Chapter 3 Flashcards
Central Nervous System
includes the brain and spinal cord
Neuron
a single neural cell
Nerve
a bundle of axons running together
- term only used in the peripheral nervous system
Tract
a bundle of axons running together in the CNS
Nucleus
group of cell bodies in CNS
Ganglion
group of cell bodies in PNS
Forebrain
contains two cerebral hemispheres, the thalamus, and the hypothalamus
Cerebral Hemispheres
large, wrinkled structures dominating brain’s appearance
- the dorsal or superior part of the brain that are covered by the cortex
Longitudinal Fissure
division running length of the brain separating cerebral hemispheres
Gyrus
each ridge in the surface of the brain
Sulcus
groove or space between two gyri
Fissure
large groove or space between two gyri
Cortex
outer surface of brain
- mostly made up of the cell bodies of neurons
The Cortex
- 1.4 to 4.0 mm thick
- convolutions provide 3x more surface area; also allow more access to cell bodies
White Matter
- primarily made up by myelinated axons
- inner cortex
Gray Matter
- made up of neuronal cell bodies
- outer cortex
Cortex; Layer 1
inhibitory
- outer most layer
Cortex; Layer 2 and 3
associational
Cortex; Layer 4
sensory
Cortex; Layers 5 and 6
motor functions
- inner most layer
Brain Size and Intelligence
- brain size does not determine intelligence, brain size is more related to body size
- the complexity of the brain is what determines intellectual power
Dorsal
toward the back
Ventral
toward the stomach
Anterior
toward the front
Posterior
toward the rear
Superior
above another structure
Inferior
below another structure
Lateral
toward the side
Medial
toward the middle
Central Sulcus
divides the frontal and the parietal lobe
Lateral Fissure
runs above the temporal lobe
Frontal Lobe
where motor messages are being sent from
Precentral Gyrus
- the primary motor cortex
- controls voluntary movement
- is in front of the central sulcus
Homunculus
a distorted image of the human body that enlarges the parts of the body which have the most cortex dedicated to the body part
- the more cortex, the more movements that part can do
Broca’s Area
controls speech production; grammar and the motor control involved in speech
- in the left hemisphere for most people
Prefrontal cortex
involved in planning and organization of behaviour, decision making, adjust behaviour in terms of consequences, and life planning/goals
- most anterior part of the brain and the largest
- accounts for almost 30% of your entire cortex
Psychosurgery
use of surgical intervention to treat cognitive and emotional disorders
Lobotomy
involves severing connections in the brain’s prefrontal cortex
- performed for schizophrenia but then people started using it for just having emotions, women’s periods, depression
- made them calmer but that is cause they were in a coma like state
- some patients acted in a child-like manner
- 50% were still hospitalized a few years later and 25% couldn’t live independently
Corpus Callosotomy
involves cutting corpus callous to limit spread of epileptic activity between hemispheres
Parietal Lobe
superior to the central sulcus
- contains the primary somatosensory cortex
Primary Somatosensory Cortex
post central gyrus
- process skin senses and motor movement senses
- body sensations
- represented in a homunculus
Association Areas
areas which combine information from different parts of the brain to create a bigger picture; combining different senses to know big things
Neglect
disorder in which the person ignores objects, people, and activity on the side opposite the damage
- most commonly occurs when the posterior parietal cortex is damaged, particularly if the damage occurs in the right parietal lobe
Temporal Lobe
under ear
- contains auditory projection area, visual and auditory association, language, involved in learning and memory
- alheizmers originates here
Primary Auditory Cortex
top gyrus in temporal lobe (superior gyrus)
- receive auditory info first
Secondary Auditory Area
where most auditory processing occurs
Wernickes Area
association area
- involved in understanding language
- receive input from auditory and visual areas
- understanding spoken and written language
- communicates to Broca’s area to help formulate responses
- damage to this area, can still speak but struggle to understand written and spoken language; including sign language
- mostly only found on the left hemisphere, on same side as the Broca’s area
Inferior Temporal Cortex
plays a major role in visual identification of objects
- bottom half
- the what pathway from the occipital lobe goes to the inferior temporal cortex
