adrenal
medulla:
– epinipherine 80%
– norepiniphrine 20%
– Also neurotransmitter
• Norepinephrine primary SNS
Effects of catecholamines depend
upon receptor type
• Activate adrenoreceptors
– Two types:  and 
1
Phospholipase C
IP3 & DAG
2
1
2
Adenylate cyclase
cAMP
Potential effects of catecholamine
receptor activation
• Heart
– , mediated  - contraction, HR
• Smooth Muscle (Blood vessels and lungs)
–  contraction
–  relaxation
• Metabolism
–  -  glycogenolysis  glucose
• Neural
–  -  K+ channel conductance
Some clinical stuff
•  adrenoreceptor agonists used to treat
asthma
•  blockers used to treat high blood
pressure
Summary
• Pituitary gland
– Hypothalamic control
– Anterior – 2 hormone system
– Posterior – direct hormone release into blood
stream
• Adrenal gland
– Cortex – steroid hormones
– Medulla - catecholamines
Blood Glucose Regulation
• Endocrine pancreas
– Only 2% of entire pancreas,
– the rest produces digestive enzymes
(exocrine)
– Islets of Langerhans
• Insulin ( cells)
• Glucagon ( cells)
• Somatostatin ( cells)
• Diabetes
– 2 million Canadians
– $9 billion per year health care costs
– Insulin isolated by Banting & Best 1922, U of T Dept of
Physiology (1923 Nobel Prize)
• Type 1
– No or very little insulin produced
• Type 2
– Reduced cellular response to insulin
• Consequences
–
–
–
–
Death
Blindness
Kidney disease
Limb amputation
Hormonal control of blood glucose
In the GI tract, 80% of all carbohydrate is digested to glucose
Basically:
Glucose
Used for ATP production
Glycogen
Used for glucose storage
Insulin
• Stimulus for secretion is high blood
glucose
• Secreted by  cells
• Leads to glucose uptake and storage in
liver, muscle and fat tissue.
• Effect is to  blood glucose
• Danger of Diabetes is hyperglycemia
Insulin Effects on Muscle and
Fat Tissue
• Insulin initiates transfer of glucose
transporters to cell membrane
•  blood glucose
•  production of glycogen
Effects in Muscle & Fat
Glycogen synthesis
Glucose
transporter
glucose
SNARE dependent
transport
Glucose
transporter
Insulin
storage
vesicle
In the Liver
• insulin stimulates the synthesis of an
enzyme (glucokinase)
• Required to ‘trap’ glucose in the cell
• initiates glycogen production
Effects in Liver
GLUT2
Glycogen synthesis
Glucose
transporter
glucose
X
glucose
Glucose 6-phosphate
glucokinase
‘trapped’
Other hormones
• Glucagon
– Secretion stimulated by low blood glucose
– Activates enzymes for gluconeogenesis and
glycogenolysis
– Leads to  blood glucose levels
• Somatostatin
– Regulates secretion of insulin and glucagon
Glucose Regulation Summary
• Endocrine pancreas
• Secretion of several hormones important
for blood glucose regulation
• Insulin  glucose uptake and storage
– Different effects on liver and muscle & fat
• Glucagon  glucose production