Download 1 List the three components of a homeostatic response mechanism

1 List the three components of a homeostatic response mechanism and briefly describe
what the function of each is. How does negative feedback control work to terminate a
homeostatic response?
Receptor – measures the internal environment for some parameter and reports value to
integrator
Integrator – evaluates info from receptor and decides whether or not to something needs
to be done. If it does, initiates the action of the effector
Effector – actually does something to modify the internal environment
In negative feedback control, the action of the effector will eventually cause the cessation
of the homeostatic response
2 With respect to the human body, distinguish between the external environment, the
internal environment, and the cellular environment
the external environment is the atmosphere in which the organisms lives, the internal
environment consists of the interstitial fluid that bathes the cells and the plasma of the
blood. The cellular environment consists of everything inside the cell membranes of all
the cells of the body.
3 List the four chambers of the human heart and for each state 1) where blood entering
that chamber has come from and 2) where blood exiting is going. What prevents blood
from flowing back in the wrong direction?
Rt atrium – thinly muscled, blood enters it from systemic loop, blood exits it into the rt
ventricle
Rt ventricle – thickly muscled, blood enters it from rt atrium, blood exits it to pulmonary
loop
Lft atrium – thinly muscled, blood enters it from pulmonary loop, blood exits it into lft
ventricle.
Lft ventricle – thickly muscled, blood enters it from lft atrium, blood exits it into
systemic loop.
One way flow valves prevent backflow of blood into all these chambers
ng is going. What prevents blood from flowing back in the wrong direction?
4 Briefly describe the basic structure of an artery, vein, and capillary
Artery: large diameter, thick muscle layer – conduct blood away from heart
Vein: largest diameter less thick muscle layer, one way flow valves – conduct blood
towards heart
Capillary – no muscle, small diameter, large collective surface area, form extensive beds,
join arterioles to venules
5 For each of the vessels you described above, state what the relative 1) velocity and 2)
pressure is of blood flowing to them (use the qualitative terms high medium low).
Artery: velocity = high, pressure = high
Capillary: velocity = low, pressure = medium
Vein: velocity = medium, pressure = low
6 What are the three basic types of cells found in blood, what is their relative abundance,
and what is their function?
Red Blood Cell – highest abundance, role = oxygen and to a lesser extent carbon dioxide
transport
Platelet – medium abundance, role = clotting
White blood cell – lowest abundance, role = immunity& defense
7 Briefly explain the concept of negative pressure breathing as it relates to
inhalation/exhalation in the human respiratory system. What are the two possible
effectors that causes this process to occur?
In order to inhale, the volume of the thoracic cavity is increased thereby lowering the
pressure. This causes air to flow in from the relatively higher pressure external
environment into the lungs. When the volume of the thoracic cavity is reduced it
becomes higher in pressure than the external environment and air is pushed out from the
lungs. The two effectors that can do this are the diaphragm and the chest muscles around
the rib cage.
8 State the three forms (and their relative percentage) in which carbon dioxide is
transported in the blood.
7 % as CO2 dissolved in the plasma
23% as CO2 in transition to being converted to carbonic acid via Red Blood Cell
70% as bicarbonate dissolved in blood
9 What is the relationship between pH and the partial pressure of carbon dioxide in the
blood?
As carbon dioxide partial pressure increases, more bicarbonate ion and H+ ions are
formed in the plasma causing the pH to drop, thus the two are inversely related
10 List the relative partial pressure (high vs low) of oxygen and carbon dioxide in the
blood entering the capillary beds of the 1) systemic and 2) pulmonary loop
systemic loop: partial pressure of oxygen is high, partial pressure of carbon dioxide is
low
pulmonary loop: partial pressure of oxygen is low, partial pressure of carbon dioxide is
high.