Section 1 Flashcards
Who was the first to define homeostasis?
Walter Cannon (1929)
What is Homeostasis?
Refers to the maintenance of nearly constant conditions in an INTERNAL environment.
internal body conditions remain nearly constant
What are adaptive responses?
The homeostatic mechanisms that allow for a return to homeostasis
What are the conditions of homeostasis?
Contains optimum concentration of nutrient, gases, ions, and water optimal temperature
optimal pressure
What is stress?
anything that creates an imbalance in the internal environment
What is the most abundant extracellular cation?
Na+
What is the most abundant extracellular anion?
Chloride
What is the most abundant intracellular cation?
K+
List the extracellular ions in decreasing order?
Na+>Chloride>HCO3->Proteins (anion)>K+, Calcium
List the intracellular ions in decreasing order?
K+, PO4^-3, protein, magnesium, Na+
What is a feedback system?
Circular situation in which the information about the status of something is continually reported to the central control region.
Negative feedback loops
A change in a parameter that causes a response that results in a reverse of the initial back to its normal parameter
Example of a negative feedback loops?
Regulation of Arterial blood pressure.
Explain what type of feedback Arterial blood pressure is and how it works
Baroreceptors in the arterial walls sense the blood pressure either by stretching. This leads to a inhibitory signal in the medulla which stimulates the vagus nerve to decrease HR and dilation of blood vessels.
Explain positive feedback system
A change in a parameter sends signals to continue to move parameter in that direction Thus making it further from the nl
Example of positive feedback system
Childbirth. The stretching of the cervix sends signals to posterior pituitary that triggers a release of oxytocin and increase in uterine contractions. Since the child is born the signal has a natural decrease and thus does not have the detrimental effect that most of the positive feedbacks do.
What is Gain?
Gain is the degree of effectiveness with which a control system maintains constant conditions.
Gain= correction/error
What does uncontrolled system mean?
Adaptive process is not working
what is error? (in terms of gain equation)
The amount of uncorrected increase
what is the gain of a system if:
Adding to liter of blood to a controlled system and to an uncontrolled system: uncontrolled rises from 100 to 175
Controlled BP rises from 100 to 125
gain= correction/error correction= -50 error= 25 gain= -2
Which of the following has to be a transmembrane protein? A.) receptor protein B.) protein binding to cytoskeleton C.) Channel protein D.) phosphorylase
C.) Channel protein
what is the function of a cell membrane?
separate intracellular and extracellular environments and controls what enters and leaves the cell.
What is the structure of a cell membrane?
all cell membranes and plasma membranes have the same basic function, known as the “unit membrane”
Unit membrane- is a phospholipid bilayer with cholesterol inserted among the phospholipids.
Proteins are associated with the membrane.
Integral proteins are inserted into the membrane on one side or the other and are exposed on either side of the membrane
Peripheral proteins- are loosely attached to either side of the membrane and are easily removed.
Cholesterol- mediates fluidity of membrane
Integral proteins
are inserted either on one side or extend through the membrane. They are exposed on one or both sides of the membrane. Removal would destroy the bilayer.