- damage, can describe something but if the object is in front of you, you couldn’t connect the description to what you are seeing
Occipital Lobe
- back of your head
- vision
- has the visual cortex
- primary visual cortex is the very tip of the back
- association areas behind, they detect individual comments of a scene and then come together; info either goes to the what or the where pathway (goes to the parietal lobe)
Thalamus
receives information from all sensory systems expect olfaction (smell)
- everything travels through here then gets sent to where it needs to go
- we have two; one in each hemisphere
Hypothalamus
plays major role in controlling produce all of our hormones
-controls pituitary gland
- we have 2, one in each hemisphere
Pineal Gland
secretes melatonin, a hormone that induces sleep
- only one
Corpus Callosum
band of fibres that carry information between brain hemispheres; relays info between hemispheres
- where the longitudinal fissure ends
- used to treat epilepsy as a last resort; seizures start on one side and get more severe when it crosses to the other hemisphere; by cutting the corpus callosum, the individual can stay concisous
Basal Ganglia
movement, reward
Hippocampus
memory
Ventricles
cavities ingrain which develop from the hollow interior of the nervous system
- two lateral, one third ( below corpus callosum), and a forth
- lateral and third are in the forebrain
Cerebrospinal FLuid
carries material from blood vessels to the CNS and transports waste materials in the other direction
Substantia Nigra
- midbrain, smallest part of brain
-project to the basal ganglia and integrate movements - involved in Parkinson’s disease; this part is not producing dopamine; without this dopamine, movements get jittery
Superior Colliculus
- two
- midbrain
- helps guide eye movement, and fixation of gaze
Inferior Colliculi
-two
-midbrain
- hearing; helps locate sounds, direction of sounds
Fourth Ventricle
Cerebral Aqueduct
major highway of cerebrospinal fluid through the brain
Hind Brain
pons, reticular formation, medulla, cerebellum
Cerebellum
- “little brain”
- ## refined movements initiated by motor cortex
Pons
contain the renters related to sleep and arousal
Reticular formation
in between pons, collection multiple different nuclei that run though the middle fo the hind brain and mid brain
- sleep and arousal, attention, and some motor activities like reflexes
Medulla
-forms lower part of hindbrain
- nuclei are involved in central life processes like heart and breathing
- damage means your dead
Spinal Cord
finger-sized cable of neurons that carries commands from the brain to muscles and organs, and sensory information into the brain
- rapid reflex responses; hand on hot stove
-helps generate pattern generated behaviours like walking
- has grey matter surrounded by white matter
Dorsal Root
a region of each spinal nerve where sensory neurons enter the spinal cord
- receives information
-sensory neurons in the dorsal root; these neurons are unipolar
Ventral Root
the region in which axons of motor neurons pass out of the spinal cord
- sends information out to the muscles
Dorsal Root Ganglia
- a nucleus found outside the spinal cord of the unipolar sensory neurons
Ventral Root Ganglia
C1-C8
cervical nerves
- connect head, neck, shoulders, and elbows
T1-T12
thoracic nerves
- connect lower arms, hands, upper torso, and most of your internal organs
S1-S5
sacral nerves
- hips and but
Coccoygeal nerve
controls rectum
L1-L5
lumbar
-legs, feet and intestines
Brain Stem
- contains hind brain and mid brain
Reflex
simple, automatic movement in response to sensory stimulus
Where does information cross over
in the spinal cord
Meninges
protective three-layered membrane
- around the brain and spinal cord
Blood-brain barrier
limits passage between bloodstream and the brain, provides constant protection from toxic substances and from neurotransmitters circulating in the blood
- formed by glial cells wrap around blood capillary and seal completely so blood can’t touch neurons; because of this, lipophillac (like fat) things can pass and hydrophilic cannot
- not all parts of brain are surrounds by this barrier; by the ventricles it very sparse
Dura
-outer most layer of the meninges
- thick tough membrane
- make sure nothing bad gets in and touch brain
Eracnoid Layers
-separates blood and CSF cause blood kills neurons
- second layer of meninges
- responsible for headaches; your eracnoid layer gets inflamed
- head injury; cause bruising between this and dura ( called subdura hematoma)
Pia Layer
- inner most layer of meninges
- shrink wrapped to brain, very thin
