A communication system using hormones as signalling molecules. Uses blood circulatory system to transport its signals.
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What are the two types of hormone?
Protein hormones which are derived of amino acids (e.g. adrenaline, insuline and glucagon). Steroid hormones (e.g. oestrogen and testosterone)
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In what ways are the two types of hormone different?
Proteins are not soluble in the phospholipid membrane and do not enter the cell. Protein hormones need to bind to the cell surface membrane and release a secondary messenger inside the cell. Steroid hormones pass through and have direct effect on DNA
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What are endocrine glands?
Ductless glands that release hormones directly into the blood
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What are first and second messengers
Non-steroid hormones are known as first messengers. they bind to cell surface membrane and catalyse the release of another signalling molecule, known as second messenger e.g. cAMP
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What type of hormones are secreted from the adrenal cortex
Adrenal cortex uses cholesterol to produce a range of steroid hormones. Pass through membrane of target cell and bind to specific receptors in the cytoplasm. Complex enters nucleus and binds to specific receptor on chromosomal material stimulates RNA
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Describe the structure of the Adrenal Cortex
Three distinct layers of cells. Outermost is Zona glomerulosa (secretes mineralcortidoids), middle is zona fasciculata (secretes glucocorticoids) innermost is zona reticularis (sex hormones)
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What are mineralocorticoids?
From zona glomerulosa and help control the concentrations of Na and K in blood, resulting in maintenance of blood pressure. Aldosterone acts on DCT cells and collecting duct, increases absorption of Na
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What are glucocorticoids?
From zona fasciculata and help control metabolism of fats, carbohydrates and proteins in liver. Cortisol is released in stress or when blood glucose is low, stimulates glycogenolysis and gluconeogenesis
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Where is adrenaline produced and how does it act?
Released from adrenal medulla into blood. Polar so can't pass through bilayer, acts as a first messenger with cAMP secondary messenger, prepares body for activity.
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How does adrenaline prepare the body for activity?
Relaxes smooth muscle in bronchioles, increases stroke volume of heart, increases heart rate, general vasocontrisction to raise BP, stimulates glycogenolysis, dilates pupils, inhibiting action of gut, hairs stand erect, increased mental awareness
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What are exocrine glands
Secrete substances into a duct
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What are the two main secretions of the pancreas?
Pancreatic juices containing enzymes secretd into small intestine (pancreatic amylase, lipase, trypsinogen). Hormones which are secreted from the islets of Langerhans into the blood
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Describe the endocrine function of the Pancreas
The islets of Langerhans contain alpha cells and beta cells. The alpha cells secrete glucagon and the beta cells secrete insulin.
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Describe how insulin is released from Beta cells
With high glucose concentration, more ATP is synthesised. This closes K ion channels changing the potential difference and making calcium ion channels to open. Diffuse in and cause vesicles of insulin to fuse with membrane and release by exocytosis
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What effects does insulin have on cells?
More glucose transporter protein placed into cell surface membrane. More glucose enters cells, more glycogenesis, more glucose is converted to fats, more glucose used in respiration
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What effects does glucagon have on cells?
Glycogen converted to glucose (glycogenolysis), more fatty acids used in respiration, amino acids and glucose are converted into additional glucose (gluconeogenesis)
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What is diabetes mellitus
Condition in which the body is no longer able to produce sufficient insulin to control its blood glucose concentration
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What is the difference between Type 1 and Type 2 diabetes
Type 1 is insulin dependent diabetes developed as autoimmune response, destroyed beta cells. Type 2 is non-insulin dependent diabetes, can't produce enough insulin, specific receptors becomes less responsive
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How can Type 1 diabetes be treated?
treated with insulin injections, blood glucose level measured and correct dose administered. Alternative may be insulin pump therapy (constant monitoring/insulin given), islet cell transplantation or pancreas transplant
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How can type 2 diabetes be treated?
Change in lifestyle, lose weight, exercise regularly, monitor their diet, match carbohydrate intake and use
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What is the source of insulin for treating diabetes and why is it advantageous?
E.Coli undergone genetic modification to manufacture human insulin. Advantages include; faster, cheaper, no rejection, lower risk of infection, faster acting, manufacturing adaptable to demand, less ethical issues than from animals
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Other cards in this set
Card 2
Front
What are the two types of hormone?
Back
Protein hormones which are derived of amino acids (e.g. adrenaline, insuline and glucagon). Steroid hormones (e.g. oestrogen and testosterone)
Card 3
Front
In what ways are the two types of hormone different?
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