endocrine vs exocrine glands endocrine glands produce and secrete hormones into the bloodstream eg....
TRANSCRIPT
THE ENDOCRINE SYSTEM
Endocrine vs exocrine glands
•Endocrine glands produce and secrete hormones into the bloodstream•eg. the pituitary gland
•Exocrine glands secrete through ducts •eg. salivary glands
Hormones
Hormones – chemical signals released by specialized cells of the body to exert an effect on cells in other parts of the body
•There are 2 classes of hormones:
a) Steroid hormones • derived from cholesterol• multi-aromatic structure• lipid soluble
a) Steroid hormones
Mode of action:
•Diffuse through cell membrane of cells (phospholipid soluble)
•Combine intercellularly with receptor molecule
• Initiates transcription of specific gene(s)
•Effect achieved by resulting protein(s)
Hormones
Hormones – chemical signals released by specialized cells of the body to exert an effect on cells in other parts of the body
•There are 2 classes of hormones:
a) Protein hormones• made of amino acids• water soluble
Insulin
Growth hormone
Parathyroid hormone
b) Protein hormonesMode of action:
•Attach to specific membrane receptors(hormone acts as ‘first messenger’)
•Signal transduction results in intercellular molecule activation(molecule is ‘second messenger’)
•Molecule up/down regulates protein activity within cell
•Effect is achieved by activated proteins
Glands of the endocrine system
Pituitary gland•Attached to the hypothalamus•Two-lobed (anterior & posterior)•Each lobe releases different hormones
Posterior pituitary•Stores/release hypothalamus-made hormoneseg. antidiuretic hormone, ADH, oxytocin
Anterior pituitary• Makes its own hormones but release is
controlled by hypothalamuseg. growth hormone, follicle-stimulating hormone, luteinizing hormone
Glands of the endocrine system
Pancreas•Small gland containing endocrine & exocrine cells
•Endocrine tissue called islets of Langerhans and contains 2 types of cells:
-cells produce insulin • released when blood sugar is high• causes muscle, liver and other organs to
take up glucose (reducing blood sugar)
-cells produce glucagon• released when blood sugar is low• causes glycogen in aforementioned
tissues/organs to be converted to glucose (raising blood sugar)
Glands of the endocrine system
Adrenal glands•Located above each kidney•Consists of adrenal medulla and adrenal cortex
Medulla•Regulated by nervous system•Makes adrenaline (epinephrine) & noradrenaline (norepinephrine)
•Sypathetic nerves cause release of both hormones
•Causes conversion of glycogen to glucose & ups heart rate, breathing rate, etc.
Cortex•Produces sex hormones and hormones involved in stress conditions (eg. cortisol) and water reabsorption (eg. aldosterone)
Glands of the endocrine system
Thyroid/parathyroid glands•Located in neck• ‘Thyroid hormones’ effect growth & specific rates of function within the body (eg. calcitonin regulates bone-calcium homeostasis)
Ovaries•Located in lower abdomen of females•Produce estrogen and progesterone which regulate reproductive health (eg. the menstrual cycle)
Testes•Located in the scrotum of males•Produce testosterone which maintains libido, muscle strength and bone density
Nervous + Endocrine =
There are 3 main pathways of hormonal control:
1.Endocrine pathway•Stimulus
•Endocrine gland
•Blood vessel
•Target
•Response
Nervous + Endocrine =
There are 3 main pathways of hormonal control:
2.Neurohormone pathway•Stimulus
•Hypothalamus
•Blood vessel
•Target
•Response
Nervous + Endocrine =
There are 3 main pathways of hormonal control:
2.Neuroendocrine pathway•Stimulus
•Hypothalamus•Blood vessel
•Endocrine gland•Target
•Response
Try this…
Read pg. 938
Section 46.5