Download Skeletal Muscles

Human Physiology
(Part I)
•Neurons and Nervous System
•Brain
•Spinal Chord
•Muscles
•Heart
Neurons and Nervous System
•Definition
A neuron is a specialized cell of the nervous
system designed to rapidly communicate
with other neurons and organs by sending
chemical and electrical signals.
Description
•The nervous system contains two major
types of cells, neurons and glia. Neurons
are specialized cells of the central and
peripheral nervous systems that play key
roles in transmitting and propagating
information from one neuron to another.
•The role of glial cells is less clear, but they
are involved in supporting the functions of
the neuron.
•There are many different types of neurons,
such as motor neurons, sensory neurons,
and interneuron. Each class of neuron is
specially designed to perform certain
functions, and therefore neuronal
populations differ in structure and chemical
composition.
Neuron Animation
Nervous System Animation (synapses)
Brain
• The cerebral is a structure within the brain with distinct
structural and functional properties. It contains all of the
centers that receive and interpret sensory information,
initiate movement, analyze information, reason and
experience emotions.
•The surface of the cerebral cortex is folded in large
mammals where more than two thirds of the cortical
surface is buried in the grooves, called "sulci".
Association areas
Association areas comprise three major groups:
Parietal, temporal, and occipital lobes - all located in the
posterior part of the brain - are involved in producing our
perceptions resulting from what our eyes see, ears hear,
and other sensory organs inform us about the position of
different parts of our body and relate them to the position
of other objects in the environment
Frontal lobe - called prefrontal association complex and
involved in planning actions and movement, as well as
abstract thought
Limbic association area - involved in emotion and memory.
•The cerebellum (Latin: "little brain") is a region of the brain
that plays an important role in the integration of sensory
perception and motor output . The cerebellum integrates these
pathways, using the constant feedback on body position to finetune motor movements. (Learned-Programmed sequences)
Brain Function Animation
Brain (continued)
Motor areas
•The motor areas are located in both hemispheres of the
cortex.
• They are shaped like a pair of headphones stretching
from ear to ear.
•The motor areas are very closely related to the control of
voluntary movements, especially fine fragmented
movements performed by the hand. The right half of the
motor area controls the left side of your body and vice
versa.
Spinal Chord
•The vertebral column is divided into the cervical, thoracic, and lumbar region. It provides
structural support for the trunk and surrounds and protects the spinal cord. The vertebral
column also provides attachment points for the muscles of the back and ribs.
•The vertebral column is divided into the cervical, thoracic, and lumbar region. It provides
structural support for the trunk and surrounds and protects the spinal cord. The vertebral
column also provides attachment points for the muscles of the back and ribs.
Spinal Chord (continued)
•These are twelve vertebra of the mid back.
• The last vertebra (on the left side of the picture)
attaches to the lumbar (lower) spine, and the top
vertebra (on the right) attaches to the cervical
(neck) section of the back.
•The vertebra are broader and stronger than the
cervical bones. This allows them to absorb the
added pressure applied to the mid back, but they
remain a common sight of injury.
•The vertebra are numbered from one to twelve
and labeled T1, T2, T3 etc. from the upper most
bones to the lowest.
Muscles
Muscles perform four essential functions: They
maintain body posture, stabilize joints, produce
movement and generate heat we need to survive.
This animation illustrates what different muscles do
and how muscles work together.
Skeletal Muscles
Skeletal muscle, or striated muscle, is the type of
muscle you can see and feel. Learn about skeletal
muscle and its complex structure, from muscle.
Skeletal muscle is also called striated muscle,
because when it is viewed under polarized light or
stained with an indicator, you can see alternating
striations.
Cardiac and Smooth Muscles
Smooth muscle and cardiac muscle contract
involuntarily. While most of the processes are
similar, there are some notable differences between
the actions of skeletal, cardiac and smooth muscle.
•Skeletal muscle is a well-organized body tissue.
During muscle contractions, sections of muscle fiber
fit together like pieces of a puzzle.
Muscle Animation
Skeletal Muscle
Heart
•The heart is a pump
•The heart is made up of four main
chambers, two ventricles and two atria. This
animation illustrates the flow of blood through
the heart, to and from the four main vessels
that connect to it.
•Each chamber has a sort of one-way valve
at its exit that prevents blood from flowing
backwards. When each chamber contracts,
the valve at its exit opens. When it is finished
contracting, the valve closes so that blood
does not flow backwards.
•The tricuspid valve is at the exit of the
right atrium.
•The pulmonary valve is at the exit of
the right ventricle.
•The mitral valve is at the exit of the
left atrium.
•The aortic valve is at the exit of the
left ventricle.
