Peripheral Nervous System

Describe the main divisions of the Peripheral Nervous System (PNS) and their subdivisions.

The PNS is connected to the CNS and consists of two main divisions:

1. Sensory (Afferent): Carries signals from the body to the CNS.
2. Motor (Efferent): Carries signals from the CNS to the body.
   • Somatic: Controls voluntary movements of skeletal muscles.
   • Autonomic: Controls involuntary functions, further divided into:
     • Sympathetic: Responsible for "fight/flight" responses.
     • Parasympathetic: Responsible for "rest/digest" functions.

Outline the typical "Sensory Pathway Chain" from stimulus reception to cortical processing.

Stimulus \rightarrow Receptor \rightarrow 1st order neuron \rightarrow Spinal cord/Medulla \rightarrow 2nd order neuron \rightarrow Thalamus \rightarrow 3rd order neuron \rightarrow Somatosensory Cortex

What is the primary function of sensory receptors, and what is their general signal pathway?

Function: Detect stimulus \rightarrow convert \rightarrow AP (electrical signal).
Route: Receptor \rightarrow Sensory Neuron \rightarrow CNS

List and describe different "Receptor Types by Modality".

1. Mechanoreceptors: Detect pressure, stretch.
2. Thermoreceptors: Detect temperature.
3. Nociceptors: Detect pain.
4. Photoreceptors: Detect light (located in retina).
5. Chemoreceptors: Detect chemicals (e.g., taste, smell, blood pH).

List and describe different "Receptor Types by Location".

1. Exteroceptors: Located externally (e.g., skin, special senses).
2. Interoceptors (Visceroceptors): Located internally (e.g., organs).
3. Proprioceptors: Detect body position (e.g., in muscle, joint, tendon).

Explain the functions of major "Proprioceptors".

1. Muscle spindle: Detects stretch \rightarrow muscle contracts.
2. Golgi tendon organ: Detects tension \rightarrow muscle relaxes.
3. Joint receptors: Detect position, angle.

Differentiate between "Tonic" and "Phasic" receptors in terms of adaptation.

1. Tonic: Slow adaptation, always active (e.g., pain, posture).
2. Phasic: Fast adaptation, adapt quickly (e.g., smell, touch) \rightarrow Stops firing if stimulus is constant.

What is a "Reflex," and how many steps are involved in its pathway?

A reflex is a fast, involuntary, and protective response. Its pathway involves 5 steps.

Detail the "5 Steps" of a "Reflex Arc".

1. Receptor: Senses stimulus.
2. Sensory neuron: Transmits signal to CNS.
3. Integration center: Processes signal (e.g., spinal cord/brain).
4. Motor neuron: Transmits signal from CNS.
5. Effector: Muscle/gland response.