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biology > C14 - Hormonal communication > Flashcards

C14 - Hormonal communication Flashcards

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1
Q

What is the endocrine system?

A

Group of glands that secrete hormones

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2
Q

What are endocrine glands?

A

Group of specialised cells which secrete hormones

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3
Q

How does the location of the pituitary gland ensure the nervous and hormonal systems are coordinated?

A

Close proximity to hypothalamus

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4
Q

List the major endocrine glands.

A

-Pituitary gland
-Pineal gland
-Thyroid gland
-Thymus
-Adrenal glands
-Pancreas
-Ovary
-Testis

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5
Q

Diagram of major endocrine glands in the body.

A
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6
Q

Describe the function of the pituitary gland.

A

Produces…
-Growth hormone: controls growth of bones and muscles
-Anti-diuretic hormone: increases reabsorption of water in kidneys
-Gonadotrophins: control development of ovaries and testes

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7
Q

Describe the function of the pineal gland.

A

Produces
-Melatonin: affects reproductive development and daily cycles

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8
Q

Describe the function of the thyroid gland.

A

Produces
-Thyroxine: controls rate of metabolism, rate glucose is used up in respiration, promotes growth

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9
Q

Describe the function of the ovary.

A

Produces:
-Oestrogen: controls ovulation and secondary sexual characteristics
-Progesterone: prepares uterus lining for receiving an embryo

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10
Q

Describe the function of the thymus.

A

Produces
-Thymosin: promotes production and maturation of wbcs

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11
Q

Describe the function of the pancreas.

A

Produces…
-Insulin: coverts glucose into glycogen in the liver
-Glucagon: converts glycogen into glucose in the liver

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12
Q

Describe the function of the adrenal gland.

A

Produces
-Adrenaline: inc heart rate, inc breathing rate, raises blood sugar level

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13
Q

Describe the function of the testis.

A

Produces
-Testosterone: controls sperm production and secondary sexual characteristics

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14
Q

What are hormones?

A

Chemical messengers which travel around the body in the blood 1stream

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15
Q

How are hormones detected?

A

-Hormones diffuse out of blood
-Bind to target cells (/tissue)
-Stimulate target cells to produce a response

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16
Q

How are hormones transported?

A

Secreted into blood, transported in the blood plasma

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17
Q

What are target cells?

A

Specific cells which hormones act on

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18
Q

What are the 2 types of hormones?

A

-Steroid hormones
-Non-steroid hormones

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19
Q

What are steroid hormones?

A

-Lipid soluble hormones
-Pass through (lipid) cell membrane
-Bind to steroid hormone receptors
-Form hormone-receptor complex
-Act as a transcription factor which facilitate or inhibit transcription of a gene (polypeptide)

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20
Q

What are non-steroid hormones?

A

-Hydrophilic
-Can’t pass through cell membrane directly
-Bind to specific receptors on cell surface membrane of target cell
-Triggers cascade reaction mediated by chemicals (second messengers)

eg. adrenaline

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21
Q

Hormonal response vs neuronal response (table)

A
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22
Q

What are the adrenal glands?

A

Two small glands that are located on top of the kidneys which are made up of the adrenal cortex, the adrenal medulla and surrounded by a capsule

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23
Q

What are the two distinct parts of the adrenal glands?

A

-Adrenal cortex: outer region, produces essential hormones (cortisol and aldosterone)
-Adrenal medulla: inner region, produces non-essential hormones (adrenaline)

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24
Q

Diagram of adrenal glands

A
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25
Q

How are hormones produced by the adrenal cortex controlled?

A

By hormones released from the pituitary gland

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26
Q

What are the 3 main types of hormones released by the adrenal cortex?

A

-Glucocorticoids
-Mineralocorticoids
-Androgens

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27
Q

Give an example of a glucocorticoid and it’s function.

A

-Cortisol
-Helps regulate metabolism by controlling how the body converts fats, proteins and carbs into energy
-Regulates blood pressure and cardiovascular function in response to stress

-Corticosterone
-Works with cortisol to regulate immune response and suppress inflammatory reactions

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28
Q

What is the release of glucocorticoids controlled by?

A

Hypothalamus

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29
Q

Give an example of a mineralocorticoid and it’s function

A

-Aldosterone
-Helps control blood pressure by maintaining salt and water conc in blood and body fluids

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30
Q

What triggers mineralocorticoids to be released?

A

Signals triggered by kidney

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31
Q

Give an example of androgens and their function

A

-Small amounts of male and female sex hormones
-Impact is relatively small in comparison to larger amounts of other hormones
-Especially important in women after menopause

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32
Q

What are the 2 hormones released by the adrenal medulla?

A

-Adrenaline
-Noradrenaline

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33
Q

When are hormone released from the adrenal medulla?

A

When sympathetic nervous system is stimulated

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34
Q

What is the function of adrenaline?

