Download Endocrine System - WCED: Curriculum Development

ENDOCRINE SYSTEM
CTLI Training:
12,13 July 2011
H.C.Adonis
HOMEOSTASIS
LIVER
SKIN
PANCREAS
ureum
Excess water,
salts, ions
KIDNEYS
LUNGS
HOMEOSTASIS: Main ideas
Maintenance of constant internal environment in the
body/keeping conditions in tissue fluid constant
 WHY?
 Cells dependant on tissue fluid to function optimally
 HOW?
 Various systems that help in maintaining tissue
fluid/internal environment constant i.e. nervous system,
excretory system, respiratory system, ENDOCRINE
SYSTEM.
 Various systems need to be coordinated in order for
body to function as a unit.
 HOW ARE THESE SYSTEMS COORDINATED?

CHEMICAL
COORDINATION:
Endocrine System
Communication through
the use of hormones:
results in slower responses
NERVOUS
COORDINATION:
Nervous system
Communication takes
place via neurons:
results in quick responses
HOW DOES CHEMICAL COORDINATION TAKE PLACE?
HOMEOSTATIC
CONTROL CENTRE:
THE BRAIN
(hypothalamus)
Nerve
impulses
Nerve
impulses/Hormo
nes in
bloodstream
EFFECTORS (glands):
react on stimuli
RECEPTORS:
detect stimuli/change
stimuli
responses
Feedback
CHEMICAL vs NERVOUS
COORDINATION
CHEMICAL COORDINATION
Co-ordinates different systems
in the body to work together
Involves hormones transported
in the bloodstream in small
quantities
Has general and local effects on
the body
Is slower acting
Has long-lasting effects
NERVOUS COORDINATION
Co-ordinates different parts of
the body to work together
Involves isensations that are
transported via neurons in
the form of impulses
Has specific targets/effectors
Is very fast acting
Has more short-term effects
HUMAN ENDOCRINE SYSTEM
Endocrine
glands
Exocrine
glands
• Ductless glands
• Release hormones directly
into bloodstream or
lymph.
• Release secretions in ducts
to be carried to body
cavity or outside of body
i.e. saliva, tears etc.
ENDOCRINE SYSTEM








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Endocrine system co-ordinates the body’s organs to help maintain
homeostasis
Based on the production of chemical messengers called HORMONES.
Hormones control body processes that require several organs of the
body to interact for a combined effect.
Are chemical "messengers“, secreted by glands.
Moves very slowly.
Most hormones are proteins and some are steroids.
Hormones have specific target organs
Regulatory effect – stimulate OR inhibit
Do not function in isolation – integrated with other hormones
Functions controlled by hormones include:
 activities of entire organs
 growth and development
 reproduction
 sexual characteristics
 usage and storage of energy
 regulate water content (osmoregulation)
 ionic (salt) regulation
 regulation of blood glucose level
ENDOCRINE GLANDS: position + function

IMPORTANT!
POSITION
OF GLANDS
HORMONES
SECRETED
FUNCTION /
EFFECT OF
HORMONES
ENDOCRINE GLANDS: location
Hypophysis / pituitary gland
Thyroid gland
Pancreas
Adrenal glands
Ovaries
Testes
ENDOCRINE GLANDS: location & function
Pituitary gland/hypophysis
Located at base of brain, attached to
hypothalamus
Nerve fibres from hypothalamus runs into
posterior lobe
Known as “master gland”
Consist of anterior (adenohypophysis) and
posterior lobe (neurohypophysis)
Anterior lobe releases:
•TSH (Thyroid-stimulating hormone)
•Growth hormone (STH)
•FSH (Follicle-stimulating hormone)
•LH (Luteinising hormone)
•Prolactin
Posterior lobe releases:
•ADH (Anti-diuretic hormone)
•Oxytocin
HYPOPHYSIS / PITUITARY GLAND
HYPOPHYSIS HORMONES: Anterior lobe
TSH
• Stimulates the thyroid to secrete
the hormone thyroxin
GROWTH HORMONE
(STH)
• Promotes growth of skeleton and
muscles by stimulating synthesis
of proteins
FSH
LH
PROLACTIN
• Stimulates development of
primary follicles in ovaries into
Graafian follicles
• Stimulates ovulation
• Stimulates the mammary glands to
produce milk after the birth of a
baby
HYPOPHYSIS HORMONES:
Posterior lobe
ADH (Antidiuretic
hormone)
• Controls re-absorption
of water into blood
from renal tubules
OXITOCIN
• Cause muscle
contractions in uterus
during birth
• Triggers milk release
during breastfeeding
ENDOCRINE GLANDS: location & function
Thyroid: consist of two lobes on
either side of trachea, just below
larynx
Produces and secretes hormone
thyroxin
The element iodine, essential for
production of thyroxin
Shortage could result in enlarged
thyroid / goitre
THYROID GLAND
Functions of thyroxine

Increases basal metabolic rate (amount of
energy the body needs to function when body is at
rest)

