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PHYSIOLOGY &
EXERCISE PHYSIOLOGY
PHYSIOLOGY
PHYSIOLOGY
• Physiology is defined as a branch of science
dealing with the study of normal function of
living organism.
• human physiology is defined as a branch of
science dealing with the study of different
system of the human body like circulatory,
respiratory, digestive, muscular system, etc
• William Harvey(1578-1657) is regarded as
the father of modern physiology.
EXERCISE PHYSIOLOGY
• Exercise physiology is a science deals with
the effect of training/physical activity on
different system of the body or normal
functioning of the body. For ex. Effect of
training on circulatory system, respiratory
system, muscular system, etc
• Exercise physiology is a science that tells
us, how the human body functions, adjust
and adapt, when exposed to varied degree
of physical activity or training.
 Exercise physiology is the study of the
acute responses and chronic adaptations
to a wide-range of physical
exercise conditions.
 To know the effect of exercise on different system of
the body.
 Selection & training of sportsperson.
 To know the nutritional aspects of performance.
 To know about energy reserves (ATP,CP) in the body.
 Promotion & advancement in scientific research.
 It provides knowledge about muscular function during
exercise.
 It provides knowledge about neuromuscular
function or coordination during exercise.
 It also explains the energy requirement of
our body during exercise.
 It helps in drawing out programme for
conditioning and physical fitness.
 It provides knowledge about the ergogenic
aids which is illegally used by the athlete in
competition.
Structure and
Function of Skeletal
Muscle
Skeletal Muscle
 Human body contains over 400 skeletal
muscles
 40-50% of total body weight
 Functions of skeletal muscle




Heat production during cold stress
Force production for postural support
Force production for locomotion and breathing
The prime function of muscle is to convert
chemical energy (ATP) into mechanical energy.
Structure of Skeletal
Muscle:
 Epimysium
 The entire muscle is surrounded by connective
tissue called epimysium.
 Perimysium
 The bundle or fasciculus is also surrounded by a
connective tissue calles perimysium.
 Fascicles
 Endomysium
 Many muscle fibre found in muscle bundle.the
indivudual muscle fibre is surrounded by
connective tissue called endomysium.
 Tendon
skeletal muscle is attaches to a bone with the help
of connective tissue called tendon.
 Sarcolemma
Each muscle fibre contains sarcoplasm covered by
membrane sarcolemma.in the sarcoplasm, ATP,
CP, fat droplets are present.
The sarcoplasmic reticulum (smooth endoplasmic
reticulum) stores calcium, which is released into
the sarcoplasm during muscle contraction.
Myofibrils
Threadlike strands within muscle fibers. It
is the smallest unit of a muscle
fibre.Myofibril has dark and light bands in
it.The dark band is known as A band and
light one’s are as I band.
These bands consists of two types of
protein filaments known as actin(thin) and
myosin(thick). Thin myofilaments are
composed of 3 proteins: actin, tropomyosin,
and troponin.
Thick myofilaments consist myosin
molecules.
A band consists of both actin and
myosin filament and I band consist of
only actin filament.
 Further divisions of myofibrils
 Z-line:-In the middle of A and I band, there is a
Z line.
 Sarcomere:- The portion between two Z line is
called sarcomere. The sarcomere is the
functional (contracting) unit of skeletal muscle.
 H zone:-the area in the centre of the A band is
called H zone.
Cross-Bridge Formation in
Muscle Contraction
Function of Skeletal
Muscle:
 Motion -- Motion can be obvious body movements or less
noticeable
 motions such as heartbeat and gut movement.

 Stabilize body positions and regulate organ volume -- Sustained
 contractions of skeletal muscle maintain body posture without
creating noticeable movement. Sustained contractions of smooth
muscle prevent outflow from hollow organs and maintain them at
an appropriate volume.

 Thermogenesis -- A by-product of muscle contraction is heat
production
 and is therefore important in homeostasis of body temperature.
Properties of skeletal
muscles
 Excitability:-This is the ability to receive and respond to
certain stimuli by producing electrical messages.