- helps keep the brain together
-only layer get goes into the sulci and fissures
The Peripheral Nervous System
- goes to and from the CNS
- contains the cranial nerves
Afferent
toward the CNS; sensory neurons
Efferent
away from the CNS; motor neurons
Cranial Nerves
-nerves that enter and leave the underside of the brain (ventral side)
- debate whether this is part of peripheral because of their complexity
- 13 cranial nerves
Spinal Nerves
- nerves which connect to the sides of the spinal cord at each vertebra
Olfactory Bulb (1)
- sensory; nose
Optic Nerve (2)
sensory (eye)
Oculomotor (3)
motor; all eye muscles except those supplied by 4 and 6
- 3,4,6 are all eye movements
Vagus (10)
- involved in pooping
- biggest nerve
- motor; heart, lungs, bronchi, gastrointestinal tract
- causes the sudden need to poop in cats; for us this nerve is longer so it is not as sudden of a feeling
- sensory; heart, lungs, bronchi, trachea, larynx, pharynx, gastrointestinal tract, external ear
Somatic nervous System
- voluntary movements and sensory receptors
- everything concious
Autonomic Nervous Systems
- controls automatic, involuntary functions
- controlled by mid and hind brain
Sympathetic
- increase blood pressure, breathing rate, muscles tense, stop digestion, stops other drives
- fight or flight
- come from thorastic and lumbar areas of the spinal cord
Parasympathetic
stop
- return to base line; breathing decrease, relax muscles, heart rate decrease, digestion recommences
- Proliferation
the cells that will become neurons divide and multiply rapidly
- 1/4 of a million new neurons every minute
- happens in the ventricular zone which later becomes out ventricles
- Migration
newly formed neurons move from the ventricular zone to their final location
- use radial glial cells guide migrating neurons
- a neurons function is determined when it was formed and where it was formed however in early stages, it’s function can change
Stages of Development
- the tube then becomes the spinal cord
- the neural groove happens in the embryo; edges of groove then curl upward and create a tube, skin and muscle forms around the tube
- once tube has formed, we move into the 4 stages of development
- Circuit Formation
- process in which the axons of developing neurons grow toward their target cells and form functional connections
- at the very end of a baby axon, the growth cone; a detector to make sure it travels the right way
- once it gets to its target, growth cone dies off and them our axon terminals forms
- this is why axons usually don’t travel in a straight line
Circuit Pruning
- the elimination of excess neurons and synapses
- helps us not need as much energy or nutrients to up keep it all
- happens also after birth, doesn’t usually stop until puberty age
Plasticity
-type of circuit pruning
- ability of a synapse to be modified
- use it or lose it
-FAS; alters the offsprings ability to do plasticity even long term
Reorganization
shift in connection that changes functions of an area of the brain
- happens a lot after injury or amputation
- if hand is amputated; areas of brain/cells dedicated to that area are gonna change function for a different part of the body
- can take months to years
Stroke
condition caused by loss of blood flow to the brain
- ischemic or hemorrhagic
Ischemic
- most common; caused by blockage of artery like a blood clot so parts fo brain with that clot can’t get nutrients
Hemorrhagic
- an artery bursts; more deadly
- don’t have the nutrients and blood and you also have a pool of blood sitting on the brain; blood kills the neurons its touching and the parts of blood not getting oxygen will die
Traumatic Brain Injury (TBI)
- condition caused baby external mechanical force, sudden acceleration or deceleration, or penetration
- account for 30% of all injury deaths annually
- 30% caused by falls and 17% by vehicle accidents
- repeated TBI increase healing time
Regeneration
growth of severed axons
- easy to do in amphibians
- doesn’t occur very often in mammals, happens more in the CNS than the PNS because Glial cells help most with regeneration
- easier with myelinated axons
Neurogenesis
birth of new neurons
- easier to do the younger you are but can happen any time in life
- happens a lot in the hippocampus and the lateral ventricles
Compensation
uninjured tissue takes over function of lost neurons
- like reorganization except compensation is only when the cells die
Stem Cells
undifferentiated cells that can develop into specialized cells,
-asult stem cells are less potent and confined to areas with high replacement rates; like skin, bone marrow and intestines
