Chapter 16 - Sensory, Motor, and Integrative Systems Flashcards
What is Sensation?
Sensation:
Conscious or subconscious awareness of changes in the external or internal environments
What is Perception?
Perception:
Conscious interpretation of sensations performed mainly by the Cerebral Cortex
What is Sensory Modality?
Sensory Modality:
Each type of sensation
Such as:
Touch
Pain
Vision
Hearing
Sensory Modalities are grouped into:
1- General Senses
2- Special Senses
What is General Senses?
Somatic:
1- Tactile
2- Thermal
3- Proprioceptive
Visceral:
1- Pressure
2- Chemicals
3- Stretch
4- Nausea
5- Hunger
6- Temperature
What is Special Senses?
1- Smell
2- Taste
3- Vision
4- Hearing
5- Equilibrium
Different types of Sensory Receptors are involved in the different senses
What is Free Nerve Endings?
Free Nerve Endings:
Bare dendrites
Used to detect:
1- Pain
2- Temperature
3- Tickle
4- Itch
5- Some touch
ex:
Cold stimulus
Receptor potential triggers action potential and propagates to CNS
What is Encapsulated Nerve Endings?
Encapsulated Nerve Endings
Dendrites enclosed in connective tissue capsule
Used to detect:
1- Pressure
2- Vibration
3- Some touch
ex:
Vibration stimulus
Receptor potential triggers action potential and propagates to CNS
What are some Sensory Receptors for Special Senses?
Sensory receptors cells synapse with First-Order sensory neuron
Some Special Senses receptors include:
1- Gustatory Receptor Cells:
(in taste buds)
2- Photoreceptors:
(in Retina of eye)
3- Hair Cells:
(in inner ear for hearing)
ex:
Sugar molecule
Gustatory (taste) Receptor has a Receptor potential
Triggers release of neurotransmitters from sensory receptor
Dendrite of sensory nerve bind neurotransmitters and trigger nerve impulse that propagates into CNS
What is Exteroreceptor?
Exteroreceptor:
Located at or near body surface
Sensitive to stimuli from outside the body (external environment)
Include:
1- Hearing
2- Vision
3- Smell
4- Taste
5- Touch
6- Pressure
7- Vibration
8- Pain
What is Interoreceptor?
Interoreceptor:
Located in blood vessels, visceral organs, and nervous system
Monitors body’s internal environment
Impulses may not always be consciously perceived, but occasionally may be felt as pain or pressure
What is Proprioceptor?
Proprioceptor:
Located in muscles, tendons, joints, and inner ear
Provide information about:
1- Body position (awareness of position in space)
2- Muscle length and tension
3- Position and movement of joints, muscles, and tendons
4- Equilibrium
What is Mechanoreceptor?
Mechanoreceptor:
Detect mechanical stimuli
Provide sensations of:
1- Touch
2- Pressure
3- Vibration
4- Proprioception
5- Hearing and equilibrium
Also monitors stretching of blood vessels and internal organs
What is Thermoreceptor?
Thermoreceptor:
Detect changes in temperature
What is Nociceptor?
Nociceptor:
Respond to painful stimuli resulting from physical or chemical damage to tissue
What is Photoreceptor?
Photoreceptor:
Detect light that strikes Retina of eye
What is Chemoreceptor?
Chemoreceptor:
Detect chemicals in mouth (taste), nose (smell), and body fluids
What is Osmoreceptor?
Osmoreceptor:
Detect chemicals in mouth (taste), nose (smell), and body fluids
ex:
Proteins
Salt
Osmotic pressure
What is Somatic Sensations?
Somatic Sensations:
1- Tactile
2- Thermal
3- Pain
4- Proprioceptive
What is Tactile Sensations?
Tactile Sensations:
1- Touch
2- Pressure
3- Vibration
4- Itch
5- Tickle
What is Sensory Receptors in Skin?
1- Free Nerve Ending:
In Epidermis
(pain, itch, tickle, cold, warmth)
2- Type I Cutaneous Mechanoreceptor (Tactile Disc):
In Epidermis
(senses continuous touch and pressure)
3- Corpuscle of Touch (Meissner Corpuscle):
In Dermis
(senses onset of touch and low-frequency vibrations)
4- Type II Cutaneous Mechanoreceptor (Ruffini Corpuscle):
In Dermis
(senses skin stretching and pressure)
5- Hair Root Plexus:
In Dermis
(sense movements on skin surface that disturb hairs)
6- Lamellated Corpuscle (Pacinian Corpuscle):
In Dermis
(senses high-frequency vibrations)
What are the 2 Types of Pain?
