Nervous System: Frontal Lobe is responsible for conscious thought; damage to
it can result in severe personality changes. Responsible for recognizing future
consequences resulting from current actions. In the poster portion of the it lies the
precentral gyrus which is also known as the Somatomoter or primary motor
cortex. Humans it reaches up to 20 years old. Parietal Lobe is associated with
spatial processing and navigation abilities. It is also important in the relaying of
signals that relate to the skin and touch. It is positioned posterior to the central
sulcus and thereby the frontal lobe, anterior and superior of the parietal occipital
sulcus and superior of the lateral sulcus or Sylvain fissure. It gets its name from
the bone that lies above it, the parietal bone. In the anterior portion of the parietal
lobe lies the somatosensory or primary sensory cortex which has nearly the same
organization as the somatomotor cortex. Occipital Lobe is the section in which
your brain processes visual images that come from your eyes. It is positioned in
the back of the head. Temporal Lobe is responsible for visual memory/object
recognition, processing sound and smell, and understanding language. It is
located inferior to the lateral sulcus or sylvian fissure, and is positioned between
the frontal and occipital lobe. 4 parts: Cerebrum, Cerebellum, Limbic System,
Brain stem. Cerebrum -or cortex is the largest part of the human brain. The higher
brain function includes thought and action. It is divided into our sections, called
“lobes” Frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Frontal lobereasoning, planning, parts of speech, movement, emotions, problem solving
parietal lobe-movement, orientation, recognition, perception of stimuli occipital
lobe- visual processing temporal lobe-perception and recognition, perception of
stimuli. Deep furrow divides the cerebrum into 2 halves, known as the left and
right hemispheres. Mostly Symmetrical but parts of it are different. Right
hemisphere is associated with creativity Left hemisphere is associated with logic
abilities Corpus callosum-bundle of axons which connects these two sides of the
brain. Nerve cells is thicker than your thumb. White nerve fibers underneath carry
signals between the nerve cells and other parts of the body and brain. Neocortex
occupies the bulk of the cerebrum. 6th lager of the cerebrum cortex The
Cerebellum: is like the cerebrum. It has 2 hemispheres and has a highly-folded
surface or cortex. Regulation and coordination of movement, posture, and
balance. Older than the cerebrum. Reptiles have cerebellum. Limbic System: the
emotional brain, buried within the cerebrum. Brocas area located in the frontal
lobe. Wernicke area is comprehension of language. cerebrospinal fluid is a
colorless fluid that flows through the brain and spinal cord. Commissural
fibers – conduct impulses between the hemispheres and form corpus callosum
Projection fibers – conduct impulse in and out of the cerebral hemispheres.
Association fibers – conduct impulses within the hemispheres. Old Thalamuslarge mass of gray matter, it’s in the topmost portion of the diencephalon. Has
sensory and motor functions. This is where neutrons send their information to the
overlying cortex. Last relay before it reaches the cerebral cortex. Hypothalamuspart of the diencephalon, ventral to the thalamus. The structure is involved in
functions including homeostasis, emotion, thirst, hunger, circadian rhythms, and
control of the autonomic nervous system. Produces Oxytocin In addition, it
controls the pituitary. Amygdala- part of the telencephalon, located in the
temporal lobe; involved in memory, emotion, and fear. The amygdala is both
large and just beneath the surface of the front, medial part of the temporal lobe
where it causes the bulge on the surface called the uncus. Hippocampus- the
portion of the cerebral hemispheres in basal medial part of the temporal lobe.
This part of the brain is important for learning and memory for converting short
term memory to more permanent memory, and for recalling spatial
relationships in the world about us. Brain stem: under the limbic system, used
for breathing, heartbeat, and blood pressure. The Pituitary gland is responsible
for controlling the release of hormones throughout the body. It is important in
growth especially puberty. It produces prolactin. The Thalamus is a dense
nucleus. The Hypothalamus's most important function is to regulates your
body's temperature using thermoreceptors and osmoreceptors. Midbrainrostral part of brain, huge bundle of axons. Pons- part of the metencephalon in
the hindbrain. It is involved in motor control and sensory analysis MedullaOblongata- this structure is the caudal. Glial Cells- support cells of the central
nervous system. Glia means glue. it reflects old ignorance of their function. The
small nucleus cells are difficult to visualize satisfactory. Oligodendrodia typically
have relatively few processes. With each sheet ending with myelin which wraps
around segment of an axon. Astrology extend branching cytoplasmic processes
in all directions. Functions of astrology are that there is growing awareness that
astrocycles play several critical roles. Foot processes of astrocycles line every
surface where central nervous tissue contracts other body tissues. The synapse
contains a small gap separating neurons. It consists of 1. a presynaptic ending that
contains neurotransmitters, mitochondria and other cell organelles 2. a
postsynaptic ending that contains receptor sites for neurotransmitters 3. a synaptic
cleft or space between the presynaptic and postsynaptic endings. Synaptic
terminal an electrical impulse will trigger the migration of vesicles Chemicals,
called neurotransmitters, are released from one neuron at the presynaptic nerve
terminal. Neurotransmitters then cross the synapse where they may be accepted
by the next neuron at a specialized site called a receptor. The action that follows
activation of a receptor site may be either depolarization or hyperpolarization.
