Hormonal communication✅ Flashcards by Sid Coombs

what is a hormone

a chemical messenger that is transported in the blood

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what is a endocrine gland

an organ that secretes hormones

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how are hormones transported

in the blood to target cells

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how does steroid hormones affect target cells, give examples and the chemistry of the hormone

chemistry: lipid soluble

How does it affect target cells: diffuses through cell surface membrane, binds to a receptor (in cytoplasm or nucleus), promotes or inhibits transcription (of a particular gene)

examples: testosterone, oestrogen

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how does non-steriod hormones affect target cells, give examples and the chemistry of the hormone

chemistry: hydrophilic (eg polypeptides or glycoproteins)

How does it affect target cells: binds to a receptor on cell surface membrane, activates a second messenger (eg cyclic AMP), a cascade of intracellular reactions activates a transcription factor (for a particular gene)

examples: glucagon, insulin, adrenaline

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why can hormones be referred to as first messengers

hormones stimulate production of second messengers (eg cyclic AMP) within target cells

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which type of hormones do cortex and medulla produce

cortex: steroid
medulla: non-steroid

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give the hormones and functions released from cortex

Glucocorticoids: regulates carbohydrate metabolism

Mineralocorticoids: regulates salt and water concentration

Androgens (eg testosterone): various functions (eg regulation of muscle mass, development of sexual characteristics

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give the hormones and functions released from medulla

adrenaline: increases HR and blood glucose concentration (by stimulating glycogenolysis)

Noradrenaline: works in concert with adrenaline by increasing HR, widening airways, increasing blood pressure

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Define A: target cell, B: second messenger (3 marks)

A: the cell to which a hormone binds and in which it produces an effect

B: a substance that is activated by a hormone, and produces a response within a target cell

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outline similarities and differences between the modes of action of steroid and non-steroid hormones (4 marks)

Similarities: transported in blood, produces a response in target cells, binds to receptors, regulate transcription

Differences: steroid hormones diffuse through cell membranes
steroid hormones receptors are in the cytoplasm or nucleus/non-steroid hormones receptors are on cell surface membrane
non-steroid hormones activate second messengers/reaction cascades

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suggest how the adrenal glands respond to physiological changes in an athlete running a marathon (5 marks)

glucocorticoids secreted, which regulate carbohydrate metabolism
more (named respiratory substrates made available
mineralocorticoids (eg aldosterone) enable more water to be reabsorbed by kidneys
adrenaline can raise heart rate (during the race)
adrenaline promotes glycogenolysis/ raises blood glucose concentration
noradrenaline increases HR/widens airways

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why is the pancreas an organ that has both endo and exocrine functions

endocrine: hormone production
exocrine: enzyme production

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what is produces and where is it produced in exocrine gland of pancreas

amylase, protease, lipases: these digestive enzymes secreted from exocrine tissue and released into pancreatic duct, which leads to duodenum (upper small intestine)

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what is produces and where is it produced in endocrine gland of pancreas

insulin: beta cells in islets of langerhans

glucagon: alpha cells in islets of langerhans

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how can you identify between the 2 types of cells in the pancreas

islets of langerhans: large cluster of cells that is usually stained blue/lilac in photographs

Acini (exocrine cell clusters): small clusters of cells stained dark pink/purple

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Describe how cells in islets of langerhans can be distinguished from pancreatic acini cells (2 marks)

differential staining
islets of langerhans stain blue/lilac and acini stain dark pink/purple

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explain the differences between exocrine and endocrine glands, using pancreas as an example (4 marks)

endocrine glands secrete hormones into the blood
exocrine glands secrete other substances such as enzymes
the pancreas operates as both types of glands
it secretes digestive enzymes
it secretes the hormones insulin and glucagon

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suggest how transmembrane transport of ions and molecules across the cell membranes of pancreatic alpha and beta cells will differ (5 marks)

beta cells have K+ channels that close when glucose concentrations are high
beta cells have Ca2+ channels that open when glucose concentrations are high
beta cells transport insulin by exocytosis
beta cells have glucose receptors/ transporters
alpha cells transport glucagon by exocytosis
alpha cells have glucose receptors/ transporters
alpha cells secrete glucagon when little glucose is entering the cells

what is secreted, where does it have an effect, what effects are produced for when blood glucose needs to be increased

what is secreted: glucagon (from alpha cells)

where does it have an effect: binds to receptors on liver cells

what effects are produced: less glucose taken up by cells, more fatty acids used in respiration, glycogen converted to glucose (glycogenolysis), amino acids and fats converted to glucose (gluconeogenesis)

what is secreted, where does it have an effect, what effects are produced for when blood glucose needs to be decreased

what is secreted: insulin from beta cells

where does it have an effect: binds to receptors on liver and muscle cells

what effects are produced: more glucose absorbed by cells, glucose converted to fats, more glucose used in respiration, glucose converted to glycogen (glycogenesis), inhibits glucagon release

how is insulin secreted from beta cells

blood glucose concentration is high,
glucose enters a beta cell through a transporter protein in cell surface membrane,
glucose metabolised to produce ATP,
ATP binds to and closes K+ channels in cell surface membrane,
K+ build up in cell causes depolarisation,
Voltage gated Ca2+ channels open,
Ca2+ diffuse into cell and triggers secretory vesicles to release insulin from cell via exocytosis

is the lowering of blood glucose by glucagon an example of positive or negative feedback

negative feedback

describe the role of ATP in the release of insulin from beta cells in pancreas (2 marks)