A

Increases heart rate
Sends blood quickly to muscles and brain
increases blood glucose levels rapidly by converting glycogen into glucose in the liver

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35
Q

What is the function of noradrenaline

A

Works with adrenaline in response to stress
Widens pupils
Widens air passages in the lungs
Narrows blood vessels in non-essential organs
increasing heart rate

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36
Q

What is the pancreas?

A

Found in upper abdomen, behind the stomach. Controls blood glucose concentration and plays a role in digestion.
Glandular organ - role to produce and secret hormones and digestive enzymes

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37
Q

What are the two main functions of the pancreas in the body

A

-Exocrine gland: produce enzymes and release them via a duct into the duodenum
-Endocrine glands - to produce hormones and release them into the blood

38
Q

Diagram of position of pancreas in the body

A
39
Q

What tissue is the pancreas mostly made up of? What is that tissue responsible for?

A

Exocrine glandular tissue

Responsible for producing digestive enzymes and pancreatic juice (alkaline fluid)
Enzymes and juice are secreted into ducts which lead to pancreatic duct
Released into duodenum

40
Q

What are the 3 important digestive enzymes the pancreas produces? What do they breakdown?

A

-Amylase: Break down starch into simple sugars (pancreatic amylase)
-Protease: break down proteins into amino acids (trypsin)
-Lipase: break down lipids inti fatty acids and glycerol (pancreatic lipase)

41
Q

What are the 3 important digestive enzymes the pancreas produces? What do they breakdown?

A

-Amylase: Break down starch into simple sugars (pancreatic amylase)
-Protease: break down proteins into amino acids (trypsin)
-Lipase: break down lipids inti fatty acids and glycerol (pancreatic lipase)

42
Q

Describe the role of the pancreas as on endocrine gland

A

Produces insulin and glucagon which control blood glucose concentration

43
Q

What are the small regions of endocrine tissue within exocrine tissue in the pancreas called?

A

Islets of Langerhans

44
Q

What is the function of islets of Langerhans

A

Specialised cells in the pancreas responsible for producing insulin and glucagon and secreting them into the blood stream

45
Q

Table with the main difference between endocrine and exocrine tissue in the pancreas when viewed under a microscope

A
46
Q

What are the two types of cells within islets of Langerhans

A

-Alpha cells: produce and secrete glucagon
-Beta cells: produce and secrete insulin

47
Q

What are the physical differences between alpha and beta cells in the islet of langerhan

A

Alpha cells are larger and numerous than beta cells within an islet

48
Q

What are the physical differences between alpha and beta cells in the islet of langerhan

A

Alpha cells are larger and numerous than beta cells within an islet

49
Q

What is the normal concentration of blood glucose?

A

90mg/100cm^3

50
Q

What factors can cause an increase in blood glucose?

A

Diet
-Carb-rich foods and sweet foods inc blood glucose conc
-Carbs broken down into glucose and absorbed into blood stream

Glycogenolysis
-Glycogen stored in liver and muscle cells and broken down into glucose
-Released into bloodstream increasing blood glucose conc

Gluconeogenesis
-Production of glucose from non-carb sources
-Glucose released into bloodstream increasing blood glucose conc

51
Q

What factors can decrease blood glucose conc?

A

Respiration
-Some glucose in blood is used by cells to release energy, req for normal bodily functions
-During exercise, more glucose used as more energy needed for muscles to contract
-Decreases blood sugar concentration

Glycogenesis
-Production of glycogen, from glucose stored in the liver when blood glucose conc is too high
-Reduced blood glucose concentration

52
Q

Where is insulin produced

A

Beta cells of the islets of Langerhans

53
Q

What is the role of insulin in blood glucose concentration

A

-Blood glucose conc is too high
-Beta cells of islets of Langerhan detect this rise
-Respond by secreting insulin

54
Q

What is the role of insulin in blood glucose concentration

A

-Blood glucose conc is too high
-Beta cells of islets of Langerhan detect this rise
-Respond by secreting insulin

55
Q

Where are insulin receptors found?

A

Almost all body cells have insulin receptors on their cell surface membrane (not rbc)

56
Q

How does insulin enter a cell?

A

-Binds to glycoprotein receptor on cell surface membrane
-Causes change in tertiary structure of the glucose transport protein channel
-Causes channels to open allowing more glucose to enter the cell
-Activates enzymes to convert glucose into glycogen and fat

57
Q

How does insulin lower blood glucose

A

-Increases rate of absorption of glucose by cells
-Increases respiratory rate of cells, increases their need for glucose so higher uptake from blood
-Increases rate of glycogenesis
-Increases rate of glucose to fat conversion
-Inhibits release of glucagon from alpha cells of islets of Langerhans

58
Q

What produces glucagon?

A

Alpha cells of islets of langerhans

59
Q

What is the role of glucagon in blood glucose concentration

A

If blood glucose is low, alpha cells detect decrease and secrete glucagon

60
Q

How does glucagon raise the blood glucose concentration?

