Transcript Chapter 2 - Fitness Mentors

Chapter 2
Basic Exercise Science
Objectives
• After this presentation, the participant will be
able to explain the basic structure and
function of:
• The nervous system
• The skeletal system
• The muscular system
• The endocrine system
• Describe how these systems respond and
adapt to exercise
Introduction
• Human Movement System
– Movement is accomplished through the functional
integration of three systems, the nervous, skeletal, and
muscular systems.
– These systems work in concert to produce human
movement.
– All components must work together to produce sound
movement if one component is not working well it will
affect the others and cause Kinetic Chain impairments.
•
Kinetic
Chain
The Kinetic Chain
– Kinetic means force or motion.
– Chain refers to a system that is linked together or
connected.
– All components work together to manipulate human
motion.
– If one component of the kinetic chain is not working
properly, it will affect the others and ultimately affect
the movement.
Kinetic Chain
Nervous System
Muscular System
Skeletal System
The Nervous System
• The Nervous System is one of the main organ
systems of the body and contains specialized cells
that transmit and coordinate signals, providing a
communication network within the body.
– The nervous system is comprised of two main
components
• The Central Nervous System (CNS) is composed of the brain
and spinal cord
• The Peripheral Nervous System (PNS) is the nerves that
communicate with the CNS
The Nervous System
• The nervous system is a
communication network within
the human body.
• It allows us to gather information
about our internal and external
environments, process and
interpret the information, and
respond.
• Three primary functions
– Sensory
– Integrative
– Motor
The Nervous System
• Sensory
– The ability of the nervous system to sense changes in either
the internal or external environment.
• Integrative
– The ability of the nervous system to analyze and interpret
the sensory information to allow for proper decision making,
producing the appropriate response.
• Motor
– The neuromuscular response to the sensory information.
Proprioception
• Is the body’s ability to sense the relative position of adjacent
parts of the body. On the test they will define proprioception as
the cumulative neural input from all sensory afferents to the
Central Nervous System. Training the body’s proprioceptive
abilities will improve balance, coordination, and posture, and
enable the body to adapt to its surroundings without consciously
thinking about movement.
• It is important to train the nervous system efficiently to ensure
proper movement patterns which can enhance performance and
decrease the risk of injury.
The Nervous System
• Movement is a response to our sensory information
and is therefore dictated by the nervous system.
– This reflects the importance of training in a
multisensory environment using different balance
tools, ex. Bosu ball, Balance pad, Dyna Disc
• The most effective way to create positive long-term
results in a client is to directly affect (properly train)
his or her nervous system.
The Neuron
• The functional unit of the
nervous system is known as
the neuron.
• Neurons are composed of
three main parts:
– Cell body
• Includes cell structures like
(nucleus, mitochondria,
lysosomes, and Golgi
complex)
– Axon
• Provides communication
from the brain or spinal cord
to other parts of the body
– Dendrites
• Responsible for gathering
information from other
structures of the body
The Neuron
• There are three main functional classifications of
neurons determined by the direction of their nerve
impulses:
– Sensory
• Transmits afferent nerve impulses from receptors to the brain
or spinal cord
– Motor
• Transmits efferent nerve impulses from the brain or spinal cord
to the effector sites such as muscles or organs
– Interneuron
• Transmits nerve impulses from one neuron to another
Central Nervous System
• Consists of the brain and the spinal cord
Peripheral Nervous System
• Contains 12 cranial nerves and 31 pairs of spinal nerves, that
branch out from the brain and spinal cord, as well as all sensory
receptors.
• Function
– Provide a connection for the nervous system to activate different bodily
organs, such as muscles (motor information).
– Relay information from the bodily organs back to the brain, providing a
constant update of the relation between the body and the environment
(sensory information).
Peripheral Nervous System
• Two further subdivisions of the PNS include the somatic and
autonomic nervous systems
– The somatic nervous system consists of nerves that serve the
outer areas of the body and skeletal muscle, and are
responsible for the voluntary control of movement.
– The autonomic nervous system supplies neural input to the
involuntary systems of the body
– The autonomic system is further dived into the sympathetic
and parasympathetic nervous systems. The sympathetic
nervous system initiates the Fight or Flight response while
the parasympathetic initiates the Rest and Digest.
Sensory Receptors
• Specialized structures located throughout the body are
designed to transform environmental stimuli (heat, light,
sound, taste, motion) into sensory information that the brain
or spinal cord can interpret to produce a response.
– Mechanoreceptors respond to mechanical forces (touch and
pressure).
– Nociceptors respond to pain (pain receptors).
– Chemoreceptors respond to chemical interaction (smell and
taste).
– Photoreceptors respond to light (vision).
– For relevance to this course, we will focus attention on the
mechanoreceptors.
Mechanoreceptors
• Muscle Spindle
– Sensitive to change in length and rate of length change in
muscle.
