Endocrine system!
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- Created by: Izzy2807
- Created on: 09-01-20 12:48
What lies in the cell membrane for hormone communication?
Protein receptors!
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Why do we need cell signalling?
Cellular activities and coordinates cell responses. Needed for growth, repair, immunity, homeostasis,
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What is a target tissue/organ?
An organ/tissue that has specific receptors on its membrane that are complementary in shape to specific hormones
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What are the two classifications of hormones?
Water soluble (hydrophilic)...usually protein hormones. Lipid soluble (hydrophobic) steroid hormones, derived from cholesterol
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What is a ligand? What is a hormone?
A molecule that binds to a receptor on a molecule (e.g. hormone or neurotrans.). Hormone: specialised organic molecule produced by an endocrine gland in response to a stimuli
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What are the two types of receptor?
Intracellular and cell surface receptors. Intracellular: steroid/thyroid hormone-receptor complex binds to promoter region on gene.
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What is the action of steroid/thyroid hormones?
They modulate gene expression in target cells. Diffuse through cell membrane, binds to receptor, H-R complex binds to DNA, switches on/off transcription
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Where do protein/peptide hormones bind and what does it initiate?
Receptors on the outside of cell membranes. Initiates a series of events that generate second messengers within the cell (signal transduction) - cyclic AMP activates enzymes to produce response
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What is the hypothalamic pituitary axis?
A neuroendocrine unit comprising of the hypothalamus, pituitary gland and adrenal glands
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What is the function of the HPA?
Involved in basal homeostasis, release hormones that regulate/control the release of other hormones. HYPO-PIT-RH-GLAND-HORMONE
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What are hypothalamic releasing and inhibiting hormones?
HRH: stimulate the secretion of a hormone. HIH: inhibit/reduce the release of a hormone by the anterior pituitary glands
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What is the mechanism that transports hormones from the hypothalamus to the pituitary gland?
Hypophyseal portal system, a series of blood vessels for hormones
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What are the two sections of the pituitary gland and what is its function?
Posterior and anterior pituitary gland. Regulates functions such as metabolism, growth/maturation and sexual development/reproduction
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What are the two ways pituitary hormones work?
Direct effect (e.g. growth hormone) or regulate the release of other hormones down the hypothalamic pituitary endocrine axis
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What endocrine glands are regulated by the hypothalamic-pituitary endocrine axis?
Ovaries, thyroid, kidneys, parathyroid. ANY glands that releasing hormones travel to.
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Why is negative feedback important in the endocrine system?
Regulates the levels of hormones in the body so there isn't too much or too little of anything (e.g. too little thyroxine, underactive metabolism)
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What would happen if the mammory glands were controlled by negative feeback, not positive?
Milk production wouldn't occur. When oxytocin levels increased, the feedback loop would decrease levels!
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Describe the feedback loop for insulin production
Stimulus (high blood glucose), hypothalamus detects this and sends signals down afferent NP to pancreas. Pancreatic Beta cells secrete insulin. Glucose uptake in liver/cells increases (glycogenesis). Lower blood glucose levels, hypothalamus stops!
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Describe the feedback loop for glucagon production
Stimulus (low blood glucose), hypothalamus detects this and sends signals down ANP to pancreas. Pancreas alpha cells secrete glucagon. Liver breaks down glycogen to glucose (glycogenolysis). Glucose levels rise, hypothalamus stops!
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What is type 1 diabetes?
Hyposecretion of insulin (beta cells destroyed), blood glucose levels are too high. Excessive thirst, lots of urination, tiredness, weight loss
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What is acromegaly?
Hypersecretion of growth hormone (anterior pit.). Bones increase in size, as to hands, feet and face.
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What is gigantism?
Hypersecretion of IGF growth hormone, usually caused by pit. gland tumour...too much growth hormone!
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What is addison's disease? (Primary adrenal deficiency disease)
Hyposecretion of cortisol. Abdominal pain, darkening of skin, weakness and weight loss
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What is cushing's syndrome?
Hypersecretion of ACTH so too much cortisol. Rapid weight gain, moon face, weakening of bones and muscles, high BP, mood swings
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What is hypothyroidism and hyperthyroidism?
Hypo: too little thyroxine...tiredness, weight gain, depression, dry skin, sensitive to cold. Hyper: too much thyroxine. Weight loss, irritability, sensitive to heat, tiredness/weak
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What is a gland? What is the difference between endo and exocrine glands?
Gland: an organised collection of secretory epithelial cells. Endo: secrete hormones directly into blood. Exo: release secretions (not hormones) into ducts
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What are agonist and antagonist ligands?
Agonists: bind to receptor to INITIATE response. Antagonists: bind to receptor to PREVENT response.
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What are the 4 types (distances) of communication between cells?
Direct: via gap junctions. Autocrine: self-signalling, affect SAME cell. Paracrine: target cells only in VICINITY (e.g. cytokines/histamines. Endocrine: travel in the blood all around the body.
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Which hormones are AA based and which are steroid based?
AA based: glucagon, insulin, parathyroid, calcitonin, ADH, adrenaline, FSH and LH. Steroid based: cortisol, oestrogen, prog, testost, thyroxine, aldosterone
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Which 3 stimuli control the release of hormones?
Humoral (changing blood levels of ions/nutrients). Neural (nerve fibres). Hormonal (hormones stimulate release of other hormones)
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Other cards in this set
Card 2
Front
Why do we need cell signalling?
Back
Cellular activities and coordinates cell responses. Needed for growth, repair, immunity, homeostasis,
Card 3
Front
What is a target tissue/organ?
Back
Card 4
Front
What are the two classifications of hormones?
Back
Card 5
Front
What is a ligand? What is a hormone?
Back
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