A

Glycogenolysis
-Liver breaks down glycogen into glucose
-Releases into bloodstream

Reducing glucose absorbed by liver cells

Increasing gluconeogenesis
-Increasing conversion of amino acids and glycerol into glucose in liver

61
Q

How are insulin and glucagon regulated?

A

Negative feedback

62
Q

What is the relationship between insulin and glucagon?

A

Antagonistic hormones

63
Q

Diagram of blood glucose concentration regulation

A
64
Q

How is insulin secretion controlled?

A

Beta cells detect when blood glucose conc rises above set level

1) At normal blood glucose conc, K channels in plasma membrane of beta cells are open (potential of -70mV)
2) When blood glucose conc rises, glucose enters cell be glucose transporter
3) Glucose metabolised inside mitochondria, producing ATP
4) ATP binds to K channels (ATP-sensitive K channels), closing them
5) K+ can no longer diffuse out cell so potential decreases to -30mV, depolarisation occurs
6) Depolarisation causes voltage-gated calcium channels to open
7) Ca2+ ions enter cell and cause secretory vesicles to release insulin through exocytosis

65
Q

What is diabetes mellitus?

A

Medical condition which affects a person’s ability to control their blood glucose concentration

66
Q

What causes diabetes mellitus?

A
67
Q

What are common symptoms of diabetes?

A

-High blood glucose conc
-Glucose present in urine
-Excessive need to urinate (polyuria)
-Excessive thirst (polydipsia)
-Constant hunger
-Weight loss
-Blurred vision
-Tiredness

68
Q

What are the two types of diabetes?

A

-Type 1 diabetes
-Type 2 diabetes

69
Q

Describe type 1 diabetes?

A

-Beta cells in islets of Langerhans don’t to produce insulin
-Cause is unknown so can’t be prevented or cured
-Auto-immune disease where body’s immune system attacks beta cells
-Treatments available (insulin)

70
Q

Describe type 2 diabetes?

A

-Cannot effectively use insulin and control their blood sugar levels
-EITHER because beta cells do not produce enough OR because body cells don’t respond properly to insulin
-Often, because glycoprotein insulin receptor on cell membrane doesn’t work
-Cells lose responsiveness to insulin and do not take up enough glucose
-Usually a result of excess body weight, physical inactivity, excessive overeating of refined carbs

71
Q

Can diabetes be cured?

A

No, it can only be controlled

72
Q

How is type 1 diabetes treated?

A

-Regular injections of insulin (insulin-dependent)
-Regularly test blood glucose conc (prick finger, drop of blood analysed by machine)
-Use calculated blood glucose conc to decide dose of insulin
-Insulin increases glucose absorbed by cells and causes glycogenesis to occur

73
Q

What is hypoglycaemia? Relative amount of insulin injected?

A

Very low blood glucose concentrations
-Can lead to unconsciousness

Too high

74
Q

What is hyperglycaemia? Relative amount of insulin injected?

A

Very high blood sugar concentrations
-Unconsciousness/death

Too low

75
Q

How is type 2 diabetes treated?

A

-Regulate carb intake through their diet and match with their exercise levels
-Overweight people encouraged to lose weight
-Drugs to stimulate insulin production, slow down rate at which body absorbs glucose from intestine, insulin injections

76
Q

Graph of blood glucose and insulin levels in a person with type 1 diabetes and without after swallowing glucose tablet

A
77
Q

How was insulin initially obtained?

A

From pancreas of cows and pigs that had been slaughtered for food
HOWEVER, it was uneconomical and could cause allergic reactions due to slight difference from human insulin

78
Q

How is insulin made now? Benefits?

A

Made by genetically modified bacteria
-Human insulin produced in pure form reducing likelihood of allergic reaction
-Insulin produced in higher quantities
-Cheaper to produce
-Ethical/religious concerns overcome

79
Q

What is the success of pancreas transplants in type 1 diabetes patients? Problems?

A

80% patients have no symptoms of diabetes after a year and stop taking insulin

Demand for transplantable pancreas outweighs supply
Immunosuppressant drugs leave patient susceptible to infection

80
Q

What is the success of injecting patients with pancreatic beta cells? Problems?

A

> 8% are successful

Immunosuppressant drugs used to prevent rejection increases metabolic demand on insulin-producing cells, exhausting their capacity to produce insulin

81
Q

How can stem cells be used in diabetes treatment?

A

-Type 1 diabetes results from loss of single cell type
-Evidence that small number of islet cells can restore insulin production
-Stem cell therapy
-Requires totipotent embryonic stem cells to differentiate into beta cells

82
Q

Advantages of potential stem cell therapy

A

-Donor availability wouldn’t be an issue as stem cells provide unlimited source of beta cells
-Reduced likelihood of rejection (somatic cell nuclear transfer?)
-People no longer have to inject themselves with insulin

83
Q

Disadvantages of potential stem cell therapy?

A

Limited ability to control growth and differentiation of stem cell, so potentially could induce formation of tumours
Ethical/religious beliefs against use of embryonic stem cells

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