• Golgi Tendon Organ
– Sensitive to changes in muscular tension and rate of
tension change.
• Joint Receptors
– Respond to pressure, acceleration, and deceleration of the
joint.
The Skeletal System
• Framework for our
structure and movement
• Resting ground for the
muscles of our body
• Bones form junctions
that are connected by
muscles and connective
tissue known as joints
Divisions of the Skeletal System
• Axial Skeleton
– Skull
– Rib cage
– Vertebral column
• Appendicular Skeleton
– Upper and lower extremities
– Shoulder and pelvic girdles
Bone Growth
• Bones under go remodeling throughout life cycle
–
–
–
–
Osteoclasts break down old bone tissue
Osteoblasts build up new bone tissue
Remodeling is the constant process of these cells
As children Osteoblasts are more active, as we age
Osteoclasts become more active
Types of Bones
• Long
– Long cylindrical shaft and
irregular or widened ends
– Epiphysis ends of long
bones
– Diaphysis shaft of long
bones main production of
red blood cells (RBC’s)
– Epiphyseal plate is
where bone growth
(length) occurs
Types of Bones
• Short
– Similar in length and
width and appear
somewhat cubical in
shape
Types of Bones
• Flat
– Thin, protective
Types of Bones
• Irregular
– Unique shape and
function
Vertebral Column
• Vertebral column: A series of irregularly shaped bones called
vertebrae that houses the spinal cord.
–
–
–
–
–
Cervical has 7 (concave curve)
Thoracic has 12 (convex curve)
Lumbar has 5 (concave curve)
Sacrum is fused triangle attached to pelvis
Coccyx is tail bone
Joints
• One bone that articulates with another bone
• Joint motion is referred to as arthrokinematics
• Typical joint motions seen in the human articular
system
– Roll: Rolling on joint surface on another
• Femoral condyles rolling over the tibial condyles during a
squat
– Slide: Sliding of a joint surface across another
• Tibial condyles moving (sliding) across the femoral condyles
during a knee extension
– Spin: Rotation of one joint surface on another
• Head of the radius rotating on the end of the humerus during
pronation and supination of the forearm
Function of Joints
• Provide the bones a means to be
manipulated, allowing for movement
throughout segments of the body
• Provide stability, allowing for movement to
take place without unwanted movement
• All joints in the human body are linked
together
– Movement of one joint will directly affect the
motion of others
Joint Connective Tissue
• Ligaments connect
bone to bone and
provide static and
dynamic stability as well
as proprioception.
– Characterized by poor
vascularity and do not
repair or adapt as easily
as other tissues in the
body
Weight Bearing Exercise
• Weight bearing exercise-exercise that forces the
body to work against gravity
– Running, lifting weights, calisthenics are weight
bearing
– Swimming and cycling are not
– Help build and maintain bones, muscles, and connective
tissues, burns lots of calories
The Muscular System
• Muscles generate internal
tension that, under the
control of the nervous
system, manipulates the
bones of our body to
produce movement.
• The Muscular System
also is needed to stabilize
and complete the cycle of
movement production.*
Structure of Skeletal Muscle
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Muscle is the compilation of many individual muscle fibers neatly wrapped
together with connective tissue to form bundles.
The first bundle is the actual muscle itself, wrapped by an outer layer of
connective tissue called fascia. The layer immediately surrounding the muscle is
called epimysium.
The next bundle of muscle fiber is a fascicle that is wrapped by connective tissue
called perimysium.
Each fascicle is made up of many individual muscle fibers that are wrapped by
connective tissue called endomysium.
Each layer of connective tissue extends the length of the muscle, helping to form
the tendon.
Connective Tissue
• Tendons are the
structures that attach
muscles to bone and
provide the anchor from
which the muscle can
exert force and control
the bone and joint.
– They have poor
vascularity (blood
supply), which leaves
them susceptible to
slower repair and
adaptation.
Muscle Fibers (Cells)
•
Contain typical cell components
– Cellular plasma called
sarcoplasm (contains
glycogen, fats, minerals, and
oxygen-binding myoglobin)
– Nuclei
– Mitochondria (transform
energy from food into energy
for the cell)
•
Unlike typical cells, they also have
structures called myofibrils.
Contractile Elements
• Myofibrils contain myofilaments
that are the actual contractile
components of muscle tissue.
– Actin
– Myosin
• Actin (thin) and myosin (thick)
filaments form sections known as a
sarcomere.
• A sarcomere is the functional unit
of the muscle, much like the neuron
is for the nervous system.
– It lies in the space between two Z lines. Each Z
line denotes another sarcomere along the
myofibril
Contractile Elements
•
Two protein structures that are
also important to muscle
contraction are tropomyosin and
troponin.
