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HUBS > L25 > Flashcards

L25 Flashcards

1
Q

Homeostasis

A

The presense of a stable internal environment

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2
Q

What happens when homeostasis is disturbed?

A

Receptors detect the change and relays info to the control centre which determines if change is required –> message sent to effectors

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3
Q

Can the receptors for increase and decrease be the same?

A

Yes but not always

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4
Q

What is a difference between set point and normal range

A

Set pt is universally determined and normal range is what an individual fluctuates around the set point because our set points are rarely static

*Each individual has their own unique normal range

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5
Q

Characteristic of an individuals normal range and the population range

A

*Individuals range is narrower than the population range due to variation
*Most individuals have a set point that is within the population reference range
*If you go out of your normal range, you can exhibit symptoms of disease

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6
Q

What is neural signalling?

A

APs in neurons and neurotransmitters at synapse
*need cells to be lined up for signal transmission
*Has the fastest transmission speed to minimise response delays
*Good for brief responses

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7
Q

What is endocrine signalling?

A

Hormones released into the blood
* Relatively slow but lasts longs
*Reaches receptors all around the body

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8
Q

Which glands secrete hormones?

A

Endocrine glands through exocytosis using vesicles

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9
Q

What must the distant target tissue have?

A

the appropriate receptors

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10
Q

What does the hypothalamus do?

A

Links neural to endocrine system and controls the secretion of a lot of endocrine glands

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11
Q

Where is the thyroid gland found?

A

Wrapped around the throat at the bottom of the neck

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12
Q

What do the adrenal glands consist of?

A

Adrenal cortex and medulla

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13
Q

What is a hormone?

A

A chemical messenger that must pass through the blood, affects cells with specific receptors for that hormone

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14
Q

What is a receptor?

A

Its a protein that can be on the target cell plasma membrane or inside the cell

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15
Q

How to classify hormones?

A

By what they dissolve in

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16
Q

Water soluble hormones

A

*Mostly peptides
* Make up 75% of all hormones
*Some catecholamines incl. adrenaline and nor-adrenaline
*Made and stored until required, released through exocytosis as they are hydrophilic and cant diffuse through the membrane
*Travels dissolved in the blood
*2nd messengers
*Milliseconds to minutes

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17
Q

Fat soluble hormones

A

Steroids and thyroid hormones incl. T3 and T4
*Steroids created from cholesterol as required
*Thyroid hormones made in thyroid cells and stored until needed (unusual)
*Travels in the blood bound to a carrier protein
*Alters gene transcription
*Hours to days

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18
Q

What is a catecholamine?

A

A single modified amino acid that is H2O soluble

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19
Q

Why are fat soluble hormones not stored?

A

They would just pass through the membrane as they are lipid soluble

20
Q

Where are the receptors of H2O soluble hormones?

A

They cannot pass through the membrane so the receptors are on the surface (plasma mem)

21
Q

Where are the receptors of lipid soluble hormones?

A

They can pass through mem so receptors are in the cytoplasm or the nucleus

22
Q

Cellular response to H2O soluble hormones

A

Hormone attaches to external domain of the receptor –> G protein activated on the internal domain –> G protein activates/deactivates the second messenger pathway production/reduction (AMP/cAMP OR Ca2+) –> downstream protein pathways activated/deactivated

23
Q

Cellular response to lipid soluble hormones

A

Hormone dissociates from carrier protein –> enters cell and binds to receptor in cyto then taken to nucleus or directly goes to nucleus –> the complex acts as a transcription factor for specific mRNA –> mRNA is translated to make protein –> protein mediates cell specific response

24
Q

Most common ways hormones are maintained

A

negative feedback
*Reduce change until stimulus is removed
*directly inhibit further release

positive feedback
*Amplify change until desired outcome is reached

25
Q

Amount of hormone in blood depends on:

A

*rate of hormone secretion
*rate of removal from blood - controlled by enzymes in blood or target cells

26
Q

what leads to endocrine disorders

A

Too much or too little hormones

27
Q

negative feedback

A

*deviation occurs in system and is detected by a ”receptor” and recognised by a control centre (sometimes the same organ is
the “receptor” and control centre, sometimes they are different)
*a mechanism is activated to bring the variable back to the set
point (or reference range), change occurs in effectors.
* in the long term, the secretion rates of many hormones are maintained at a fairly constant level by negative feedback

28
Q

What is the pancreas?

A

An exocrine and endocrine gland
*Pancreatic acini secrete digestive enzymes
*Pancreatic islets : Alpha (secretes glucagon) and beta cells (secretes insulin)

29
Q

Concentration of blood glucose levels

A

Must be regulated at narrow ranges

30
Q

Too high blood glucose =

A

Diabetes

31
Q

Too low blood glucose =

A

Hypoglycemia

32
Q

Brain mostly uses

A

Glucose for fuel

33
Q

Fed state

A

Uptake of nutrients and anabolic metabolism i.e synthesis of glycogen (E storage), proteins and fats

34
Q

Fasting state

A

Using the nutrients and Catabolic metabolism i.e breakdown of glycogen (E storage), proteins and fats

35
Q

Reference range for blood glucose levels

A

70 - 110mg dL-1

36
Q

Hormones that regulate blood glucose levels

A

Insulin and glucagon

37
Q

Increases in blood glucose

A

increases insulin secretion

38
Q

Synthesis of new glucose is called

A

Gluconeogenesis - cut glucose from glycogen
Fatty and amino acids –> glucose

39
Q

What are beta cells?

A

The control centre and the sensors for changes in blood glucose levels

40
Q

What so muscle cells make

A

Takes amino acids and makes glycogen and proteins

41
Q

What so adipose cells make

A

Fats

42
Q

What so liver cells make

A

net glucose uptake and makes glycogen and fats

43
Q

What is insulin

A

A peptide hormone (h2o sol) and has a plasma mem receptor, once blood glucose levels are back, negative feedback i.e insulin is stooped being produced by beta cells

44
Q

What happens when blood glucose levels go down?

A

Pancreas’ islet alpha cells release glucagon –> affects the liver where :
*Glycogen is broken down (glycogenolysis)
*Glucose levels increases (glucogeneogenesis)
*Ketone levels increase as some parts of the body uses ketones so glucose can be left for the brain

Negative feedback once blood glucose conc. and ketone conc. goes up

45
Q

Why is Glucagon

A

Peptide hormone (H2O sol) and has its receptors on target cells membranes

HUBS (27 decks)

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