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Biology > 5.4 - Hormonal communication > Flashcards

5.4 - Hormonal communication Flashcards

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1
Q

What are hormones?

A

Chemical messengers, made in the endocrine glands that travel in the blood

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2
Q

What are all the major glands in the body and where are they located?

A
  • Hypothalamus and pituitary - In the head
  • Thyroid - In the neck
  • Pancreas - In the stomach
  • Adrenal glands - Above the kidney
  • Ovary - In the female reproductive system
  • Testes - In the male reproductive system
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3
Q

What are the functions of each gland?

A
  • Thyroid - Releases thyroxine & controls metabolic rate
  • Pancreas - Endocrine + Exocrine functions
  • Adrenal glands - Produce adrenaline
  • Ovary - Produces Oestrogen and progesterone
  • Testes - Produce testosterone
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4
Q

How do steroid (lipid soluble) hormones work?

A

Dissolve through the phospholipid bilayer, meaning they don’t bind to the receptors on the cell surface but instead they bind to receptors inside the cell

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5
Q

What are some examples of steroid (lipid soluble) hormones?

A

Oestrogen and testosterone

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6
Q

How do non-steroid (protein based) hormones work?

A

Non-steroid hormones work via the second messenger pathway:

  • The hormone binds to the G protein coupled-receptor on the surface of the cell membrane
  • This causes a conformational change in shape of the receptor
  • This, then causes another change in shape of the G protein
  • The G protein is now activated so it slides along the inside of the cell membrane
  • The G protein activates Adenyl cyclase
  • Adenyl cyclase converts ATP inside the cell into Cyclic AMP which is the second messenger
  • The cAMP can now work to open channel proteins to open or activate other enzymes
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7
Q

What are Endocrine and Exocrine functions?

A

Endocrine- Producing hormones into the blood
Exocrine- Produces enzymes or products that are put into ducts (Mammary glands that produce milk into ducts, Digestive glands in the pancreas that produce digestive juices that are put into ducts or sweat glands that produce sweat which is sent into sweat ducts which empties sweat onto the skin)

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8
Q

What is the structure of the pancreas?

A
  • Acinus cells (Exocrine) on the outside
  • Duct in the middle of the acinus cells that carries the products (The enzymes produced) to eventually go to the digestive system
  • Islet of Langerhans (Endocrine) in the middle
  • Alpha and Beta cells in the Islet of Langerhans
  • Capillaries in the Islet of Langerhans that carry the hormones away in the blood
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9
Q

What are the products of the parts of the pancreas?

A
  • Acinus cells (Exocrine) - Pancreatic juice full of enzymes such as: Amylase, lipase and protease released into the upper part of the small intestine via a duct
  • Alpha cells (Endocrine) - Make glucagon [Released when there is a low glucose concentration in the blood]
  • Beta cells (Endocrine) - Make insulin [Released when there is a high glucose concentration in the blood]
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10
Q

What type of feedback controls the blood glucose levels?

A

Negative feedback

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11
Q

What is the normal blood glucose levels?

A

90mg per 100ml

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12
Q

What happens if the blood glucose levels are too high?

A
  • Blood glucose level increases from eating
  • Beta cells detect the change
  • Beta cells release insulin which travels in the blood
  • Body cells take in glucose & liver and muscle cells are signalled to convert glucose into glycogen for storage of energy
  • This lowers glucose levels back to normal (90mg)
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13
Q

What happens if the blood glucose levels are too low?

A

-Blood glucose level decreases from lack of eating or from prolonged exercise
-Alpha cells detect the change
[Beta cells will stop producing insulin]
-Alpha cells releases glucagon
-The glucagon breaks down glycogen into glucose in the liver and muscle cells
-Gluconeogenesis occurs forming new glucose molecules from lipids and sometimes proteins under extreme cases (Starvation)
-This increases glucose levels back to normal (90mg)

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14
Q

What is the structure and the function of glycogen?

A

-Polysaccharide
-Alpha 1-4 glycosidic bonds
-Alpha 1-6 glycosidic bonds
-Branched structure, enzyme can easily hydrolyse it into glucose
(Glycogenolysis = the hydrolysis process of glycogen to glucose)
-Monomer = Alpha glucose
-Relatively insoluble, less soluble than glucose itself so it means it is a good storage molecule

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15
Q

What is gluconeogenesis?

A

Making new glucose from lipids and sometimes proteins under extreme cases (Starvation)

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16
Q

What is glycogenolysis?

A

The hydrolysis process of glycogen to glucose

17
Q

What is the process of releasing insulin in beta cells?

