Chapter 4, Cell Physiology Flashcards
Fluid compartments in the body include
intracellular
Interstitial - surrounding cells, and
intravascular -found in lymphatic and blood vessels)
What is an electrolyte
An electrolyte is a charged particle (an anion or a cation) capable of conducting an electric current in solution.
Give examples of cations found in the body
Cations are positively charged and include potassium (K+), magnesium (Mg2+), calcium (Ca2+), and sodium (Na+).
Give specific examples of solutes in the body
Large molecules such as soluble proteins, phospholipids, cholesterol, and triglycerides
Smaller electrolytes such as sulfate, hydrogen phosphate, chloride, bicarbonate, magnesium, calcium, potassium, and sodium.
What is the relationship between solutes and osmolaty
Osmolality is a measurement of the concentration of solute in fluid. As the concentration of solute increases (or decreases), so too does the osmolality. In other words, fluids that have a high concentration of solutes have a high osmolality.
Why do changes in osmolaty cause fluids to move from one compartment to another
Normally, osmolarity in the intracellular fluid and extracellular fluid is equal. If either side ever has a few more solutes, than water will flow in that direction to lower the concentration slightly and maintain the balance. This process is called osmosis.
Give 2 examples of conditions that result in fluid shifts
Pulmonary edema and cutaneous edema
How do changes in osmolaty of body fluids affect an animals thirst and it’s ability to concentrate or dilute it’s urines.
A hormonal feedback loop helps maintain the osmolality of body fluids within a very narrow range of normal.
An increase in the osmolality of blood, for example, stimulates the desire to drink and the release of antidiuretic hormone (ADH). ADH then stimulates the kidney to resorb water from protourine resulting in the concentration of urine.
The opposite happens if the osmolality of blood becomes too low. The release of ADH in the brain is repressed and urine becomes concentrated via active removal of water from protourine in the kidney.
What is diffusion? Is it active or passive?
Diffusion is the passive movement of solute down a concentration gradient. (Greater to lesser until equilibrium).
What molecules are more likely to diffuse into a cell?
Small molecules, lipid soluble and charged molecules (through channel proteins).
How is facilitated diffusion different from simple diffusion? What is the limiting factor in the rate of facilitated diffusion
Facilitated diffusion requires the assistance of an integral protein or carrier protein located in the bilayer. The number of available carrier proteins limits the rate of facilitated diffusion.
What effect does a hyportonic solution have on a cell? What passive membrane process causes this effect?
If the extracellular fluid is hypotonic, the inside of the cell contains a higher concentration of solutes, so water would flow by osmosis into the cell and cause it to swell and possibly burst.
What is the relationship between hydrostatic pressure and filtration
Filtration is based on a pressure gradient. Liquids may be pushed through a membrane if the pressure on one side of the membrane is greater than that on the other side. The force that pushes a liquid is called hydrostatic pressure.
What is another name for hydrostatic pressure in the body
Blood pressure
What defines passive membrane process
A passive membrane process is one that does not require energy (ATP).
When is a membrane process considered active
The movement of molecules and substances across the cell membrane is considered active when the process requires ATP.
How do electrolytes enter the cell
Electrolytes enter cells via active transport (without the assistance of a concentration gradient).
What is the difference between a symport and an antiport system
Both symport and antiport move more than one substance at a time.
Symport- If all the substances are moved in the same direction, the system is called a symport system.
Antiport- when some substances are moved in one direction and others moved in the opposite direction, the system is called an antiport system.
Describe how potassium and sodium enter and leave the cell
Because of the concentration gradients of sodium (Na+) and potassium (K+), potassium tends to diffuse out of the cell and sodium diffuses in. To maintain appropriate levels of intracellular potassium and extracellular sodium, the cell must pump potassium into the cell and pump out sodium. The rate of transport depends on the concentration of sodium ions in the cell.
Because diffusion is ongoing, the active transport system must work continuously. ATP is provided by cellular respiration and, with the assistance of the enzyme ATPase, is broken down for use as energy on the inner surface of the cell membrane. The pump can cycle several times using just one molecule of ATP, so that for every molecule of ATP, two potassium ions are moved intracellularly and three sodium ions are moved extracellularly.
What is Endocytosis.
Endocytosis transports large particles or liquids into the cell by engulfing them. An example is neutrophils (White blood cells)
What is excretion? Secretion? They are examples of what?
Excretion is the movement of waste products from the intracellular to the extracellular environment, and secretion is the movement of manufactured molecules from the intracellular to the extracellular environment. Both are examples of exocytosis.
What are the principle electrolytes (ions) involved in maintaining a cells resting membrane potential
Sodium and Potassium
Is there normally a higher concentration of Sodium inside or outside the cell? What about Potassium
Sodium is 10 to 20 times higher outside the cell than it is inside. Potassium is 10 to 20 times higher inside the cell than outside.
What are the two major phases of a cell’s life
Interphase, when the cell is growing, maturing, and differentiating; and mitotic phase, when the cell is actively dividing.
Is the cell resting during interphase? Why or why not
No. Before each cell can divide, a perfect copy of the DNA must be created to pass on to the daughter cells In addition, all of the enzymes and other proteins needed to drive cell division must be created during interphase.
Describe prophase
Invisible chromatin- turns into two identical chromatids linked in middle by centromere
Spindle apparatus forms with centriole’s astal fibers
Nuclear envelope disintegrates
P- Chromatid Pops up, Centrioles Pushed apart
Less important-
Chromatin visible with light microscopy.
Cytoplasm becomes more viscous as microtubules from the cytoskeleton are disassembled and the cell becomes round.
Microtubules lengthen, they push the centrioles farther and farther apart.
Mitotic spindle is formed.
Because transcription and protein synthesis cannot occur while the DNA is tightly coiled, the appearance of chromosomes marks the cessation of normal synthetic processes. Prophase is thought to conclude with the disintegration of the nuclear envelope.
Describe Anaphase
The centromeres of the chromosomes split apart and each chromatid becomes its own chromosome as they move away from each other
Anaphase - Apart and Away
Less important -The
Spindle fiber separates & each spindle segment shortens
Chromosomes take on a V shape as they are dragged at their midpoint toward the centrioles at opposite ends of the cell.
The cell becomes elongated, and the cytoplasm begins to constrict along the plane of the metaphase plate.
Shortest phase
Describe Metaphase
Chromosomes line up randomly in the exact center of the spindle, known as the equator.
Metaphase- middle
Less important
Evenly spread chromosomes form what is called the metaphase plate midway between the poles of the cell.
The centromere of each chromosome is attached to a single spindle fiber. (In meiosis there are two successive divisions, ultimately producing four daughter cells. In mitosis, there is only one division and it produces two daughter cells.)
