Chapter 27- Nervous System

osteoperosis

-bone disorder0 -more common in women after menopause ------>estrogen contributes to normal bone maintenance, and with lowered production of the hormone, bones may become thinner, more porous, and more easily broken -treatments include calcium and vitamin supplements, hormone replacement therapy, and drugs that slow bone loss or increase bone formation

fractures and breaks

-bones are rigid but not inflexible, they will bend in response to external forces -if a force is applied that exceeds a bone's capacity to bend them, the result is a broken bone, or fracture

drugs

-caffeine, nicotine, and alcohol can affect the actions of neurotransmitters at the brain's trillions of synapses

muscle

-consists of bundles of parallel muscle fibers -each muscle fiber is a single, long cell with many nuclei -each muscle fiber is itself a bundle of smaller myofibrils

bones

-consists of several kinds of living tissues -a sheet of fibrous connective tissue covers most of the outside surface ------>tissue can form a new bone during normal growth or in the event of a fracture -at either end of the bone is a thin sheet of cartilage, also living tissue, that cushions joints, protecting the ends of bones as they move against each other -contains cells that secrete a surrounding material, or matrix -blood vessels course through channels in the bone, transporting nutrients and regulatory hormones to its cells and waste material from them

pons

-controls breathing

medulla oblongata

-controls breathing, circulation, swallowing, digestion

caffeine

-counters the effects of inhibitory neurotransmitters, ones that normally suppress nerve signals

cerebrospinal fluid

-cushions the central nervous system and helps supply it with nutrients, hormones, and white blood cells

brain structure

-divided into three regions: the hindbrain, midbrain, and forebrain

Vertebrate peripheral nervous system

-divided into two functional components: the voluntary nervous system and the autonomic nervous system

electrical synapse

-electric current passes directly from one neuron to the next -found in the heart and digestive tract, where they help maintain steady, rhythmic muscle contractions

pivot joint

-enables us to rotate the forearm at the elbow

endorphins

-example of peptide -they decrease our perception of pain during times of physical or emotional stress -may be released in response to a wide variety of stimuli, including traumatic injury, muscle fatigue, and even eating certain foods like chocolate

alzheimer's disease

-form of mental deterioration, or dementia -characterized by confusion, memory loss etc... -chance of getting it rises with age -disease is progressive; patients gradually become less able to function and eventually need to be dressed, bathed, and fed by others -people with this often lose their ability to recognize people, even family members, and may even treat them with suspicion and hostility

Nervous System

-forms a communication and coordination network throughout an animal's body

cerebrum

-found in forebrain -consists of right and left cerebral hemispheres

thalamus

-found in forebrain -contains most of the cell bodies of neurons that relay information to the cerebral cortex, whichis the most extensive portion of the cerebrum -first sorts data into categories, and also suppresses some signals and enhances others, then sends the sorted information on to the appropriate brain centers for further interpretation and integration

hypothalamus

-found in forebrain -controls the pituitary gland and the secretion of hormones -regulates body temperature, blood pressure, hunger, thirst, the sex drive, and the fight-or-flight response, and it helps us experience emotions, such as rage or pleasure -'pleasure center' is also the addiction center, because it can be strongly affected by certain addictive drugs

endoskeleton

-hard supporting elements situated among soft tissues -human endoskeleton is a combination of cartilage and 206 bones that make up the skeletal system -cartilage provides flexibility in certain areas -organized into two basic units; the axial skeleton and the appendicular skeleton

parietal lobe

-has association areas for reading and speech -these areas receive visual information from the vision centers, then if the words are spoken out loud, the information is arranged into speech patterns and passed to a speech center in the frontal lobe, which signals he motor cortex to move the tongue, lips, and other muscles to form words

resting neuron

-has potential energy that can be put to work to send nerve signals from one part of the body to another -potential energy exists in the form of an electrical charge difference cross the neuron's plasma membrane =inside of the cell is negatively charged relative to the outside -because opposite charges tend to move toward each other, the membrane stores energy by holding opposite charges apart

downside of durgs

-have the potential to disrupt the brain's finely tuned neural pathways, altering the chemical balances that are the product of evolution

hinge joints

-in the elbow -permits movement in a single plane

sensory neurons

-in the peripheral nervous system -conveys the information from the sensory input

ball and sock joints

-in the shoulder and the hip -enable us to rotate our arms and legs and move them in several planes

amphetamines and cocaine

-increases the release and availability of norepinephrine and dopamine at synapses -can therefore produce symptoms resembling schizophrenia

arthritis

-inflammation of the joints -occurs as a result of aging -joints become stiff and sore and often swell as the cartilage between the bones wears down -sometimes the bones thicken at the joints, producing crunching noises when they rub together and restricting movement ----->irreversible, but not crippling

