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What is Cannon's first postulate?
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What is Cannon's second postulate?
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Physio Homeostasis
Ch 6 Homeostasis pg 196 - 210
| Question | Answer |
|---|---|
| What is Cannon's first postulate? | The nervous system has a role in preserving the "fitness" of the internal environment. |
| What is Cannon's second postulate? | Some systems of the body are under tonic control |
| What is Cannon's third postulate? | Some systems of the body are under antagonistic control |
| What is Cannon's fourth postulate? | One chemical signal can have different effects in different tissues |
| What is the difference between tonic control and antagonistic control? | Tonic control usually involves one control system, but antagonistic control uses two |
| How can one chemical signal have opposite effects in two different tissues? | A signal can have opposite effects by using different receptors or different signal pathways |
| What is the difference between local control and reflex control? | Local control takes place in or very close to the target cell. Reflex control is mediated by a distant integrating center |
| Name the seven steps in a reflex control pathway in their correct order | Stimulus, sensor or sensory receptor, afferent pathway, integrating center, efferent pathway, target or effector, response (tissue and systemic) |
| What is the drawback of having only a single control system (a heater) for maintaining aquarium water temperature in some desired range? | If the aquarium water became overheated, there is no control mechanism for bringing it back to the desired range |
| Does the aquarium heating system function using positive feedback or negative feedback? | Negative feedback shuts off the heater. |
| Reflex Pathway | An integrating center located away from the affected cell or tissue receives information, evaluates it, and decides whether to send a chemical or electrical signal to initiate a response |
| Long distance reflex pathways involve two control systems: | the nervous system and the endocrine system |
| Local control occurs when | a cell or tissue senses a change in its immediate vicinity and responds within the region where the change took place |
| Three primary components of a response loop | an input signal, the integration of the signal, and an output signal |
| What is a threshold? | a minimum stimulus that must be achieved to set the reflex response in motion |
| What is tonic control? | Has a basal level of activity (not zero or max) that can increase or decrease that response. Like the volume knob on the radio |
| What is antagonistic control? | Systems that work in opposition to each other which contain set points and normal ranges of regulated variables. Has a sinusoidal curve. Ex. body temp |
| What is acclimatization? | The adaptation of physiological processes to a given set of environmental conditions (natural approach) |
| What is acclimation? | The process is induced artificially in a lab setting |
| What is a feedback loop? | Feedbackloops are homeostatic which means that they are designed to keep the system at or near a set point so that the variable being regulated is relatively stable. |
| What is a positive feedback loop? | It occurs when the response reinforces the stimulus rather than decreasing or removing it. Its response sends the regulated variable further from its normal value and needs some intervention or event outside the loop to stop the response. |
| What is oxytocin? | It is a hormone which causes the uterus to contract and push the baby's head harder against the cervix, further stretching it. |
| What is feedforward control? | A reflex that evolved for the body to predict or anticipate that a change is about to occur. It starts the response loop. ex. salivation reflex |
| What is the pathway of a simple neural reflex? | Stimulus, receptor, sensory neuron (afferent pathway) CNS integrating center, efferent neuron, release of neurotransmitter onto target cell (effector) causes a respons |
| What is the pathway of a simple endocrine reflex? | Stimulus, receptor on an endocrine integrating center, releases classic hormone, which goes into the bloodstream, binds to target cell (effector) which causes a response |
| What is the pathway of a neurohormone reflex? | Stimulus activates receptor&binds to sensory neuron(afferent pathway) which goes to CNS integrating center &releases NT. The NT is picked up by efferent neuron &releases neurohormone to bloodstream,exits,binds to target cell (effector), causes a response |
| What is an example of a simple neural reflex? | A knee jerk |
| What is an example of a neurohormone reflex? | Secretion of oxytocin in response to suckling |
| What is an example of a simple endocrine reflex? | Insulin release in response to an increase in blood glucose |
Created by:
audrey90