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Biology > 5.4 - Hormonal Communicaton > Flashcards

5.4 - Hormonal Communicaton Flashcards

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1
Q

(MA) What is the role of the adrenal medulla?

A

Makes and secretes adrenaline

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2
Q

(MA) What is the role of the adrenal cortex?

A

Produces steroid hormones e.g. glucocorticoids

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3
Q

(MA) How does adrenaline travel around the body and cause a response in the target cell?

A
  • adrenaline is known as the first messenger as it transmits the signal around the body in the blood
  • binds to receptors initiate change inside cell
  • binding causes a G-protein to activate adenyl cyclase converting ATP to cyclic AMP
  • cAMP is the second messenger as it transmits the signal inside the cell + causes more enzyme controlled reactions to take place + cause an effect on a cell
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4
Q

(MA) Describe the endocrine and exocrine glands of the pancreas.

A
  • endocrine glands release hormones directly into the blood
  • e.g. pancreas - alpha cells release glucagon + beta cells release insulin
  • exocrine glands release molecules into ducts
  • e.g. pancreas - releases digestive enzymes into pancreatic duct which leads to small intestine
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5
Q

(MA) What happens when blood glucose levels are too high?

A
  • beta cells detect rise in blood glucose level
  • rise inhibits glucagon secretion/production
  • stimulates production of insulin (by beta cells)
  • insulin secreted into blood
  • insulin binds to receptors on hepatocytes (+ muscle cells)
  • more glucose channels inserted into plasma membranes of target cells so more glucose enters hepatocytes (+ muscle cells)
  • glucose converted to glycogen (glycogenesis)
  • glucose converted to fats
  • more glucose used in more respiration in target cells
  • this results in less glucose in the blood
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6
Q

(MA) What happens when blood glucose levels are too low?

A
  • fall detected by alpha cells
  • fall inhibits insulin secretion/production
  • stimulates secretion/production of glucagon (by alpha cells)
  • into blood
  • binds to receptor on hepatocyte
  • stimulates hydrolysis of glycogen to glucose/glycogenolysis
  • gluconeogenesis/detail of gluconeogenesis
  • glucose leaves hepatocytes through glucose channels into the blood stream
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7
Q

(MA) How is insulin release controlled in a beta cell?

A
  • glucose enters beta cell through carrier proteins
  • glucose is phosphorylated in glycolysis + ATP is produced
  • ATP causes K ion channels to close
  • cell membrane becomes depolarised/more positive (as K+ can no longer leave cell)
  • causes v-g Ca ion channels to open + Ca ions to enter
  • Ca ions causes vesicles full of insulin to move towards the cell surface membrane, fuse with it + release the insulin
  • via exocytosis
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8
Q

Where are hormones produced?

A

endocrine glands

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9
Q

What is the adrenal medulla?

A

Centre of the gland, makes + secretes adrenaline and noradrenaline

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10
Q

What does adrenaline cause?

A
  • relax smooth muscles (widens airways, larger lumen, more O2 into lungs for aerobic respiration = energy)
  • increases stroke volume of heart
  • increase heart rate (more O2/glucose supplied for respiration)
  • vasoconstriction (lose less energy, redirecting blood flow for more supplied to respiring cells)
  • glycogen converted to glucose (more glucose availability for respiration)
  • dilates pupil (more light enters eye = better vision)
  • increase mental awareness (more alert + can respond quicker to danger)
  • inhibits action of gut (less energy wasted in digestion)
  • body hairs erect (hairs stand up, appear bigger)
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11
Q

What is a non steroid hormone?

A

Protein/amino acid based hormone (not lipid)

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12
Q

How can you recognise a steroid hormone from its name?

A

usually end in -(cortic)oid

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13
Q

What is the role of the adrenal cortex?

A

Uses cholesterol to produce steroid hormones

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14
Q

What are the 3 regions of the adrenal cortex and what are their functions?

