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OCR Biology A Level > 5.1.4 Hormonal Communication > Flashcards

5.1.4 Hormonal Communication Flashcards

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1
Q

Define cell signalling

A

Communication between cells that allows cells to work together to trigger a response or a reaction inside the cell

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2
Q

Compare the nervous system and endocrine system’s response

A

Nervous System
- fast response
- short lived

Endocrine System
- generally a slower response
- generally a longer lasting effect

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3
Q

Give key aspects of hormones

A
  • chemicals made in endocrine cells
  • may be steroids, proteins, glycoproteins, polypeptides, amines or tryosine derivatives
  • made from stimulated gland
  • reach target organ via blood
  • can be made + stored for rapid release
  • can have an effect on different target organs
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4
Q

Name glands and the hormones they secrete

A

Pituitary gland: ADH, FSH, LH, Growth Hormone
Thyroid gland: Thyroxine
Thymus: Thymosin
Adrenal gland: Adrenaline
Pancreas: Insulin, Glucagon
Ovaries: Oestrogen, Progesterone
Testes: Testosterone

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5
Q

Define hormone

A

Molecules secreted by endocrine glands into the blood, communicating with specific target tissues

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6
Q

Define target tissue

A

A group of cells that have specific complementary receptors on their plasma membranes to a specific hormone

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7
Q

Define endocrine gland

A

Ductless gland that secretes hormones directly into the blood

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8
Q

Define exocrine gland

A

Glands that have ducts and secrete molecules into the duct to transport it to where it is used

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9
Q

Explain hormonal communication

A
  1. Hormones are secreted into the blood
  2. They’re transported in the blood
  3. Detected by target cells or tissues by receptors
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10
Q

Explain key aspects of steroid based hormones

A
  • non polar
  • lipid soluble
  • can pass through phospholipid bi-layer + plasma membrane
  • receptors inside the cell
  • form hormone receptor complex + affect gene expression
  • e.g. testosterone, oestrogen, progesterone
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11
Q

Explain key aspects of non-steroid based humans

A
  • hydrophilic
  • not lipid soluble
  • cannot pass through phospholipid bi-layer + plasma membrane
  • bind to receptors on the outside of plasma membrane
  • cause changes in the cell by the activation of enzymes + production of 2nd messengers
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12
Q

What does the pancreas do?

A

Exocrine
- secretes pH8 juice + digetive enzymes (amylase/lipase) into ducts
- Pancreatic secretions go into dudoenum

Endocrine
- Islets of Langerhans monitor blood glucose concentration
- beta cells secrete insulin
- alpha cells secrete glucagon
- directly into blood

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13
Q

Explain the structure of Islets of Langerhans

A
  • lightly stained and form large spherical clusters
  • secrete hormones direclty into the blood stream
  • Beta cells - stained blue, secrete insulin
  • Alpha cells - stained pink, secretes glucagon
  • pancreatic acini - secrete digestive enzymes
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14
Q

What is glycogenesis, glycogenolysis and gluconeogenesis

A
  • gluconeogenesis = making glucose from other molecules in the liver
  • glycogenesis = making glycogen from glucose in the liver
  • glycogenolysis = hydrolysing glycogen into glucose in the liver
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15
Q

Explain how insulin causes glycogenesis

A
  1. Insulin binds to specific protein receptor
  2. Chemical released
  3. Causes more glucose transport proteins to be inserted into the cell surface membranes of liver and muscle cells
  4. Increases permeability of liver + muscle cells to glucose by allowing more facilitated diffusion of glucose in
  5. Insulin activates enzyme to convert glucose into glycogen
  6. Steep glucose diffusion gradient maintained
  7. More respiration of glucose to produce ATP
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16
Q

Explain how blood glucose level is decreased

A
  1. B cell receptors in pancreas detect a change
  2. B cells in pancreas secrete insulin
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17
Q

Explain how the release of glucagon causes glycogenolysis

A
  1. Glucagon binds to receptors on liver cells
  2. Activates enzymes that hydrolyse glycogen into glucose
  3. Or convert fatty acids or amino acids into glucose
18
Q

Explain the negative feedback loop when blood glucose rises

A
  1. B cell receptors in pancreas detect a change
  2. B cells in pancreas secrete insulin
    3.Insulin
    - increases glucose uptake by muscles
    - increases glucose uptake by liver
    - glycogenesis
    - reduces insulin secretion and glucagon secretion
  3. Blood glucose levels return to a set point
19
Q

Explain the negative feedback loop when blood glucose falls

A
  1. A cell receptors in pancreas detect a change
  2. A cells in pancreas secrete glucagon
  3. Glucagon
    - increases glycogen hydrolysis in liver
    - stimulates formation of gluose from amino acids
    - reduces insulin secretion + glucagon secretion
  4. Blood glucose levels return to a set point
20
Q