2 Types of pain:
1- Fast Pain:
Acute, sharp or pricking
Perceived within 1 second
2- Slow Pain:
Chronic, burning, aching, or throbbing
Perceived a second or more after stimulus
What is Superficial Somatic Pain?
Arising from skin receptors
What is Deep Somatic Pain?
Skeletal muscles, joints, tendons, and fascia
What is Visceral Pain?
Stimulation of pain sensors in visceral organs
Usually presents in or just deep to the skin that overlies the stimulated organ
Referral Pain:
Pain in one area indicative that another area with the same innervation is affected
What is Muscle Spindles?
Muscle Spindle:
Type of proprioceptor in skeletal muscles
Monitor muscle length
Involved in stretch reflexes
Sensory nerve endings wrap around area of encapsulated intrafusal muscle fibers within most skeletal muscles
Slow
What is Tendon Organs?
Tendon Organs:
Type of proprioceptor in junction of a tendon and a muscle
Protects muscles and tendons from damage due to overstretching
Capsule encloses collagen fibers and sensory nerve endings at junction of tendon and muscle
Slow
What is Joint Kinesthetic Receptors?
Join Kinesthetic Receptors:
Exists in and around the joint capsule of synovial joints
Respond to pressure, acceleration, and deceleration during movement
Help protect against excessive strain
Lamellated Corpuscles, Type II Cutaneous Mechanoreceptors, Tendon Organs, and free nerve endings
Rapid
What is Corpuscle of Touch (Meissner Corpuscle)?
Structure and Location:
Capsule surrounds mass of dendrites in dermal papillae of hairless skin
Sensations:
Onset of touch
Low-frequency vibrations
Adaptation Rate:
Rapid
What is Hair Root Plexuses?
Structure and Location:
Free nerve endings wrapped around hair follicles in skin
Sensations:
Movements on skin surface that disturbs hair
Adaptation Rate:
Rapid
What is Type I Cutaneous Mechanoreceptors (Tactile Discs)?
Structure and Location:
Saucer-shaped free nerve endings make contact with tactile epithelial cells in epidermis
Sensations:
Continuous touch and pressure
Adaptation Rate:
Slow
What is Type II Mechanoreceptors (Ruffini Corpuscles)?
Structure and Location:
Elongated capsule surrounds dendrites deep in dermis and in ligaments and tendons
Sensations:
Skin stretching and pressure
Adaptation Rate:
Slow
What is Lamellated Corpuscles (Pacinian Corpuscles)?
Structure and Location:
Oval, layered capsule surrounds dendrites
Present in dermis and subcutaneous layer, submucosal tissues, joints, periosteum, and some viscera
Sensations:
High-frequency vibrations
Adaptation Rate:
Rapid
What is Itch and Tickle Receptors?
Structure and Location:
Free nerve endings in skin and mucous membranes
Sensations:
Itching and tickling
Adaptation Rate:
Both slow and rapid
What is Warm and Cold Receptors?
Structure and Location:
Free nerve endings in skin and mucous membranes of mouth, vagina, and anus
Sensations:
Warmth or cold
Adaptation Rate:
Initially rapid, then slow
What is Nociceptors?
Structure and Location:
Free nerve endings in every body tissue except brain
(Headaches are vascular pain - pressure)
Sensations:
Pain
Adaptation Rate:
Slow
What is Somatic Sensory Pathways?
Somatic Sensory Pathways:
Carry information from somatic sensory receptors to the Primary Somatosensory Area in the Cerebral Cortex and to the Cerebellum
The pathways to the Cortex consist of thousands of sets of 3 neurons classified as 1st, 2nd, and 3rd-order neurons
What is First-Order Neuron?
Impulses from somatic receptors to the Brainstem or Spinal Cord
What is Second-Order Neuron?
Impulses from the Brainstem and Spinal Cord to the Thalamus
What is Third-Order Neuron?
Impulses from the Thalamus to the Primary Somatosensory Area of the Cortex on the same side
What are the 3 General Pathways for Somatic Sensory Impulses Ascending to the Cerebral Cortex?
1- Posterior Column-Medial Lemniscus Pathway
2- Anterolateral (Spinothalamic) Pathway
3- Trigeminothalamic Pathway
What is Posterior Column-Medial Lemniscus Pathway?
