copyright 2010, john wiley & sons, inc. chapter 13 the central nervous system
Post on 29-Jan-2016
219 Views
Preview:
TRANSCRIPT
Copyright 2010, John Wiley & Sons, Inc.
Chapter 13
The Central Nervous System
Copyright 2010, John Wiley & Sons, Inc.
Chapter 13: The Central Nervous System
The Central Nervous System (CNS) is the major control center for the body
In about 3 pounds of tissue, the CNS has 100 billion neurons
The brain collects sensory information, evaluates it, and sends instructions to effectors to direct appropriate responses
The spinal cord serves two major roles Serves as a pathway for information to and from the brain It controls rapid reactions (reflexes) to specific stimuli
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Main Parts of the CNS The CNS consists of
The brain Cerebrum Diencephelon Brainstem Cerebellum
The spinal cord
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Main Parts of the CNS
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Main Parts of the CNS
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Protection of the CNS
The CNS is protected by Bone
Cranial bones protect the brain Vertebrae protect the spinal cord
Three meninges (layers of connective tissue surrounding the CNS)
Cerebrospinal fluid (CSF) - the CNS is cushioned by a thin layer of fluid
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Protection of the CNS
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Protection of the CNS
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Meninges and the Brain
The meninges are three connective tissue layers that surround the brain and spinal cord Dura mater
Epidural space Dural sinuses
Arachnoid mater Subarachnoid space
Pia mater
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Meninges and the Brain
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Meninges and the Brain
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Meninges and the Spinal Cord
The meninges also surround the spinal cord, and the cranial and spinal meniniges form a single unified protective covering for the CNS.
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Meninges and the Spinal Cord
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Blood Flow to the Brain Blood supply to the brain is a crucial source of O2
and nutrients
The brain receives much greater blood supply than expected based on its size and mass
Blood flow to active areas of the brain increases during higher levels of metabolic activity
Interruptions in blood flow have very serious consequences (unconsciousness, stroke, death)
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Blood Flow to the Brain
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Blood Flow to the Brain
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Blood Flow to the Brain
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: The Blood-Brain Barrier The blood-brain barrier (BBB) prevents pathogens and
harmful chemicals from entering the brain
The BBB consists of 3 components Tight junctions between capillary endothelial cells A thick basement membrane underlying the endothelium A layer of astrocytes that cover the capillaries
The BBB helps prevent polar chemicals from entering the brain (but small, nonpolar chemicals enter easily)
Damage to the BBB exposes the brain to changes in blood chemistry and to pathogens
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Cerebrospinal Fluid
Cerebrospinal fluid (CSF) is a nutrient-rich fluid that circulates within and around the CNS
CSF serves three key homeostatic functions in the CNS
Mechanical protection
Chemical protection
Circulation
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Cerebrospinal Fluid
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Cerebrospinal Fluid
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Production of CSF CSF is produced in each ventricle Ependymal cells control which chemicals pass into CSF
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Circulation Pattern of CSF
Copyright 2010, John Wiley & Sons, Inc.
CNS Overview: Circulation Pattern of CSF
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Introduction The cerebrum is by far the largest part of the brain All conscious activities of the brain occur in the
cerebrum - this involves massive amounts of neural processing
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Introduction
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Terminology
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Terminology
Key structural terms
Cerebral cortex Gray and white matter Cerebral hemispheres
Gyrus Sulcus Sissure
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Lobes of the Cerebrum■Each cerebral hemisphere has several regions known as lobes:
Frontal lobe Parietal lobe Occipital lobe Temporal lobe The insula (deep to temporal lobe)
■Major grooves in cerebral surface Central sulcus Lateral sulcus Parieto-occipital sulcus
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Lobes of the Cerebrum
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Lobes of the Cerebrum
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Cerebral White Matter■Most of the cerebral white matter consists of fiber tracts - major groups of axons connecting distant regions of cerebral neurons
Association tracts connect gyri in the same hemisphere Commissural tracts connect areas in opposite
hemispheres Corpus callosum
Projection tracts connect the cerebrum to other brain regions
Internal capsule
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Cerebral White Matter
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Basal Nuclei
■Deep within the cerebrum are areas of gray matter called basal nuclei
■Major basal nuclei include Globus pallidus Putamen Caudate nucleus
■Basal nuclei are involved in the coordination of motor output, learning and many other functions
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Basal Nuclei
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: Basal Nuclei
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: The Limbic System■This ring-like set of structures (aka the “emotional
brain”) lies along the border of the cerebrum and diencephelon
■The limbic system mediates behaviors and emotions Pleasure and pain Fear/rage Affection
■The limbic system also has a major role in memory
Copyright 2010, John Wiley & Sons, Inc.
