Homeostasis (wk1)

Question 1

What is Homeostasis (definition)?

Answer 1

-Is the condition of equilibrium (balance) in the body’s internal environment

Question 2

Describe the process of homeostasis:

Answer 2

-It is achieved through constant interactions of the body’s processes. It is a dynamic process by which we adopt and adjust to changes in the environment to maintain functional integrity
-All variables of physiological mechanisms must operate within a narrow range of values, but there needs to be a balance between different variables

Question 3

Who is the ‘founder’ of homeostasis?

Answer 3

Claude Bernard (1857)

Question 4

Describe homeostasis and feedback systems:

Answer 4

-The mechanisms keep a regulated variable in the internal environment within a range of values compatible with life

Question 5

Describe and draw the components within feedback systems:

Answer 5

-Sensor -> Afferent (enter) information
-Effector -> Efferent (exit) information via nerves or hormones
-Set-point -> Represent the ideal or target values for specific physiological variables
-Control centre
-Regulated variable
-Effector response

Question 6

Describe and draw the feedback system in response to a decrease in temperature

Question 7

What are varying homeostatic patterns?

Answer 7

-The body is generally in a state of homeostasis, however the pattern in which different variables are controlled can vary considerably
-Tight control of variables -> Most likely to be of predicted values e.g. pH levels
-Looser control of variables -> Response will fluctuate but mechanisms will slowly return levels to normal levels e.g. blood glucose, body temperature

Question 8

Set point and control of regulated variables

Answer 8

-The set-point dictates what we want our variable ‘in;
-There may be a correction and re-set of the set-point at certain times.
-For example, the set-point of body temp may be increased at certain times to allow the body to fight off pathogens if the body is unwell

Question 9

What is the gain of a regulated variable?

Answer 9

-The precision by which a control system can prevent deviation from homeostasis
-Gain = amount of correction needed/ amount of abnormality after correction

Question 10

Describe a regulatory negative feedback loop

Answer 10

-Negative feedback acts to reduce an effect (most loops are negative feedback)
-Draw diagram of body temperature

Question 11

Describe a regulatory positive feedback loop:

Answer 11

-Positive feedback acts to increase an effect
-An example is the clotting of blood when you have cut yourself, to minimise the amount of blood leaving the body

Question 12

Feedforward loops, reflex response and local response

Answer 12

-Feedforward -> Physiological responses in anticipation of a change in a variable. For example, HR increasing prior to a running race
-Reflex response -> This requires knowledge form an integrating centre and a circuitry that connects the receptor and the effector. Intercellular communication -> It relies on hormones and nerve cells for communication and a response.
-Local response -> Highly significant because they allow individual parts of the body to self-regulate their responses to certain conditions. Intercellular communication -> They rely on autocrine and/or paracrine agents for communication (in the local tissue)

Question 13

What is allostasis?

Answer 13

-It is a broader concept that encompasses the body’s adaptive responses to changing external and internal conditions
-It involves maintaining stability and anticipating to prepare for future challenges
-Allostasis has both short and long-term adaptations (homeostasis is concerned with short-term)