Feed back mechanism (1 Viewer)

[wishful-thinker]

hey if anyone could help me that would be awsome does anyone have or know where i can find a diagram of a feedback mechanism that works both in the negative and positive?:S it would mean heaps thanks

 

[Mature Lamb]

Physiological Homeostasis - Biology Online

First result when I googled 'feedback mechanism diagram'. I don't think we need to know about positive feedback do we?

 

[bouncing]

they usually dont give questions on positive feedback systems but just know about child birth and that hormone thing that tells your brain whether or not to have contractions....

that should do it (Y)

 

[mareetothemaxxx]

Physiological Homeostasis - Biology Online

First result when I googled 'feedback mechanism diagram'. I don't think we need to know about positive feedback do we?

Technically the syllabus leaves the door wide open, the actual dot point being 'gather, process and analyse information from secondary sources and use available evidence to develop a model of a feedback mechanism'
which clearly leaves BoS free to ask either positive or negative, since the specific as to which is ignored, but I think, due to the commonality of negative feedback models, many teachers neglect to teach the positive feedback model. But it is of the utmost importance to know both:- it could be the difference between a band 5 and a band 6 !

 

[bouncing]

haha that is very true..
my teacher neglected it i had to google stuff on that myself!
kind of weird googling childbirth....

are there any other examples of positive feedback mechanisms?

 

[Mature Lamb]

Hey can you explain the childbirth and hormone thing to me?

 

[bouncing]

Hey can you explain the childbirth and hormone thing to me?

of course
okay so a positive feedback system is when the response INCREASES the effects of the original stimulus (instead of decreasing it like a negative one does because basically the negative one is when the detector says no! this is very bad we must decrease the effect of this stimulus! - eg you start shivering when it gets cold)

okay well in childbirth, contractions occur which releases oxytocin (a mamallian hormone which acts as a neurotransmitter in the brain) you can wikipedia it if you want more information LOL apparently this hormone is linked to orgasms?! (did not know that part - and would not advise you to put this into your short answer if ever a question about positive feedback systems came up in the hsc hahaha)
well anyway the level of this particular hormone increases causing more contractions and allowing childbirth. i believe it is also important in facilitating breastmilk? or something about breastfeeding i forgot

well hope that helped you! ps its INCREASING FOR POSITIVE (perhaps you can think of this childbirth thing like when the doctor says PUSH! PUSH! PUSH! that baby out or something... lol) and DECREASING FOR NEGATIVE

 

[alexx-12]

Temperature is a good one that can go both ways
or you could also do CO2 in blood but temp is easier

I've tried looking for a useful picture but I can't find any :S

 

[bouncing]

Temperature is a good one that can go both ways
or you could also do CO2 in blood but temp is easier

I've tried looking for a useful picture but I can't find any :S

yeah i'd definitely go with temperature if they asked you to give an example
oh god the pictures on google are awful

okay i have a pciture but bos wont let me upload it sorry

 

[Annum]

Hey guys, can someone please help me with this questions? pleasee?
Explain how negative feedback mechanisms operate to regulate blood volume and urine output.

 

[Kimyia]

Hey guys, can someone please help me with this questions? pleasee?
Explain how negative feedback mechanisms operate to regulate blood volume and urine output.

You need to look at ADH and aldosterone.
Blood volume: if there's a lot of salt in your blood, more water is going to be drawn into your blood to try and even out the concentrations. This will increase your blood volume, which isn't always a good thing. So the levels of aldosterone are reduced, so less salt is retained in your body, meaning less is in your blood, meaning less water will move into your blood, meaning your blood volume is kept under control. Basically: too much salt = reduced aldosterone. too little salt = more aldosterone. thus, negative feedback.
Urine output: if your losing too much water in your urine, the amount of ADH released is reduced so more water is retained and vice versa. thus negative feedback.
Does that help?

 

[Annum]

This is so helpful, thankyou so much!

You need to look at ADH and aldosterone.
Blood volume: if there's a lot of salt in your blood, more water is going to be drawn into your blood to try and even out the concentrations. This will increase your blood volume, which isn't always a good thing. So the levels of aldosterone are reduced, so less salt is retained in your body, meaning less is in your blood, meaning less water will move into your blood, meaning your blood volume is kept under control. Basically: too much salt = reduced aldosterone. too little salt = more aldosterone. thus, negative feedback.
Urine output: if your losing too much water in your urine, the amount of ADH released is reduced so more water is retained and vice versa. thus negative feedback.
Does that help?

 

[Annum]

Hi again, just wondering would this be a good answer for the question i had:
Blood volume: If there is a lot of salt in your blood, more water is going to be drawn into your blood to try and even out the concentrations. This will increase your blood volume, which isn’t a good thing. Thus the levels of Aldosterone are reduced, so less salt is retained in your body, this means that there are less salts in your blood and hence less water will move into your blood and as a result your blood volume is kept under control.

This is how the negative feedback mechanism operates when regulating blood volume. The osmo-receptors in the hypothalamus of the brain will detect a fall in the concentration of water in the blood. This will then stimulate neurosecretory to synthesise and secret the hormone ADH. This hormone then passes from the hypothalamus to the posterior pituitary where it is passed and released into the blood. ADH is a hormone which has the ability to increase the permeability if the kidneys collecting duct to water so that more water is reabsorbed and thus urine volume decreases.

You need to look at ADH and aldosterone.
Blood volume: if there's a lot of salt in your blood, more water is going to be drawn into your blood to try and even out the concentrations. This will increase your blood volume, which isn't always a good thing. So the levels of aldosterone are reduced, so less salt is retained in your body, meaning less is in your blood, meaning less water will move into your blood, meaning your blood volume is kept under control. Basically: too much salt = reduced aldosterone. too little salt = more aldosterone. thus, negative feedback.
Urine output: if your losing too much water in your urine, the amount of ADH released is reduced so more water is retained and vice versa. thus negative feedback.
Does that help?

 

[Boonyak]

 

[Kimyia]

Hi again, just wondering would this be a good answer for the question i had:
Blood volume: If there is a lot of salt in your blood, more water is going to be drawn into your blood to try and even out the concentrations. This will increase your blood volume, which isn’t a good thing. Thus the levels of Aldosterone are reduced, so less salt is retained in your body, this means that there are less salts in your blood and hence less water will move into your blood and as a result your blood volume is kept under control.

This is how the negative feedback mechanism operates when regulating blood volume. The osmo-receptors in the hypothalamus of the brain will detect a fall in the concentration of water in the blood. This will then stimulate neurosecretory to synthesise and secret the hormone ADH. This hormone then passes from the hypothalamus to the posterior pituitary where it is passed and released into the blood. ADH is a hormone which has the ability to increase the permeability if the kidneys collecting duct to water so that more water is reabsorbed and thus urine volume decreases.

Sorry Annum for the exceptionally late reply. If you were still wondering, I would focus more on the decrease/increase, release more/release less rather than the actual transport of the hormone. I would word it something like: the osmoreceptors in the hypothalamus detect a fall in the concentration of water in the blood, hence a decrease in blood volume and increase in solute concentration. This stimulates the secretion of the hormone ADH. ADH increases the permeability of the walls of the distal tubules and collecting ducts in the kidneys to water so more water is absorbed. This increases the concentration of water in the blood,and as the concentration and volume of blood returns to a stable level, less ADH is released. Now you can add something about the reverse - when the concentration of water increases. Otherwise, it looks like you've covered most things.

View attachment 24403

^ good diagram.