Module 2 Nervous System Function Flashcards
How Does the Nervous system function
- Overview of Brain Function and Structure
- Evolutionary Development of the Nervous System
- The Central Nervous System: Mediating Behavior
- Somatic Nervous System: Transmitting Information
- Autonomic Nervous System: Balancing Internal Functions
- Ten Principles of Nervous-System Function
Overview of Brian Function and Structure
-Evolution of Brain Size and Human Behavior (RECALL)
- Human brain has optimized its overall size, (size and number of neurons, the number and length of connections, energy consumption)
- Changing these features would compromise the others and neutralize any performance improvements
Overview of Brain Function and Structure
-The brain’s primary function is to produce behavior. To do so, is a must:
- Receive information about the world
- Integrate information to create a sensory reality
- Produce commands to control the movement of muscles
Plastic Patterns of Neural Organization
-The brain is PLASTIC
~Neural tissue has the capacity to adapt to the world by changing how its functions are organized
-NEUROPLASTICITY
~The nervous system’s potential for physical or chemical change that enhances its adaptability to environmental change and its ability to compensate for injury
Phenotypic Plasticity
-An individual’s genotype (genetic makeup) interacts with the environment to elicit a specific phenotype from a large genetic repertoire of possibilities, a phenomenon the results from EPIGENETIC influences
Functional Organization of the Nervous System (RECALL)
-Brain and spinal cord together make up the CNS, and all the nerve fibers radiating out beyond the brain and spinal cord as well as all the neurons outside the brain and spinal cord from the PNS
Functional Organization of the Nervous System
-The CNS and the PNS constitute an interacting, 3-part system
-The CNS
~The brain and spinal cord
-The Somatic Nervous System (SNS)
~Spinal and cranial nerves carrying sensory information to the CNS and motor instructions away from the CNS for movement
-The Autonomic Nervous System (ANS)
~Prepares internal organs for “rest and digest” or “fight or flight”
Direction of Neural Information Flow is Important
- AFFERENT information (Sensory) is sensory information coming into the CNS (Incoming information)
- EFFERENT information (Motor) is information leaving the CNS (outgoing information)
Anatomical Divisions of the Nervous System
-Nervous system ~Central Nervous System (CNS) *Brain *Spinal ~Peripheral Nervous System (PNS) *Somatic Nervous System (Transmits sensation, produces movement) **Cranial Nerves **Spinal Nerves *Autonomic Nervous System (Balances internal functions) **Sympathetic Division (arousing) **Parasympathetic Division (calming)
The Basics
-Finding Your Way Around the Brain
-Many names for the nervous-system structures include information about anatomical locations
~With respect to other body parts of the animal
~With respect to their relative locations
~With respect to a viewer’s perspective
“Brain-Body Orientation”
illustrates brain structure location from the frame of reference of the face
- Structures atop the brain or structure within the brain are Dorsal (TOP)
- Structures toward the brain’s midline are Medial (MIDDLE)
- Structures located toward the sides are Lateral (SIDES)
- Structures located towards the front are Anterior (FRONT)
- Structurers located towards the back Posterior (BACK)
- Structures towards the bottom of the brain or one of its parts are Ventral (BOTTOM OR BELOW)
“Anatomical Orientation” illustrates the direction of a cut, or section, trough the brain (Part A) from the perspective of a viewer (Part B)
-Coronal Section
~Cut in a vertical plane, from the crown of the head down, yielding a frontal view of the brain’s structures (Cuts top to bottom and evenly cuts both left and right hemispheres)
-Horizontal Section
~The view or the cut falls along the horizon, is usually viewed looking down on the brain from above- a dorsal view (Parallel to the floor cutting from front to back)
-Sagittal Section
~Is cut length way from front to back and viewed from the side. (Imagine the brain split by an arrow- in Latin, SAGITTA.) Here, a cut in the midsagittal plane divides the brain into symmetrical halves, a medial view (Cuts front to back, but is at a 90 degree angle to horizontal cuts the brain exactly in half of separate left and right hemispheres)