spinal tap

-inserting a narrow needle through the spinal column to collect a sample of cerebrospinal fluid to detect an infection of that fluid

myelin sheath

-insulating -its a chain of bead-like supporting cells -helps speed electrical transmission along an axon -signals can travel along a myelinated axon about 150m/sec

interneurons

-located entirely in the central nervous system -performs integration

peripheral nervous system

-made up mostly of nerves that carry signals into and out of the central nervous system

muscular system

-made up of all the skeletal muscles in the body

appendicular skeletone

-made up of the bones of the limbs, shoulders, and pelvis -the bones of the skeleton are held together by ligaments

brainstem

-made up of the medulla oblongata and the pons of the hindbrain, and the midbrain -where all the sensory and motor neurons carrying information to and from other brain regions pass through (conducts data to and from other brain centers) -selects which information to pass on -also regulates sleep and arousal and helps coordinate body movements -maintains homeostasis

association areas

-makes up most of our cerebral cortex -sites of higher mental activities (thinking)

brain

-master control center of the nervous system -includes homeostatic centers that keep the body functioning smoothly, sensory centers that integrate data from the sense organs, and centers of emotions and intellect -also sends out motor commands to muscles -contains cerebrospinal fluid

major depression

-may experience persistent sadness, loss of interest in pleasurable activities, changes in body weight and sleep patterns, loss of energy, and suicidal thoughts -low level of serotonin, which makes serotonin the target of antidepressant medications ----->these drugs can block the reuptake of neurotransmitter at synapses, increasing the amount of time that serotonin is available to stimulate neurons in the brain

neurons

-nerve cells that carry electrical signals from one part of the body to another -each neuron may communicate with thousands of others, forming networks that enable us to move, perceive our surroundings, learn, and remember

voluntary nervous system

-neurons of the motor system carry signals to skeletal muscles in response to external stimuli

frontal lobe

-one region, called the motor cortex, functions mainly in sending commands to skeletal muscles -frontal association areas use varied inputs from many other areas of the brain to evaluate consequences, make considered judgements, and plan for the future

bipolar disorder

-or manic depressive disorder -extreme mood swings -the manic phase is characterized by high self esteem, increased energy, a flood of thoughts and ideas, and extreme talkativeness, as well as behaviors that often court disaster, such as increased risk taking, promiscuity, and reckless spending ------>this phase is associated with great creativity -the depressive phase is marked by sleep disturbances, feelings of worthlessness, and decreased ability to experience interest and pleasure

supporting cells

-outnumbers neurons -they protect, insulate, and reinforce the neurons

quadriplegia

-paralysis from the neck down (both this and paraplegia are permanent because the nerves in the spinal cord cannot be repaired)

paraplegia

-paralysis of the lower half of the body

cerebellum

-part of the hindbrain -a planning center for body movements -receives sensory information about the position of limbs and the length of muscles, as well as information from the auditory and visual systems -also receives input from the motor pathways, telling it which motor actions are being carried out, and the cerebellum uses this info to provide coordination of movement and balance

sympathetic division

-prepares the body for intense, energy-consuming activities, such as fighting, fleeing, or competing in a strenuous game -when this is stimulated, the digestive organs are inhibited, the bronchi dilate so that more air can pass through, and the adrenal glands secrete the hormones epinephrine and norepinephrine

chemical synapse

-prevalent in most other organs, including skeletal muscles, and in the central nervous system -they have a synaptic cleft

parasympathetic divisions

-primes the body for activities that gain and conserve energy for the body -effects include stimulating the digestive organs, decreasing the heart rate, and narrowing the bronchi, which correlates with a decreased breathing rate

LSD and mescaline

-produce their hallucinatory effects by activating serotonin and dopamine receptors

meninges

-protects the brain and spinal cord -it is layers of connective tissue -if the cerebrospinal fluid becomes infected by bacteria or viruses, the meninges may become inflamed, a condition called meningitis

skeletal system

-provides anchoring, support, and protection -most land animals would sage from their own weight if they had no skeleton to support them -skeletons also protect an animal's soft organs -ribs form a cage around your heart and lungs

midbrain

-receives and integrates auditory data -coordinates visual reflexes -sends sensory data to higher brain centers

autonomic nervous system

-regulates the internal environment by controlling smooth and cardiac muscles and the organs and glands of the digestive, cardiovascular, excretory, and endocrine systems -generally involuntary movements -contains two sets of neurons with opposing effects on most body organs ------->parasympathetic divisions ------->sympathetic division

synaptic terminal

-relays signals to another neuron or to an effector cell such as a muscle cell

axon

-second extension -a single long fiber -transmits signals toward another neuron or toward an effector cell -some axons can be over a meter long (such as the ones that reach from your spinal cord to muscle cells in your feet) -axons that convey signals rapidly are enclosed along most of their length by the myelin sheath

dendrites

-short and highly branched -they receive incoming messages from other neurons and convey this information toward the cell body.

