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Unit 9B:Human regulation and reproduction Assignment B Grade achieved Distinction
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Unit 9B: Human Regulation and Reproduction Assignment B Grade achieved Distinction
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Unit 9: Human Regulation and Reproduction:Learning Aim B: Understand the homeostatic mechanisms by the human body
B.P2: Describe how homeostatic mechanisms maintain normal function.
B.M2: Explain the role of hormones in homeostatic mechanisms.
B.D2: Analyse the impact of homeostatic dysfunction on the human body.
B.P2: Describe how homeostatic mechanisms maintain normal
function.
Introduction:
Homeostasis is the ability to maintain a stable and constant
environment. It is maintained by the autonomic nervous system along
with the endocrine system as well as controlled by the hypothalamus (a
structure in the brain which links the endocrine and nervous system to
allow them to perform homeostasis). The hypothalamus is also Homeostasis (no date) Western Oregon
responsible for regulating body temperature, heart rate, blood pressure University. Available at:
https://wou.edu/chemistry/courses/online-
and circadian rhythms (wake and sleep cycles). For instance, the liver is
chemistry-textbooks/ch103-allied-health-
metabolises toxic substances by receiving signals from the pancreas and chemistry/ch103-chapter-9-homeostasis-and-
maintains carbohydrate metabolism. The liver also regulates lipid cellular-function/ (Accessed: February 27, 2023).
metabolism and produces cholesterol. The kidneys regulate blood water
levels, re-absorb substances into the blood, maintaining salt and ion levels of the blood, regulate
blood PH and excrete the urea and other waste products.
The process of maintaining homeostasis:
Homeostasis is influenced by the internal (existing) and external (environmental) conditions and is
maintained by different mechanisms. All control homeostatic mechanisms have at least three
components for it to be regulated:
A receptor detects change in the internal or external environment. For example, the
peripheral chemoreceptors detect the change in the blood PH.
The control centre receives this information from the receptors and initiates a response to
maintain homeostasis. For example, the hypothalamus which controls everything from heart
rate, blood pressure, satiety to circadian rhythms and wake sleep cycles.
The effector (any organ or tissue) receives this information from the control centre and acts
to the changes needed to maintain homeostasis. For example, the kidney retains water of
the blood pressure is low.
Negative and Positive Feedbacks:
Although, the receptors, control centres and effectors are basic components for every homeostatic
response, the negative and positive feedbacks are more complex mechanisms that allow these three
basic components to maintain homeostasis for more complicated physiological processes. Feedback
loops regulate when the response to a stimulus effects on the original stimulus.
Negative feedback is a mechanism in which the response to a stimulus reduces the original stimulus.
It uses one of the products from the reaction to reduce the activity of the process in the purpose of
returning an organ or a system to its normal range in order for it to function properly. Most of the
, homeostatic processes use negative feedback to regulate a set point range in response to
maintaining homeostasis.
An example of a negative feedback is thermoregulation. The
receptors in the periphery and the brain inform the hypothalamus
that the temperature has strayed from its set point. For example, if
you have been exercising hard, the body temperature rises above
its set point. These mechanisms activate to cool you down. The
blood flow in the skin also speed up the heat loss into your
surroundings, and as a result you might start sweating so the
evaporation from the skin can help you cool down. Heavy
breathing is also contributed in increasing heat loss. However, if
you were sitting in a cold environment and aren’t dressed warmly
enough, the hypothalamus triggers responses to warm you up. Blood Homeostasis (article) | feedback (no date) Khan
flow in the skin increases, and as a result you might start to shiver to Academy. Khan Academy. Available at:
https://www.khanacademy.org/science/ap-
generate more heat. You might also get goose bumps so the hair on biology/cell-communication-and-cell-cycle/
the body stands and traps the layer of air on your skin. This also leads feedback/a/homeostasis (Accessed: February
to the increase of hormones which act to increase heat production. 27, 2023).
Positive feedback is a mechanism in which process are accelerated or enhanced in response to the
output created by the stimulus that has already been activated. It is
designed to push processes to their competition and are not used
often as the negative feedback. To achieve this, a series of events
need to take place in order to increase the effect of the stimulus.
An example of a positive feedback is childbirth in which the baby’s
head pushes on the cervix, through which the baby should emerge
and activates the neurones in the brain. These neurons signal the
pituitary gland to release the hormone oxytocin. The hormone
oxytocin increses the uterine contractions and pressures the cervix. Homeostasis (article) | feedback (no date) Khan
As a result, more oxytocin is released which produces even more Academy. Khan Academy. Available at:
https://www.khanacademy.org/science/ap-
stronger contractions. The postive feeback continues until the baby is biology/cell-communication-and-cell-cycle/
born. feedback/a/homeostasis (Accessed: February
27, 2023).
Disruptions to feedbacks during homeostasis:
The process of homeostasis depends on negative feedback if feedback
mechanisms fail to engage, it will usually disrupt homeostasis. As a
result, in case of humans this may lead to disease.
An example of this is diabetes which is caused by a broken feedback
loop in the hormone insulin. The broken feedback loop which makes it
difficult or even impossible for our bodies to bring the high blood sugar
concentration down to a healthy level. As we may know, in type-1
diabetes people do not produce enough insulin because of an auto-
immune destruction of the insulin in producing cells, whilst people with
type-2 diabetes it causes high blood glucose levels that cause
insulin resistance. In diabetes, blood glucose levels are increased by Homeostasis (article) | feedback (no date) Khan
Academy. Khan Academy. Available at:
glucagon, however the lack of resistance to insulin means that the https://www.khanacademy.org/science/ap-
blood sugar levels are not able to return to normal. Therefore, biology/cell-communication-and-cell-cycle/
feedback/a/homeostasis (Accessed: February
28, 2023).
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