Impulses from the limbs, trunk, neck, and posterior head
1- Receptors from lower limbs and lower trunk send nerve impulses into Lumbar Spinal Cord through First-Order Neuron
2- Ascend through Posterior Column (Gracile Fasciculus) to Medulla Oblongata
3- Transmit impulse to Second-Order Neuron and decussate to opposite side’s Gracile Nucleus
4- Ascend to Midbrain through Medial Lemniscus
5- Ascend to Thalamus at Ventral Posterior Nucleus and transmit impulse to Third-Order Neuron
6- Ascend to Primary Somatosensory Area of Cerebral Cortex
1- Receptors from upper limbs, upper trunk, neck, and posterior head send nerve impulse into Cervical Spinal Cord through First-Order Neuron
2- Ascend to Medulla Oblongata through Cuneate Fasciculus to Cuneate Nucleus
3- Impulse transmitted to Second-Order Neuron and decussate to opposite side’s Cuneate Nucleus
4- Impulse ascend to Midbrain through Medial Lemniscus
5- Impulse ascends to Thalamus
6- Impulse transmitted to Third-Order Neuron then ascend to Primary Somatosensory Area of Cerebral Cortex
What is Anterolateral (Spinothalamic) Pathway?
Impulses for pain, temperature, itch, tickle, and posterior head
1- Receptors send nerve impulse to Spinal Cord to Posterior Gray Horn through First-Order Neuron
2- Impulse transmitted to Second-Order Neuron and decussate
3- Impulse ascends to Medulla Oblongata through Anterior Spinothalamic Tract and Lateral Spinothalamic Tract
4- Impulse ascends to Midbrain through Lemniscus then to Thalamus
5- In Thalamus’ Ventral Posterior Nucleus impulse transmitted to Third-Order Neuron
6- Impulse ascends to Primary Somatosensory Area of Cerebral Cortex
What is Trigeminothalamic Pathway?
Impulses for most somatic sensations
Tactile, thermal, and pain
From face, nasal cavity, oral cavity, and teeth
1- Receptors send nerve impulse through First-Order Neuron to Pons
2- Either impulse transmitted to Second-Order Neuron in Pons or descends to Medulla Oblongata and then transmitted to Second-Order Neuron
3- Impulse decussate and ascend to Midbrain via Trigeminothalamic Tract
4- Impulse ascend through Midbrain to Thalamus via Medial lemniscus
5- Impulse transmitted to Third-Order Neuron at Thalamus’s Ventral Posterior Nucleus
6- Impulse ascends to Primary Somatosensory Area of Cerebral Cortex
What is Spinocerebellar Tracts?
Somatic sensory impulses reach the Cerebellum via the Spinocerebellar Tracts
Posterior Spinocerebellar Tract and Anterior Spinocerebellar Tract carry proprioceptive impulses to Cerebellum
These pathways are critical for posture, balance, and coordination of skilled movements
Convey nerve impulses from proprioceptors in trunk and lower lib of one side of the body to the same side of Cerebellum
Proprioceptive inputs inform Cerebellum of actual movements, allowing it to coordinate, smooth, and refine skilled movements and maintain posture and balance
What is Postcentral Gyri?
Postcentral Gyri:
Located on both Parietal Lobes of brain
Sites for the Primary Somatosensory Area
Each region in this area receives sensory input from a different part of the body on the opposite side
Each point of the body maps to a specific region in the Primary Motor Area
What is Somatic Motor Pathways?
Nerves that extend out of the Brainstem and Spinal Cord are called Lower Motor Neurons (LMN)
LMN innervate skeletal muscles of the face and head through Cranial Nerves, and skeletal muscles of the limb and trunk through Spinal Nerves
What is Somatic Motor Pathways’ 4 Circuits?
Somatic Motor Pathways provide input into LMN and are divided into 4 distinct circuits:
1- Local Circuit Neurons:
Located close to LMNs in the Brainstem and Spinal Cord
2- Upper Motor Neurons (UMN):
Input to both Lower Circuit Neurons and LMNs
3- Basal Nuclei Neurons:
Assist movement by providing input to UMNs
4- Cerebellar Neurons:
Assist movement via control of activity of UMNs
How do Upper Motor Neurons extend to Lower Motor Neurons?
UMNs extend to LMNs via 2 types of pathways:
1- Direct Motor Pathways:
Deliver signals to LMNs from Cerebral Cortex
2- Indirect Motor Pathways:
Deliver signals to LMNs from Motor Centers in the Basal Nuclei, Cerebellum, and Cerebral Cortex
What are the 2 Types of Direct Motor Pathways?