 Contractibility :- Contractility is the ability to shorten and
thicken (contract), thus generating force to do work.
 Extensibility:- Extensibility is the ability to stretch without
damaging the tissue.
 Elasticity:- It is the property of muscle to lengthens during
stretching by pulling force & can return again to its normal
resting position.
 Muscle tone:- it refers to the partially contracted state of
the muscle in a constant state of readiness for action.
THE MOTOR UNIT
 One motor neuron plus ALL of the
skeletal muscle cells it
 stimulates is called a motor unit. On
average, a single motor neuron makes
contact and thus stimulates about 150
individual skeletal muscle cells. All the
cells contract and relax together, as a
unit.
 An alpha-motor neuron is a nerve cell that connects
with and innervates many muscle fibers. A single amotor neuron and all the muscle fibers it directly
signals are collectively termed a motor unit . The
synapse or gap between the a-motor neuron and a
muscle fiber is referred to as a neuromuscular junction.
This is where communication between the nervous and
muscular systems occurs.
MUSCLE TONE
 Sustained, small contractions of motor
units give skeletal muscles a
 firmness known as muscle tone.
Muscular Contraction
 The sliding filament model
 Muscle shortening occurs due to the
movement of the actin filament over the
myosin filament
 Formation of cross-bridges between actin
and myosin filaments
 Reduction in the distance between Z-lines of
the sarcomere
The Sliding Filament
Model of Muscle
Contraction
 Sliding filament theory in its simplest
form states that muscle fibres shorten
when actin filaments slide inward on
myosin filaments - pulling the z-lines
closer together
 When actin filaments (the light bands
in the diagram above) slide over
myosin filaments (the dark bands) the
H-zone and I-band decrease
 The sliding filament theory is the basic
summary of the process of skeletal
muscle contraction. Myosin moves along
the filament by repeating a binding and
releasing sequence that causes the thick
filament to move over the thinner
filament. This progresses in sequential
stages. By progressing through this
sequence the filaments slide and the
skeletal muscles contract and release.

 http://bcs.whfreeman.com/thelifewire/cont
ent/chp47/4702001.html
 http://www.blackwellpublishing.com/pates
tas/animations/myosin.html
 http://outreach.mcb.harvard.edu/animatio
ns/actionpotential_short.swf
 http://bigpictureeducation.com/animationsliding-filament-theory
Stage First
 The first stage is when the impulse gets to the unit. The
impulse travels along the axon and enters the muscle
through the neuromuscular junction. This causes full
two to regulate and calcium channels in the axon
membrane to then open. Calcium ions come from extra
cellular fluid and move into the axon terminal causing
synaptic vessels to fuse with pre synaptic membranes.
This causes the release of acetylcholine (a substance
that works as a transmitter) within the synaptic cleft. As
acetylcholine is released it defuses across the gap and
attaches itself to the receptors along the sarcolemma
and spreads along the muscle fiber.

Stage Second
 The second stage is for the impulse
spreads along the sarcolemma. The
action potential spreads quickly along the
sarcolemma once it has been generated.
This action continues to move deep
inside the muscle fiber down to the T
tubules and the action potential triggers
the release of calcium ions from the
sarcoplasmic reticulum.
Stage Third
 During the third stage calcium is released from
the sarcoplasmic reticulum and actin sites are
activated. Calcium ions once released begin
binding to Troponin. Tropomyosin blocking the
binding of actin is what causes the chain of
events that lead to muscle contraction. As
calcium ions bind to the Troponin it changes
shape which removes the blocking action of
Tropomyosin (thin strands of protein that are
wrapped around the actin filaments). Actin
active sites are then exposed and allow myosin
heads to attach to the site.
Stage Fourth
 The fourth stage then begins in which
myosin heads attach to actin and form
cross bridges, ATP is also broken down
during this stage. Myosin binds at this
point to the exposed binding sites and
through the sliding filament mechanism
the muscles contract.
