chapter 2 exploring the nervous system. anatomical views horizontal section - shows structures...
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Chapter 2Chapter 2
Exploring the Nervous System
Anatomical ViewsAnatomical ViewsHorizontal section
- Shows structures viewed from above
Sagittal section - Divides structures into right and left parts
Coronal section - Shows views from the front
Anatomical DirectionsAnatomical DirectionsAnatomical directions are used for
locating structures with the body:
• Anterior - toward the front• Posterior - toward the rear • Ventral - toward the belly• Dorsal - toward the back• Rostral - toward the head• Caudal - toward the tail• Medial - toward the midline• Lateral - away from the midline• Superior - above a structure• Inferior - below a structure
The Importance of the Nervous The Importance of the Nervous SystemSystem
1) Detect stimuli in the environment2) Determine the significance of the
environmental stimuli3) Make a decision based on the stimuli4) Execute a response
Organization of the Nervous System:Organization of the Nervous System:Two Major DivisionsTwo Major Divisions
Peripheral Nervous System (PNS) Detects environmental information
inside and outside the body, which is transmitted to the CNS
Executes responses to stimuli Central Nervous System (CNS)
Recognizes and analyzes information from the PNS
Makes and transmits decisions to glands, organs, and muscles for execution
Cells of the Nervous Cells of the Nervous System:System:
Nerve cells – neurons perform the information processing and communication functions of the nervous system
Glial cells - supportive cells in the nervous system. The glial cells surround neurons and provide support for and insulation between them.
Cells of the Nervous System: Cells of the Nervous System: NeuronsNeurons
Perform information processing and communications functions of the nervous system
Consist of three major parts: 1. Soma - contains nucleus, mitochondria,
and ribosomes2. Dendrites - portions of the neuron that
transmit information toward the cell body3. Axon - a structure on the neuron which
transmits information away from the cell body
Cells of the Nervous System:Cells of the Nervous System:TerminologyTerminology
Groups of neurons form four functional groups:A collection of axons
Nerve – in the Peripheral Nervous System (PNS) Tract – in the Central Nervous System (CNS)
A collection of cell bodies Ganglion – within the PNS Nucleus - within the CNS
Cells of the Nervous System:Cells of the Nervous System:Functional Types of NeuronsFunctional Types of NeuronsSensory neurons - carry
information to the CNSInterneurons - connect sensory
and motor neurons or communicate with other interneurons
Motor neurons - carry information from the CNS to muscles, organs, and glands to control their functioning.
PhysicalPhysicalTypes ofTypes ofNeuronsNeurons
Cells of the Nervous System:Cells of the Nervous System:Types of SynapsesTypes of Synapses
Axodendritic - the axon synapses with dendrites of another neuron
Axosomatic - the axon synapses with the cell body of another neuron
Dendrodendritic synapse - occurs when the dendrites of one neuron synapses with the dendrites of another neuron
Axoaxonic synapse - the axon of one neuron synapses with the axon of another neuron
Neuromuscular junction - the axon synapses with a muscle
Cells of the Nervous System:Cells of the Nervous System:Glial CellsGlial CellsGlial cells
• One-tenth the size of neurons• Ten times as numerous as neurons
Types of Glial cells• Astrocytes - provide physical support to
neurons, nourishment and other functions. • Microglial cells - remove debris• Oligodendrocytes - produce myelin which
covers the axons of neurons in CNS• Schwann cells - produce myelin which
covers the axons of neurons in PNS
MyelinationMyelination
Organization of the Nervous Organization of the Nervous System:System:The Peripheral Nervous SystemThe Peripheral Nervous SystemDetects internal and external
environmental information; relays information to CNS
Executes CNS’ decisions in muscles, glands and organs
Spinal nerves and Cranial nervesPeripheral Nervous System includes:
Somatic Nervous System - Includes both sensory and motor systems
Autonomic Nervous System - Regulates the internal environment
The Peripheral Nervous The Peripheral Nervous System: System: Somatic Nervous Somatic Nervous SystemSystemEnables us to interact with the physical
environment• Afferent neurons – transmit messages from
sensory receptors to the CNS• Efferent neurons – transmit messages from
the CNS to skeletal muscle• Spinal nerves – 31 pairs of nerves that
send messages to/from the brain thru the spinal cord
• Cranial nerves – 12 pairs of nerves that link sensory receptors in the head directly to the brain and the brain to certain muscles
Cranial NervesCranial Nerves
The Peripheral Nervous The Peripheral Nervous System:System:Autonomic Nervous SystemAutonomic Nervous SystemPrimarily efferent neuronsControls internal environment -
glands and internal organsConsist of two parts that are
typically antagonistic:• Sympathetic • Parasympathetic
The The AutonomiAutonomic Nervous c Nervous SystemSystem
Organization of the Nervous Organization of the Nervous System:System:The Central Nervous SystemThe Central Nervous System Recognizes and analyzes information
received from the PNS Makes and transmits decisions to
glands, organs, and muscles for execution
Central Nervous System includes: Spinal cord - responsible for limited
analysis and decision making, transmits information to and from the brain.