•
Tropomyosin is located on the
actin filament and blocks myosin
binding sites located on the actin
filament, keeping myosin from
attaching to actin while the muscle
is in a relaxed state.
•
Troponin, also located on the actin
filament, plays a role in muscle
contraction by providing binding
sites for both calcium and
tropomyosin when a muscle
needs to contract.
Troponin
Generating Force in a Muscle
• Neural Activation
– Essential for a muscle to
manipulate force for either
movement or stabilization.
– Generated by the
communication between the
nervous system and the
muscular system or the
motor unit.
• Motor unit = motor neuron
and the muscle fibers with
which it connects.
Neural Activation
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Electrical impulses are transported from the central nervous system down the axon of the
neuron.
When the impulse reaches the end of the axon (axon terminal), chemicals called
neurotransmitters are released.
Neurotransmitters (chemical messengers) cross the synapse between the neuron and muscle
fiber, transporting the electrical impulse from the nerve to the muscle. The specific
neurotransmitter that initiates muscular contraction is acetylcholine (ACh).*
ACh falls into receptor sites on the muscle fiber, specifically designed for its attachment.
Once attached, ACh stimulates the muscle fibers to go through a series of steps that produce
muscle contractions.
Either a summation causes all motor fibers of a unit to fire or none, this is the “all or nothing
law”
Sliding Filament Theory
• The proposed process of how the contraction of the
filaments within the sarcomere takes place.
– A sarcomere shortens as a result of the Z lines moving closer
together.
– The Z lines converge as the result of myosin heads attaching to
the actin filament and asynchronously pulling (power strokes) the
actin filament across the myosin.
Muscle Fiber Types
• Type I: Slow Twitch
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Higher in capillaries, mitochondria, and myoglobin
Increased oxygen delivery
Smaller in size
Produce less force
Slow to fatigue
Long-term contractions (stabilization)
• Type II: Fast Twitch
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Lower in capillaries, mitochondria, and myoglobin
Decreased oxygen delivery
Larger in size
Produce more force
Quick to fatigue
Short-term contractions (force and power)
Muscles as Movers
• Agonist muscles act as prime movers
– Gluteus maximus is an agonist for hip extension
• Synergist muscles assist prime movers during
movement
– Hamstring and the erector spinae are synergistic with the
gluteus maximus during hip extension
• Stabilizer muscles support or stabilize the body while
the prime movers and the synergists perform the
movement patterns
– Transversus abdominis, internal oblique, and multifidus
stabilize the low back, pelvis, and hips during hip extension
Endocrine System
• System of glands that secrete hormones that
control bodily function
– Consists of host organs, chemical messengers, target
cells
– Target cells bind specifically to hormones
– Regulates body functions (growth, metabolism,
response to stress)
Endocrine Glands
• Primary glands of the endocrine
system include:
• Pituitary “master gland” with
anterior, posterior and
intermediate globes,
hypthalamus, thyroid and
adrenal glands
Endocrine Glands
• Pituitary- Master control gland has three lobes
– Anterior- Secretes growth hormone, prolactin, ACTH
(adrenal glands) TSH (Thyroid), FSH (sex organs) and
LH (sex organs).
– Intermediate lobe secretes MSH (skin)
– Posterior lobe secretes ADH (fluid retention), oxytocin
(childbirth),
Endocrine Glands
• Thyroid gland-regulates metabolism
• Adrenal glands-fight or flight hormones and
inflammation (epinephrine “adrenaline” and
norepinephrine
• Testosterone is produced in testes and adrenal
glands, men produce 10 times more than women
Blood Glucose Control
• Control of blood glucose levels regulated by the
pancreas to prevent wide swings in blood glucose
levels
• Insulin- brings glucose into cells from blood stream,
results in net drop in blood sugar levels
• Glucagon- Signals the liver and muscles to breakdown
glycogen stores and release, results in net rise on blood
sugar levels
• Exercise improves bodies utilization of glucose
Hormones
• Both produced by men and women
– Testosterone-men produce 10 times more is produced in
testes and adrenal glands, major anabolic agent
– Estrogen-produced in ovaries and adrenal glands,
women produce significantly more
– Cortisol produced in adrenal is main catabolic agent
– Growth Hormone-produced in pituitary major anabolic
agent
– Thyroid-Found in in neck, controls metabolism
– Exercise can elevate all these hormones
Summary
• The three components of the kinetic chain (nervous, muscular,
and skeletal systems) all work together to produce movement.
• The nervous system is composed of billions of neurons that
transfer information throughout the body, through two
interdependent systems: the central nervous system and the
peripheral nervous system.
• The skeletal system is the body’s framework and is made up of
bones and joints in two divisions: axial and appendicular.
• The muscular system is made up of many individual fibers
attached to bones by way of the tendons. Muscles generate force
through neural activation, sliding filament theory, and excitation–
contraction coupling.