Homeostasis and feedback mechanisms

Question 1

Homeostasis

Answer 1

Dynamic maintenance of stable conditions for cells so that cell is able to survive.
Not an exact point but a range of normal for various parameters.
Internal environment is defined as the extracellular fluid.

Question 2

What are regulated directly by homeostasis

Answer 2

plasma and ECF

-organ systems function to homeostatically maintain some extracellular parameter.

Question 3

what is regulated indirectly by homeostasis

Answer 3

ICF

Question 4

What kind of things do cells need

Answer 4

ecf (high in sodium), certain ph, temperature, glucose, osmolarity, nutrient balance, waste disposal

Question 5

3 body compartments

Answer 5

extracellular compartment (outside the cells and plasma 3L), intracellular compartment (28 L) and interstitial fluid (11 L)

Question 6

ECF divided into…

Answer 6

plasma (3L) within the vascular system
interstital fluid (14L) directly bathing cells

Question 7

ECF is high in

Answer 7

NA+, Cl-, HCO3-, 02, glucose and fatty acids

Question 8

ICF size and contains…

Answer 8

28L

k+, Mg+ and PO4

Question 9

where are most of the proteins found

Answer 9

ICF

Question 10

what parameters are are regulated by homeostasis

Answer 10

appropriate concentration of gasses, ions, nutrients, ions and H20, appropriate temperature level and appropriate plasma volume

Question 11

Two basic mechanisms for homeostatic regulation

Answer 11

intrinsic regulation and extrinsic regulation

Question 12

Example of intrinsic regulation

Answer 12

occurs within a cell or tissue without the help of a hormone or nerve.

ex. scientist should be able to remove a tissue and/or organ and provided with the same physiological conditions and still see the regulatory response
ex: local control of blood flow, frank starling law of the heart

Question 13

forms of intrinsic regulation

Answer 13

active hyperemia (increase in blood flow in response to the products of metabolism)
autoregulation (keeps blood flow constant despite changes in mean arterial blood pressure)

Question 14

extrinsic regulation

Answer 14

occurs from outside of the tissue by an endocrine or nervous system.
ex. activation of the PNS or SNS

Question 15

neuro extrinsic mechanisms

Answer 15

tends to be rapid, fast on and off,

Question 16

endocrine mechanisms

Answer 16

slower and have longer effects

Question 17

feedback loop

Answer 17

way to control some physiologic parameter. A change in that parameter exerts a stimulus on the system. The system sense the stimulus then communicates the intensity with the control center or integrating center. The control center evaluates from normal or from the setpoint. If an action is needed the control center communicates this to an effector (muscle or gland). Effector produces a response to the stimulus.

Question 18

Negative feedback loop

Answer 18

The response from the effector opposes the stimulus and returns the system to setpoint.
ex: BP, temp, H20, oxyhemoglobin curve baroreceptors, body fluids, furnace

Question 19

Positive feedback system

Answer 19

response from the effector reinforces the stimulus and adds an additional increase to the stimulus.

ex: labor, orgasm, action potential, lactation, blood clotting, hormonal chages leading to ovulation
- good for building to a completion event

Question 20

Factors that affect normal ranges or set point

Answer 20

age, gender, genetics, environmental factors

Question 21

ability to maintain homeostasis is dependent on

Answer 21

Integrity of the physiologic system (age, gender, genetics) the nature of the stress and situational factors (time and place) if homeostatic mechanisms cannot be maintained disease results

Question 22

examples of stressors that can change physiologic parameters

Answer 22

pathogens and parasites, genetic disease, cancer, autoimmune disease, degenerative changes, trauma, toxins, environmental factors, nutritional deficiencies or excesses

Question 23

Parts of the feedback loop

Answer 23

Receptor (monitors some parameter)
Afferent (receptor communicates to the integrating center and a neuro mechanisms via this pathway)
Control Center (determines what the parameter should be and what type of action should be taken to maintain the parameter)
Efferent (motor pathway, acts on an effector)
Effector (either a gland or muscle brings about some response that effects the parameter)