Neuroglia (also known as glial cells or simply glia): Neuroglia are non-neuronal
cells that maintain homeostasis, form myelin, and provide support and protection
for neurons in the central and peripheral nervous systems. CNS astrocyte - named
so because it resembles a star. These are the support cells of the CNS, they help
form the blood-brain barrier, supply nutrients to neurons, and help regulate the
extra cellular chemical environment most notably, removing potassium ions, to
keep the concentration gradient. These are the most numerous of th CNS glial
cells. oligodendrocyte - these are like Schwann cells, but in the CNS. Like
Schwann cells, they provide myelination to axons. However, they can myelinate
many axons around they instead of just one. microglia-these are the macrophages
of the CNS. They protect the neurons from bacteria and viruses through
phagocytosis. These are the least numerous of the CNS glial cells.
Communication of information between neurons is accomplished by movement
of chemicals across a small gap called the synapse. These structural changes
cause the opening of pores – channels – through which ions can flow down their
electrochemical gradient. rapid, transient membrane potential change is called the
action potential. The action of ion transporters creates substantial transmembrane
gradients for most ions. These transporter-dependent concentration gradients are
the indirect source of the resting neuronal membrane potential. Atoms are small,
but toms are made of even smaller particles. They differ in mass. Physical
Properties- can detect with our senses Chemical properties-how atoms interact
with each other. The central nervous system controls most functions of the body
and mind. It consists of two parts: the brain and the spinal cord. The spinal cord
is the highway for communication between the body and the brain. When the
spinal cord is injured, the exchange of information between the brain and other
parts of the body is disrupted. The axons differ in several ways. The dendrites
tend to taper and are often covered with little bumps called spines. In contrast, the
axon tends to stay the same diameter for most of its length and doesn't have spines.
The axon arises from the cell body at a specialized area called the axon hillock.
In motor neurons and interneurons, it's at the axon hillock that the action potential
is initiated. Finally, many axons are covered with a special insulating substance
called myelin, which helps them convey the nerve impulse rapidly. Myelin is
never found on dendrites. Towards its end, the axon splits up into many branches
and develops bulbous swellings known as axon terminals (or nerve terminals).
These axon terminals make connections on target cells. Bipolar Neuron- they
have two processes extending from the cell body Sensory neurons(afferent) send
information from sensory receptors (e.g., in skin, eyes, nose, tongue,
ears) TOWARD the central nervous system. Motor (efferent) neurons- send
information AWAY from the central nervous system to muscles or glands.
Interneurons: send information between sensory neurons and motor neurons.
Most interneurons are in the central nervous system. In most neurons, the resting
potential has a value of approximately −70 mV. Functions of sleep: General
body maintenance. Allows body to accomplish functions such as waste removal,
cell repair, replenishment of certain imp. chemicals, fluids. Also, reinforcement
of immune defense system. Peripheral Nervous system- PNS- nerves and
ganglia not including CNS. Afferent-sensory efferent- motor. An aggregation of
nerve cell bodies located in the peripheral nervous system. Motor neurons that
control muscle contractions have a cell body on one end. Sensory neurons have
dendrites on both end, connected by a long axon with a cell body in the middle.
Interneurons or associative neurons carry information between motor and
sensory neurons. Parasympathetic- control homeostasis and the body’s rest and
digest response. Sympathetic- mobilize the body’s fight or fight response.
