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HUBS > L27 > Flashcards

L27 Flashcards

1
Q

Shape of thyroid

A

Butterfly

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2
Q

Location of thyroid

A

Anterior and lateral surfaces of trachea, just below the larynx, wrapped around trachea

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3
Q

hormone that thyroid produces

A

Thyroid hormone and calcitonin

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4
Q

What is thyroid hormone useful for?

A

Essential for optimal metabolic activities

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5
Q

Calcitonin uses

A

Maintains calcium homeostasis, not a lot of this hormone is produced

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6
Q

Structure of the thyroid gland

A

*Has small spherical sacs called follicles
*Has simple cuboidal epithelial cells surrounding the follicle called folicular cells
- this is the site of thyroid hormone synthesis
*Entire thing called the thyroid follicle

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7
Q

What makes Calcitonin

A

C cells

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8
Q

What is thyroid

A

A modified amino acid

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9
Q

Process of thyroid synthesis

A

Thyroglobulin (contain amino acid tyrosine [Y]) –> Iodine from our food travels to thyroid as only thyroid usues it as a substrate and binds to tyrosine –>. iodised tyrosine (3-4 iodines can be attatched) –> either T3/T4 produced

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10
Q

What is T3

A

3 iodines
*The active form - targets cells and causes an effect

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11
Q

What is T4

A

*Repository form
*More abundant
*Enzymes can just cut off an I to make the more active T3

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12
Q

What gland causes release of thyroid hormone

A

signal from Anterior pituitary

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13
Q

How is the hormone stored and released

A

On a protein Thyroglobulin (TGB), when signalled, it is cut from protein and as its lipid soluble, it diffuses into the blood

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14
Q

How is T3 and T4 carried around the body

A

Through Thyroid binding globulin (TBG) which is a carrier protein

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15
Q

Where does T3 bind to?

A

An intracelluluar receptor site on the DNA

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16
Q

What is the response time of T3

A

45mins (as it can be stored) - days

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17
Q

What does biding of T3 do?

A

Initiates transcription of mRNA and increases the production of proteins involved in E use

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18
Q

production of proteins involved in E use?

A

eg Na+ K+ pump

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19
Q

What initiates TRH release?

A

External and internal stimuli causes CNS input to hypothalamus

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20
Q

What is TRH

A

Thyrotropin releasing hormone

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21
Q

Where is TRH released?

A

Hypo secretes In the portal blood vessels of the AP

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22
Q

What does AP secrete?

A

Thyroid stimulating hormone (TSH)

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23
Q

What does TSH impact?

A

Travels to the thyroid gland and cleaves the T3 and T4 from the protein TGB

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24
Q

What happens when the Thyroid hormones are released?

A

Causes an increase in the basal metabolic rate
-Making and using the Na+ K+ pump
-stimulates growth in foetus and early childhood
-Involved in normal levels of alertness

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25
Q

What does the negative feedback of Thyroid hormones affect

A

TRH and TSH production

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26
Q

What is basal metabolic rate?

A

The rate of energy expenditure when the body is doing as little as possible eg no eating for 12-18 hours, at comfortable temp, no movement

27
Q

When is BMR the highest?

A

In children

28
Q

More muscle mass means….

A

A higher BMR, sexual diorphism as females have more body fat percentage

29
Q

What is thyroid hormone required for?

A

Normal growth, alertness and metabolism

30
Q

What does increase in activity and metabolism do?

A

The demand for E goes up
*Increases body heat - O2 consumption and more ATP is made
*Breakdown of fats (stored fat) and proteins (from muscle)
*Liver breaks down glucose from glycogen i.e increase in gluconeogenesis and glycogenolysis

31
Q

Why is Thyroid not considered to increase blood glucose levels?

A

As the glucose made is also used up

32
Q

How is Ca2+ conc. regulated?

A

Similar to pancreatic control of blood glu conc., Ca2+ is controlled without the hypo and pit involved

33
Q

How much Ca2+ usually taken through food?

A

1000mg everyday

34
Q

How much Ca2+ is lost?

A

Most absorbed into the plasma but 1/3 (350mg) is lost through fecal matter as it wasnt absorbed

35
Q

What organ modifies the Ca2+ levels in blood?

A

It is filtered through the kidneys and either reabsorbed into the blood or lost through urine

36
Q

How is homeostasis of Ca2+ regulated?

A

What goes in, comes out. 2/3s lost through

37
Q

As we are growing,…

A

We lose less Ca2+ and it is used in bone growth

38
Q

What happens if Ca2+ is lost through digestive through events like diarhoea

A

The osteoclasts of bones breakdown matrix and release Ca2+ into the blood

39
Q

What other functions is Ca2+ essential for?

A

Contraction of muscles and release of neurotrans, 2nd ory based messenger systems

40
Q

3 main hormones involved in Ca2+ regulation

A

Parathyroid hormone (PTH), Calcitonin and Calcitriol

41
Q

Main hormone involved in Ca2+ regulation

A

PTH

42
Q

Where is PTH made?

A

In the parathyroid glands, 4 dots behind the thyroid

43
Q

What happens if there was a genetic malformation that prevented PTH production

A

Foetus doesn’t develop as Ca2+ is not regulated

44
Q

Receptor and control centre in Ca2+ production

A

The parathyroid glands

45
Q

What happens if there is a drop in blood Ca2+ conc.

A

Para secretes PTH, increases bone breakdown and release of store Ca2+
*increases Ca2+ absorbed in Kidneys
*Turns Vit D into Calcitriol (activated form of vit D) –> encourages absorbtion from digestive system

Negative feedback

46
Q

Why don’t our bodies usually make Calcitonin

A

Unless there’s a v high conc of Ca2+

47
Q

What does Calcitriol do?

A

Further increases Ca2+ absorption into blood from kidneys + resorption of Ca2+ from bones

48
Q

As there is Calcitriol, what does it prevent

A

Conversion of vit D into more Calcitriol

49
Q

What does Calcitonin do?

A

Negative feedback for bone resorption, kidney absorption and intestine absorption, given to patients as medication for high Ca2+ levels

50
Q

What is the adrenal glands controlled by?

A

Hypo

51
Q

Shape of adrenal

A

Triangular

52
Q

Parts of adrenal

A

Red/greyish - is the medulla
Yellow is the cortex

53
Q

Where are the adrenal glands

A

on top of kidneys, posterior near ribs, near major arteries that go down abdominal cavity

54
Q

Outer region of the adrenal glands

A

Adrenal cortex - has 3 layers

55
Q

What does the outer layer secrete

A

Aldosterone (Na+ homeo)

56
Q

What does the middle layer secrete (biggest layer)

A

Cortisol

57
Q

What does the inner layer secrete

A

Androgens (minor repro role)

58
Q

What does the medulla secrete (central region, middle)

A

Adrenaline

59
Q

When is Adrenaline and Noradrenaline released

A

In response to the sym NS response to stress

60
Q

What can noradrenaline act as

A

Both neurotrans (synapse) and hormone (blood)

61
Q

What do these hormones in blood mean

A

Can have a prolonged response of flight or fight in addition to synapses

62
Q

How is adrenaline and nor released from adrenal medullary secretion cells?

A

Pregan uses ACh –> synapses with adrenal medullary secretion cells –> secretes NE and A into blood, circulates until reaches target cells –> secondary messenger pathway –> amp of cellular response

63
Q

Pathway of adrenaline secretion

A

Hypo integrates stress stimulus and initiates response –> pregan fibres –> stim adrenaline release into blood –> target cells –> breakdown of glycogen to glucose and fats to fatty acids (non glucose substrate) –> fuel increase

HUBS (27 decks)

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