Stage Fifth
 During the fifth stage the myosin head
pulls the Actin filament and ADP and
inorganic Phosphate are released. ATP
binding allows the myosin to detach and
ATP hydrolysis occurs during this time.
This recharges the myosin head and then
the series starts over again.
Stage Six
 Cross bridges detach while new ATP
molecules are attaching to the myosin
head while the myosin head is in the lowenergy configuration. Cross bridge
detachment occurs while new ATP
attaches itself to the myosin head. New
ATP attaches itself to the myosin head
during this process.
Stage Seven
 During stage seven the ATP is broken
down and used as energy for the other
areas including new cross bridge
formation. Then the final stage (stage 8)
begins and a drop in stimulus causes the
calcium concentrate and this decreases
the muscle relaxation.
Excitation-Contraction
Coupling
 As calcium is relased it binds with a protein
called troponin that is situated along the
actin filaments. Sliding filament theory
states that this binding causes a shift to
occur in another chemical called
tropomyosin. Because these chemicals
have a high affinity for calcium ions they
cause the myosin cross bridges to attach to
actin and flex rapidly.
 For contraction to contiune the
myosin cross bridges must detach,
"recock" and reattach. Significant
muscle shortening depends on the
continuous sequence of the following
events:
 Calcium released by sarcoplasmic
reticulum binds with troponin
 Myosin cross bridge couples with actin
filament
 Cross bridge flexes and moves actin a
small amount
 Cross bridge detaches and re-cocks
 Process is repeated
Molecular Participants
 The chemical players in muscle
contraction are:
 1. myosin (protein)
 2. actin (protein)
 3. tropomyosin (protein)
 4. troponin (protein)
 5. ATP (nucleotide)
 6. calcium ions
SUMMERY
Muscle Fiber Contraction
 Distal end of motor neuron releases
acetylcholine (ACh)
 ACh diffuses across the gap at the
neuromuscular junction (synaptic cleft)
 Muscle fiber membrane stimulated.
Muscle impulse travels through
transverse tubules. Reaches
sarcoplasmic reticulum (SR)

 Ca++ diffuse from SR to bind on troponin
 Troponin and tropomyosin exposes
binding site on actin
 Actin + myosin filaments form links
 Myosin cross-bridge pull actin filament
inwards
 Muscle fiber shortens
Muscle Fiber Relaxation
 Acetylcholinesterase decomposes ACh.
Muscle fiber not stimulated.
 Ca++ transported back to SR
 ATP causes links between actin and
myosin to break (ATP doesn’t break
down)
 Troponin and tropmyosin interact and
block the binding site on actin
 Muscle fiber relaxes
 ATP breakdown “cocks” myosin cross
bridge.
Effect of training/exercise
on circulatory system
 Physical exercise and training affects the
circulatory parameters as follows: Size of the heart(cardiac hypertrophy)
 Decrease resting heart rate(Brady cardia)
 Stroke volume
 Cardiac output
 Blood volume & increased haemoglobin
 Blood flow
 Blood pressure
Size of the heart (cardiac
hypertrophy): size of the heart is important to all
individuals as the blood is supplied to the
whole body by this unique pumping
machine. The size of the heart gets
changed as a result of endurance
training. Endurance training more than
12weeks increases the heart weight and
volume.
Decrease resting heart
rate (Brady cardia)
 heart rate is the number of times the
heart beats per minute. Resting heart
rate decreased as a result of endurance
training. After 10to12weeks of endurance
training, resting heart rate can come
down from normal 70to80beats/min to 45
to 55 beats/minute. Heart rate recovery
period also decreases as a result of
endurance training.
Stroke volume
 the amount of blood pumped by the left
ventricle into the aorta in per beat is
called stroke volume. As a result of
endurance training the stroke volume
increases.
 Athlete
volume)at rest
exercise
 Untrained
100-120ml/beat
 Trained
150-200 ml/beat
 Highly trained
ml/beat
(stroke
during
55-75 ml/beat
80-90 ml/beat
100-120
200 ml/beat
Cardiac output
 the cardiac output is the amount of blood
pumped in one minute by either the left
or right ventricle of the heart.
