Homeostasis Flashcards
Define and detail Homeostasis
- Homeostasis is the maintenance of a stable internal environment
- Various control systems act to prevent harmful changes in the composition of body fluids and the environment inside our cells
- Failure to maintain homeostasis leads to illness or even death
Describe what Homeostatic regulation is
- Homeostatic regulation refers to the physiological systems the body uses in order to preserve and maintain homeostasis
- The two general mechanisms can be can be divided into Auto regulation and Extrinsic Regulation
- Homeostatic regulation involves a Receptor - sensitive to a particular environmental change, A Control Center - receives and processes information from receptor and an Effector - responds to command of CNS to oppose or reinforce the stimulus
What is Auto regulation in regards to Homeostasis
Auto regulation involves cells, tissues, organs and organ systems and is the process of these elements adjusting in response to environmental change.
Give an example of auto regulation in Homeostasis
When oxygen levels decrease in a tissue, the cells release chemicals that dilate the blood vessels in turn increasing the amount blood flow and providing more oxygen in the needed region
What is Extrinsic regulation
- Extrinsic regulation specifically involves the Nervous system or the Endocrine system
- These systems detect a change in the external environment and send either an electrical signal (Nervous system) or a Chemical messenger (endocrine system) to control or adjust the activities of other or many systems simultaneous
Give an example of extrinsic regulation involving the nervous system
- For instance, if you expose your hand to an open flame, the heat from the flame would produce pain and disturb the localized homeostasis
- The nervous system would send a signal to muscle to contract and pull the hand away from the heat.
- The signal is rapid and short term
Give an example of extrinsic regulation involving the endocrine system
- The regulation of Blood Glucose levels
- Endocrine system (specifically the pancreas) detects a change in the blood glucose levels and as a result instructs the pancreas to releases insulin
- Insulin binds to receptors of various cells causing them to take in glucose form the bloodstream and convert it to glycogen
- This brings the blood glucose levels down to a normal level
What are the 6 main components to Homeostasis
Stimulus - Initial change in environment
Receptor - they detect the change in environment
Afferent Signal - this is a signal going toward the control center
Control Center - Brain evaluates information and makes a decision
Efferent Signal - A signal going away from the control center
Effector - Receives efferent signal and makes a change
Describe what negative feedback is
Negative feedback is where the effector/outcome negates or opposes the stimulus
e.g. change in temperature might be the stimulus, the outcome of the effector would be the opposite of the stimulus. So if the stimulus was an increase in temp the effector would decrease the temp
Give an example of negative feedback
Body Temperature control
- Stimulus (hot day increases the body temprature)
- Receptors (Thermo - receptors pick up this increase in temperature and sends an electrical signal to the CNS)
- Afferent signal (signal toward the control center)
- Control center - Hypothalmus (thermoregulator in the brain) decides what to do with the received information in this case decrease body temp
- Efferent Signal - signal away from the CNS TO AN EFFECTOR
- Effector - Blood vessels and sweat glands in the skin respond by increasing blood flow and increase sweating to bring the temperature down. NEGATING OR OPPOSING THE INITIAL STIMULUS
Describe what positive Feedback
Positive feedback is when the effector amplifies the initial stimulus
e.g. Child Birth
Stimulus - Initial stimulus would be the baby’s head stretching the Cervix, the effector would be the Uterus contracting which would in turn stretch the Cervix even more
Give an example of posostive feedback in homeostasis
Child Birth
Stimulus - stretching of the cervix
Receptor - picked up by receptors in the cervix
Afferent signal - sent to CNS
Control center - Hypothalamus Decides to release Oxytosin (Hormone which causes the uterus to contract)
Efferent Signal - sent from the CNS to the effector
Effector - Hormone reaches the Muscle causing Uterus to contract and further stretch the cervix. The initial stimulus is reinforced/amplified
Define equilibrium
A state of equilibrium exsists when opposing processes or forces are in balance.
e.g. when muscles become more active more heat is produced. in order to establish a state of equilibrium more heat must be lost from the skin surface to return the body temperature to within its optimal range
Why is negative feedback the primary mechanism of Homeostasis
Positive feedback is much less common than negative feedback in body systems because it creates a rise in response. It accelerates the process, allowing the cell no control over it. Also, positive feedback leads the system away from the balance whereas negative feedback naturally aims to maintain homeostasis.
