Lecture 1 homeostasis

Question 1

How do the receptor, control centre and effector work together to maintain homeostasis?

Answer 1

they work together as- the receptor tracks/registers changes in homeostasis (caused by a stimulator) - the control centre then receives signal down the afferent pathway indicating of a change in the homeostasis and the control centre then sends a message along to the efferent pathway to the effector (the target organ) and the target organ moves to change certain parameters to bring the affected variable back into the physiological range.

Question 2

What is homeostasis?
why is it important?

Answer 2

homeostasis is the maintenance of a stable internal environment.
it is important because it is essential for the healthy functioning of the bodies cells, tissues and organs.

Question 3

when is the body in homeostasis?
Why does it need homeostasis?

Answer 3

the body is in homeostasis when its needs are met and it is functioning correctly
organs and tissues and cells need consistency of variables in several physiological parameters to ensure they function correctly

Question 4

What variables are maintained by homeostasis?

Answer 4

blood glucose
blood pressure
ion balance
water balance

Question 5

Which 2 organ systems are especially important for homeostasis and why?

Answer 5

the endocrine and nervous system are especially important because they allow for communication throughout the body- this communication allows the body to maintain a stable internal environment and adapt to changes

Question 6

What are the physiological and disease ranges?

Answer 6

physiological ranges are the healthy, normal ranges variables can be in to allow for normal functioning-it is determined by the control centre (brain)
the disease ranges are when the variables move outside of the set physiological ranges and can represent a shift out of homeostasis and indicate something is wrong

Question 7

What are some mechanisms for maintaining homeostasis?

Answer 7

the feedback loop- can be both positive an negative

Question 8

What is the feedback loop?

Answer 8

feedback loop is a control system that acts to return the level of a given variable back to the physiological range after it has been disturbed
- it usually goes against the direction of stimulus

Question 9

Examples of homeostasis?
How is blood pressure increased or decreased

Answer 9

blood pressure
body temperature
blood glucose
calcium levels
-regarding blood pressure
when it increases: vasoconstriction occurs and greater reabsorption at the kidneys to increase blood volume
when BP falls: vasodilation occurs and increased excretion at the kidneys so blood volume is lower

Question 10

What are the components that allow us to maintain homeostasis?

Answer 10

sensor
control centre
signal
effector

Question 11

How are homeostasis components linked to each other? Describe it in terms of negative feedback loops

Answer 11

sensor detects changes to a variable and sends a message along afferent pathway where the comparator receives the message and compares it to set levels determined by the control centre and then decides on whether to send a strong or weak signal down the efferent pathway to the effector to counter the move of the variable out of its physiological range

Question 12

What does a stimulus do?

Answer 12

the stimulus shifts the actual variable value so that it is no longer within the physiological range- it is an internal or external change to the actual value of the variable and disturbs homeostasis

Question 13

What does a comparator do?

Answer 13

a comparator compares the signal received from the sensor (the value given by the afferent pathway) down the afferent pathway to the set values determined by the control centre (which are within the physiological range) and then uses the information to send a message to the target organ down the efferent pathway

Question 14

What does a sensor do?

Answer 14

detects a variable and tells the control centre when something is not within the acceptable physiological range

Question 15

What is an efferent pathway?

Answer 15

the efferent pathway is the pathway from the comparator or control centre to the effector organ/gland

Question 16

what is a control centre?

Answer 16

the control centre decides what to do with the information from the sensor (it is usually the brain)

Question 17

what is the signal?

Answer 17

the signal is a transfer of information and informs the next decision it can be called a signal particle and often hormones are signals

Question 18

what is an effector?

Answer 18

the effector is the target organ where the signal has its effect- the effector carries out the process to adjust the controlled variable

Question 19

What will happen if there is a difference between set level and input?

Answer 19

if there is a difference the operator will move toward nullifying the difference by sending either a strong or weak message along the efferent pathway to bring the variable back into the physiological range

Question 20

What makes modifications of some parameters and why?

Answer 20

the target organ makes modifications to parameters to ensure the variable is brought back into the physiological range

Question 21

what does the sensor measure?

Answer 21

the actual value of the variable
- it obtains the current- real tome information of given variable and moniters the environment and responds to stimulus by sending information to the control centre along the afferent pathway

Question 22

what does the effector do?

Answer 22

modifies parameters so it can restore the variable back to its physiological raneg

Question 23

What will happen if there is a difference between set level and input at the comparator?

Answer 23

an output to the target organs will modulate the variable and bring it back into its physiological range

Question 24

What is the control variable influenced by?

Answer 24

can be influenced by external factors such as temperature

Question 25

Where is the feedback information relayed to? What kind of influence can it have? What pathway is it relayed along?

Answer 25

feedback info is relayed to the comparator and it can have a positive or negative influence and it is along the afferent pathway

Question 26

Give an example of negative feedback

Answer 26

the blood pressure
when it increases: vasoconstriction occurs and greater reabsorption at the kidneys to increase blood volume
when BP falls: vasodilation occurs and increased excretion at the kidneys so blood volume is lower

Question 27

What is the difference between a positive and negative feedback loop?

Answer 27

positive feedback-
goes in the same direction as the original stimuli
- it is an increase in function in response to a stimuli and enhances the stimuli so that the reaction happens at an even faster rate

Negative feedback-
when a change occurs in the opposite direction of the original stimuli
- a feedback that reduces the output of a system
a decrease in function in response to a stimulus
the bodies variables are restored back to the steady state

Question 28

Give an example of negative feedback

Answer 28

acute restoration of blood pressure
return of plasma osmolality back to normal
temperature regulation

Question 29

What are most hormonal control mechanisms made up of?

Answer 29

negative feedback

Question 30

What happens if the variable is decreased?

Answer 30

-sensor registers a reduced signal
-so a reduction in the amount of info that passes along the afferent pathway to the comparator
- the comparator responds by increasing the signal along the efferent pathway
- the comparator output will act to increase the value of the variable

Question 31

If the sensor registers an increased signal what happens to the feedback information to the comparator?

Answer 31

• the sensor will register a increased signal
• more information and signals will be sent along the afferent pathway
• the comparator will send a reduced signal along the efferent pathway
  the operator output will work to decrease the value of the variable