Explain how beta cells ensure they don’t release insulin when it isn’t needed

A

1.K+ ion channels open so K+ ions diffuse out
2. -70mw potential difference maintained
3. Outside of cell is more positive than the inside
4. Vesicles containing insulin don’t move towards the cell surface membrane
5. Ca2+ ion channels closed - no Ca2+ ions can enter

21
Q

Explain how beta cells release insulin at the right time

A
  1. K+ channels open so K+ ions diffuse out maintaining potential difference
  2. Glucose enters B cell via transport protein when concentration is high
  3. Glucose is phosphorylated through glycolysis to produce ATP
  4. ATP closes K+ ion channcels causing depolarisation as K+ ions build in the cell
  5. Change in K+ ion cocentration changes potential difference to -30mw which opens Ca2+ ion channels - Ca2+ ions diffuse in
  6. Ca2+ ions fill cell, causing insulin filled vesicles to move and fuse with cell surface membrane
  7. Insulin released into blood by exocytosis
22
Q

Give key aspects of Type 1 diabetes

A
  • rapid onset
  • occurs at young age
  • autoimmune reponse - immune system attacks B cells
  • little/no insulin secreted
  • often genetic/hereditary
  • can be caused by a virus
23
Q

Give key aspects of Type 2 diabetes

A
  • slow onset
  • occurs at older age
  • glycoprotein receptors on liver + muscle cells no longer respond to insulin - so don’t take up enough glucose from the blood
  • insulin levels may decline as well
24
Q

What is type 2 diabetes linked to?

A
  • obesity
  • high sugar diet
  • Asian/African origin
  • family history
  • lack of excersise
  • males
  • high blood sugar
  • excessive alcohol
25
Q

How is type 1 diabetes treated?

A
  • insulin injections
  • constant blood glucose measurements
26
Q

How is type 2 diabetes treated?

A
  • low carbohydrate/sugar diet
  • drugs that stimulate insulin production or slow down glucose absorbance rate from intestine
  • sometimes insulin injections
27
Q

Explain symptoms of type 2 diabetes?

A
  • tiredness due to lack of glucose taken into cells - less ATP
  • excess urine because water potential of blood very low so more water moves in
28
Q

List advantages of GM bacteria insulin

A
  • exact cop of human insulin
  • less likely to cause an allergic reaction
  • produced in much higher quantities
  • dependable supply of insulin
  • cheaper production costs
  • no animals killed
  • less chance of disease
  • no religious objections
  • more rapid response to glucose levels
29
Q

How could type 1 diabetes be treated in the future and what are its advantages?

A

Treated with stem cells
- permanent
- no repeated treatments
- cure for the disease

30
Q

What are the parts of the adrenal glands?

A

Adrenal cortex + adrenal medulla

31
Q

What hormones are released by the adrenal medulla?

A
  • adrenaline
  • noradrenaline
32
Q

What hormones are released by the adrenal cortex?

A
  • cortisol
  • corticosterone
  • aldosterone
  • androgens
33
Q

Give key details about adrenaline

A
  • amino acid derivative
  • hydrophillic
  • can’t pass through the phospholipid bi-layer
  • binds to plasma membrane receptors (outside)
  • increases heart rate
  • relaxes bronchioles muscles
  • increases heart stroke volume
  • vasoconstriction
  • converts glycogen to glucose
  • dilates pupils
  • inhibits gut action - more blood flow to muscles
34
Q

What hormones are released by the adrenal medulla?

A
  • amino acid derivative
  • works with adrenaline in response to stress
35
Q

Give key details about the adrenal cortex

A
  • produces steroid hormones
  • controlled by hormone released from pituitary gland
36
Q

Give key details on mineralocorticoids (Aldosterone)

A
  • enters cells causing control of NA+ & K+ in the blood
  • helps control blood pressure
37
Q

Give key details on glucocorticoids (Cortisol)

A
  • controls metabolism of proteins + carbohydrates in liver
  • helps regulate blood pressure + cardiovascular function when stressed
38
Q

Give key details on Corticosterone

A

Works with cortisol to regulate immune response + suppress inflammatory reactions

39
Q

What is the difference between a first and second messenger?

A

First messenger
The hormone that transmits a signal around the body e.g. adrenaline

The Second Messenger
The chemical that transmits the signal inside the cell e.g. AMP made inside the cell when adrenaline binds

40
Q

Explain the secondary messenger model works with adrenaline

A
  1. Adrenaline binds to its complementary + specific shaped receptor
  2. Receptor changes shape
  3. Activates G protein
  4. The G protein activates adenyl cyclase
  5. Adenyl cyclase converts ATP into cAMP
  6. Activates kinase enzyme, which activates other enzymes

OCR Biology A Level (21 decks)

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