peptides

-short chains of amino acids -serve as neurotransmitters -endorphins is an example of this, which also acts acts as hormones

stimulus

-stimulating a neuron's plasma membrane can trigger the use of the membrane's potential energy to generate an electrical nerve signal -it is any factor that causes a nerve signal to be generated examples: light, sound, touching a hot surface, or a chemical signal from another neuron

tendons

-strong fibrous tissue that connects muscles to bones

ligaments

-strong fibrous tissues that hold together the bones of the skeleton at movable joints -three types of movable joins:ball-and-sock joints, hinge joints, pivot joints

right hemisphere

-stronger at spatial relations, patterns and face recognition, and nonverbal thinking

axial skeleton

-supports the axis, or trunk, of the body - includes the skull, enclosing and protecting the brain; the vertebrae of the spinal column, enclosing the spinal cord; and the ribs

central cavity

-surrounded by the shaft of the long bone in arm -contains yellow bone marrow, which is mostly stored fat brought into the bone by the blood

movement of the muscles

-the ability to move the forearm in opposite directions requires that two muscles work as an antagonistic pair, or the two muscles must perform opposite tasks -contractions of the biceps muscle shortens the muscle and pulls up the forearm -the triceps muscle is the bicep's antagonist; contraction of the triceps pulls the forearm down -when one muscle is contracted, the antagonistic muscle is relaxed

Integration

-the analysis and interpretation of sensory signals and the formulation of appropriate responses

resting potential

-the difference in charge (voltage) that exists across the plasma membrane of a resting neuron -caused by the presence of differently charged ions on either side of the membrane (primarily sodium and potassium) -the hydrophobic interior of the membrane's phospholipid bilayer doesn't let ions pass through -however, the membrane has protein channels and pumps that can allow positive ions across, so by carefully controlling the passage of these ions, a neuron can tap into the energy stored in the resting potential

red bone marrow

-the ends of the bone have cavities of this, which is a specialized tissue that produces blood cells

cell body

-the part of the cell, such as a neuron, that houses the nucleus and other organelles -two types of extensions project from the cell bod

sensory input

-the process of sending signals from sensory receptors, such as light detecting cells of the eyes, to the central nervous system

motor output

-the process of sending signals from the integration centers to effector cells

hemispherectomy

-the removal of almost one half of the brain -performed to alleviate severe seizures disorders that originate from one of the hemispheres as a result of illness, abnormal development, or stroke -patients recover quickly -the side of the body opposite the surgery always has partial paralysis, but they have undiminished intellectual capacities

amines

-they are neurotransmitters derived from amino acids -examples: serotonin, dopamine, epinephrine, and norepinephrine -serotonin and dopamine affect sleep, mood, attention, and learning -imbalances of amines are associated with types of depression (lack of norepinephrine and seritonin), Parkinson's disease (lack of dopamine), and schizophrenia (excess of dopamine)

treatment of a fracture

-two steps: putting the bone back into its natural shape and then immobilizing it until the body's natural bone-building cells can repair the fracture -a splint or cast is sufficient to protect the area, prevent movement, and promote healing -in severe cases, a fracture can only be repaired surgically by inserting plates, rods, and/or screws that hold the broken pieces together

opiates

-used to relieve pain

left hemisphere

-usually becomes more adept at language, logic, and mathematical operations

synapse

-when the signal of an action potential is passed between a neuron and a receiving cell -the receiving cell can be another neuron or an effector cell such as a muscle cell or endocrine cell -comes in two varieties ------->electrical ------->chemical

neurotransmitter

-a chemical that carries information from a nerve cell to another cell that will react, such as another nerve cell or an effector cell -once it conveys a chemical signal from the sending neuron, an action potential may then be generated in the receiving cell

nerve

-a communication line made from cable-like bundles of neuron fibers tightly wrapped in connective tissue

rheumatoid arthritis

-a debilitating autoimmune disease -joints become highly inflamed, and their tissues may be destroyed by the body's immune system -beings between 40 and 50 and effects more women than men

cerebral cortex

-a highly folded layer of tissue that forms the surface of the cerebrum -less than 5mm thick -accounts for over 80% of the total brain mass -contains 10 billion neurons and hundreds of billions of synapses -helps produce the most distinctive human traits; reasoning and mathematical abilities, language skills, imagination, artistic talent, and personality traits -assembling info from our eyes, ears, nose, taste buds, and tough sensors, the cortex creates our sensory perception -regulates our voluntary movement -divided into right and left sides, connected by the corpus callosum ------>bc the nerve fibers from the cortex cross in the medulla oblongata, each hemisphere receives information from and controls the movement of the opposite side of the body -each side of the cortex has four lobes: frontal, parietal, temporal, and occipital lobes -has centers that receive and begin processing sensory info such as taste, vision, hearing, and smell

