Homeostasis and the Internal Environment

You should be able to differentiate between a agonistic and antagonistic chemical message.

. An antagonistic blocks chemicals from going into receptor .Agonistic chemical that produces a response such as inhibition of action potential when it binds to a receptor like opiates or cannabis, nicotine.

12. You should be able to name the different types of chemical messages and explain how they differ from one another.

1) Paracrines• Local chemical messengers • Exert effect only on neighbouring cells in immediate environment of secretion site 2) Neurotransmitters• Short-range chemical messengers • Diffuse across narrow space to act locally on adjoining target cell (another neuron, a muscle, or a gland)2 Chapter 4 Principles of Neural and Hormonal Communication Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning Chemical Messengers 3) Hormones• Long-range messengers • Secreted into blood by endocrine glands in response to appropriate signal • Exert effect on target cells some distance away from release site 4) Neurohormones• Hormones released into blood by neurosecretory neurons • Distributed through blood to distant target cells

10. You should be able to identify specific components of reflex arcs.

1. Receptor—reacts to a stimulus and found at the end of a sensory neuron. 2. sensory (afferent) neuron—sends impulses towards the CNS along an afferent pathway. 3. Integration center—consists of one or more synapses in the CNS. 4. Motor (efferent) neuron—nerve impulses conducted along an efferent pathway from the integration center to an effector. 5. Effector—recieves info. from the motor (efferent) neuron and does that action.(tissue or organ).

9. You should be able to list, in the correct sequence, the components of a generic reflex arc.

:1.receptor 2.sensory (afferent) neuron 3. Integration center CNS and endocrine system 4. Motor (efferent) neuron 5. Effector

11. You should be able to explain how cells communicate with one another.

:Cell to cell recognition...Chemical signals...Hormones

4. You should be able to list the parameters regulated by homeostatic mechanisms.

:body temperature, arterial blood pressure, and ph at 7.4

3. You should be able to explain why the maintenance of homeostasis is so important, and describe the consequences of a departure from this state.

:ph balance...a body too acidic or alkaline would not survive .. you would die

8. You should be able to differentiate between reflexes and local homeostatic responses, intrinsic and extrinsic controls

:reflexes deal with involuntary muscle reactions...local homeostatic responses(int,extrin) deal with changes in our bodies that involve a disruption in homeostasis and also a return to it.

2. You should be able to explain what constitutes the human "internal environment".

:the internal environment is made up of tissue fluid. That bathes all cells making up the body. Extracellular fluid!

7. You should be able to explain how a positive feedback system works against homeostasis.

:there is a stimulus moving in one direction in a pfs and there is no response. If there eventually is no negative feedback loop we will die.

5. You should be able to explain how a negative feedback loop works to maintain homeostasis.

:when a stimulus moves away from the set point there is always a response bringing it back to the set point, therefore maintaining homeostasis.

6. You should be able to explain one physiological negative feedback system (glucose or temperature regulation).

:when the external temperature drops far below our bodies temperature , which is a negative feedback, then our bodies respond by making adjustments that result in the generation of body heat.

13. You should be able to explain and diagram the relationship between the shape of a chemical message and its receptor molecule.

Shape of chemical message must be the same as receptor but must also contain what the receptor needs chemically- Lock and Key the key might fit the lock but also has to turn

extracellular fluid—

body fluid outside of cells(20% plasma..80% interstitial fluid)

intracellular fluid—

fluid within the cell:

: negative feedback loop

has a stimulus that moves away from the set point and always a response that moves back to the set point achieving homeostasis:

: positive feedback loop

has a stimulus that moves away from the set point and no response moving back toward the set point but eventually all pfl's are eventually controlled by negative feedback loops.

intercellular fluid—same as extracellular:

intercellular fluid—same as extracellular:

homeostasis—

maintenance of a relatively constant internal environment:

: transcellular fluid

not inside cells, separated from plasma and interstitial fluid.. it is a fluid for specialized compartments such as occular and spinal:

interstitial fluid

—solution that bathes and surrounds the cells: plasma—colorless watery fluid of the blood and lymph that contains no cells but which blood cells travel in