Textbook Notes (362,734)
Canada (158,032)
Psychology (1,036)
PSY2301 (26)
Chapter 2

PSY2301 Chapter 2: How Does the Nervous System Function?

14 Pages
Unlock Document

University of Ottawa
Patrick Davidson

Chapter 2: The Nervous System • the brains primary function is to produce behaviour or movement o without outside stimulation, the brain cannot orient and direct the body to produce an appropriate response o the organs of the nervous system are designed to admit information from the world and convert it to information into biological activity called perception • 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 • phonotypical plasticity: the individual's capacity to develop into more than one phenotype- characteristics that can be seen or measured. • Nerves of the PNS carry sensory information to the CNS and motor instructions from the CNS to the body's muscles and tissues including those that perform autonomic functions such as digestion and blood circulation. • Neurons in the somatic division of the PNS connect through the cranial and spinal nerves to receptors on the body's surface and on its muscles to gather sensory information for the CNS and to convey information from the CNS to move the muscles of the face, body or limbs. • The autonomic division of the PNS enables the CNS to govern workings of your body's internal organs-beating of the heart, stomach contractions etc. . • CNS: includes the brain and spinal cord, structures at the core of nervous system that mediate behaviour • SNS: somatic nervous system, all the spinal and cranial nerves carrying sensory information to the CNS from the muscles, joints, and skin, also transmits outgoing motor instructions to produce behaviour. • ANS: balances the body's internal organs to 'rest and digest' through the parasympathetic (calming) nerves or “flight or fee” or engage in vigorous activity through the sympathetic (arousing) nerves Neural Flow: • afferent: information is sensory information coming into the CNS or one of its parts (incoming information) • efferent: information leaving the CNS or one of its parts (outgoing information) Surface Brain Features: Cerebral Security: Meninges: three layers of protective tissue-dura mater, arachnoid, and pia mater- that encase the brain and spinal cord. • Dura mater (outer layer): is a tough double layer of fibrous tissue that encloses the brain and spinal cord in a kind of loose sack • arachnoid: (middle-like a spider web) a very thin sheet of delicate connective tissue that follows the brain's contour • pia-matter (inner layer): moderately tough membrane of connective tissue fibres that cling to the brain's surface • Between the arachnoid layer and the pia matter flows cerebrospinal fluid, colorless solution of salts and sodium chloride. This cushions the brain so that it can move or expand slightly without pressing on the skull Skull-Dura-Arachnoid-pia-matter- subarachnoid space Anatomical Location Anterior: located near or toward the front of the animal or the front of the head Caudal: located near or toward the tail of the animal Coronal: cut vertically from the crown of the head down; used in reference to the plane of a brain section that reveal frontal view dorsal: on or toward the back of the animal or, in reference to human brain nuclei, located above; in reference to brain sections, a viewing orientation from above Frontal: 'of the front': in reference to brain sections Horizontal: cut along the horizon; used in reference to the plane of the brain section that reveals a dorsal view Inferior: located below (see ventral) Lateral: toward the side of the brain or body Medial: toward the middle, specifically the body's midline; in reference to brain sections, a side view of the central structures Posterior: located near or toward the tail of the animal (see caudal) Rostral: toward the 'beak' front of the animal (see anterior and frontal) Sagittal: cut lengthways from front to back of the skull, the plane that reveals a view into the brain from the side; a cut in the midsaggital plane divides the brain into symmetrical halves, a medial view Superior: located above (see dorsal) Ventral: on or toward the belly or the side of the animal where the belly is located; in reference to the brain nuclei, located below (see inferior) Section cuts: Coronal section: is cut in a vertical plane, from the crown of the head down, yielding a frontal view of the brain's internal structure. Horizontal section: the cut falls around the horizon, is usually viewed looking down on the brain from above- a dorsal view. Sagittal section: cut lengthways from the front to back and viewed from the side.Acut is made midsaggital plane divides the brain into symmetrical halves, a medial view. Cerebrospinal fluid: between the arachnoid layer and the pia mater. It is a colorless solution of sodium chloride. This fluid cushions the brain so that it can move or expand slightly without pressing on the skull. Cerebral cortex: thin, heavily folded film of nerve tissue composed of neurons that are the outer layer of the fore-brain.Also called neocortex temporal lobe: part of the cerebral cortex that functions in connection with hearing, language, and musical abilities; lies below the lateral fissure, beneath the temporal bone at the side of the skull. Frontal lobe: part of the cerebral cortex often generally characterized as performing the brains 'executive' functions, such as decision making; lies anterior to the central sulcus and beneath the frontal bone of the skull. Parietal