Lecture 1 - Homeostasis And Cell Function Flashcards
Define Homeostasis
- Refers to the maintenance of constant conditions in the internal environment
- Condition where the body’s internal environment is kept constant within limits
- A homeostatic mechanism is made up of adaptive responses
What conditions define an organism in homeostasis?
Define Stress
- An organism is said to be in homeostasis when its internal environment contains the optimum concentrations of gases, nutrients, ions, and water, has an optimal temperature, and has an optimal pressure for the health of the cells.
- Stress is any stimulus that creates an imbalance in the internal environment.
What cation is most abudant in the extracellular environment?
In the intracellular fluid?
3. What anion is most abundant in the extracellular fluid?
- Sodium
- Potassium
- Chlorine
Define a feedback system
Circular situation in which the information about the status of something is continually reported to a central control region
Give characteristics and examples of a negative feedback loop
A change in some parameter (i.e., blood pressure) causes a response that results in a return of that parameter to normal (baseline). The response reverses the direction of the initial condition.
- Characteristics: Diminishes the original change
- Stabilizing
Give the definition, characteristics, and examples of positive feedback loops
- A change in some parameter that causes an intensification of the original effect.
- Generally this enhances the original input/change, but is often destabilizing and can lead to runaway effects.
- A time when it works is when the stretch of the cervix during delivery sends back signals that increase the force of uterine contractions which increases the stretch on the cervix, which is terminated naturally by childbirth.
What is the Gain of a Feedback Loop?
What is it’s general formula?
Gain is the degree of effectiveness with which a control system maintains constant conditions
Gain = Correction / Error Correction = The amount of change a feedback loop emits on a function relative to it's uncorrected change. Error = The amount of increase that still occurs in a corrected setting despite the feedback loop.
If Blood pressure spikes due to a blood drop such that:
Uncorrected/Uncontrolled Goes from 100 bpm to 175 bpm
And 2 liters of blood are added to the system such that
Corrected/Controlled goes from 100 to 125
What is the gain?
Corrected = (-50) Error = (25)
Gain = (-2)
Give a basic description of the unit membrane
- All cells (and most organelles) possess a cell membrane, comprised mostly of phospholipids and cholesterol.
- Integral proteins are either 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.
- Peripheral proteins are loosely attached to one surface of the membrane or the other and are easily removed.
What are the primary functions of the cell membrane?
- Serves as a selective filter and limits what can pass from one side to the other.
- Lipid soluble substances can generally pass readily across the membrane.
- Plays an integral role in defining the intracellular and extracellular fluid composition.
- Plays a role in information exchange between the cell and its environment.
What is the definition of Endocytosis Exocytosis Pinocytosis Phagocytosis
- Active transport absorption of vesicles outside of the cell
- Exocytosis - The process of releasing components through the cell membrane
- Pinocytosis - Cell drinking- The process of liquid absorption
- Phagocytosis - Cell…swallowing? - A little unclear here, but this is the process of absorbing whole solids or cells.
Which organelles are involved in cell digestion?
- Endocytosis absorbs cell “food” into capsules called phagocytic vesicles. The lysosome fuses with these vesicles to form the Secondary Lysosome.
- Contain hydrolytic enzymes at a low pH
- Result of a hydrogen-ion pump
- Undigested material is left behind within residual bodies.
- Residual bodies may be eliminated via exocytosis
Describe the functions of ribosomes along with the Endoplasmic Reticulum
- They are Both associated with protein synthesis
- Proteins bound for lysosomes or for secretion are synthesized on rough ER (RER) to which the ribosomes attach.
- Proteins bound for the cytoplasm, nucleus, mitochondria, or to other cell membranes are synthesized on free ribosomes.
Describe the function of the golgi apparatus:
Plays a role in packaging proteins for secretion:
- i.e., O-glycosylation
- Forms lysosomes
- Modifies proteins from the RER
List the two forms of cellular respiration
Glycolysis - Anaerobic respiration
Kreb’s Cycle and Electron Transport Chain - Aerobic Respiration