Surface Features of the Brain
-Cerebral Cortex (RECALL)
-Each hemisphere is divided into four lobes
~Frontal (executive function and decision making)
*Mainly hearing, language, and music
~Parietal (sensory integration)
*Direct movements towards or away from objects
~Temporal (auditory, taste, smell, memory)
~Occipital (visual)
Surface Features of the Brain
-Cerebral Cortex (RECALL)
- The cerebral cortex is a thin sheet of nerve tissue folded many times to fit inside the skull
- Your right first can serve as a guild to the orientation of the brain’s left hemisphere and its lobes
- Bumps in the brain’s folded surface are called GYRI
- Cracks in the brain are called SULCI
Surface Features of the Brain
-Meninges: Three layers of protective tissue
-Dura Mater
~”hard mother”; tough outer layer of fibrous tissue (lays beneath the skull)
-Arachnoid layer
~”like a spider’s web”, thin sheet of delicate connective tissue (lays above the Subarachnoid space (filled with Cerebral Spinal Fluid (made up of water and salt compositions)))
-Pia mater
~”soft mother”; moderately tough inner layer that clings to the brain’s surface (then the brain)
Surface Features of the Brain
-Cerebrum and Cerebellum
-Cerebrum
~Major structure of the forebrain, consisting of two virtually identical hemispheres (left and right)
-Cerebellum: “Little Brain”
~Involved in the coordination of motor and possibly other mental processes
*Anything thing that need to be done fast involves the cerebellum (walking and running as well as someone talking)
Surface Features of the Brain
-Gyrus, Sulcus, Fissure
-Gyrus (gyri)
~A small protrusion or bump formed by the folding of the cerebral cortex
-Sulcus (sulci)
~A groove in brain matter, usually found in the neocortex or cerebellum
-Fissure
~A very deep sulcus
Surface Features of the Brain
-Brainstem
- Central structures of the brain, including the hindbrain, midbrain, thalamus, and hypothalamus, responsible for most unconscious behavior
- Could survive for the most part with out the cerebrum, but missing on part of the brainstem could kill you
Surface Features of the Brain
-Surface blood Vessels
-Anterior, middle, and posterior cerebral arteries
-Stroke
~Sudden appearance of neurological symptoms as a result of severe interruption of blood flow
Internal Features of the Brain
-Four Ventricles
-Cavities in the brain that contain cerebrospinal fluid (CSF)
~Two lateral ventricles (left and right)
~Third ventricle
~Fourth ventricle
Internal Features of the Brain
-Cerebrospinal Fluid (CSF)
-Sodium chloride and other salts
-Fills the ventricles and circulates around the brain and spinal cord in the subarachnoid space (located between the arachnoid layer and the pia mater)
-Cushions the brain
-Meningitis
~Infection of the meninges and CSF
Internal Features of the Brain
-Macro
-Gray Matter
~Areas of the nervous system predominately composed of cell bodies and blood vessels
-White Matter
~Areas of the nervous system rich in fat-sheathed neural axons
-Corpus Callosum
~Fiber system connecting the two cerebral hemispheres
Internal Features of the Brain
-Microscopic
-Neurons ~Carry out the brain's major functions ~Approximately 80 billion -Glial Cells ~Aid and modulate neurons' activates (giving nutrients, getting rid of waste products, managing the environment) ~Approximately 100 billion
Internal Features of the Brain
-Nucleus, Nerve, Tract
-Nucleus (nuclei)
~A group of cells forming a cluster that can be identified with special stains to form a functional grouping
-Nerve
~Large collection of axons coursing together outside the central nervous system
-Tract
~Large collection of axons coursing together within the central nervous system
Evolutionary Development of the Nervous System
-Human brain is a complex mammalian brain, yet it still retains most of the features of other, less complex mammalian brains
-Most behaviors are not the product of a single locus in the brain, but rather of many brain areas and levels
-Our evolutionary history, our developmental history, and our own personal history are integrated at various anatomical and functional levels of the nervous system
