exam 2 a&p

BSC 251 – Unit 2 Master Study Guide

Sensation vs Perception

• Sensation:
  • Definition: The detection of stimuli by sensory receptors.
• Perception:
  • Definition: The conscious interpretation of sensory information in the cerebral cortex.
• Key Point: Not all sensations reach conscious perception.

Types of Sensory Receptors

• Mechanoreceptors:
  • Function: Detect touch, pressure, and vibration.
• Thermoreceptors:
  • Function: Detect temperature changes.
• Photoreceptors:
  • Function: Respond to light.
• Chemoreceptors:
  • Function: Responsible for smell (olfaction) and taste (gustation).
• Nociceptors:
  • Function: Detect pain stimuli.

Receptor Adaptation

• Tonic Receptors:
  • Characteristic: Slow adapting receptors.
  • Example: Pain receptors that continue to send signals.
• Phasic Receptors:
  • Characteristic: Fast adapting receptors.
  • Example: Smell receptors and Pacinian corpuscles that quickly adjust to changes.

Major Ascending Sensory Tracts

• Spinothalamic Tract:
  • Function: Transmits pain, temperature, and crude touch information to the brain.
• DCML Pathway (Dorsal Column-Medial Lemniscus):
  • Function: Carries signals for fine touch, vibration, and proprioception.
• Spinocerebellar Tract:
  • Function: Relays proprioception information to the cerebellum.

Motor Control

• Upper Motor Neurons:
  • Origin: These neurons originate in the brain.
  • Function: Control the activity of lower motor neurons.
• Lower Motor Neurons:
  • Origin: These neurons originate in the spinal cord.
  • Function: Directly stimulate muscle contractions.

Direct vs Indirect Motor Pathways

• Direct (Pyramidal) Pathways:
  • Examples: Corticospinal and corticobulbar tracts are involved in voluntary motor control.
• Indirect (Extrapyramidal) Pathways:
  • Function: Involved in controlling posture, balance, and reflexive movements.

Basal Nuclei and Cerebellum

• Basal Nuclei:
  • Function: Initiate movement and suppress unwanted movements.
• Cerebellum:
  • Function: Coordinates movement, maintains balance, manages posture, and integrates timing of movements.

Speech Areas

• Broca's Area:
  • Function: Responsible for motor aspects of speech production.
• Wernicke's Area:
  • Function: Important for language comprehension and processing.

Brain Waves

• Alpha Waves:
  • State: Indicate a relaxed state of mind.
• Beta Waves:
  • State: Associated with alert and active thinking.
• Theta Waves:
  • State: Present during light sleep.
• Delta Waves:
  • State: Indicate deep sleep.

Special Senses

• Smell:
  • Mechanism: Olfactory neurons detect airborne chemicals.
• Taste:
  • Components: Five tastants include sweet, salty, sour, bitter, and umami.
• Vision:
  • Rods: Responsible for night vision.
  • Cones: Responsible for color vision.
• Hearing:
  • Mechanism: Hair cells bend stereocilia to generate auditory signals.

Vision Pathway

• Sequence of Signal Transmission:
  • Light → rods/cones → bipolar cells → ganglion cells → optic nerve → thalamus → occipital cortex.

Equilibrium

• Static Equilibrium:
  • Organs Involved: Utricle and saccule contain otoliths, which assist in balance.
• Dynamic Equilibrium:
  • Organs Involved: Semicircular canals and crista ampullaris detect rotational movements and changes.

Autonomic Nervous System (ANS)

• Sympathetic Division:
  • Function: Activates the fight or flight response during stressful situations.
• Parasympathetic Division:
  • Function: Promotes rest and digest functions.
• Key Control: ANS regulates involuntary functions including heart rate, digestion, gland activity, and smooth muscle contraction.

Preganglionic and Postganglionic Neurons

• Preganglionic Neuron:
  • Pathway: Exits the Central Nervous System (CNS) and synapses in an autonomic ganglion.
• Postganglionic Neuron:
  • Pathway: Travels from the ganglion to the effector organ to carry out its function.

Dual Innervation

• Definition: Most organs receive input from both sympathetic and parasympathetic divisions, allowing for precise control of physiological responses.