homeostasis Flashcards
what is homeostasis?
- Maintaining the body’s internal environment despite changes in the external environment
- Optimal working condition
- Allows for chemical reactions in the body to progress normally
what happens if we cannot maintain homeostasis?
leads to illness or disease
what 2 systems are involved in maintaining homeostasis? what speed do they act at, how do they accomplish this?
- autonomic nervous system
- fast acting
- shorter duration
- releases neurotransmitters - endocrine system
- slower acting
- longer lasting
- releases hormones
what are the 3 necessary conditions for homeostasis?
- proper concentration of gases, nutrients, water, salt etc
- optimum temperture (37 C)
- optimum pressure
what is stress?
any stimulus that causes an imbalance in the internal environment
- can be internal or external
eg. lack of oxygen, extreme temperature, change sin blood pressure, level of nutrients
what mechanism does the body use to deal with stress in order to regain homeostasis? what is called, what is it?
- a feedback loop
- A circular situation where the status of something is monitored and then reported back to a control centre which may cause some action to change the status
what are the 2 types of feedback loops called? what are they?
- positive feedback loop
- A continuous condition where the output is the same as input until an outside factor breaks the cycle
eg. childbirth, vomiting, urination - negative feedback loop
- The output is the opposite of the input
what are the 5 steps of a feedback loop?
- Input
- Stimulus disrupts homeostasis - Receptor
- Controlled condition is monitored by receptors and sends info to control centre - Control centre
- Receives and monitors input and makes some decisions and send out signals - Effector
- Bring about a change - Output
- Response that alters the controlled condition
- Return to homeostasis → or continued loop if not back to normal
what is more common in the body, negative or positive feedback loops?
negative feedback loops
what is the feedback loop when the body is too hot?
- Stimulus → increase in body temperature
- Receptor → Thermoreceptors → take info of temp, send to control centre
- Control centre → hypothalamus decides too hot, must cool down
- Effectors → 1. Sweat glands are activated (so evaporation can cool skin, and 2. Blood vessels in the skin dilate to help cool blood at skin surface
- Output → temp decrease
what is the feedback loop when the body is too cold?
- Stimulus → decrease in body temperature
- Receptor → Thermoreceptors → take info of temp, send to control centre
- Control centre → hypothalamus decides too cool, must warm up
- Effectors → 1. Shivers, skeletal contractions to warm up, and 2. Blood vessel constriction, pulls blood closer to where its warmer
- Output → temp increase
how are blood glucose levels controlled?
by “battling” of hormones- insulin and glucagon.
what is the feedback loop when the glucose levels in blood increase?
- Stimulus → glucose levels rising
- receptor –> sugar receptors in pancreas
- Control centre → pancreas, beta cells release insulin
- effectors –> 1. Liver takes up glucose and stores it as glycogen, and 2. Body cells take up more sugar (out of blood)
- Output → reduction in blood glucose levels
what is the feedback loop when the glucose levels in blood decrease?
- stimulus → drop in glucose levels
- receptors –> sugar receptors in pancreas
- control centre → pancreas, alpha cells release glucagon
- Effector → liver starts to break down stored glycogen and releases glucose into the blood
- Output → blood glucose level rise
what 3 things can be an effect of diabetes?
- Loss of insulin
- No uptake of glucose
- Leads to ketoacidosis