~The forebrain grows dramatically in the evolution of the mammalian brain
The Central Nervous System
-Mediating Behavior
-Three Major Components
~Spinal Cord
~Brainstem
~Forebrain
Spinal Cord
-Controls most body movements
-Can act independently of the brain
-Spinal Reflex
~Automatic movement
~Hard to prevent (brain cannot inhibit)
~Example
*Knee-jerk reflex (patellar tendon)
Brainstem
-Begins where the spinal cord enters the skull
-Receives afferent nerves coming from senses and sends efferent nerves out to control movements
-Three regions (Developed as simple animals evolved a brain)
~Hindbrain (forearm)
~Midbrain (wrist)
~Diencephalon (fist)
-Medial view of the brain shows the relation of the brainstem to the cerebral hemisphere
-The shapes and relative sizes of the brainstem’s parts can be imagined as analogous as to your fist, wrist, and forearm
-Hindbrain
~Evolutionarily the oldest part of the brain
~Contains
*Cerebellum
*Reticular Formation
*Pons
*Medulla
~Controls various motor functions ranging from breathing to balance to fine movements
~Integrates both voluntary and involuntary body movements
The Brainstem
-Hindbrain
-Cerebellum
~Controls complex movements and cognitive functions
~Size increases with the physical speed and dexterity of a species
~Relatively large cerebellum enable fine, coordinated movements such as flight and landing in birds and prey catching in cats
~Slow-moving animals such as the sloth have smaller cerebellums relative to their brain size
-Reticular Formation
~Reticular activating system
~Netlike mixture of neurons (gray matter) and nerve fibers (white matter)
~Stimulates the forebrain
*Regulation of sleep-wake behavior and behavioral arousal
-Pons (“bridge”)
~Connects cerebellum to the rest of the brain
~Controls important movements of the body
-Medulla
~Rostral tip of spinal cord
~Vital functions
*Control of breathing and heart rate
The Brainstem
-Midbrain
-Tectum (roof of midbrain) ~Sensory processing (visual and auditory) ~Produces orienting movements (turning head to see source of sound) ~Superior Colliculus *Receives visual input ~Inferior colliculus *Received auditory input -Tegmentum (floor of midbrain) ~eye and limb movements ~Species-specific behavior ~Perception of pain
The Brainstem
-Diencephalon
-Integrates sensory and motor information on its way to the cerebral cortex
-The two principal structures include
~The Hypothalamus
~The Thalamus
-Hypothalamus
~Hormone Function
*Through connections with the pituitary gland
~Feeding (eating/drinking)
~Sexual Behavior
~Sleeping
~Temperature Regulation
~Emotional Behavior
-Thalamus
~Gateway for channeling sensory information to the cortex
~Primary role is sensory processing systems (integrates and projected into the appropriate region of the neocortex)
~Motor processing
~Integrative functions
Forebrain
-Neocortex (cerebral cortex)
~Regulates various mental activities
-Basal Ganglia
~Control of voluntary movement
-Limbic System
~Regulates emotions and behaviors that create and require memory
-Integrates sensation, emotion, and memory
-Cognitive functions such as thinking, planning, and language
Forebrain
-The Cortex
-Neocortex ("new bark") ~6 Layers of gray matter ~Creates and responds to a perceptual world -Limbic Cortex ~Evolutionarily older ~3 or 4 layers of gray matter Controlling motivational states
Forebrain
-The Neocortical Lobes
-Occipital ~Vision -Parietal ~Tactile functions -Temporal ~Visual, auditory, and gustatory functions -Frontal ~Motor and executive functions
Forebrain
-Neocortical Layers and Cytoarchitectonic Map
-Neocortical Layers
~Different layers have different cell types
~Density of cells in each layer varies
~Differences in appearance relate to function
-Cytoarchitectonic Map
~Map of neocortex based on the organization, structure, and distribution of the cells
Motor and Sensory Cortex
- Afferents connect to layer IV (coming from the thalamus) as well as to layer II and III
- Efferents in layers V and VI connect to the other parts of the cortex and to motor structures of the brain
Cytoarchitectonic Map
- Brodmann defined areas by organization and characteristics of the cells
- The simplest sensory perceptions of touch (red), Vision (purple) and hearing (orange)
Forebrain
-The Basal Ganglia
-Collection of nuclei just below the white matter of the neocortex