Somatic- distant from the mind. Sensory system- responsible for processing
sensory information. The efferent nervous system is split into the autonomic and
somatic nervous systems. autonomic - controlled by the subconscious. Happens
"automatically. Can control all types of muscle. somatic - controlled by the
conscious brain. Always effects skeletal muscle. The autonomic nervous system
is split into the sympathetic and parasympathetic nervous systems. It includes the
cranial nerves, spinal nerves and their roots and branches, peripheral nerves, and
neuromuscular junctions. The anterior horn cells, although technically part of the
central nervous system (CNS), are sometimes discussed with the peripheral
nervous system because they are part of the motor unit. In the peripheral nervous
system, bundles of nerve fibers or axons conduct information to and from the
central nervous system. The autonomic nervous system is the part of the nervous
system concerned with the innervation of involuntary structures, such as the heart,
smooth muscle, and glands within the body. It is distributed throughout the central
and peripheral nervous systems.
Disorders Nervous System: Epilepsy can be described as a "seizure disorder,"
or a disorder that causes a person to have unprovoked or unexpected seizures.
These seizures can seem to have absolutely no cause whatsoever, and after two
of these "unprovoked seizures" a person is considered to have epilepsy. A
progressive, degenerative disorder that attacks the neurons, resulting in loss of
memory, thinking and language skills, and changes in behavior. The most
common form of dementia, it affects memory and comprehension. Multiple
Sclerosis -A chronic, often disabling disease that attacks the Central Nervous
System (CNS). Myelin (fatty substances that surrounds and protects the nerve
fibers) is damaged, as well as the nerve fibers themselves. Parkinson- A chronic
and progressive movement disorder which involves malfunction and death of
neurons. Shingles- Caused by varicella (same virus that causes chickenpox), it
mostly occurs in a band or strip on one side of the body called a dermatome, the
area where one of the nerves from your spinal cord connects with the skin.
Cerebral Palsy- A disorder that affects muscle tone, movement, and motor skills;
usually caused by prenatal brain damage or during first 3-5 years of a child’s life.
The brain damage may lead to other health issues including vision, hearing,
speech problems, and learning disabilities. Glaucoma is a group of diseases that
can damage the eye's optic nerve and result in vision loss and blindness. While
glaucoma can strike anyone, the risk is much greater for people over 60. Pink eye
(conjunctivitis) is an inflammation or infection of the transparent membrane
(conjunctiva) that lines your eyelid and covers the white part of your
eyeball. Effects of Drugs- Alcohol is a central nervous system depressant. It acts
at many sites, including the reticular formation, spinal cord, cerebellum and
cerebral cortex, and on many neurotransmitter systems. Alcohol is a very small
molecule and is soluble in "lipid" and water solutions. Low does- produces a
relaxing effect, reduces tension, slows reflexes. Medium doses-slurs speech,
causes drowsiness, alters emotions. High does- vomiting, breathing difficulties,
un consciousness, comas. Caffeine- is a alkaloid which acts as a stimulant drug.
In humans, it temporarily stimulates the central nervous system, increasing
alertness and attention. However, it can cause addiction. If one takes in too much
caffeine, they can develop a buildup, called tolerance, in which the caffeine's
effects are reduced, and therefore more is needed to create the same effects as
when there was less tolerance. Nicotine (also spelled nicotine) is a alkaloid which
constitutes about 0.6-3% of tobacco plants. As well as being a chemical, which,
when contained in plants, resists animal consumption, it is also a stimulant for
mammals. About 1 milligram is contained in the average cigarette, and it is
responsible for the addiction to smoking. When nicotine enters the body, it
quickly enters the bloodstream. Marijuana comes from a plant called "cannabis
sativa"; the chemical in the plant that produces the altered states of consciousness
is called "delta-9 tetrahydrocannabinol" or "THC". THC acts on cannabinoid
receptors, which are found on neurons in many places in the brain. These areas
are involved in memory (hippocampus), concentration (cerebral cortex),
perception (sensory portions of the cerebral cortex), and movement (cerebellum,
substantia nigari, Globus pallidus). Low-medium dose- causes relaxation, reduces
coordination, reduces blood pressure. High dose- creates delusions, impairs
memory, disorientation. Nose, the organ of smell. Special senses and their
functions- The nose is the organ responsible for the sense of smell. The cavity of
the nose is lined with mucous membranes that have smell receptors connected to
the olfactory nerve. The smells themselves consist of vapors of various
substances. The smell receptors interact with the molecules of these vapors and
transmit the sensations to the brain. The nose also has a structure called the vomer
nasal organ whose function has not been determined, but which is suspected of
being sensitive to pheromones that influence the reproductive cycle. Tongue, the
organ of taste. The receptors for taste, called taste buds, are situated chiefly in the
tongue, but they are also located in the roof of the mouth and near the pharynx.