The Cerebrum: The Limbic System
Copyright 2010, John Wiley & Sons, Inc.
Functional Areas of the Cerebral Cortex■Regions of the cerebral cortex specialize in different
types of information processing
Sensory areas receive and process sensory impulses
Motor areas initiate voluntary movements
Association areas perform integrative functions
Copyright 2010, John Wiley & Sons, Inc.
Functional Areas of the Cerebral Cortex
Copyright 2010, John Wiley & Sons, Inc.
Sensory Areas of the Cerebral Cortex■Major sensory regions of the cerebral cortex include
Primary somatosensory area
Primary visual area
Primary auditory area
Primary gustatory area
Primary olfactory area
Copyright 2010, John Wiley & Sons, Inc.
Sensory Areas of the Cerebral Cortex
Copyright 2010, John Wiley & Sons, Inc.
Motor Areas of the Cerebral Cortex■Major motor regions of the cerebral cortex include
Primary motor area
Broca’s area
Copyright 2010, John Wiley & Sons, Inc.
Motor Areas of the Cerebral Cortex
Copyright 2010, John Wiley & Sons, Inc.
Integrative Areas of the Cerebral Cortex■Major integrative regions of the cerebral cortex include
Somatosensory association area Prefrontal cortex Visual association area
Wernicke’s area Common integrative area Premotor area
Copyright 2010, John Wiley & Sons, Inc.
Integrative Areas of the Cerebral Cortex
Copyright 2010, John Wiley & Sons, Inc.
Hemispheric Lateralization of the Cerebral Cortex
■There is functional asymmetry between the two cerebral hemispheres
Sensory information passes to the opposite side on its way in
Signals to voluntary muscles pass to the opposite side on their way out
■Many integrative functions are localized in one of the hemispheres, leading to terms such as “left brain” and “right brain” functions
Copyright 2010, John Wiley & Sons, Inc.
Hemispheric Lateralization of the Cerebral Cortex
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon
The diencephelon is a small but crucial brain region that sits below and is surrounded by the cerebrum
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon Thalamus: Relays almost all sensory input to the cerebral cortex. Contributes to motor functions by transmitting information from the cerebellum and basal ganglia to the primary motor area of the cerebral cortex. Also plays a role in the maintenance of consciousness.
Hypothalamus: Controls and integrates activities of the autonomic nervous system and pituitary gland. Regulates emotional and behavioral patterns. Controls body temperature and regulates eating and drinking behavior. Helps maintain the waking state and establishes patterns of sleep. Produces hormones.
Pineal gland: Secretes melatonin, sets the body’s biological clock.
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Thalamus
The thalamus has paired masses of gray matter, organized into many nuclei, located on either side of the third ventricle
The thalamus is a major relay center for information entering and leaving the brain, as well as for information moving within the brain
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Thalamus
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Thalamus
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Hypothalamus
The hypothalamus is a small but critical brain region
Specific nuclei are involved in the control of Production of hormones
Emotions and behavior
Eating and drinking
Body temperature
Circadian rhythms and consciousness
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Hypothalamus
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Pineal Gland
This small region of the diencephelon secretes the hormone melatonin, and is involved in regulation of circadian rhythms and sleep
Copyright 2010, John Wiley & Sons, Inc.
Diencephelon: The Pineal Gland
Copyright 2010, John Wiley & Sons, Inc.
Brainstem Brainstem fiber tracts connect the spinal cord, the
diencephelon, and the cerebellum to each other Brainstem nuclei control many critical autonomic body
functions
Copyright 2010, John Wiley & Sons, Inc.
Brainstem Midbrain: Relays motor impulses from the cerebral cortex to the pons and sensory impulses from the spinal cord to the thalamus. Superior colliculi coordinate movements of the head, eyes, and trunk in response to visual stimuli, and the inferior colliculi coordinate movements of the head, eyes, and trunk in response to auditory stimuli. Contributes to control of movements.
