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z - A Level Biology > 5.1.4: Hormonal communication > Flashcards

5.1.4: Hormonal communication Flashcards

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1
Q

Exocrine glands

A

Secrete molecules into a duct which transports them to their site of action
• Don’t secrete hormones
• e.g. salivary glands

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2
Q

Endocrine glands

A

Secrete hormones directly into the bloodstream, have no ducts.

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3
Q

How does a hormone know where to act?

A
  • Target cells have specific receptors that are complementary to the shape of the hormone.
  • Cells only respond to the hormones for which they have receptors.
  • Target cells are usually grouped together to form target tissues.
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4
Q

Types of hormones

A

• Protein, peptide, amino acid derivatives
⟶ e.g. adrenaline, insulin
⟶ Act on cell surface receptors triggering a cascade reaction mediated by second messengers
• Steroid hormones = lipid based

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5
Q

Adrenal glands are exocrine/endocrine glands?

A

Endocrine glands

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6
Q

Adrenal cortex

A

Outer region of adrenal gland

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7
Q

The adrenal cortex secretes

A

Hormones vital to life
• Glucocorticoids
• Mineralocorticoids
• Androgens

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8
Q

Adrenal medulla

A

Inner region of adrenal gland

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9
Q

The adrenal medulla secretes

A

Non-essential (for the day-to-day) hormones that help the body respond to stress
• Adrenaline
• Noradrenaline

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10
Q

Mineralocorticoids

A
  • controls blood pressure by maintaining salt and water concentrations of blood and bodily fluids
  • mediated by signals from kidney
  • e.g. aldosterone
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11
Q

Glucocorticoids

A
  • regulate metabolism by controlling how body converts fats, proteins, etc. to energy
  • regulate immune response
  • associated with responses to stress
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12
Q

Androgens

A
  • small amounts of male and female hormones

* effect is minor by important

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13
Q

Adrenaline

A
  • increases heart rate

* stimulates glycogenolysis in the liver

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14
Q

Noradrenaline

A
  • dilates bronchi

* stimulates narrowing of blood vessels to non-essential organs which raises blood pressure

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15
Q

Pancreas contains

A

both exocrine and endocrine tissues
• Exocrine tissue secretes digestive enzymes (pancreatic amylase) into pancreatic duct to duodenum
• Endocrine tissue secretes insulin, glucagon into blood

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16
Q

Islets of Langerhans

A
  • Endocrine tissue: produce and secrete hormones
  • Large spherical clusters made up of 𝜶 and 𝛽 cells
  • Lightly staining
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17
Q

Pancreatic acini

A

• Exocrine tissue: produce and secrete digestive enzymes
• Small, berry-like clusters
• Darkly staining
• 1 acinar cell –cluster of–> an acinus
many clusters = acini

18
Q

Normal blood glucose level

A

90mg per 100cm³ of blood

19
Q

Hyperglycaemia

A

Abnormally high blood glucose

⟶ Can impact osmotic balance leading to water being excreted

20
Q

Hypoglycaemia

A

Abnormally low blood glucose

⟶ Can mean insufficient glucose for respiration, leading to coma and death

21
Q

Insulin is produced by

A

𝛽 cells in the Islets of Langerhans in the pancreas

22
Q

Glucagon is produced by

A

𝜶 cells in the Islets of Langerhans in the pancreas

23
Q

Insulin (effect on body)

A
  • Inhibit the release of glucagon from 𝜶 cells
  • Increase respiratory rate of body
  • Stimulates glycogenesis in liver and muscle cells
  • Activates enzymes which convert glucose into fat
24
Q

Glucagon (effect on body)

A
  • Stimulates glycogenolysis in liver cells
  • Liver cells absorb less glucose from blood
  • Liver cells convert amino acids and glycerol into glucose (gluconeogenesis)
  • Fatty acids are used in respiration rather than glucose
25
Q

Which hormone responds to low blood glucose?

A

Glucagon

26
Q

Which hormone responds to high blood glucose?

A

Insulin

27
Q

Control of blood sugar (and homeostatic control generally) is an example of

A

negative feedback

28
Q

Negative feedback

A

feedback causes the corrective measures to be switched off when the system returns to ‘set point’

29
Q

Control of insulin secretion (resting state)

A
  • K+ channels in the plasma membrane of 𝛽 cells are open
  • K+ ions diffuse out of the cell
  • The potential difference across the membrane is -70mV
30
Q

Control of insulin secretion (increase in blood glucose)

A

• Glucose enters cell via glucose transporter
• Glucose is used in respiration –> mitochondria synthesise ATP
• ATP binds to ATP-sensitive K+ channels, causing them to close
• K+ ions can no longer diffuse out of the cell
The potential difference across the membrane reduces to -30mV as the membrane becomes depolarised
• Voltage gated Ca2+ ion channels open
• Ca2+ ions diffuse into the cell
• This causes secretory vesicles containing insulin to fuse with the plasma membrane and release insulin by exocytosis

31
Q

Cause of Type 1 diabetes

A

𝛽 cells in the Islets of Langerhans do not produce insulin

32
Q

Cause of Type 2 diabetes

A

𝛽 cells do not produce enough insulin
or
person’s body cells do not respond to insulin

33
Q

Original cause of Type 1 diabetes

A

Not known; maybe an autoimmune attack on 𝛽 cells

34
Q

Original cause of Type 2 diabetes

A
  • (generally) excess body weight, physical inactivity, overeating of refined carbohydrates
  • genetic components in some cases
35
Q

Typically age of onset Type 1 diabetes

A

Childhood (usually)

36
Q

Typically age of onset Type 2 diabetes

A

Traditionally 40+

37
Q

Treatment for Type 1 diabetes

A

Regular insulin injections

38
Q

Treatment for Type 2 diabetes

A
  • Regulation of carbohydrate intake
  • Increased exercise
  • Drugs to stimulate insulin production
39
Q

Current treatments for diabetes

A

Pancreas transplant

Insulin produced by genetically engineered bacteria

40
Q

Future treatments for diabetes

A

Potential use of stem cells to create person’s 𝛽 cells

z - A Level Biology (25 decks)

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