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Unit 12 – Assignment 3 – P4 & P5

Unit 12 – Assignment 3- M3
How hormones control the function of cells and tissue in the body
The primary function of endocrine glands is to secrete hormones into the bloodstream
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Hormones serve as messengers; they control and coordinate activities
throughout the body
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This results in the activation of a signal transduction mechanism; this leads to
cell type-specific responses
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It will then transmit a message
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This causes the target site to take action
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Cells
can have many receptors for the same hormone
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The amount of receptors which respond to a hormone, affects the cell's
sensitivity and response to the hormone
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This will cause the cell sensitivity to increase or decrease
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This is in response to the rising hormone levels
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Should the amount
of receptors decreases in response to rising hormone levels, called down-regulation, it causes
cellular activity to be reduced
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They can affect many
processes such as growth and development, reproduction and sexual characteristics
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Some hormones affect only one or two organs, however others can
affect organs throughout the body
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This
hormone is produced in the pituitary gland and it affects only the thyroid gland
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For example, regulating the growth of cells, controlling the heart rate
and affecting the speed at which calories can be burned
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This affects the metabolism of glucose, protein, and fat in the body
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uk/bitesize/higher/bio
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This gland also produces
the hormone ADH
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This hormone increases the
permeability of the kidney tubules
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Should the blood water concentration decrease, then more water reabsorption would be
required
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As a result, the production of ADH is increased
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This is so that more water is lost as urine
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Positive homeostatic feedback - Childbirth

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candelalearning
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This stimulates the
contraction of the uterus
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Instead of decreasing the level of oxytocin and causing the pain to decrease, more oxytocin would be
produced
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In a feedback loop, the product of a process will have an effect on the rate of a process
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The rate of a process will
accelerate continuously under positive feedback, as long as substrate is available and the product is
not used up by another process
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Positive feedback will take place if the rate of the process
increases while the concentration of the product increases
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Negative feedback will occur if the rate of the process decreases whilst the concentration of the
product increases
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The output reduces the original effect of the stimulus
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Unit 12 – Assignment 3- D2
How the nervous system and endocrine system interact to maintain
homeostatic control – Adrenal medulla
When a threat is seen, the body will respond to this by releasing hormones to prepare it for the
"fight-or-flight" response
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The SNS will regulate this response of stress through the hypothalamus
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The adrenal
medulla mediates short term stress responses, whilst the adrenal cortex mediates long term stress
responses
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As soon as the
threat is identified, the SNS will cause blood glucose levels to increase
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The actions of the hormones of the endocrine system ensures to maintain
homeostatic control
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The sympathetic division
of the vertebrate ANS ensures the fight-or-flight response to oppose stress-caused disruptions of
homeostasis
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The adrenal medulla will release adrenaline and
noradrenaline; this increases the blood glucose levels by stimulating the liver and skeletal muscles to
break down glycogen and by stimulating glucose that are release by liver cells
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This is done by increasing the heart rate and
dilating the bronchioles
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For example, the heart, brain, and skeletal muscles
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For
example, the skin, digestive system, and kidneys
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Glycogen can
only be used for a certain amount of time in a "fight or flight" response; they cannot meet the longterm energy needs
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In such a situation as this, the long term energy
demand is able to by met through the actions of glucocorticoids
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There is a difference between long term and short term stress
responses
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As a result, the body will use other hormones instead
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As a result, the adrenocorticotropic hormone stimulated the adrenal
cortex to release corticosteroids (these are steroid hormones)
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They alter the concentration of enzymes in
the cytoplasm and affect cellular metabolism
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These fatty acids are released into the
bloodstream for other tissues to use for producing ATP
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This is done by stimulating glucose synthesis
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An example of this is
cortisone
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Unfortunately, it can not be used
for long amount of time
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The function of mineralocorticoids is to regulate the balance of ion and
water in the body
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This causes the blood pressure and volume to increase
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This is characterized by a shifting of fat storage areas of
the body
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On the other hand, the hyposecretion of the
corticosteroids can cause a condition known as Addison's disease
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Unit 12 – Assignment 3- D3
How the nervous and endocrine systems interact
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This concentration of glucose is controlled by the pancreas within the range 0
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Low levels (hypoglycaemia) and high levels (hyperglycaemia) of glucose in the blood are
very dangerous and can result in death
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The pancreas also has endocrine cells (both α-cells and βcells); these secrete hormones
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Glucagon causes the blood glucose level to
increase
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As a result, the blood glucose level is decreased
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After a person eats a meal, glucose is
absorbed from the intestines into the hepatic portal vein; this causes an increase in blood glucose
concentration
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The hormone insulin will cause glucose to be taken by the liver which then converts it in to
glycogen
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Once the blood glucose level is at a desired
level, the pancreas will stop secreting insulin
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Glucagon
causes the liver to break down some of the glycogen that is stored to glucose; this will be diffused
into the blood
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The regulation of body temperature: The body will normally keep its body temperature at around 35
- 40°C
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One kind of these receptors in the
hypothalamus keep track of the temperature of the blood as it goes through the brain
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Both sets of information are
required; this is to ensure that the body can make the appropriate adjustments
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Once
a person experiences a hotter of colder environment, the first response we take is voluntary
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If these responses are not enough to keep the body
temperature to a desired level, it will cause the thermoregulatory centre to be stimulated which is
part of the ANS
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If the environment is too hot, the
heat loss centre in the hypothalamus is stimulated, however, if the environment is too cold the heat
conservation centre of the hypothalamus will be stimulated
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Some responses to high temperature actively
cool the body down, whereas others reduce heat production or transfer heat to the surface
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When the
hypothalamus senses that the body temperature is too high, it sends impulses which cause blood
vessels supplying the capillaries in the skin to dilate
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On the other hand, an example of the body's
involuntary response to high temperatures is vasoconstriction
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This causes the blood flow to the surface tissues under the skin to
be reduced
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Vasodilation helps the body to lose heat, while
vasoconstriction helps to keep heat within the body
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The homeostasis of blood water is maintained by the
hypothalamus
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As a result, the hypothalamus
controls the sensation of thirst whilst also secreting antidiuretic hormone
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The only way water molecules can cross the membranes of the endothelial
cells is through water channels
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Antidiuretic hormone causes
the aquaporin's to open so that water is reabsorbed into your blood
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The level of water in your blood increases until it is back to
normal
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As
a result, the hypothalamus will detect the change and therefore sends a message to the pituitary
gland
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Without anti diuretic hormone, the kidneys will not save as much water and you produce
large volumes of dilute urine
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This is an
example of negative feedback
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As the level of water in the blood rises negative
feedback ensures that the amount of anti diuretic hormone decreases
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This is a reaction can occur if
someone is taking insulin of oral medications
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The way the blood glucose level is tested by using a blood glucose test strip
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The most common causes of
hypoglycaemia are having too much insulin, having too much exercise, or not having enough food
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There are many symptoms hypoglycaemia
can be associated with, for example, sweating, weakness, anxiety, trembling, fast heartbeat, inability
to think straight, irritability, grouchiness, hunger, headache and sleepiness
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A hypoglycaemic reaction should be
treated immediately by consuming a form of a fast-acting sugar

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