A chemical messenger release from one cell which produces a specific receptor-mediated change in another cell.
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What are the 3 categories of hormones?
1.Modified Amino Acid - oxytocin, vasopressin (released by posterior pituitary gland)
2. Protein hormone - insulin from pancreatic islets
3. Steroid - cortisol (adrenal), oestrogen/testosterone (gonads)
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How do the 3 categories of hormones bind?
Amino acid and protein hormones bind to membrane-bound receptors on cells of target organs.
Steroid hormones diffuse across the membrane and bind to intracellular receptors (soluble in lipids)
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What are 4 processes hormones are involved in?
Development
Metabolism
Reproduction
Fluid homeostasis
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Define gland
An organ that synthesises and releases a substance into the bloodstream, body cavity or skin.
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What are the 5 different ways a gland can be?
Endocrine-ductless
Exocrine-uses a duct
Mucous-produce rich glycoprotein mucin, absorbs H2O to form mucus.
Serous-most common, produce saliva
Sebaceous-secrete waxy matter sebum, lubricates hair on skin.
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What are the ways cells can communicate through hormones?
Autocrine- hormone binds to autocrine receptor on same cell which changes its activity.
Paracrine- hormone induces change in nearby cells.
Endocrine- hormone travel long distance through blood to target
Neurocrine- function of neurones
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What is Cortisol?
Steroid hormone made in adrenal gland, secretion is controlled by hypothalamus and pituitary gland.
Cortisol has many functions as the bond has many receptors.
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Give some functions of Cortisol
Control blood pressure.
Regulate metabolism.
Prepare body for 'fight or flight' repose by flooding with glucose (source of energy for muscles).
Support developing fetus.
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What does Insulin do in muscle, liver and adipose tissue?
Means high blood-glucose sugar levels.
Muscle - stores glucose to glycogen.
Liver - stores glucose to glycogen (mainly) or triglycerides.
Adipose - stores glucose to triglycerides
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What does Glucagon do in the muscle, liver and adipose tissue?
Muscle - converts proteins to amino acids which travel to the Liver are converted to glucose.
Liver- converts glycogen to glucose.
Adipose - converts triglycerides to fatty acids which travel to the liver and are converted to ketone bodies.
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What causes an Endocrine disorder and give an example
Lack of biological response to a hormone.
e.g. an excess secretion of growth hormone causes acromegaly
A signalling hormone released by adipose tissue that controls/moderates food uptake through a series of reactions.
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What is Adiponectin?
A hormone released by adipose tissue which increases insulin sensitivity of target organs ultimately regulation peripheral glucose and fatty acid metabolism.
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What hormones do:
Kidney
Heart
Gut
Adipocytes
Pancreas
secrete?
Erythropoietin
Atrial natriuretic peptide (ANP)
Gastrin and Secretin
Leptin and Adiponectin
Insulin
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Relationship between the Hypothalamus and Pituitary gland.
Hypothalamus sends signals to control the pituitary gland which controls hormone secretion. Base of hypothalamus is connected to the gland by a funnel-shaped stalk called Infundibulum
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How does the Hypothalamus communicate with the Pituitary gland?
Sends either a releasing hormone or releasing inhibitory hormone signal which are neurosecretions through the capillary bed (in hypothalamus) - portal vein in infundibulum - second capillary bed of the anterior pituitary gland
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What are the lobes of the Pituitary gland (also known as Hypophysis)?
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