homeostasis

Question 1

whats homeostasis?

Answer 1

• What is Homeostasis?

• The maintenance of a stable, internal environment
• Homeostasis keep the body in balance, for example producing the correct amount of cells, to replace those that are worn out. It is essential for maintaining health, but the monitoring of vital signs in illness are essential to helping to restore homeostasis
• A constant, dynamic process which allows for readjustment of physiological variables, mainly controlled by negative feedback mechanisms.

Question 2

How is homeostasis maintained?

Answer 2

• Homeostasis is maintained through control systems which pick up changes and respond to them appropriately. There are 3 basic parts to the control systems: detector, control centre and effector.
• Control centre- this sets the limits that should be maintained and receives information from the detector (like a sensor). When that signal is received from the sensor (detector) the control centre responds and the message or output to the effector changes appropriately.
-Its response can be electrical- sent by the nervous system, or chemical via the endocrine system.
• The body has detectors (otherwise known as receptors) that detect changes in chemicals- known as chemoreceptors, blood pressure (baroreceptors), temperature (thermoreceptor) or touch or heat so extreme that cause pain (nociceptors).
• The kidneys can regulate salt, water and pH, oxygen is distributed to the cells, carbon dioxide is expelled and heat are all transported via blood. This is another example of homeostasis.

Question 3

what is negative feedback and why is this important? give example in relation to homeostasis?

• too cold
• too hot

Answer 3

• Negative feedback works by altering the direction of change- meaning that any change in a variable, such as temperature for example, NF makes it go the opposite way keeping it as close as possible to a set point.
• For example, if we are too cold NF mechanisms work by detecting a decrease in body temperature by the thermoreceptors and this information is transmitted to the hypothalamus in the brain- this then sends nerve impulses to the skin, which cause vessels to narrow (vasoconstrict) which reduces the flow of blood around the body, concentrating it within the core organs and the brain, conserving heat in the body. Shivering is another mechanism- these are rapid muscle contractions which help to increase the temperature.
• If our temp rises above 37 degrees this is detected by thermoreceptors which send impulses to the hypothalamus. Nerve impulses sent to skin so start to sweat which cools the skin as it evaporates, our blood vessels dilate which also results in heat loss. NF can also cause our behaviour to change so we might find shelter and drink cold drinks.

Question 4

what is positive feedback and give an example?

Answer 4

• Positive feedback mechanisms

• Change can also be caused by positive feedback mechanism and this is another example of homeo.
• Example can be wound in skin:
  1) break/ tear in blood vessel so feedback cycle initiated
  2) clotting occurs as platelets adhere to site and release chemicals
  3) released chemicals attract more platelets
  4) clotting proceeds until break is sealed with newly formed clot
  5) feedback cycle ends

Question 5

what is another example of positive feedback?

Answer 5

-Other examples include the production of oxytocin in childbirth which stimulates uterine contractions and the milk let down reflex in breast feeding- as suckling triggers the sensory nerve impulses in the breast tissue alveoli, the pituitary glands release oxytocin

Question 6

what are the healthy ranges for vital signs?

what is the importance of monitoring vital signs?

Answer 6

• NEWS2 ranges:
• BP (120/80 mmHg)
• Temperature 36.1 – 37.2°C
• Heart Rate 60-99 beats per minute
• Respiratory Rate 12-20 breaths per minute
• Oxygen saturation >94%
• Capillary refill 2 secs
• When monitoring vital signs, it is also essential to consider fluid balance which is calculated at 0.5-1.0 mls/kg/hr
• These are an objective measure of homeostasis and evidence has shown that through the assessment of vital signs, this can allow deterioration in condition to be recognised and treated quickly, affecting your patients outcome, making a difference between a full recovery or one with on going issues. (Kim et al 2017, Kenzaka et al 2012)
• When monitoring patient observations, it is essential to do this thoroughly and accurately record all variables. A study by Chen et al in 2009 of patients in 23 Australian hospitals illustrated that 77% of patients who later experienced adverse events, had at least one vital sign missing from their records
• Our role as nurses is important to ensure any changes to homeostasis are picked up and can then be acted on rapidly.