1.1 Works alongside the nervous system to control and co-ordinate body functions.
(nervous - corrects immediately) (endocrine - gradual). This is achieved by the
release of hormones. Endocrine responses are slower but tend to last longer.
1.2.1 Regulating: chemical composition of internal
fluids, metabolism and energy balance, contraction
of smooth and cardiac muscle fibres, glandular
secretions, immune system activities.
1.2.2 Controlling: Growth and development
1.2.3 Regulating operation of reproductive system
1.2.4 Helping to establish cicadian rhythms.
Most hormones are circulating hormones
but some act locally.
2 Major endocrine glands
2.1 2 types of glands within the body: >Exocrine - secretes
product into ducts, then to lumen of organ, body cavity or
surface of body. > Endocrine - Secretes product into
intersitual fluid, then into blood stream to target cells.
2.2 Pituitary: >Master gland - it secretes several
hormones which control other endocrine glands.
Pituitary has its own master - the hypothalamus, It
has 2 lobes. -Anterior -Posterior
2.3 Thyroid: > Butterfly shaped gland located below larynx. >
Produces thyroid hormones T & T3 >Produces calcitonin
2.4 Parathyroid glands: > Partially embedded in the posterior walls of the lobes
of the thyroid gland. Produce one hormone called PTH parathormone.
2.5 Adrenal: Lie superior to kidney > 2 regions, cortex and medulla. >cortex - produces
mineralcorticiods > Medulla - produces epinephrine and noepinephrine (fight or flight)
2.6 Pancreas - Has both exocrine (digestive enzymes)
and endocrine (hormonal) function.
2.7 Ovaries and Testes: Ovaries - Produce oestrogen and progesterone -
work with FSH & LH. Testes - Testosterone. Inhibits secretes of FSH.
3 Define Hormone
3.1 'Mediator' molecules released in one point of the body but regulating the activity of cells in other parts.
4 Control of hormone secretions
4.1 Hormones can be divided into 2 classes:
4.1.1 Lipid soluble - Fat soluble including steroid and thyroid hormones.
4.1.2 Water soluble - Surface of cell includes, amine hormones, peptide
and protein hormones
4.2 Most hormones are secreted in short bursts in response to stimulation. Regulation prevents over or under
production. Secretion regulated by: > Signals from nervous system >Chemical changes in the blood >Other
5 Define negative and positive feedback
5.1 Most hormones work by negative feedback, however a few operate by positive feedback.
5.2 NEGATIVE FEEDBACK: Reverses any upward or downward change to the normal
range of a controlled condition. ie the activity the effector negates the original
5.3 POSITIVE FEEDBACK: System strengthens or reinforces the change in
bodys controlled condition. Activity continues until the stimulus is removed
or outside force interrupts the activity.