 Cardiac output = heart rate * stroke
 volume
 Cardiac output at rest remains unchanged
but at maximal level of exercises, it
increases considerably. This increase
results mainly from the increase in maximal
stroke volume.
 Cardiac output (during rest) :- 4-6 litre/min
 During exercise: Untrained = 14-20 L/min
 Trained = 25-35 L/min
 Endurance athlete = 40 L/min
Blood volume
 physical training particularly endurance
training results increase in blood volume
and haemoglobin concentration, which is
mainly due to increase in blood plasma
volume(liquid portion of the blood).no of
red blood cells also increases.
 Highly trained athlete = 7 L
 Untrained athlete
= 5.6 L
Blood flow
 physical training changes the function
and structure of heart. It is well known
fact that active muscles require more O2
and nutrients. To fulfill these
requirements, more blood must be
supplied to these muscles during
exercise. As the muscles become more
trained, the circulatory system adopts to
increase blood flow to them.
 The blood supply is increased to the
muscles due to following reason:-- Increased blood volume
 Increased in capillaries density
 Good and more effective redistribution of
blood.
 Physical exercise increases the blood
flow to muscles.
Blood pressure
 the blood pressure is the driving force that
moves blood through the circulatory
system. Due to physical exercise arterial
blood pressure changes very little during
maximal workout. But resting blood
pressure is lowered in individuals who are
having high blood pressure. This reduction
takes place in both systolic (higher) and
diastolic (lower) blood pressures.
Effect of exercise on
muscular system
 Physical exercise or training, particularly
weight training, affects our muscular
system to a great extent. Many
parameter of muscular system get
changed after weight training or
endurance training.
Hypertrophy of muscles
 an increase in thickness or size of
individual muscle fibre is called
hypertrophy of muscle. Two types of
hypertrophy can occur: transient and
chronic. Transient hypertrophy is the
pumping of the muscle that happens during
a single exercise bout. This is mainly due
to the accumulation of fluid (edema) in the
muscle.
 Transient hypertrophy last only for a short
time.the fluid return to the blood within
hours after exercise.
 Chronic hypertrophy refers to the
increase in muscle size that occurs with
long term weight training.
 Gains in strength and muscular
endurance usually depend on the size of
muscle fibre. the weight training causes
the following effects: Total amount of protein increases, which
is essential for muscle growth.
 Due to resistance/weight training the size
of muscle fibre increases.
 The muscles, bones and ligaments
become stronger to cope with the
additional stresses and impact put
through them.
 The amount of myoglobin within skeletal
muscle increases, which allows more
Oxygen to be stored within the muscle,
and transported to the mitochondria.
 Enzymes involved in energy production
become more concentrated and efficient
to aid the speed of metabolism.
 Capillary density per fibre also increases
which cause more energy production.
 Amount of connective tissues increases.
 Blood supply in the muscles increases.
 Due to hypertrophy, muscular strength
and muscular endurance increases
Biochemical changes in
the muscles
 Aerobic changes (due to endurance
training):--- Myoglobin content increases.myoglobin
is an oxygen binding pigment found in
muscle tissue which acts as an oxygen
store and helps in diffusion of oxygen.
 Oxidation (breakdown) of fat and
carbohydrates increases
 Number of mitochondria also increases thus
more muscular energy is produced.
 Levels of activity of concentration of
enzymes increases. enzymes are protein
compound that speed up chemical reactions
in the muscles.
 Amount of glycogen stores increases as a
result of endurance training. It is essential
for energy production.
 An increase in the number of capillaries
surrounding each muscle fiber.capillary
allows greater exchange of gases, heat,
wasts and nutrients.
Anaerobic changes (due to
weight or sprint training): ATP-PC system capacity increases as a
result more energy is produced.ATP-PC
system is an anaerobic energy system in
which ATP is manufactured when PC is
breakdown.
 Glycolytic capacity also increases as a
result of training.
 Cappillary density per fiber also
increases.
 Blood supply in the muscle increases.