lobe: part of the cerebral cortex that functions to direct movements toward a goal or to perform a task, such as grasping an object; lies posterior to the central sulcus and beneath the parietal bone at the top of the skull. Occipital Lobe: part of the cerebral cortex where visual processing begins; lies at the back of the brain and beneath the occipital bone. Gyrus: a small protrusion or bump formed by the folding of the cerebral cortex Sulcus (sulci): a groove in brain matter, usually a groove found in the neocortex or cerebellum Stroke: sudden appearance of neurological symptoms as a result of severely interrupted blood flow Gray matter: areas of the nervous system composed predominantly of cell bodies and capillary blood vessels that function either collect and modify information or to support this activity. • The nervous system like the body, is symmetrical o structures that lie on the same side are ipsilateral o structures that lie on the opposite side are contralateral o if a structure lies in each hemisphere it is bilateral o structures that are close to each other are proximal, and those far are distal Fissure: groove in the brain, natural division Meningitis: • Affects the meninges, but particularly the pia mater, arachnoid layer and CSF that lead to meningitis. • Encephalitis: infection of the brain • the brainstem and cerebrum are visible in the lateral and medial view • cerebral cortex is almost invisible for the brain's surface • longitudinal fissure: runs between the cerebral hemispheres and the lateral fissure at the side of the brain are both shown • Ventral view: we can see cerebrum and cerebellum, smooth whitish structure with little tubes attached o central set of structures is the brainstem and the little tubes are cranial nerves Cerebral Circulation • the brain's surface is covered with blood vessels o brain receives blood through arteries and sends it back through veins to the kidneys and lungs for cleaning and oxygenation • the cerebral arteries emerge from the neck to wrap around the outside of the brainstem, cerebrum, and cerebellum, finally piercing the brain's surface to nourish its inner regions • 3 major arteries send blood to the cerebrum: o anterior, middle and posterior cerebral arteries • stroke: loss of blood or blockage or break in a cerebral artery leading to the death of the affected region o because there are 2 different arteries that support blood flow to different regions of the brain, a stroke disrupts different brain functions depending on the artery affected o Because the brain's connections are crossed, stroke in the left hemisphere affects sensation and movement on the right side of the body. Internal Features of the Brain Macro View: • slicing downward through the middle, parallel to the front of the body, in a coronal section • this frontal view makes it apparent that the interior is not homogeneous o both dark and light regions of tissue are visible • Darker regions are called gray matter largely composed of cell bodies and capillary blood vessels. o The neurons of the gray matter function either to collect and modify information or to support this activity • the lighter regions are called white matter which are mostly nerve fibres with fatty coverings that produce that white appearance o the fibers of the white matter form the connections between the cells • Ventricles: contain cerebrospinal fluid , the brain contains four ventricles o The ventricles are connected; so the CSF flows from the two lateral ventricles to the third and fourth ventricles that lie on the brain's midline and into the cerebral aqueduct, a canal that runs the length of the spinal cord. o The function of ventricles is not understood but is thought to play a role in maintaining brain metabolism. o The CSF may allow certain compounds access to the brain, and probably helps the brain excrete metabolic waste. Cut from Front to Back (Sagittal) • If we do a midsaggital cut, we would divide the cerebrum into its two hemispheres- revealing medial view. • We can now see the corpus callosum: long band of white matter that runs the length of the cerebral hemispheres. • Also contains 200 million nerve fibres that join the two hemispheres and allow communication between them. White matter: areas of the nervous system rich in fat-sheathed neural axons that form the connections between the brain cells. Ventricle: one of four cavities in the brain that contain cerebrospinal fluid that cushions the brain and may play a role in maintaining brain metabolism. Corpus Callosum: band of white matter containing 200 million nerve fibres that connects the two cerebral hemispheres to provide a route for direct communication between them. • Subcortical regions : brainstem and forebrain structures o brainstem controls basic physiological functions o forebrain structures: related to the cortical areas that process motor, sensory, perceptual and cognitive functions o sub-cortical and cortical are redundant functions, likewise for both hemispheres being symmetrical • One of a kind structures: third and fourth ventricles (found in the brain's midline) and the pineal gland Cells and Fibres • fundamental units of the brain- cells • the brain has 2 types of cells o Neurons :carries out the brain's major functions o Glial cells: aid modulate the neuron's activities Ex: insulating neurons o they come in many forms depending on the activities that they do • we stain these cells selectively to see their distribution in the grey matter, the distribution is no homogenous but rather forms in layers revealed by bands of tissues • stained subcortical region are seen to be composed of clusters or nuclei of similar cells • a key feature of neurons is that they are connected to one another by fibres called axons o When axons run along together, much like a car engine, they form a nerve or a tract.  