2 Protective Tissues The CNS consists of the brain and spinal cord The CNS is surrounded by layers of protective tissue known as the meninges.Swelling of the meninges due to bacterial or viral infection is known as meningitis.
3 CSF and the VentriclesThe brain has a series of internal chambers that make and distribute CSF. They are known as the ventricles.CSF is made from blood in the ventricles and resembles blood plasmaThe CSF:Supports weight of brain (makes it neutrally buoyant)Cushions it (protects from injury)Maintains chemical balanceIf there is a blockage to the draining of the CSF, brain damage can result
4 Spinal cordLong cable of axons that connects the brain to the peripheral nervous system.Runs down the inside of the vertebral columnSize:As thick as your pinkie fingerOnly 2/3 the length of the vertebral column (17-18in)FunctionCarries information through motor neurons from brain to muscles and glandsCarries information through sensory neurons from sense organs to brainCreates some reflexes
5 Spinal Nerves (PNS)Nerves branch off of the spinal cord at each vertebral joint.These nerves follow blood vessels and carry sensory and motor neuron axonsThe extent of damage from injury can be determined by location of injury
6 HindbrainThe hindbrain is responsible for life-saving functions common to all vertebrates.Major areas:CerebellumReceives visual, auditory, vestibular and somatosensory information and coordinates it.Works to make muscle movement smooth and coordinated.
7 Hindbrain (cont)PonsInvolved in sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and postureAlso controls switch from inhalation to exhalationDamage to this area can lead to “locked-in syndrome”Aware and awake but unable to communicate!
8 Hindbrain (cont) Medulla Regulates vital functions such as breathing, heart rate, blood pressure, etc.It is the brain’s connection to the spinal cord.
9 MidbrainFunctions:primary processing of auditory and visual information (before it is passed to thalamus and cortex)In lower vertebrates, these are the only processing areas.Motor functionsSpecies-typical behaviorsSleep/arousal
10 ForebrainThalamusMajor relay center of information coming into the brain from the sensesRegulates states of sleeping and wakefulness
11 Forebrain Hypothalamus rests below the thalamus and above the pituitaryIt is the link between the autonomic nervous system and the endocrine systemIt is responsible for maintaining homeostasishunger, thirst, body temp, sleep
12 Forebrain Basal Ganglia Involved in movement selection and initiation Allows muscles to relax in motion
13 Forebrain Amygdala Hippocampus Responsible for fear, aggression, emotionHippocampusResponsible for formation of long-term memories
14 Forebrain Cerebrum: Cerebral Cortex Largest part of human brain (most evolved)Where conscious “thinking” takes placeCerebral CortexOuter 3mm of cerebrum (surface area = 2.5ft2)Highly convoluted (2/3 of area is in folds)Mostly made of cell bodies of neurons (grey matter)The rest of the cerebrum is made of the myelinated axons of these neurons and the fat makes this area look white - “white matter”
15 Regions of the Cortex In all cases: the “primary cortex” area for a sense receives input directly from sense organsDamage causes loss of senseThe “association areas” get input from primary cortex areas and process it. Also where memories tied to those senses are stored.Damage causes loss of understandingWith the exception of taste and smell, the cortex receives information from the contralateral side of the body
16 Regions of the Cortex Visual Cortex and Association Area SightAuditory Cortex and Association AreaSoundMotor Cortex and Prefrontal Cortex (Motor Assoc. Area)Controls movement and planning for movementSpecific areas control specific body parts.
17 Regions of the Cortex Somatosensory Cortex and Association Area Strip that transects the cerebrum is divided into areas that respond to specific body parts (touch, feel, etc.)The more input and processing required for a region, the more area it is givenTongue/mouth and thumb/hand get most
18 Regions of the CortexThe Cerebral Cortex is often divided in lobes based upon the bones on top of the areas:Frontal lobeHigher thinking, morality, decision makingParietal LobeIntegrates sensory info and determines spatial sense and navigationTemporal LobeAuditory and visual processing, speech and long-term memoryOccipital LobeVision and dreams
19 Regions of the CortexSome tasks are shared equally by the hemispheres, and some tasks are lateralized. Each hemisphere has a majority of responsibility for the following:Left:SequenceAnalysisDetailsTalkingUnderstandingReadingWritingRightSynthesisPerceiving shape and sizeRead mapsBuilding objectsCreativityThe Corpus Callosum bridges the gap between the two hemispheres.