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hormonii 1 Flashcards

1
Q

what are hormones important for

A

to understand basic biological functions of the brain and the body
we can better understand psychological states and behaviour

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2
Q

what is the endocrine system

A

a chemical communication system of the body

includes glands and hormones

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3
Q

what are glands

A

structures which secrete or produce specific chemical substances

glands are the target for signals that tend to come from the brain

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4
Q

what are hormones

A

chemical messengers released in response to these signals

hormones are the ways in which certain parts of the body communicate

hormones are released through the blood stream

glands release hormones in the capillary and hormones travel towards a target

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5
Q

what are the functions of the endocrine system

A
  1. maintenance of the internal environment in the body - homeostasis
  2. regulation of growth and development
  3. control, maintenance and instigation of sexual reproduction
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6
Q

what is the neuroendocrine system

A

hypothalamus and pituitary gland - located in the brain

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7
Q

what is hormonal signalling

A

a complex way to refer to the way hormones are produced and target the destination cells or glands

  1. There is a change in the body or environment which is picked up by hypothalamus - master mind of the endocrine system
  2. Hypothalamus works in close collaboration with the pituitary gland by releasing a set of hormones that induce or trigger a number of responses in the pituitary gland
  3. Pituitary gland triggers additional hormones and those hormones either target a tissue or another gland and 4. those would exert a particular action
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8
Q

what is the hypothalamus

A

deep inside the brain
made up of a number of subparts which take the name of nuclei

nuclei are critical for different functions in the hypothalamus

nuclei allow the hypothalamus to be specialised in a variety of functions

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9
Q

what does the hypothalamus aim

A

to maintain homeostasis - internal balance

our body needs to have certain balance in order to operate optimally

hypothalamus operates to promote the releasing or stop the releasing of hormones so that certain basic functions like temperature are maintained at optimal level

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10
Q

what is the pituitary gland

A

small structure
controls a number of other glands and organs

connected to the hypothalamus to form the neuroendocrine system

divided into anterior and posterior lobe

hard to reach in case of injury

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11
Q
A
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12
Q

what are the properties of hormones

A

hormones are produced and released in secreting cells

hormones have an effect at a site different from where they are made - target cells

hormones travel through the bloodstream

they fit precisely onto a target cell’s receptors so they are specific for a particular cell

= specific hormones for specific receptors

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13
Q

what is the classification of hormones

A
  1. chemical criteria
    - steroid hormones
    - peptide hormones
  2. functional criteria
    GENERAL
    - activating effects
    - organisational effects

SPECIFIC
- homeostatic hormones
- glucocorticoids hormones
- gonadal (sex) hormones

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14
Q

what are steroid hormones (chemical classification)

A

steroid hormones are hormones that are fat soluble - they can cross the cell membrane

this means hormones are capable on acting on the target cells DNA

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15
Q

what is the journey of the steroid hormones

A

they cross the cell membrane

in cytoplasm they find steroid receptor

hormone will bind onto steroid receptor

then enters nucleus of the cell

here it will bind to mRNA and act on the cell DNA

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16
Q

What are peptide hormones

A

hormones which are not fat soluble so can’t cross the cell membrane

peptide hormones bind on a receptor on brown structures which sit on the cell membrane and it will not be able to enter cell

so they do not act directly on cell’s DNA

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17
Q

what are the 2 GENERAL functions of hormones

A

Activating effect or
Organisational effects

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18
Q

What are activating effects

A

activating effect is a reversible change in terms of the properties of the cell

it happens when the hormone is sitting on the receptor of a cell

the effect would last for a short amount of time

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19
Q

what are organisational effects

A

permanent or semi-permanent change in the structure of the nervous system

happens during a particular point in life - sensitive period in early development

hormones aka steroid hormones enter the cell’s nucleus and affect gene expression

steroid hormone can reach all the way into the nucleus and bind onto the mRNA and act on DNA

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20
Q

what are the 3 types of SPECIFIC functions

A
  1. Homeostatic hormones
  2. Glucocorticoids hormones
  3. Gonadal (sex) hormones
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21
Q

what are homeostatic hormones

A

hormones that aim to maintain a metabolic balance - homeostasis

and they regulate a number of physiological systems

homeostatic hormones exert an activating effect so action is only temporary

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22
Q

what is keeping the balance important

A

certain critical parameters need to be at a constant level so that the rest of the organs can function normally

e.g.
if we are asleep we are not able to control temperature so those functions need to look after themselves

there are a no. of physiological conditions that need to be maintained in a balanced way so we can operate normally

any imbalance will have devastating effect on the organs

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23
Q

what is an example of homeostatic hormones

A

insulin

makes sure glucose is maintained at optimal level
produced by pancreas
- the action of insulin promotes glucose intake by being released in the bloodstream and unblocking cells so they can take up glucose

24
Q

why is the action of insulin important

A

cells use glucose for their energy requirements and cells can obtain glucose from blood

25
Q

who uses insulin

A

muscles cells use glucose but they can also use other substances for fuel like protein and fat

HOWEVER
neurones can only use glucose

if glucose is low, priority is given to neurones
neurones cannot store glucose so they depend on the availability of glucose in the bloodstream

HENCE
we need to have a system in place that is able to maintain glucose at an optimal level

26
Q

how does insulin work

A

when insulin is in proximity with cell, insulin receptors bind with insulin molecule

glucose channel opens up and glucose enters cells and is used as energy supply

SO
insulin enters bloodstream from pancreas
insulin binds to receptor
insulin on receptor opens glucose channel
glucose leaves bloodstream and enters cell through glucose channel

27
Q

what is the step by step process of insulin

A

Physiological changes happen.
These changes are picked up by the hypothalamus.
Change is translated into a message that is sent to medulla in brainstem.
Message will travel towards pancreas via the vagus nerve.
That induces pancreas to secrete insulin.