ATP is produced when glucose enters the cell,
binds to K+ channels,
which causes depolarisation/opens Ca2+ channels

suggest why liver cells have specialised receptors for glucagon (3 marks)

Liver cells contain stores of glycogen, glucagon is secreted by pancreas in response to low blood glucose concentration, when glucagon binds to receptors on liver cells, glycogen within these cells is broken down into glucose molecules

what is insulin production, cause, genes vs environment, age at onset, speed of onset, usual treatments for Type 1 (insulin dependant diabetes)

insulin production: little or none cause: usually autoimmune response (beta cell destruction, which stops insulin production) genes vs environment: genetic age at onset: childhood speed of onset: quick usual treatments: insulin injections

what is insulin production, cause, genes vs environment, age at onset, speed of onset, usual treatments for Type 2 (insulin independent diabetes)

insulin production: often reduced cause: effector cells lose responsiveness to insulin genes vs environment: genetic and environmental (eg diet and activity levels) factors influence risk of developing disease age at onset: adulthood speed of onset: slow usual treatments: dietary control of carbohydrate intake

why is type 1 diabetes sometimes called insulin-dependant and type 2 insulin independent (2 marks)

type 1: because people with this form produce insufficient insulin type 2: because people with this form produce sufficient insulin but target cells are insensitive to hormone

suggest why the prevalence of type 2 diabetes is likely to have a greater impact on future population than the prevalence of type 1 diabetes (5 marks)

Type 1 diabetes is not affected by lifestyle to a great extent, the prevalence of type 2 diabetes is increasing, this is because of an aging population and an increase in obesity levels, the increasing prevalence will cost health care services more money to treat and manage in the future

what is transmitted, how quick is communication, for how long do effects last for endocrine system

what is transmitted: chemicals (hormones in blood) how quick is communication: relatively slow for how long do effects last for: long-lasting and can be permanent

what is transmitted, how quick is communication, for how long do effects last for nervous system

what is transmitted: electrical impulses along neurones how quick is communication: rapid for how long do effects last for: short-lived and temporary

what is increased during flight or fight, how does it benefit the mammal

HR: O2 and glucose are circulated faster Blood-glucose concentration: respiration rate in cells is raised Pupil dilation: improves vision

what is decreased during flight or fight, how does it benefit the mammal

blood flow to skin surface + digestion rate: more blood diverted to skeletal muscle, the brain and the heart concentration on small tasks: brain focuses on immediate threat

how does adrenaline produce its effects

binds to cell surface receptor activates adenylyl cyclase (am enzyme) adenylyl cyclase converts ATP to cyclic AMP (a second messenger) cAMP activates protein kinases, which activate other enzymes (known as cascade effect)

describe role of adenylyl cyclase in liver cells (2 marks)

activated by (the binding of) adrenaline, on liver cell surface membrane, converts ATP into cAMP

explain why fight or flight response is considered a coordinated response (ie controlled by both endocrine and nervous system) (2 marks)

both systems work together to produce responses, the sympathetic nervous system stimulates release of hormones

suggest why a mammal responding to danger may experience a loss of hearing (2 marks)

hearing non (usually) essential for responding to threats, blood flow diverted from auditory region of brain to other regions

which branch of nervous system is used, which nerve transmits impulse from medulla oblongata, what effect is produced in heart to increase HR

which branch of nervous system is used: sympathetic which nerve transmits impulse from medulla oblongata: accelerator what effect is produced in heart: increases rate at which SAN generates impulse

which branch of nervous system is used, which nerve transmits impulse from medulla oblongata, what effect is produced in heart to decrease HR

which branch of nervous system is used: parasympathetic which nerve transmits impulse from medulla oblongata: vagus nerve what effect is produced in heart: decreases rate at which SAN generates an impulse

where are they located, what do they detect, what response is produced for chemoreceptors

where are they located: aorta, carotid artery and medulla oblongata what do they detect: changes in pH what response is produced for: high Co2 concentration in blood=low pH, which triggers increase in HR. Low Co2=high pH, causes HR to decrease

where are they located, what do they detect, what response is produced for baroreceptors

where are they located: Aorta, carotid artery, vena cava what do they detect: changes in blood pressure what response is produced for: HR increased when blood pressure to low. HR decreased when blood pressure higher than normal

how does adrenaline and noradrenaline increases HR

by binding to cardiac cells and increasing frequency of impulses generated by SAN

describe the role of receptors in regulating HR (3 marks)

chemoreceptors detect changes in blood pH that reflects Co2 levels, pressure receptors detect changes in blood pressure, the receptors pass information to medulla oblongata, which initiates necessary response

explain why HR must be altered in response to increased physical activity (3 marks)

increased physical activity raises amount of energy required by muscles, muscles require more O2 and glucose for respiration, cardiac output must be increased to supply muscles with these molecules at necessary rate

imagine vagus nerve is cut, suggest what would happen if organisms blood pressure increases above its normal value (3 marks)

blood pressure would remain high, parasympathetic nervous system is no longer able to carry impulses/transmit to the heart, medulla oblongata cannot stimulate SAN to lower HR