2 Types of Direct Motor Pathways used for voluntary movement:
1- Corticospinal Pathways:
Lateral Corticospinal Tract and Anterior Corticospinal Tract
2- Corticobulbar Pathway
What is Lateral Corticospinal Pathway?
1- UMN descends from Cerebral Cortex to Midbrain through Cerebral Peduncle
2- Descend to Pons
3- Descend to Medulla Oblongata and 90% decussate at Pyramid to other side Pyramid
4- Descend to Spinal Cord through Lateral Corticospinal Tract
5- Impulse transmitted to LMN in Anterior Gray Horn
6- Impulse sent to skeletal muscle in distal parts of limb
What is Anterior Corticospinal Pathway?
1- UMN descends from Cerebral Cortex to Midbrain through Cerebral Peduncle
2- Descend to Pons
3- Descend to Medulla Oblongata through Pyramid
4- Descend to Spinal Cord through Anterior Corticospinal Tract
5- 10% Decussate to other side’s Anterior Gray Horn
6- Impulse transmitted to LMN
7- Impulse sent to skeletal muscles in trunk and proximal parts of limbs
What is Corticobulbar Pathway?
1- UMN descends from Cerebral Cortex through Corticobulbar Tract
2- Descends to Midbrain through Cerebral Peduncle
3- Descend to Pons
4- Three options now, either impulse transmitted to LMN and sent to Facial Nerve VII (7)
5- Or decussate to other side of Pons, transmitted to LMN and sent to Facial Nerve VII (7) to skeletal muscles of facial expression
6- Or descends to Medulla Oblongata and either transmits to LMN and sent through Hypoglossal Nerve XII (12), or decussate and transmitted to LMN on other side of Medulla Oblongata then sent to Hypoglossal Nerve XII (12) to Skeletal muscles of the tongue
What are Indirect Motor Pathways?
Indirect Motor Pathways (Extrapyramidal Pathways):
1- Rubrospinal Tract
2- Tectospinal Tract
3- Vestibulospinal Tract
4- Lateral Reticulospinal Tract
5- Medial Reticulospinal Tract
What is Tectospinal Tract?
(opposite sides)
1- UMN Impulse descend through Superior Colliculus in Midbrain
2- To Pons and decussate to other side
3- To Medulla Oblongata
4- To Tectospinal Tract in Spinal Cord
5- To Anterior Gray Horn then transmitted to LMN
6- Then to skeletal muscles
What is Rubrospinal Tract?
(opposite sides)
1- UMN impulse descend through Red Nucleus in Midbrain
2- To Pons and decussate to other side
3- To Medulla Oblongata
4- To Rubrospinal Tract in Spinal Cord
5- To Anterior Gray Horn then transmitted to LMN
6- Then to skeletal muscles
What is Vestibulospinal Tract?
(same side)
1- UMN impulse descend through Vestibular Nucleus in Pons (which receives input about head movements from inner ear)
2- To Medulla Oblongata
3- To Vestibulospinal Tract in Spinal Cord
4- To Anterior Gray Horn then transmitted to LMN
5- Then to skeletal muscles
What is Reticulospinal Tract?
(same side)
1- UMN impulse descend through Reticular Formation in Medulla Oblongata
2- To Rubrospinal Tract in Spinal Cord
3- To Anterior Gray Horn then transmitted to LMN
4- Then to skeletal muscles
What Activities does the Cerebellum do?
Cerebellum performs 4 activities:
1- Monitor intentions for movements
2- Monitor actual movements
3- Compare command signals with sensory information
4- Send out corrective feedback
What are the Integrative Functions of the Cerebrum?
1- Wakefulness and sleep
Relies on the Reticular Activating System (RAS)
REM Sleep (Rapid Eye Movement Sleep)
NREM Sleep (Non Rapid Eye Movement Sleep
2- Coma:
State of unconsciousness in which an individual has little to no response to stimuli
3- Learning and Memory:
Immediate
Short-Term
Long-Term Memory
4- Language:
Wernicke’s Association Area
Broca’s Motor Area
What are some Disorders of Sensory, Motor, and Integrative Systems?
Parkinson’s Disease:
Mostly affects people around age 60
Too little Dopamine is produced
(normally balance between Dopamine and ACh, if low Dopamine, more ACh is present, so tremors)
Tremor
Bradykinesia
Hypokinesia