~3 principal structures: caudate nucleus, putamen and globus pallidus
-Controls voluntary and involuntary movement
-Related disorders
~Parkinson’s disease and Tourette’s syndrome possibly OCD
-Control and coordination of movement patterns rather than in activating the muscles to move
Forebrain
-The Limbic System
-Group of structures between the neocortex and brainstem
~Principal structures: amygdala, hippocampus, and cingulate cortex
-Regulation of
~Emotional and sexual behavior
~Memory
~Spinal navigation
Forebrain
-The Olfactory System
- Olfactory bulbs
- Pyriform Cortex
- Thalamus
- Neocortex
The Somatic Nervous System (SNS) Transmitting Information
-The SNS is monitored and controlled by the CNS
-The cranial nerves by the brain
~12 pairs of Cranial Nerves
*Olfactory (Smell)
*Optic (Vision)
*Oculomotor (Eye movement)
*Trochlear (Eye movement)
*Trigeminal (Masticatory movements and facial sensations)
*Abducens (Eye movement)
*Facial *Facial movement and sensation
*Auditory Vestibular (Hearing and balance
*Glossopharyngeal (Tongue and pharynx movement and sensation
*Vagus (Heart, blood vessels, viscera, movement of larynx and pharynx
*Spinal Accessory (Neck Muscles)
*Hypoglossal (Tongue muscles)
-The spinal nerves by the spinal cord segments
Cranial Nerves
- Afferent functions, such as sensory inputs to the brain from the eyes, eras, mouth, and nose
- Efferent functions such as motor control of the facial muscles, tongue, and eyes
- Both functions, such as modulation of both sensation and movement in the face
Spinal Nerves
-Dermatome
~Area of the skin supplied with afferent nerve fibers by a single spinal-cord dorsal root
-Spinal-cord segments are interconnected so adjacent segments can operate together to direct complex coordinated movements
Spinal Nerves
-Dorsal and Ventral
-Dorsal
~Fibers are afferent
*They carry information from the body’s sensory receptors
-Ventral
~Fibers are efferent
*They carry information from the spinal cord to the muscles
The Autonomic Nervous System
-Sympathetic System
~Arouses the body for action
~Example
*Increases heart rate and blood pressure
~Mediates the “fight of flight” response
-Parasympathetic System
~Opposite of sympathetic: prepares the body to “rest and digest”
~Reverses the “fight or flight” responses
Ten Basic Principles on How the Nervous System is Organized
-Principle 1
-The Nervous System Produces Movement Within a Perceptual World the Brain Creates
~Individual realities are rough approximations of what is actually present
~The brain produces a reality that is adaptive for the species to survive
~The behavior that the brain produces is directly related to the world that the brain has created
Ten Principles
-Principle 2
-The details of Nervous-system functioning are constantly changing, an attribute called neuroplasticity
~Experience alter the brain’s organization, and neuroplasticity is required for learning and memory functions as well as for survival
~Information is stored in the nervous system only if neural connections change
Ten Principles
-Principle 3
-Many of the brain’s circuits are crossed
~Each hemisphere receives sensory stimulation from the opposite (contralateral) side of the body and controls muscles on the contralateral side as well
Ten Principles
-Principle 4
-The Central Nervous System functions on multiple levels
~Simple animals such as worms have a spinal cord, more complex animals such as fish have a brainstem as well, and yet more complex animals have evolved a forebrain
~Each new addition to the CNS has added a new level of behavioral complexity without discarding previous levels of control
Ten Principles
-Principle 5
-The brain is both symmetrical and asymmetrical
~The left and the right hemispheres look like mirror images; they have some dissimilar features
~Language is usually on the left side, and spatial functions are usually on the right
Ten Principles
-Principle 6
-Brain system are organized both hierarchically and in parallel
~CNS comprises multiple levels of function, these levels must be extensively interconnected to integrate their processing and create unified perceptions or movements
~Subsystems of the brain are organized into multiple parallel pathways, yet our conscious experiences are always unified