Homeostasis and Cell Function Flashcards
Define Homeostatis
Maintenance of nearly constant conditions in the internal environment. It is the condition in which the body’s internal environment remains relatively constant within limits
An organism is said to be in homeostasis when its internal environment has…?
Optimum concentrations of gases, nutrients, ions, and water. Optimal temperature. And optimal pressure for the health of the cells.
What is stress?
Stress is any stimulus that creates an imbalance in the internal environment
List the basic differences between extracellular and intracellular fluid compartments
Extracellular: Most abundant cation = Na+; Anion = Cl-
Intracellular: Cation = K+
What is a feedback system?
Circular situation in which the information about the status of something is continually reported to a central control region.
What is a homeostatic mechanism made up of?
Adaptive responses
What is Negative feedback?
The response reverses the direction of the initial condition.
A change in some parameter causes a response that results in a return of that parameter to normal (baseline)
Give an example of negative feedback
Baroreceptors associated with the carotid system sense increase in arterial pressure. Baroreceptors send inhibitory signals to vasomotor receptors in medulla.
Heart pumping capacity is reduced and blood vessels dilate. Arterial pressure decreases.
What is a Positive feedback?
The change is some parameter causes a response that continues to change that parameter in the same direction as before. There is no natural end in most cases. Death usually results
Give an example of Positive feedback
Birth
Stretch of cervix sends back signals that increase force of uterine contractions, which then increase the stretch on the cervix
What is Gain?
Gain is the degree of effectiveness with which a control system maintains constant conditions
In the uncontrolled system: Pressure rises from 100 to 200
In the controlled system: pressure rises from 100 to 125
What is the correction, the error and gain?
Correction = 125-200 = 75 Error = 125-100 = 25 Gain = 75/25 = 3
Which of the following would have to be a transmembrane protein? Receptor protein Protein binding to the cytoskeleton Channel protein Phosphorylase
Channel protein
What is the function of the cell membrane?
Separates the intracellular from the extracellular environments and regulates what enters and leaves the cell. Plays a role in information exchange and involved in exocytosis and endocytosis
What is the structure of the cell membrane?
Phospholipid bilayer with cholesterol inserted among the phospholipids. And proteins are associated with the membrane. Permeable to hydrophobic molecules.
What is an intergral protein?
Proteins inserted into the membrane on one side or the other or pass all the way through and are exposed on either side of the membrane
What is a peripheral protein?
Proteins loosely attached to one surface of the membrane or the other. Easily removed
Which organelle(s) is/are associated with intracellular trafficking?
Golgi Apparatus and SER
Which organelle(s) is/are associated with most ATP production?
Mitochondrion
Which organelle is directly associated with the synthesis of proteins for secretion?
RER
Pits coated with what are often associated with endocytosis?
Clatherin
Compare pinocytosis to phagocytosis
Both are endocytosis processes. Pino is cell drinking and phago is cell drinking
Endocytosis form what?
phagocytic vesicles
What makes a membrane thermodynamically unstable?
When a membrane has a free edge. Membrane must always be part of a continnum
What do lysosomes contain?
Hydrolytic enzymes at a low pH. Result of a hydrogen - ion pump
Protein synthesis involves what parts of the cell?
Ribosomes and ER
Proteins bound for lysosomes or for secretion are synthesized on what?
The RER to which the ribosomes attach
Explain digestion in the cell
Lysosomes fuse with phagocytic vesicles to form secondary lysosomes. Undigested material is left behind in residual bodies to be eliminated via exocytosis.
Proteins bound for the cytoplasm, nucleus, mitochondria, or other cell membranes are synthesized where?
Free ribosomes
What is the function of the Golgi apparatus?
Packaging proteins for secretion, forms lysosomes, modifies proteins from the RER
Explain Glycolysis
Begins with glucose, occurs in the cytoplasm of all cells.
Does not require oxygen
Produces pyruvic acid (latic acid) and small amount of ATP
What is anaerobic respiration?
Glycolysis, does not require oxygen
Explain the Kreb’s cycle and ETC
Untilizes pyruvic acid from glycolysis Only occur in the mitochondria Requires oxygen as the final electron recepor Produces CO2 and H2O Produces many ATP
What are the three forms of locomotion
Amoeboid movement
Cilia and Flagella
Microtubules
What process does not require the presence of mitochondria?
Breakdown of glucose to pyruvic acid
