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PHYSIOLOGY STUDY GUIDE

Terms in this set (29)

What is internal environment? Where is it located?
The method by which our cells obtain nutrients and get rid of wastes indirectly. It is also called extracellular fluid. Located within the ECF, which is outside the cell but inside your body.
A semiliquid medium surrounding most cells of the body.
Located in the body and is 20% of body weight and extracellular fluid.
What should be the function of extracellular fluid?
To provide cells with basic needs and if the cell survives, the organism survives.
What is a definition of homeostasis?
Relatively stable physical and chemical composition of the internal environment, which results from the actions of regulatory systems.
What is meant by "relatively stable" physical and chemical composition?
Prove it with body temperature.
What are 2 divisions of the internal environment?
Extracellular Fluid and Plasma
What is meant by a regulatory system?
A system that regulates a homeostatic variable like our body temperature or sodium levels in plasma.
Be able to list the organ systems.
Circulatory System
Integumentary system
Respiratory
Reproductive
Cardiovascular
Musculoskeletal
Immune
Digestive
Endocrine
Lymphatic
Nervous
Urinary
Understand what is meant by the relative constancy of homeostasis.
relative constancy: The body needs to be kept as constant as possible, but must be able to vary somewhat to allow for changing "external conditions"

The value can be referred to as "set points", and it required a lot of energy.
Understand also how the body uses a hierarchy to preserve homeostasis.
In order to survive, the body may sometime sacrifice the homeostasis of one or more organ system to keep others going.
For example, shivering when it's cold.
Shock: the cardiovascular system fails. In compensated shock the kidneys essentially shut down so that the cardiovascular system can survive.
What are the components of a stimulus-response sequence?
- 1. Receptors
Sense a change in a variable
- 2. Afferent pathway
- 3. Integrating center
Interprets the stimulus (you will use your brain)
- 4. Efferent pathway
- 5. Effector organs
Responds to the original stimulus
Do most homeostatic systems employ negative feedback or positive feedback?
Negative feedback because most effector organs push homeostatic variable in the direction opposite that of the original change.
It favors the relative constancy
Are some positive feedback systems necessary?
Yes, some positive feedbacks are necessary, such as blood clotting, or labor/childbirth.
What is the purpose of receptors located on the surface of cells?
Receptors on the surface of the cells
Understand the following: specificity, affinity, saturation, agonists, antagonists.
Specificity
Affinity
Saturation
Agonists
Antagonists
Molecules move in groups in response to pressures. This is known as?
It is called the Bulk flow.
What is the goal of any diffusing system? How can diffusion be defined?
The goal of diffusion is equilibrium.

The movement of a group of molecules from an area of relatively higher to an area of relatively lower concentration.
Understand the 5 factors that affect diffusion rate.
1. Gradient*. Most easily defined as the "difference in concentrations" between 2 points. The greater the difference, the faster the diffusion rate.
2. Molecular weight: the lower the MW, the faster the rate of diffusion.
3. Distance: the closer molecules are to the membrane, the faster the diffusion rate.
4. Cross-sectional area of the surface through which molecules can diffuse. Increase the cross-sectional area; increase diffusion rate.
5. Temperature. Increased temperature increases diffusion rate.
What are the 3 forms of gradients?
a) Concentration
b) Pressure
c) Electrical
What are the 3 main structural features of a membrane?
A. Phospholipid bilayer- tends to repel water

B. Pores- protein "holes" in the membrane

C. Receptors- proteins imbedded in the membrane
What are 2 functions of plasma membranes?
1. Holds the cell together.

2. Regulates passage of materials in and out of the cell. Materials can pass through the membrane via:
A. Simple diffusion through the lipid bilayer
B. Simple diffusion through pores
C. Passage through receptors (CMT)
Identify the 3 routes of passage of materials across membranes (these are the same as structural features).
1. Simple diffusion through the lipid bilayer
2. Simple diffusion through pores
3. Passage through receptors (CMT)
Understand which types of molecules can pass through membranes, and the routes used:
lipid bilayer: O2 and CO2

pores: water

receptors: glucose, Na+, K
because of the diameter of the pores.
Be able to distinguish between simple diffusion and facilitated diffusion.
simple diffusion:
Simple diffusion: Material passage from areas of higher to areas of relatively lower concentration, either through the lipid bilayer or through pores. Requires no energy; the goal is equilibrium

Facilitated Diffusion: follows all the rules of simple diffusion (higher to lower, no energy, equilibrium) except that receptors are used for material passage. (glucose, amino acids, Na+, K+)
What is the purpose of an active transport system?
Mechanisms that "push back" the molecules
Be able to explain 2 differences between active transport and diffusion.
1. Molecules move from lower to higher concentrations

2. Requires energy!
Do homeostatic systems maintain equilibrium or a steady state?
Maintain a steady state
Is osmosis the diffusion of water? What are solutes and solvents in a solution?
Yes, solute is the solid forms and solvent is in the liquid forms. A simple diffusion.
What is meant by a system that relies on osmotic pressure?
Some living systems, notably capillaries, rely on osmotic pressure. Water moves freely but solutes do not. Here the solutes will be plasma proteins:
In capillaries, blood pressure forces water out of the capillary. Water is lost to the surrounding tissue; there is the possibility of plasma loss in blood, and edema in surrounding tissues.
Osmosis draws the water back; edema is prevented, and blood retains its water volume.
Be able to explain how osmosis occurs with isotonic, hypotonic, and hypertonic solutions.
Plasma is an Isotonic solution. If red blood cells are placed in plasma, the plasma should have the same osmolarity as RBC, so that there is no NET movement of water.

If RBC are placed in a Hypotonic solution, they will swell and burst. (Erythrolysis)

If RBC are placed in a Hypertonic solution, they will shrivel up. (crenate)
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