Strand 1: Life processes in plants and
animals
HUMAN ENDOCRINE
SYSTEM
PPT 1
Important Terminology
• Antagonistic: have the opposite effect to one another.
• Co-ordination: the process of picking up a stimulus from the
external or internal environment, interpreting the information,
making a decision and adjusting the body in response to the
stimulus.
• Homeostasis: the maintenance of a constant internal environment.
• Hormone: chemical produced by an endocrine gland that travels
into the blood to target organs.
• Target organ: The specific cells/organ that are/is affected by
hormone
• Negative feedback mechanism: a self-regulating system that
occurs in the body and that maintains a state of equilibrium
• Stimulus: any change in the external or internal environment to
which an organism responds.
• Prefix: Hypo – below/under
• Prefix: Hyper – above
• Suffix: -genesis (formation; making)
CHE
Endocrine
Glands
Electrical
impulses
Nervous
system
Hormones
Homeostasis
NERVOUS CO-ORDINATION
CHEMICAL CO-ORDINATION
Message carried as nerve impulse
Message carried chemically by
hormone
Impulse travels fast
Message carried slower
Message carried along nerves
Message carried by blood
Message acts for a very short time
Message acts for a long time
Targets a specific area
Acts over wide area
Causes an immediate reaction
Results in long term reaction
Two types of glands in body
• ENDOCRINE GLANDS
o ductless glands.
o release hormones directly
into the blood or lymph.
o blood transports the
hormones to the target
organs
• Exocrine glands
o contain ducts
o Ducts are tubes leading from
a gland to its target organ.
o salivary glands.
What are hormones?
• Are chemical "messengers" .
• Moves very slowly.
• Most hormones are proteins/ insulin and some are
steroids/ testosterone.
• Secreted by ductless glands - carried in blood- target organs
• Concentration is low but effect powerful
• Short life – broken down by enzymes
• Normally stimulate target cells - TSH
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
HYPOTHALAMUS
Part of brain above pituitary
ADH
Osmoregulation
GONADOTROPINRELEASING HORMONE
(GNRH) - stimulates posterior
pituitary gland
OXYTOCIN
Contraction of uterus
PITUITARY GLAND/ HYPOPHYSIS
 Hormone release under control of
hypothalamus
 Pituitary gland often refers to as
‘MASTER GLAND
Abnormalities in the secretion of growth hormone
DWARFISM
Hypo-secretion of STH
GIGANTISM
Hypersecretion of STH
ACROMEGALY – in adults – over secretion of GH
THYROID GLAND
Anterior part of neck
H-shaped two lobed organ
Either side of trachea below
larynx
Stimulated by TSH
releases hormone THYROXINE
Iodine essential
• Increases metabolism
• Development and functioning of
heart
• Development and functioning of
nervous system
• Normal functioning of organs
Abnormalities in the secretion of Thyroxine
HYPERTHYROIDISM
Too much thyroxin
 increased metabolic rate
Weight loss
Increased heart rate,
respiration and blood
pressure
Anxiety, hyperactivity
Very tired
 Graves disease
 Bulging of eyes
HYPOTHYROIDISM
Too little thyroxin – lack of
iodine
 low metabolic rate
In children - Cretinism
In adults myxoedema
Anxiety, hyperactivity
Very tired
 Goitre
ADRENAL GLANDS
On top of each kidney
Adrenal cortex - ALDOSTERONE
Adrenal medulla - ADRENALIN
ADRENAL GLANDS
• Increases heart beat and thus
blood circulation
• Increases blood pressure
• Increase breathing rate- and
depth
• Air passages widen
• Cellular respiration increases
• More blood flow to strategic
organs like muscles
• Muscle tone increases
• Less blood flow to less
important organs like digestive
system, skin etc
• Glycogen converted to glucose
• Pupils dialates / widen
• Under control of ACTH from
hypophysis
• Regulates amount of salt in
blood
• Works with ADH to control
water balance
ISLETS OF LANGERHANS in PANCREAS
ALPHA CELLS
GLUCAGON
INSULIN
Increase
blood sugar
level
Decrease
blood sugar
level
Two types of cells:
PANCREATIC CELLS - exocrine
ISLETS OF LANGERHANS- endocrine
BETA CELLS
•Glycogen to
glucose
• absorption of glucose
• glucose to glycogen
•Inhibits glycogen to
glucose
SUGAR DIABETES/ DIABETES MELLITUS
TOO MUCH GLUCOSE IN BLOOD
TYPE 1 DIABETES-insulin
dependent
• Usually start in childhood
• Can be heredity
• Autoimmune- destroys beta
cells
• Pancreas cannot produce
insulin
• Insulin injections
• Sugar must be tested frequently
TYPE 2 DIABETES – insulin
independent
• More common than type I
• Caused by age, high sugar
and fat diet, lack of exercise
• Less insulin produces and
body cannot use it correctly
• Balanced diet
• Low GI carbohydrates
• Losing weight and exercise
OESTROGEN
PROGESTERONE
Secreted by Graafian Follicle
FUNCTIONS
Secondary female
characteristics
Development of female sex
organs
Thickening of endometrium
wall in preparation for
pregnancy
Suppresses the release of FSH
Released by corpus luteum
FUNCTIONS
Further thickening of
endometrium for
implantation of egg
Maintains endometrium
during pregnancy
Blocks production of FSH
and LH
TESTOSTERONE
Secondary male characteristics
Maturation of reproductive organs
Maturation of sperm cells
Sex drive
HOMEOSTASIS
Living organisms can be thought of having two environments:
-the
external environment being the surroundings where the organism
lives,
-the internal environment is the liquid (tissue fluid) that fills up the
spaces between cells.
The process to
maintain a relatively
constant optimal
state despite
changes in the world
outside
HOMEOSTASIS
The internal environment is
balanced within suitable limits.
HOMEOSTASIS
Factors that must be kept constant during homeostasis
Various factors such as
concentrations of CO2,
O2, salt, urea and
glucose, as well as
temperature and pH
are kept constant.
NEGATIVE FEEDBACK SYSTEM
A negative feedback loop occurs in biology when the
product of a reaction leads to a decrease in that reaction
Receptor cells: detects changes
Control centre: receives information and
issues new instructions
Effector: responds by carrying out
corrective action to bring factor back to
normal
Feedback (message) to receptor cells
about the corrective action
Finally message (NEGATIVE) from
receptor to effector to stop or reverse
action so that it does not go too far in
opposite direction
https://www.youtube.com/watch?v=z0H8Jbge
P9I
• box 1 -changed levels of factor. The levels can either go too high or too
low.
• Box 2 Any change is detected by the receptor
• The message (3) goes to the effector (4), which carries out the corrective
action, shown by arrow 5.
• Feedback shown by arrow 6 is sent to the receptor to show that the
change has been corrected.
• Arrow 7 shows the negative message going to the effector, shown in 4, to
tell it to stop or reverse its corrective action.
NEGATIVE FEEDBACK SYSTEM
HELPS MAINTAINING HOMEOSTASIS – detection of a change in
the normal levels which results in a reaction that counteracts the
change and returns it to normal. Return to normal is detected
and the corrective action is switched off
THYROXINE PRODUCTION- NEGATIVE FEEDBACK SYSTEM
NEGATIVE FEEDBACK MECHANISM
CONTROLLING TYROXINE RODUCTION
Less TSH
Too much thyroxine
THYROID
INHIBIT
PITUITARY
STIMULATE
Too little thyroxine
More TSH
Use of Hormones in sport
Hormones used to enhance performance in sports
Growth hormone
Anabolic steroids
Erythropoietin
Read through pages 51-52 and discuss in class