Heart Pumping Simulation
Heart (continued)
•When the heart muscle contracts or beats
(called systole), it pumps blood out of the heart.
The heart contracts in two stages. In the first
stage, the right and left atria contract at the
same time, pumping blood to the right and left
ventricles. Then the ventricles contract together
to propel blood out of the heart.
•Then the heart muscle relaxes (called diastole)
before the next heartbeat. This allows blood to
fill up the heart again.
Blood Pressure Simulation
The right and left sides of the heart have separate functions.
•The right side of the heart collects oxygen-poor blood from the body and
pumps it to the lungs where it picks up oxygen and releases carbon dioxide.
•The left side of the heart then collects oxygen-rich blood from the lungs and
pumps it to the body so that the cells throughout your body have the oxygen
they need to function properly.
Heart (continued)
Electrical System:
•A special group of cells that have the ability to
generate electrical activity on their own are
responsible for the heart beating.
•The natural pacemaker of the heart is called
the sinoatrial node (SA node). It is located in
the right atrium. The heart also contains
specialized fibers that conduct the electrical
impulse from the pacemaker (SA node) to the
rest of the heart
•The electrical impulse leaves the SA node (1)
and travels to the right and left atria, causing
them to contract together. This takes .04
seconds. There is now a natural delay to allow
the atria to contract and the ventricles to fill up
with blood. The electrical impulse has now
traveled to the atrioventricular node (AV
node) (2). The electrical impulse now goes to
the Bundle of His (3), then it divides into the
right and left bundle branches (4) where it
rapidly spreads using Purkinje fibers (5) to the
muscles of the right and left ventricle, causing
them to contract at the same time.
Heart Electrical Impulses Simulation
Heart (continued)
Although the pacemaker cells create the electrical impulse that causes the heart to beat,
other nerves can change the rate at which the pacemaker cells fire and the how strongly
the heart contracts. These nerves are part of the autonomic nervous system. The
autonomic nervous system has two parts - The sympathetic nervous system and the
parasympathetic nervous system. The sympathetic nerves increase the heart rate and
increase the force of contraction. The parasympathetic nerves do the opposite.
All this activity produces electrical waves we can measure. The measurement is typically
represented as a graph called an electrocardiogram (EKG). Here is an example of three
heartbeats from an EKG
Each part of the tracing has a lettered name:
• P wave - coincides with the spread of electrical activity over the atria and the beginning
of its contraction.
• QRS complex - coincides with the spread of electrical activity over the ventricles and
the beginning of its contraction.
• T wave - coincides with the recovery phase of the ventricles.
Heart (continued)
Arrhythmia
•An irregular heartbeat, or arrhythmia, can result from a change in the heart's standard
electrical conduction system.
•A serious variety of arrhythmia is known as fibrillation. The muscle cells of the heart normally
function together, creating a single contraction when stimulated. Fibrillation occurs when the
heart muscle begins a quivering motion due to a disunity in contractile cell function. Fibrillation
can affect the atrium (atrial fibrillation) or the ventricle (ventricular fibrillation); ventricular
fibrillation is imminently life-threatening.
•Atrial fibrillation is the quivering, chaotic motion in the upper chambers of the heart, known
as the atria.
•Ventricular fibrillation occurs in the ventricles (lower chambers) of the heart; it is always a
medical emergency. If left untreated, ventricular fibrillation (VF, or V-fib) can lead to death within
minutes. When a heart goes into V-fib, effective pumping of the blood stops. V-fib is considered
a form of cardiac arrest, and an individual suffering from it will not survive unless
cardiopulmonary resuscitation (CPR) and defibrillation are provided immediately.
•CPR can prolong the survival of the brain in the lack of a normal pulse, but defibrillation is the
intervention which is most likely to restore a more healthy heart rhythm. It does this by applying
an electric shock to the heart, after which sometimes the heart will revert to a rhythm that can
once again pump blood.
Almost every person goes into ventricular fibrillation in the last few minutes of life as the heart
muscle reacts to diminished oxygen or general blood flow, trauma, irritants, or depression of
electrical impulses themselves from the brain.
Arrhythmia simulation
EYE
•Structures in the eye translate light into images. By
way of refraction, the image is actually reversed and
upside-down when it reaches the retina. The occipital
lobe in the brain "rights the image" so we perceive it
properly
•As light enters the eye, it strikes the receptor cells of
the retina, called the rods and cones.
•A rod cell is sensitive enough to respond to a single
photon of light, and is about 100 times more sensitive
to a single photon than cones. Since rods require less
light to function than cones, they are therefore the
primary source of visual information at night (scotopic
vision). (black and white)
• Cone cells, on the other hand, require tens to
hundreds of photons to become activated. (color vision)
Eye (General) Simulation
Eye (rods and cones) shory