spinal cord

-a jellylike bundle of nerve fibers that lies inside the spine -acts as the central communication conduit between the brain and the rest of the body -millions of nerve fibers within the cord carry motor information from the brain to the muscles, while other fibers convey sensory information from the body to the brain -well protected by the bony spinal column (a traumatic blow to the spinal columns can crush the nerve bundles and prevent signals from passing) -contains cerebrospinal fluid

synaptic cleft

-a narrow gap that separates the synaptic terminal of the sending neuron from the receiving cell -when the action potential (an electrical signal) reaches the end of the sending neuron, it is converted to a chemical signal consisting of molecules of neurotransmitter

motor neurons

-a nerve cell that conveys command signals from the central nervous system to effector cells, such as muscle cells or gland cells -has a large cell body housing the nucleus and other organelles

action potential

-a stimulus of sufficient strength can trigger this -it is a nerve signal that carries information along a neuron -the signal is actually a propagating change in the voltage across the plasma membrane -it is a localized event-- a rapid change from the resting potential at a specific place along the neuron -a nerve signal starts out as an action potential generated near the cell body of the neuron. to function as a long distance signal, this local event must be passed along the neuron.

alcohol

-a strong depressant -precise effect on nervous system is not known, but it seems to increase the effects of another inhibitory neurotransmitter

corpus callosum

-a thick band of nerve fibers that connects the cerebral hemispheres, enabling them to process information together

Phineas Gage

-accidentally exploded a dynamite charge that propelled a 3 foot long spike through his head, which entered his left cheek and traveled upward behind his left eye and out the top of his skull -he walked away from the accident and appeared to be able to think normally -however, he had a new propensity for meanness and vulgarity and an inability to control his behavior -the rod had pierced both frontal lobes of his brain, resulting in irrational decision making and difficulty processing emotions

nicotine

-acts as a stimulant by binding to and activating receptors for a neurotransmitter called acetylocholine

depression

-affects 20 million adults -two broad forms of depressive illness have been identified: major depression and bipolar disorder

nervous system in vertabrates

-all vertebrates have a nervous system that is concentrated at the head end and all have a central nervous system distinct from a peripheral nervous system -the brain and the spinal cord make up the central nervous system

effector cells

-are things such as muscle cells -performs the body's responses (such as moving a leg) -performed by motor neurons in the peripheral nervous system

skeletal muscles

-attached to the skeleton and produce body movement by interacting with it

multiple sclerosis

-autoimmune disease -leads to a gradual destruction of the myelin sheath by the individual's own immune system -causes a progressive loss of the ability to send signals and control muscles -no cure -drugs that suppress the immune system can relieve symptoms and slow its progress

marijuana

-binds to brain receptors normally used by other neurotransmitters that seem to play a role in pain, depression, appetite, memory, and fertility

events that occur at a synapse between two neurons

1. an action potential arrives at the synaptic terminal 2. the action potential causes vesicals filled with neurotransmitter to fuse with the plasma membrane of the sending neuron 3. the fused vesicles release their neurotransmitter molecules into the synaptic cleft 4. the released neurotransmitter molecules diffuse across the cleft and bind to complementary receptors on ion channel proteins in the receiving neuron's plasma membrane 5. the binding of neurotransmitter to receptors opens the ion channels. With the channels open, ions can diffuse into or out of the receiving neuron. This may trigger a new action potential, or it can cause a neurotransmitter to inhibit the generation of an action potential 6. the neurotransmitter is broken down or transported back to the sending neuron, causing the ion channels in the receiving cell's plasma membrane to close. this ensures that the neurotransmitter's effect on the receiving neuron is brief and precise

Series of events involved in generating an action potential (two diff. sets of ion channels are involved in this process)

1. at first, the membrane is at its resting potential, positively charged outside and negatively charged inside 2. A stimulus triggers the opening of a few of the first set of ion channels in the membrane allowing a few positive ions to enter the neuron. this tiny change makes the inside surface of the membrane slightly less negative than before. If the stimulus is strong enough, a sufficient number of channels open to reach the threshold 3. Once threshold is reached, more of these channels open and more positive ions rapidly rush in. As a result, the interior of this region of the cell becomes positively charged with respect to the outside 4. This electrical change triggers the closing of the first set of channels. Meanwhile, a second set of channels opens, allowing other positive ions to diffuse rapidly out and return the membrane to its resting potential. Within a living neuron, this whole process takes just a few milliseconds, meaning a neuron can produce hundreds of nerve signals in a second

central nervous system

consists of the brain and, in vertebrates, the spinal cord

propagation of the signal in action potential

see page 578 bc they dont explain it very well unless you have the diagram and stuff

threshold

the minimum change in a membrane's voltage that must occur to trigger the action potential