A
  • Glucose is taken in by the beta cells (more is taken in if blood glucose levels are high)
  • The glucose is metabolised (Broken down) and more ATP is made inside the beta cells
  • ATP binds to the potassium channels which causes them to close (Depolarisation)
  • The depolarisation leads to an opening of the voltage gated calcium ion channels
  • Calcium floods into the cell
  • The influx in calcium causes insulin vesicles to fuse with the outside of the cell membrane releasing insulin via exocytosis
  • The process is fast as the insulin is already packaged in vesicles ready to fuse with the membrane and be released once there is an influx in calcium ions
  • This is important because it means the body can respond quickly to a change in blood glucose levels
18
Q

How would the cell be described if the potassium channels were open?

A
  • The cell is polarised as the inside is more negative

- This is because more positive ions are able to flow out of the cell so the inside becomes more negative.

19
Q

What is the process of Insulin action? (In liver & Muscle cells)

A
  • Insulin binds to the receptors on the surface of the cell membrane
  • This causes a conformational change in the shape of the receptor
  • This then activates the enzyme tyrosine kinase which also changes the shape of it
  • The tyrosine kinase can now work to activate other enzymes this is called phosphorylation of enzymes
  • The active enzymes can cause vesicles containing glucose transport proteins to move
  • The vesicles insert into the membrane increasing the number of glucose transport proteins
  • This lowers blood glucose level as it allows more glucose to be taken into the cell
  • The glucose in the cell can be used in respiration to make ATP or converted into glycogen/fat
20
Q

Why are glucose transport proteins needed with facilitated diffusion in order for glucose to go through the membrane?

A

Glucose is large and hydrophilic meaning that it can’t cross the membrane via simple diffusion and it must rely on facilitated diffusion with a transport protein

21
Q

What happens with someone who has diabetes?

A

(type 1)
-No insulin is released
-Beta cells are destroyed
-Autoimmune disease (The persons immune cells attack and destroy their beta cells)
-Developed in childhood or teenage years
-Blood glucose increases constantly until insulin is injected
-Genetic component, the person must have genes that make them susceptible but there may also be an environmental trigger (E.g: A virus that attacks the immune system and causes it to target the beta cells)
-Insulin dependent
(type 2)
-Treatment is insulin injections/pump
-Insulin is released
-Cells are less sensitive (resistant to insulin)
-Cells become resistant to insulin due to the continuous insulin signal from a sugary diet over the persons life
-Blood glucose increases to a point but falls slowly due to the low levels of insulin
-Treatment is mostly a guidance towards a better diet and exercise for the person

22
Q

Where are the adrenal glands located and what is their structure?

A

-Located on top of the kidneys (Ad-Renal)
-Triangular/pyramid shape
-Made up of the adrenal cortex and the medulla
-Adrenal medulla = produces adrenaline responsible for the fight or flight response
-The brain will detect a danger/shock and a signal will be sent down a nerve to the adrenal gland where adrenaline is released into the blood
-The adrenaline then flows round the body causing effects that are seen in the fight or flight response to prepare the body for action
-Adrenal cortex = releases hormones:
Mineralocorticoids, Cortisol, Precursor sex hormones

23
Q

What are the effects of the fight or flight response?

A
  • Increase of heart rate
  • Increase stroke volume
  • Increased cardiac output
  • Increased ventilation (breathing rate)
  • Pupils dilate
  • Mental alertness
  • Reduce digestion
  • Breakdown of glycogen
  • Increased blood pressure
  • Hairs stand up (evolutionary response to make the person/animal look bigger in response to danger or to prepare for danger/fighting)
24
Q

What is the purpose of cortisol?

A
  • Cortisol is a stress hormone

- Cortisol causes elevated blood glucose level due to the break down of glycogen into glucose (glycogenolysis)

25
Q

What is in the hypothalamus and pituitary?

A
  • Osmoreceptors that detect water potential changes in the blood, e.g: If the blood is more salty (Lower WP) then the cells shrivel up
  • This creates a signal which goes to ADH producing nerve cells, this causes them to produce ADH which travels down the axons to be secreted by the posterior pituitary
26
Q

What is cyclic AMP?

A
  • Cyclic AMP or cAMP is the secondary messenger that is found in many different hormone response pathways and is used when transporting non-steroid hormones through a membrane
  • The cAMP can open channel proteins and activate other enzymes to trigger changes inside the cell to allow the hormone to enter the cell
27
Q

Why are insulin injections needed for someone who has diabetes?

A
  • People with diabetes are unable to produce sufficient insulin via their beta cells
  • Insulin is needed when blood glucose levels are too high
  • The insulin is injected into the person with diabetes and it works to move glucose from their bloodstream into their body’s cells to make energy
28
Q

What is the function of “Kinase” enzymes?

A
  • Kinase enzymes phosphorylate other enzymes

- This means they add a phosphate to the existing enzyme to activate it

29
Q

What is cardiac output?

A
  • The amount of blood the heart pumps through the circulatory system in a minute
  • The stroke volume and the heart rate determine the cardiac output
30
Q

What is stroke volume?

A

The amount of blood put out by the left ventricle of the heart in one contraction

Biology (23 decks)

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