Body composition
changes: For most individuals weight training
produces little or no changes in total
body weight but the body composition
changes considerably.
 There can be significant losses of relative
and absolute body fat.
 Fat free weight or muscle mass
increases.
 Changes in muscle and joint motion also
take place.
 After training flexibility increases.
 After endurance training fat tissues
losses.
CIRCULATORY SYSTEM
 The circulatory system means heart and
blood vessels system, the course taken
by the blood through the arteries,
capillaries and veins and back to the
heart. Heart is the pumping organ which
maintains the circulation throughout the
body.
 Blood vessels consists of arteries which
carry blood from the heart and vein carry
blood to the heart, capillaries (formed by
arteries and veins) exchange the
nourishing food and the waste materials
whereas lymphatic collect, filter and pass
back the blood to its stream.
HEART
 The heart is hollow, muscular cone
shaped or pear shaped organ about the
size of a clenched fist. It is situated in the
thoracic cavity between the lungs
towards left side. It is about 300 grams.
 The human heart is a muscular pumping
organ that lies above the diaphragm
somewhat between the two lungs.
 It is roughly triangular and is placed in
the centre with its narrow end slightly
displaced to the left side. It is about the
size of a person’s fist and weighs around
300 gm. It is enclosed in a double walled
membranous sac the pericardium. The
inner membrane is attached to the heart
and between the two membranes is
present a pericardial fluid that protects
the heart from any shock
STRUCTURE OF HEART
 The heart is composed of a cardiac muscle,
surrounded by three tissue layers which
surround the heart.
 Pericardium:- it is the outer most layer of the
heart which also serves as the lining of the
pericardium.
 Endocardium:-the inner layer of the heart is
known as endocardium.
 Myocardium:-it is the thickest layer of the
heart.
CHAMBERS OF HEART
 Heart has four chambered. Two chamber
on left side and two chambers on right
side.
 Right auricle (atrium):-It receives the
venous blood returning from the body
tissues.
 Right ventricle:-this chamber pumps the
venous blood dropped into it from the
right atrium and pushes it to the lungs.
 Left auricle (atrium):-It receives the
blood high in oxygen content
(oxygenated blood) as it returns from the
lungs.
 Left ventricle:-This chamber has a
thickest wall. It pumps oxygenated blood
to all the parts of the body. This blood
goes through the arteries.
VALVE OF THE HEART
 There are four valves in the heart. They
are formed by the endocardium.They
allow the blood to pass only in the one
direction.
 Right atroventricular valve (Tricuspid
valve):-it is situated between the right
atrium and the right ventricle. It has three
flaps or cusps which allows the blood
from the right atrium to the right ventricle
only.
 Left atrioventricular valve (mitral valve
or bicuspid valve):-It is situated
between the left atrium and left ventricle.
It has two strong cusps or flaps, which
allow blood from the left atrium to the left
ventricle only.
 Pulmonary semilunar valve:-It is
situated between the right ventricle and
the pulmonary artery which allows blood
to pass from the right ventricle to the
lungs through pulmonary arteries.
 Aortic semilunar valve:-It is situated
between the left ventricle and the aorta
which allows blood to pass from the left
ventricle to all parts of the body through
aorta.
Course of circulation
through human heart
 The circulatory system is an organ
system that passes nutrients (such as
amino acids and electrolytes), gases,
hormones, blood cells, nitrogen waste
products, etc. to and from cells in the
body to help fight diseases and help
stabilize body temperature and pH to
maintain homeostasis.
 This system may be seen strictly as a
blood distribution network, but some
consider the circulatory system as
composed of the cardiovascular
system, which distributes blood, and the
lymphatic system,[2] which distributes
lymph. While humans, as well as other
vertebrates, have a closed
cardiovascular system (meaning that the
blood never leaves the network of
arteries, veins and capillaries),
 The main components of the human
circulatory system are the heart, the
blood, and the blood vessels. The
circulatory system includes: the
pulmonary circulation, a "loop" through
the lungs where blood is oxygenated;
and the systemic circulation, a "loop"
through the rest of the body to provide
oxygenated blood.