Tract: refers to collections of nerve fibres found within the brain and spinal cord, whereas bundles of fibres are located outside these CNS structures referred to as simply nerves. • The pathway from the eye to brain is called the optic nerve, whereas pathway from cerebral cortex to the spinal cord is known as the corticospinal tract. Nucleus: 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. Evolution of the Nervous System • bilateral symmetry of worms are common in complex nervous systems • the spinal cord constituting the nervous system is also another feature in simple beings but also in complex • the neocortex is very complex in humans and dolphins, but also found in other species • the nervous system of young vertebrates embryo begins as a sheet of cells that form into a hollow tube and develops into 3 regions: forebrain, midbrain, and hindbrain o these 3 regions are recognizable as a series of three enlargements at the end of the embryonic spinal cord o prosencephalon (front brain): is responsible for olfaction, the sense of smell o mesencephalon (middle brain): vision and hearing o rhombencephalon (hindbrain): controls movement and balance – spinal cord is considered hindbrain • In mammals, the prosencephalon develops into the cerebral hemispheres, the cortex, and subcortical regions known collectively as telencephalon (endbrain), and the diencephalon (between brains) contains the thalamus, among other structures. Hindbrain develops into the metencephalon (across brain) which includes the cerebellum, and the myencephalon (spinal brain) includes the medulla and spinal cord. • The human brain is more complex version of the mammalian brain, however the human brain has larger cerebral hemispheres • invertebrates have a complex nervous system as well that strays away from the path of vertebrates, they are intelligent enough to learn by condition and observation Central Nervous system Spinal Cord • produces most body movements, usually from instructions from the brain but can also move independently • The spinal cord is not just one structure. It is segmented. Each segment receives information from a discrete part of the body and sends out commands to that area • spinal nerves, part of the somatic nervous system, carry sensory information to the cord from the skin, muscles and related structures and, in turn, send motor instructions to control each muscle Brainstem • begins where the spinal cord enters the skull and extends upward into the lower areas of the forebrain • Brainstem receives afferent nerves coming in from all of the body's senses, and sends efferent nerves out to the spinal cord to control the whole body’s movements except the complex movements of the toes and fingers. • brainstem=directs movements and creates a sensory world • brainstem is responsible for unconscious behaviour o has 3 regions  hind brain, midbrain and diencephalon (between brain) borders brains upper and lower parts  the hindbrain is long and thick like a forearm, midbrain is short and compact like your wrist, and diencephalon is at the end like bulbous like your hand forming a fist  hindbrain and the midbrain are extensions of the spinal cord- they first developed in vertebrates evolving a brain at the anterior end of the body • hindbrain is responsible for motor functions • midbrain is responsible for sensory information • diencephalon is responsible for tasks Hindbrain • controls various motor functions ranging from breathing to balance to fine movements • cerebellum is one of the largest parts of the brain o relative size of the cerebellum increases with physical speed and dexterity of species o i.e. animals like sloths, who move slowly, have small cerebellums • cerebellum is also involved in cognitive tasks and splits into 3 regions o reticular formation, pons, and the medulla o Reticular formation: netlike mixture of neurons (gray matter) and nerve fibres (white matter) that gives the structure of a net. o The nuclei is localized along its length into small patches, each with special function in simulating the forebrain (ex. Waking from sleep) o The pons and medulla contain substructures that control many vital movements in the body. o The nuclei within the pons receive inputs from the cerebellum and actually form a bridge from it to the rest of the brain o the medulla's nuclei control such vital functions as regular breathing and the cardiovascular system Midbrain Tectum: the sensory component (the roof) is located dorsally. • Receives massive amount of sensory information from the eyes and ears • optic nerve sends a large bundle of nerve fibres to the superior colliculus whereas inferior colliculus receives much of its input from auditory pathways Tegmentum: the motor structure (floor located ventrally); collection of nuclei with movement related, species specific, and pain perception functions • control eye movements • red nucleus controls limb movements • substantia nigra connected to the forebrain to initiate these movements ( Parkinson’s disease is the destruction of the substantia nigra) • the colliculi function for sen
More Less

Related notes for PSY2301

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.