They can detect four basic tastes: salty, sweet, bitter, and sour. The tongue also
can detect a sensation called "umami" from taste receptors sensitive to amino
acids. Generally, the taste buds close to the tip of the tongue are sensitive to sweet
tastes, whereas those in the back of the tongue are sensitive to bitter tastes. Spinal
cord- the spinal cord makes up the central nervous system. It is divided into 31
pairs of nerves, making 62 nerves composed of sensory and motor neurons. The
nerves are named off of where they leave the spine. They are divided into 5
groups, cranial, thoraic, lumbar, sacral, and coccygeal. 8 pairs in the cervical
region, 12 pairs in the thoracic region, 5 pairs in the lumbar, 5 pairs in the sacral,
1 pairs in the coccygeal. The spinal cord itself in an adult usually ends around the
L1 or L2 vertebra, while the remaining axons, forming the cauda equine, continue
heading down through the spine and exit where they are supposed to. This
happens because the spinal cord stops growing at 4 years of age, while the spine
continues to grow. The spinal cord contains both white and gray matter. The white
matter travels in tracts to and from the brain. The gray matter forms a sort of h,
with 3 horns on either side of the spinal cord. When a neuron is not sending a
signal, the inside of the neuron is negative relative to the outside. Although the
concentrations of the different ions attempt to balance out on both sides of the
membrane, they cannot because the cell membrane allows only some ions to pass
through channels (ion channels). At rest, potassium ions (K+) can cross through
the membrane easily. Disorders sense organs- Myopia- When you look at an
object, light rays reflect off that object and pass through the cornea and the lens
of the eye, which bend (or refract) the light and focus it on the retina at the back
of the eye. If you have perfect vision, the rays focus directly on the surface of the
retina. Myopia can also be the result of a cornea that is too curved for the length
of the eyeball or a lens that is too thick. For some people, their myopia may be
caused by a combination of problems in the cornea, lens, and length of
the eyeball. you have trouble seeing things far away, but you can see nearby
things clearly. Therefore, myopia is commonly called nearsightedness.
Hyperopia-also known as farsightedness, is a common type of refractive error
where distant objects may be seen more clearly than objects that are near.
However, people experience hyperopia differently. Some people may not notice
any problems with their vision, especially when they are young. For people with
significant hyperopia, vision can be blurry for objects at any distance, near or far.
Presbyopia is a common type of vision disorder that occurs as you age. It is often
referred to as the aging eye condition. Presbyopia results in the inability to focus
up close, a problem associated with refraction in the eye. Nyctalopia- Night
blindness is also called “Nyctalopia.” It’s a type of vision impairment. People
with night blindness experience poor vision at night or in dimly lit environments.
There are 3 Conditions for this. Cataract, is a dense, cloudy area that forms in the
lens of the eye. A cataract begins when proteins in the eye form clumps that
prevent the lens from sending clear images to the retina. Diabetic retinopathy is a
condition that occurs because of damage to the blood vessels of the retina in
people who have diabetes. Diabetic retinopathy can develop if you have type 1 or
2 diabetes and a long history of uncontrolled high blood sugar levels. While you
may start out with only mild vision problems, you can eventually lose your sight.
Abetalipoproteinemia (ABL) is an inherited condition that prevents the body
from completely absorbing certain dietary fats. Astigmatism- a common
imperfection in the eyes curvature Conjunctivitis- Inflammation or infection of
the outer membrane of the eyeball and the inner eyelid Color blind- a reduced
ability to distinguish between certain colors Otitis Media- infection of the airfilled space behind the eardrum the middle ear. Endocrine system- Hormonesare chemical messengers, created by one tissue, and moved by the Circulatory
system to change the activities of certain cells in other tissues. These cells are
known as target cells. Target Cells are as the name implies, the cells that
Hormones are meant to alter the activity of. Each hormone has a specific Target
Cell type that will have a specific receptor that will bind to the hormone.
Hormones are exposed to lots of cells in the body, but is these cells only that will
be affected. 3 classes of hormones amines- these are simple molecules proteinswhich are made from chains of amino acids steroids- which are derived from
cholesterol mechanisms of hormone action- communication with long distances.
Extracellular domains: Some of the residues exposed to the outside of the cell
interact with and bind the hormone - another term for these regions is the ligandbinding domain. Transmembrane domains: Hydrophobic stretches of amino acids
are "comfortable" in the lipid bilayer and serve to anchor the receptor in the
membrane. Cytoplasmic or intracellular domains: Tails or loops of the receptor
that are within the cytoplasm react to hormone binding by interacting in some
way with other molecules, leading to generation of second messengers.
