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What is Homeostasis?
What is Homeostasis?
Homeostasis is...
"The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions."
~Biology Online.org
Basically:
A characteristic of our body systems that regulates stable and constant properties.
It maintains the body temperature, blood pressure, pH, and glucose concentration.
What is the Peripheral Nervous System (PNS)?
What is the Peripheral Nervous System (PNS)?
- It is a complex structure consisting of all the nerves and neurons outside of the brain and spine, transmitting signals to coordinate actions.
- It picks up data and sends it via a signal to the Central Nervous System (CNS).
- It then receives a signal back from the CNS with the command, and then carries out the action.
Important Parts of the PNS:
Important Parts of the PNS:
Autonomic Nervous System (ANS) : controls all involuntary muscle systems
- Parasympathetic Nervous System (PSNS):
- Produces what's needed for everyday life (Rest and Digest)
- Sympathetic Nervous System (SNS):
- Quick response actions (Fight or Flight)
How does Homeostasis Work with the PNS?
How does Homeostasis Work with the PNS?
Negative Feedback Loops:
Negative Feedback Loops:
They counteract the various changes in properties:
- A deviation from a normal set point causes receptors to send a signal to the brain (this is the PNS in action).
- The brain then sends an effector that creates an adaptive response.
- This adaptive response then returns the body to it's normal state, and the receptor, brain, and effector will stop their activity.
Example: Body Temperature
When you exercise, your body temperature increases. The high temperature is detected by receptors (from the PNS), which sends a signal to your brain. The control centre there then processes this information, and then activate the effectors (in this instance it's sweat glands) which will bring the body temperature back to normal.
Negative Feedback Loops also work the other way:
If you're body temperature is too low, your body will then cause to contract involuntarily (shiver), causes the hair on your body to stick out to trap a layer of air near your skin (goosebumps), and increase the release of hormones to increase heat production.
Disruptions to Feedback Distribution Loops:
Since homeostasis depends completely on feedback loops, anything that inhibits these loops will disrupt homeostasis. This could lead to bodily diseases. An example of this is diabetes.
Diabetes:
- Insulin is needed to bring down your blood glucose levels down after we eat - turning glucose into glycogen (a storage molecule).
- This pulls sugar out of the bloodstream, reducing the secretion of the insulin hormone, creating homeostasis.
- Diabetes happens when either the pancreas can't create enough of the hormone insulin, or the cells simply stop responding to it. This means that the sugar-level in the bloodstream remains high for a long time after eating.
- This creates problems:
- Muscle and fat cells don't obtain enough sugar and energy, making people feel fatigued and wearing away muscle and fat tissues
- It causes symptoms such as dehydration, and increased urination, which, over time, can create a bigger issue.
Positive Feedback Loops
Positive Feedback Loops
This sort of feedback loop is less common than the negative feedback loop, but it is still very important.
Instead of counteracting the various changes in properties, you are intensifying the change.
A common example of this is in childbirth:
- First, the baby's head pushes on the cervix, activating neurons in the brain.
- The neurons then send a signal to the pituitary gland which then secretes the hormone oxytocin.
- The oxytocin increases urine contractions, increasing the pressure on the cervix.
- This then releases more oxytocin, which increases the strength of the contractions, and so on.
- The Positive Feedback Loop continues until the baby is born.
This video gives an explanation as well as a couple more examples of Homeostasis and Feedback Loops.
This video gives an explanation as well as a couple more examples of Homeostasis and Feedback Loops.
References:
References:
Text:
Text:
B. (n.d.). Introduction to the Autonomic Nervous System. Retrieved November 08, 2017, from https://courses.lumenlearning.com/boundless-ap/chapter/introduction-to-the-autonomic-nervous-system/
Body Systems and Homeostasis. (n.d.). Retrieved November 08, 2017, from http://www.mhhe.com/biosci/genbio/maderbiology/supp/homeo.html
Homeostasis. (n.d.). Retrieved November 08, 2017, from https://www.khanacademy.org/science/biology/principles-of-physiology/body-structure-and-homeostasis/a/homeostasis
Pictures:
Pictures:
(n.d.). Retrieved November 08, 2017, from https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwixrfeCxLDXAhVP1WMKHfe1BEMQjRwIBw&url=https%3A%2F%2Fwww.khanacademy.org%2Fscience%2Fbiology%2Fprinciples-of-physiology%2Fbody-structure-and-homeostasis%2Fa%2Fhomeostasis&psig=AOvVaw0-Y_Uax-6J50wAbFU2QWZ1&ust=1510277093541720
(three pictures are from this address)
(n.d.). Retrieved November 08, 2017, from https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwifluDTxbDXAhUL3mMKHYyfD7cQjRwIBw&url=http%3A%2F%2Fwww.wickersham.us%2Fanne%2Fautonomic.htm&psig=AOvVaw0Y3yVxNcqhCnzogz7p7f9c&ust=1510284315679618
(n.d.). Retrieved November 08, 2017, from https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwiXueTzxbDXAhUS32MKHWfUDcAQjRwIBw&url=https%3A%2F%2Fcourses.lumenlearning.com%2Fwsu-sandbox%2Fchapter%2Fparts-of-the-nervous-system%2F&psig=AOvVaw0KvYRfcxEfS5Q4b-aeEnIj&ust=1510284382550583
Video:
Video:
A. (2017, September 07). Homeostasis and Negative/Positive Feedback. Retrieved November 08, 2017, from https://www.youtube.com/watch?v=Iz0Q9nTZCw4
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