27
Q
A
28
Q

how are levels of glucose in the blood detected

A

there are chemoreceptors that can detect how much glucose is in the blood

29
Q

what happens if there is too much glucose in the blood

A

Triggers the released of insulin
Cells take up the glucose

30
Q

what happens if there is too little glucose

A

secretion of insulin is stopped and cells are unable to pick up glucose
There has to be residual glucose available in case neurones need it

31
Q

what happens if there is fall in blood sugar levels

A

Hypoglycaemia

can cause fainting or coma
Neurones do not function properly as they depend on glucose
Symptoms resolve when the sugar level returns to normal

32
Q

what happens when there is rise in blood sugar levels

A

Hyperglycaemia

deficiency in production of insulin or defective insulin receptors

type 1 and 2 diabetes

you have sugar but cells are not capable of using it

33
Q

what is type 1 diabetes

A

little or no insulin produced

we have glucose in the stomach and enters the blood stream
pancreas should make insulin so glucose can be used by cells

instead there is little insulin made and sugar remains available in the blood stream and is not used up

34
Q

what is type 2 diabetes

A

insulin receptors become defective.

body produces insulin but insulin molecules are not able to bind to receptors so less glucose is used by cells

35
Q

what are glucocorticoids hormones

A

control stress and regulate metabolism

exert an activating effect so action is only temporary

36
Q

what is stress

A

the body’s reaction to feeling threatened or under pressure.
stress is stimulus that challenges homeostasis of the body and triggers arousal in humans

37
Q

what is the physiological response of stress

A

response to stress is the same irrespective of the stressor - exciting or frightening

38
Q

how do we activate a stress response

A

when we face a stressful situation we mobilise our body resources so we can respond to stress and achieve a point where we rebalance the situation and restore homeostasis

39
Q

what is fast acting system based on

A

Nervous system: sympathetic pathway

Hormonal system: adrenaline and noradrenaline

39
Q

what is the slow acting system based on

A

Hormonal response: HPA (Hypothalamus pituitary gland adrenal cortex) axis - from adrenal cortex

39
Q

how are fast actions implemented by the endocrine system - adrenal gland

A

adrenal gland - made of cortex and medulla

39
Q

how can we activate a stress response using 2 systems

A

Fast acting
Slow acting

39
Q

what is the fast acting system

A

when we make a split second decision about if something dangerous requires escaping it or facing it

we need certain level of energy resources which result from cell metabolism being stimulated to prepare for action

increase heart rate

decrease in digestive system

immune system is stimulated to use if we get injured

39
Q

what are glucocorticoids

A

glucocorticoids hormones break down protein and fat metabolism

40
Q

what is the slow acting stress response based on

A

the action of the endocrine system

hypothalamus sends trigger to anterior pituitary gland which sends a message to adrenal cortex which produces 2 types of hormones - glucocorticoids hormones and mineralocorticoids hormones

40
Q

how is adrenaline triggered using the fast acting system

A

the trigger to produce adrenaline is coming from the hypothalamus which picks up a certain level of stress stimulus and sends the trigger to produce adrenaline vis spinal cord to adrenal medulla

40
Q

what is the adrenal medulla

A

part of the autonomic nervous system

capable of secreting hormone adrenaline which activates sympathetic responses - increase in heart beat

41
Q

what are mineralocorticoids

A

hormones that act on blood volume and pressure which tends to increase and they act on the balance of water which is reabsorbed by kidneys

42
Q

what is the slow acting response as used by the HPA axis

A

HPA axis:
from hypothalamus to pituitary gland to adrenal cortex

glucocorticoids hormones like cortisol are produced

43
Q

what is the action of glucocorticoids hormones

A

cortisol is a typical glucocorticoid hormone

glucocorticoids make sure glucose is released from fat and proteins by the liver

all systems that are not required to deal with stressor are turned off - reproductive functions are off

44
Q

what happens if stress response is not shut down

A

if stress does not result in restoring homeostasis, results in chronic stress

continued production of glucocorticoids has a neurotoxic effect on the brain

45
Q

what are the physical consequences of stress

A

Proteins are used up which results in muscle wasting and fatigue

Growth hormone is inhibited

Reproductive functions are inhibited

46
Q

what are the cognitive consequences of stress

A

memory and learning

hippocampus deals with memory

the hippocampus contains high density of cortisol receptors - able to detect amount of cortisol in blood

constant high level of cortisol damages the hippocampus

hippocampus informs the hypothalamus when cortisol is too high and induces hypothalamus to induce pituitary gland to reduce amount of cortisol

too much cortisol can become toxic and neurones in hippocampus are unable to respond

then they are less able to inform hypothalamus that there is too much cortisol produced

47
Q
A

unu bst (18 decks)

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