A
  • Zona Glomerulosa (nearest outside): secretes mineralocorticoids to help control Na+K in blood + blood pressure
  • Zona Fasciculata: secretes glucocorticoids to help control metabolism of carbs, fats + proteins in liver
  • Zona Reticularis (nearest medulla): secretes precursors to the sex hormones
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15
Q

How do steroid hormones cause a response in a cell?

A
  • enter cells by dissolving in cell surface membrane
  • bind w a receptor in cytoplasm, receptor-hormone complex enters nucleus, binds to another receptor on chromosome
  • causes mRNA to be made which then produces proteins
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16
Q

Describe the endocrine function of the pancreas.

A
  • majority of cells produce digestive enzymes (pancreatic juice)
  • cells form groups (acini), secrete enzymes into tubules which lead to pancreatic duct which takes them to small intestine
17
Q

What is in the pancreatic juice (involved in the exocrine function of the liver)?

A
  • amylase
  • trypsinogen
  • lipase
  • sodium hydrogencarbonate
18
Q

Describe the endocrine function of the pancreas.

A
  • islets of Langerhans contain alpha + beta cells
  • they detect change in blood glucose levels
  • alpha cells: produce + secrete glucagon hormone
  • beta cells: produce + secrete insulin hormone
  • hormones secreted directly into closely associated capillaries
19
Q

What is the normal blood glucose levels?

A

90mg/100cm^3

20
Q

How would you identify the parts of the pancreas on a micrograph?

A
  • most cells = exocrine
  • acini: groups of cells surrounding smallest hollow tubes
  • tubules leading to pancreatic duct: slightly larger (circularish) hollow tubes
  • islets of Langerhans: patches (circularish) w a different staining
21
Q

Describe the process of gluconeogenesis.

A

-amino acids have amino group removed
-creates pyruvate (used as carbon skeleton)
-in presence of triode phosphate enzyme
-controls condensation reaction in glucose
amino acid –> pyruvate –(triode phosphate)–> glucose

22
Q

What are the benefits of storing glucose as glycogen?

A
  • insoluble: doesn’t affect water potential of cell
  • branched: lots of endings for enzymes to attach to
  • compact so more energy stored in less space
  • unreactive
  • cant diffuse out of cell
23
Q

(MA) What does the term diabetes mellitus mean?

A

Can’t control blood glucose levels

24
Q

(MA) Describe type 1 diabetes.

A
  • insulin dependent diabetes
  • beta cells have been damaged by body’s own immune system (autoimmune response)
  • can’t produce sufficient glucose
  • can’t store glucose as glycogen, excess glucose in blood, hyperglycaemia
  • when blood glucose falls, no/little glycogen stored converted to glucose, causing hypoglycaemia
  • can be inherited
  • treated with injections of insulin into subcutaneous fat
25
Q

(MA) Describe type 2 diabetes.

A
  • non insulin dependent diabetes
  • receptors on target cells for insulin become unresponsive to insulin (still produce insulin)
  • treatment: diet low in carbs/sugars, regular exercise
  • risk factors…
26
Q

(MA) What are the risk factors that increase one’s chance of getting type 2 diabetes?

A
  • increasing age
  • obesity
  • more common in males + some ethnic groups
  • high blood pressure
  • excessive alcohol intake
27
Q

How do you treat type 1 diabetes?

A
  • monitor blood glucose levels + insulin injections administered
  • insulin pump: permanently pumps insulin at a steady rate
28
Q

What is meant by the term hyperglycaemia and what can it cause in the long term?

A

Blood glucose too high, can lead to organ damage (long term)

29
Q

What is meant by the term hypoglycaemia and what can it cause in the long term?

A

Blood glucose too low, not enough glucose to cells, especially brain. Causes tiredness + irritability, brain damage, seizures + death

30
Q

What are the advantages of obtaining insulin from genetically engineered bacteria?

A
  • if insulin wasn’t obtained from bacteria, would be obtained from animals (pigs)
  • ethical issues i.e. vegetarian, religious
  • lots can be made as bacteria reproduces quickly
  • bacterial sources slightly more effective as produces human insulin
  • cheaper from bacteria as lots made in one culture
  • less chance of infection
  • avoids side effects, allergies, immune response

Biology (20 decks)

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