Cytoplasmic residues of the receptor are thus the effector region of the molecule.
Fat Soluble hormones pass through the plasma membrane of the cell and act in a
twostep process. Steroid hormones bind, once inside the cell, to the nuclear
membrane receptors, producing an activated hormone-receptor complex. The
activated hormone-receptor complex binds to DNA and activates specific genes,
increasing production of proteins. Steroids are fat-soluble. Water
Soluble hormones do not enter the cell but bind to plasma membrane receptors,
generating a chemical signal (second messenger) inside the target cell. Five
different second messenger chemicals, including cyclic AMP have been
identified. Second messengers activate other intracellular chemicals to produce
the target cell response. Peptides and Amines are water soluble. Thyroid located
in the front part of the lower neck, is shaped like a bow tie or butterfly and
produces the thyroid hormones thyroxine and triiodothyronine. These
hormones control the rate at which cells burn fuels from food to produce energy.
Pineal gland, is located in the middle of the brain. It secretes melatonin a
hormone that may help regulate when you sleep at night and when you wake in
the morning. Reproductive Gland Testosterones and estrogen. Pancreas
produces insulin and Glucagon. Disorders endocrine system: Diabetes mellitus
(or diabetes) is a chronic, lifelong condition that affects your body's ability to use
the energy found in food. There are three major types of diabetes: type 1
diabetes, type 2 diabetes, and gestational diabetes. All types of diabetes mellitus
have something in common. Normally, your body breaks down the sugars and
carbohydrates you eat into a special sugar called glucose. Glucose fuels the cells
in your body. But the cells need insulin, a hormone, in your bloodstream in order
to take in the glucose and use it for energy. Type 1 diabetes is also called insulindependent diabetes. It used to be called juvenile with type 1 diabetes, the
damaged pancreas doesn't make insulin.-onset diabetes, because it often begins in
childhood. Type 1 diabetes is an autoimmune condition. It's caused by the body
attacking its own pancreas with antibodies. Treatment for type 1 diabetes
involves taking insulin, which needs to be injected through the skin into the fatty
tissue. Type 2 diabetes used to be called adult-onset diabetes, but with the
epidemic of obese and overweight kids, more teenagers are now developing type
2 diabetes. Type 2 diabetes was also called non-insulin-dependent diabetes. Type
2 diabetes is often a milder form of diabetes than type 1. Nevertheless, type 2
diabetes can still cause major health complications, particularly in the smallest
blood vessels in the body that nourish the kidneys, nerves, and eyes. Type 2
diabetes also increases your risk of heart disease and stroke. Diabetes that's
triggered by pregnancy is called gestational diabetes (pregnancy, to some
degree, leads to insulin resistance). It is often diagnosed in middle or late
pregnancy. Because high blood sugar levels in a mother are circulated through
the placenta to the baby, gestational diabetes must be controlled to protect the
baby's growth and development. Hypoglycemia, also called low blood glucose or
low blood sugar, occurs when the level of glucose in your blood drops below
normal. For many people with diabetes, that means a level of 70 milligrams per
deciliter (mg/dL) or less. Severe hypoglycemia is when your blood glucose level
becomes so low that you’re unable to treat yourself and need help from another
person. Severe hypoglycemia is dangerous and needs to be treated right away.
This condition is more common in people with type 1 diabetes. Graves' disease
is an autoimmune disorder that causes hyperthyroidism, or overactive thyroid.
With this disease, your immune system attacks the thyroid and causes it to make
more thyroid hormone than your body needs. The thyroid is a small, butterflyshaped gland in the front of your neck. Thyroid hormones control how your body
uses energy, so they affect nearly every organ in your body—even the way your
heart beats. A goiter (GOI-tur) is an abnormal enlargement of your thyroid gland.
Your thyroid is a butterfly-shaped gland located at the base of your neck just
below your Adam's apple. Although goiters are usually painless, a large goiter
can cause a cough and make it difficult for you to swallow or breathe. The most
common cause of goiters worldwide is a lack of iodine in the diet. In the United
States, where the use of iodized salt is common, a goiter is more often due to the
over- or underproduction of thyroid hormones or to nodules that develop in the
gland itself. Treatment depends on the size of the goiter, your symptoms and the
underlying cause. Small goiters that aren't noticeable and don't cause problems
usually don't need treatment
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