Pons: Relays impulses between cerebral cortex and cerebellum and between the medulla and midbrain. Pneumotaxic and apneustic area, together with the medulla oblongata, help control breathing.
Medulla oblongata: Relays motor and sensory impulses between other parts of the brain and the spinal cord. Vital centers regulate heartbeat, breathing (together with pneumotaxic and apneustic area of pons), and blood vessel diameter. Other centers coordinate swallowing, vomiting, coughing, sneezing, and hiccuping.
Reticular formation: Helps maintain consciousness, causes awakening from sleep, filters repetitive sensory input, and contributes to regulation of muscle tone.
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Midbrain
Major midbrain structures include the cerebral peducles, the corpora quadrigemina, and the cerebral aqueduct
The midbrain includes major fiber tracts, as well as nuclei involved in responses to visual and auditory stimuli
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Midbrain
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Midbrain
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Midbrain
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Pons Major pons fiber tracts connect the cerebral cortex to the cerebellum
The pneumotaxic and apneustic areas help regulate breathing
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Pons
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Pons
Copyright 2010, John Wiley & Sons, Inc.
Brainstem - Medulla Oblongata
Large fiber tracts in the medulla connect the spinal cord to the brain
The medulla includes control centers for respiration, heart rate, blood pressure, and other functions (e.g., coughing, vomiting, etc.)
Copyright 2010, John Wiley & Sons, Inc.
Brainstem - Medulla Oblongata
Copyright 2010, John Wiley & Sons, Inc.
Brainstem - Medulla Oblongata
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Reticular Formation
The reticular formation is a diffuse collection of small nuclei in the brainstem - they act together to help maintain consciousness, and to regulate muscle tone
Copyright 2010, John Wiley & Sons, Inc.
Brainstem: Reticular Formation
Copyright 2010, John Wiley & Sons, Inc.
The Cerebellum The cerebellum is 10% of brain mass but contains almost 50% of all brain neurons
The cerebellum is critical to coordinated movements, and provides constant feedback to motor areas
Copyright 2010, John Wiley & Sons, Inc.
The Cerebellum
Compares intended movements with what is actually happening to smooth and coordinate complex, skilled movements. Regulates posture and balance. May have a role in cognition and language processing.
Copyright 2010, John Wiley & Sons, Inc.
The Cerebellum: Internal Structures
■Major structures and regions of the cerebellum are
Cerebellar hemispheres
Vermis
Arbor vitae
Cerebellar peduncles
Vitae
Copyright 2010, John Wiley & Sons, Inc.
The Cerebellum: Internal Structures
Copyright 2010, John Wiley & Sons, Inc.
The Cerebellum: Internal Structures
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord
The spinal cord is the pathway taken by information traveling between our brains and our bodies
The spinal cord includes interneurons mediating spinal reflexes, as well as the cell bodies of all somatic motor neurons
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord
Conducts sensory nerve impulses toward the brain and motor nerve impulses from the brain toward skeletal muscles and other effector tissues. Integrates spinal reflexes.
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Gross Anatomy
■ The spinal cord has several distinctive features
Cervical enlargement
Lumbar enlargement
Conus medullaris
Filum terminale
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Gross Anatomy
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Spinal Nerves
■The spinal cord gives rise to the spinal nerves
Anterior root
Posterior root
Posterior root ganglion
Spinal nerve
■The most inferior of the spinal nerves form the
Cauda equina
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Internal Structure ■The spinal gray matter has a distinctive pattern
Anterior gray horns Lateral gray horns Posterior gray horns Gray commissure Central canal
■The spinal white matter has 3 sets of columns Anterior columns Lateral columns Posterior columns
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Internal Structure
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Sensory and Motor Tracts ■The spinal cord has a number of well understood fiber tracts and columns, that are named according to their origins and destinations.
Copyright 2010, John Wiley & Sons, Inc.
The Spinal Cord: Sensory and Motor Tracts
Copyright 2010, John Wiley & Sons, Inc.
Somatic Sensory and Motor PathwaysInteractions Animations Somatic Sensory and Motor Pathways
You must be connected to the internet to run this animation.
Copyright 2010, John Wiley & Sons, Inc.
End of Chapter 13
Copyright 2010 John Wiley & Sons, Inc.All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.
top related