 An average adult contains five to six
quarts (roughly 4.7 to 5.7 liters) of blood,
which consists of plasma, red blood cells,
white blood cells, and platelets. Also, the
digestive system works with the
circulatory system to provide the
nutrients the system needs to keep the
heart pumping.
 Two types of fluids move through the
circulatory system: blood and lymph. The
blood, heart, and blood vessels form the
cardiovascular system. The lymph, lymph
nodes, and lymph vessels form the
lymphatic system. The cardiovascular
system and the lymphatic system
collectively make up the circulatory
system.
Pulmonary circulation
 Pulmonary circulation is the portion of the
cardiovascular system which transports
oxygen-depleted blood away from the heart,
to the lungs, and returns oxygenated blood
back to the heart.
 Oxygen deprived blood from the vena
cava enters the right atrium of the heart
and flows through the tricuspid valve into
the right ventricle where it is pumped
through the pulmonary semilunar valve
into the pulmonary arteries which go to
the lungs
 Pulmonary veins return the now oxygenrich blood to the heart, where it enters
the left atrium before flowing through the
mitral valve into the left ventricle. Also,
from the left ventricle the oxygen-rich
blood is pumped out via the aorta, and on
to the rest of the body.
Systemic circulation
 Systemic circulation is the portion of the
cardiovascular system which transports
oxygenated blood away from the heart, to
the rest of the body, and returns oxygendepleted blood back to the heart.
Systemic circulation is, distance-wise,
much longer than pulmonary circulation,
transporting blood to every part of the
body except the lungs.
 The heart pumps oxygenated blood to
the body and deoxygenated blood to the
lungs. In the human heart there is one
atrium and one ventricle for each
circulation, and with both a systemic and
a pulmonary circulation there are four
chambers in total: left atrium, left
ventricle, right atrium and right ventricle.
 The right Atrium, which is the upper chamber of
the right side. The blood that is returned to the
right atrium is deoxygenated (poor in oxygen)
and passed into the right ventricle to be
pumped through the pulmonary artery to the
lungs for re-oxygenation and removal of carbon
dioxide. The left atrium receives newly
oxygenated blood from the lungs as well as the
pulmonary vein which is passed into the strong
left ventricle to be pumped through the aorta to
the tissues of the body.
The heart and pulmonary
system
 The heart is located roughly in the center
of the chest cavity. It is covered by a
protective membrane, the pericardium.
 Deoxygenated blood from the body
enters the right atrium.
 It flows through the tricuspid valve into
the right ventricle. The term tricuspid
refers to the three flaps of tissue that
make up the valve.
 Contraction of the ventricle then closes
the tricuspid valve and forces open the
pulmonary valve.
 Blood flows into the pulmonary artery.
 This branches immediately, carrying
blood to the right and left lungs.
 Here the blood gives up carbon dioxide
and takes on a fresh supply of oxygen.
 The capillary beds of the lungs are
drained by venules that are the tributaries
of the pulmonary veins.
 Four pulmonary veins, two draining each
lung, carry oxygenated blood to the left
atrium of the heart.
Respiratory System
 Human have lungs as a respiratory
organ.
 Parts of respiratory system: Nasal cavity
 Nasopharynx
 Larynx
 Glottis
 Epiglottis








Trachea(Wind pipe)
Bronchi(Right & left)
Bronchioles
Respiratory Bronchioles
Alveolar tubes
Alveoli
Lungs
Diaphragm
Mechanics of pulmonary
respiration
 Pulmonary ventilation
 Exchange of gases between alveolar air
and lung capillaries
 Transport of gases in blood(transport of
oxygen from lungs to tissue and that of
carbon di oxide from tissue to lungs)
 Release of gases at the lung level
Pulmonary ventilation
 It is simply taking in of air from the
atmosphere & giving out of air from the
lungs. It is carried out by breathing which
constantly renews the air present in the
lungs. It involves two process: Inspiration
 Expiration