Brain - responsible for analyzing sensory information and making appropriate responses to it.
The Protective Features of The Protective Features of the Central Nervous Systemthe Central Nervous System
Protecting the spinal cord• Vertebral Column - outer bony
covering that encases the spinal cord
Protecting the brain • Skull - outer bony covering that
encases the brain• Ventricular system
Meninges protects both• Dura matter• Arachnoid matter• Pia mater
The Central Nervous System: The Central Nervous System: Spinal CordSpinal Cord
• Serves as a conduit to and from the brain• Controls spinal reflexes
The Central Nervous System: The Central Nervous System: The BrainThe BrainThree main functions:
• Recognizing stimuli detected by the PNS• Analyzing the information• Initiating the appropriate response
Three main areas:• Hindbrain• Midbrain• Forebrain
The Brain: The HindbrainThe Brain: The HindbrainMyelencephalon
Medulla oblongata, which controls basic life functions
Metencephalon Pons - a “bridge” for fibers passing from
one side of the brain to the other. Sensory fibers, fibers from the cortex to cerebellum, and fibers that relay information on sleep, arousal and dreaming pass through it.
Cerebellum - involved in the development and coordination of movement
• Reticular formation Involved in arousal, begins in the medulla
and extends to other areas of the brain
The HindbrainThe Hindbrain
The Brain: The MidbrainThe Brain: The Midbrain
MesencephalonTectum - relays visual and auditory
information and controls simple reflexes, eye and ear orientation movements
Tegmentum -• substantia nigra - integration of
voluntary movements• red nucleus - controls basic body
movements• reticular formation - controls arousal
and consciousnessBrain stem = midbrain + hindbrain not
including the cerebellum
Diencephalon• Epithalamus - contains habenula
(olfactory functions) and pineal gland• Thalamus - major relay station for
sensory information• Hypothalamus - detects need states,
controls the autonomic nervous system, and controls pituitary hormone production and release
• Pituitary - regulates other glandular activity of the body; often called the “master gland”
The Brain: ForebrainThe Brain: Forebrain
The DiencephalonThe Diencephalon
Telencephalon
Limbic System The limbic system is a group of
structures surrounding the brain stem. The limbic system structures include
the amygdala, cingulate gyrus, and hippocampus.
Governs emotions such as anger, fear, and happiness, and is involved in the storage and retrieval of memories.
The Brain: Forebrain The Brain: Forebrain
The Limbic SystemThe Limbic System
The Brain: Forebrain The Brain: Forebrain TelencephalonBasal Ganglia - have widespread
connections to the cortex and forebrain and are involved in the initiation of voluntary movements, maintaining muscle tone and posture
The Brain: ForebrainThe Brain: Forebrain
TelencephalonCerebral Cortex - the convoluted outer
layer of the forebrain that processes sensory information, controls thinking, decision making, stores and retrieves memory, and initiates motor responses
The cortex is divided into two hemispheres connected by the corpus callosum and each hemisphere has four lobes
The Cerebral The Cerebral CortexCortex
The Brain: The Brain: Lobes of the Cerebral CortexLobes of the Cerebral CortexOccipital lobe - primary function is the
analysis of visual informationParietal lobe - The anterior portion
analyses sensory information such as pain, pressure and body position. The posterior portion is involved in spatial perception.
Temporal lobe - includes the primary auditory cortex, a visual area and language centers
The Brain: The Brain: Lobes of the Cerebral CortexLobes of the Cerebral CortexFrontal lobe -
Broca’s area - area for programming and sequencing of motor movements for speech production
Prefrontal cortex - controls complex intellectual functioning such as planning and sequencing of behavior.
Motor cortex - area of the frontal lobe anterior to the central sulcus.
Representation of body parts Representation of body parts in the somatosensory cortex in the somatosensory cortex and motor cortexand motor cortex