Increases breathing rate and heart rate

Development and functioning of nervous
system

Normal growth and development of
important organs
Thyroid Disorders
Over secretion:
Hyperthyroidism
m
• Increased metabolic rate
• Weight loss
• Increased heart rate, respiration
rate and blood pressure
• Increased irritability
Under secretion:
Hypothyroidism
• Causes very low metabolism
• In children: cretinism
• In adults: myxoedema
Cretinism
• Abnormal growth
• Mental retardation
• Do not reach sexual maturity
Myxoedema
• Mental decline, physical lethargy
• Thickening of skin, increase in body
mass
HYPERTHYROIDISM
HYPOTHYROIDISM
THYROID DISORDERS
HOMEOSTATIC CONTROL
More TSH
Less thyroxin
HYPOPHYSIS
THYROID
More thyroxin
less TSH
NEGATIVE FEEDBACK SYSTEM
HYPOSECRETION

Dwarfism
HYPERSECRETION

Gigantism & Acromegaly
GROWTH DISORDERS
ENDOCRINE GLANDS: location & function
Pancreas
Two types of cells:
• Pancreatic cells
• Islets of Langerhans (small groups of
cells)
Pancreatic cells have exocrine function
and secrete pancreatic juice into
pancreatic duct which leads to duodenum
Islets of Langerhans have endocrine
function and secretes 2 hormones directly
into bloodstream i.e. glucagon and insulin
Alpha cells secrete glucagon and beta
cells produce insulin
Insulin and glucagon responsible for
homeostatic control of blood glucose
levels through negative feedback system
PANCREAS
PANCREAS
INSULIN & GLUCAGON:
Homeostatic control
INSULIN: Beta
cells
• Stimulates absorption of glucose
to body cells
• Stimulates conversion of glucose
to glycogen in liver and muscles
• Inhibits conversion of glycogen
to glucose
GLUCAGON:
Alpha cells
• Stimulates conversion of
glycogen to glucose in the liver
• Inhibits conversion of glucose to
glycogen
LOW BLOOD GLUCOSE
1.
Low blood
glucose(stimulus)
2.
3.
glucagon
Blood glucose levels return to
normal , feedback to hypothalamus
4.
HIGH BLOOD GLUCOSE
1.
High blood
glucose(stimulus)
2.
3.
Blood glucose returns to normal,
feedback to hypothalamus
insulin
4.
HOMEOSTATIC CONTROL: BLOOD GLUCOSE
DIABETES mellitus: Type 1



Dysfunction of beta cells, little or no insulin is
produced - can cause elevation of glucose level in
blood.
The excess glucose is now removed from the body
through urine.
Excess glucose is also removed through
sweating.
SYMPTOMS:
Frequent urination
Increased hunger
Inexplicable weight loss
Repeated infections
Impaired vision
Exhaustion and dizziness
Wounds that heal slowly
Treatment and management
Daily insulin injection
 A specially adapted diet
 Regular testing of blood sugar levels

Type 2 diabetes
Characterised by insulin resistance
 Life style disease
CAUSES:

Overweight and obesity
Inactivity
Age
TREATMENT AND MANAGEMENT
Maintain normal body mass through balanced diet
Regular exercise
Oral medication or insulin
ENDOCRINE GLANDS: location & function
Adrenal glands
Located at top of each kidney ; consist of
outer cortex and inner medulla
Adrenal cortex produces hormone
aldosterone.
Adrenal medulla produces adrenalin.
ADRENAL GLANDS
Effects of Adrenalin & Aldosterone:
ADRENALIN:
 Known as “fight or flight” hormone
 Increases heart rate - more blood with oxygen and glucose to
muscles
 Increases blood pressure due to vasoconstriction of vessels in
skin- more blood to muscles ,heart and brain
 Increases conversion of glycogen to glucose – increase glucose
levels in blood which releases energy
 Increase rate and depth of respiration – more oxygen absorbed
in blood
 Increase muscle tone – muscles can react faster
 Pupils dilate – allow more light into eye for improved vision
 Increase sweat production – cool body during activity
ALDOSTERONE:
Steroid hormone that regulates ionic balance of tissue fluid
ENDOCRINE GLANDS: location & function
Gonades: testes and ovaries
Testes located outside body in
scrotum
Interstitial cells (Leydig cells)
produces hormone testosterone
Ovaries located in abdominal
cavity, on either side of uterus
Graafian follicles produce
hormone oestrogen
Corpus luteum produces
hormone progesterone
GONADS: Testes & ovaries
TESTOSTERONE
Secondary male sex characteristics
 Role in development of male sex organ during puberty
 Neccesary for maturation and quality of sperm cells

OESTROGEN
 Secondary female sex characteristics
 Role in development of female sex organs during puberty
 Responsible for thickening of endometrium and preparation
for implantation
PROGESTERONE
 Responsible for further thickening of endometrium and
maintenance therof during pregnancy
 Suppresses release of FSH and LH
END