Anatomy 2 Lecture Exam 2 Chap. 16

Page 1: Introduction to Brain Functionality

Chapters Overview

• Sensory, Motor, and Integrative Systems

Page 2: Sensation and Perception

Definitions

• Sensation: Awareness of changes in the external or internal environment, can be conscious or subconscious.

• Perception: The conscious interpretation of sensations, primarily processed by the cerebral cortex.

Page 3: Types of Sensation

Processing of Stimuli

• Types: The distinctions are made based on the conscious processing of stimuli:

  • Special Senses: Focus on senses like taste, smell, sight, hearing, and balance.

  • Somatic Senses: Touch, temperature, pain, etc.

Page 4: Subconscious Stimulus Processing

Subconscious Stimuli

• Somatic Stimuli: Includes proprioception, muscle length, and tension.

• Visceral Stimuli: Includes internal monitoring of blood pressure, glucose concentration, gastrointestinal tract distension, body temperature, osmolarity, lung inflation, and blood chemistry (e.g., pH).

Page 5: Types of Receptors

Receptor Classification

• By Structure:

  • Free nerve endings

  • Encapsulated receptors

  • Separate cells

• By Location:

  • Exteroceptors: Near/at body surface responding to external stimuli.

  • Interoceptors: Inside the body responding to internal stimuli.

Page 6: Neuron Selectivity

Free Nerve Endings

• Respond to a variety of stimuli such as:

  • Pain

  • Temperature

  • Tickle/Itch (some touch)

Page 7: Encapsulated Nerve Endings

Specialized Receptor Functions

• Encapsulated Nerve Endings: Respond to pressure, vibration, and some touch sensations.

Page 8: Separate Cells for Special Senses

Specialized Sensory Cells

• Gustatory receptor cells: Found in taste buds.

• Photoreceptors: Located in the retina of the eye.

• Hair cells: Present in the inner ear, crucial for hearing and balance.

Page 9: Stimulus Origin Types

Classification of Receptors

• Exteroceptors: Deal with external environmental stimuli (Hearing, Vision, Smell, Taste, Touch, Pressure, Vibration, Pain).

• Interoceptors: Monitor body’s internal state (Blood Pressure, Osmolarity, Body Position, Muscle Length, Tension).

• Proprioceptors: Specialized for body position monitoring.

Page 10: Nociceptors

Pain Detection

• Nociceptors: Detect signals indicating tissue damage or potential harm through chemical, thermal, and mechanical signals.

Page 11: Receptor Adaptation

Tonic vs. Phasic Receptors

• Tonic Receptors: Adapt slowly and maintain response for the duration of the stimulus.

• Phasic Receptors: Adapt rapidly, often turning off if the stimulus remains constant.

Page 12: Types of Somatic Sensations

Somatic Sensation Categories

• Somatic Sensations: Include tactile, thermal, pain, and proprioception.

• Tactile Sensations: Encompass touch, pressure, vibration, itch, and tickle.

Page 13: Pain Characteristics

Fast and Slow Pain

• Fast Pain: Quick, acute, sharp sensation perceived within 1 second.

• Slow Pain: Chronic, burning, or aching pain perceived after a second or more post-stimulus.

Page 14: Somatic Pain Types

Pain Classification

• Superficial Pain: Originates from skin receptors.

• Deep Pain: Arises from deeper structures like muscles and joints.

• Visceral Pain: Pain felt in skin areas overlaying stimulated organs; known as referred pain.

Page 15: Referred Pain Visualization

Illustration

• Diagram illustrating referred pain regions for various organs (e.g., liver, heart, stomach).

Page 16: Proprioception

Body Position Awareness

• Proprioceptors: Sensory receptors located in muscles and tendons that detect body position and facilitate reflexes.

  • Muscle Spindles: Monitor muscle length.

  • Tendon Organs: Monitor tension in muscles, protect against overstretching.

  • Joint Kinesthetic Receptors: Found in joint capsules, respond to pressure and motion.

Page 17: Proprioceptor Structures

Proprioceptor Anatomy

• Overview of different proprioceptors and their connections to central nervous system (CNS).

Page 18: Somatic Motor Pathways

Circuit Overview

• Motor Pathways: Input into lower motor neurons is divided into:

  • Local circuit neurons

  • Upper motor neurons (UMNs)

  • Basal nuclei neurons

  • Cerebellar neurons

Page 19: Somatic Sensory Pathways

Pathways Overview

• Sensory impulses ascend to the cerebral cortex through established pathways.

  • First-order neurons from receptors to spinal cord/brainstem.

  • Second-order neurons ascending to thalamus.

  • Third-order neurons connecting to the cortex.

Page 20: Sensation Recap

Summary of Sensations

• A summary page for reiterating key points on sensation pathways.

Page 21: Primary Somatosensory Area

Brain Mapping

• Located in the postcentral gyrus, providing contralateral input with specific body mapping (somatotopy) in the primary somatosensory area.

Page 22: Somatic Sensory Pathways Ascension

Pathway Types

• Posterior Column-Medial Lemniscus Pathway

• Anterolateral (spinothalamic) Pathway

• Spinocerebellar Pathway to cerebellum.

Page 23: Posterior Column-Medial Lemniscus Pathway

Sensory Input Overview

• Sensory impulses from the right side of the body (pressure, vibration, proprioception) get relayed to different brain areas, concluding in the primary somatosensory area.

Page 24: Anterolateral Pathway

Pathway Context

• Transmission of impulses related to pain, temperature, itch, and tickle; connects sensory input to the brain.

Page 25: Spinocerebellar Pathway

Proprioceptive Impulses

• Dedicated to sending proprioceptive impulses to the cerebellum, facilitating posture, balance, and coordination.

Page 26: Somatic Motor Pathways Layout

Illustration and Diagram

• Structures and pathways involved in motor function.

Page 27: Primary Motor Area Details

Motor Mapping

• Similar to sensory mapping, specific regions of the primary motor area correlate with different body parts.

Page 28: Upper Motor Neurons

Direct Motor Pathways

• Signals from upper motor neurons to lower motor neurons impact both trunk and limb movement.

Page 29: Lateral Corticospinal Pathway

Fine Motor Skills

• Controls distal movements and fine motor skills, crossing over at the medulla.

Page 30: Anterior Corticospinal Pathway

Trunk and Proximal Limb Movement

• Framework for coordinating trunk and proximal limb movements, providing pathway structure.

Page 31: Lower Motor Neurons (LMNs)

Motor Innervation

• Overview of how LMNs innervate skeletal muscles through cranial and spinal nerves.

Page 32: Motor Circuit Types

Division of Circuits

• Description of motor pathways and their roles in motor control and coordination.

Page 33: Motor Pathways Integration

Neural Circuit Overview

• The interconnection of sensory, upper motor, basal nuclei, and cerebellar neurons.

Page 34: Cerebellar Functions

Cerebellum Activities

• Key roles performed by the cerebellum related to movement and coordination include monitoring intent and actual movements and sending corrective feedback.

Page 35: Cerebellar Input/Output

Integrating Sensory Signals

• Overview of inputs from various sources (e.g., proprioceptors, vestibular apparatus) and their impact on motor control via feedback.

Page 36: Disorders of Motor Control

Parkinson’s Disease

• Key features:

  • Typically affects individuals around age 60.

  • Involves insufficient dopamine production leading to:

    • Tremors

    • Bradykinesia

    • Hypokinesia.