Chapter # 16
SUPPORT AND MOVEMENT
Multiple choice questions.
(i) The
disorder in which bones are porous and thin but bone composition is normal is;
(a) osteomalacia (b) osteoporosis
(c) rickets (d) arthritis
(ii) The organic
portion of bone's matrix is important in providing all but;
(a) tensile strength (b) hardness
(c) to resist stretch (d) flexibility
(iii) The remodeling of bone is a function of which cells?
(a) chondrocytes and osteocytes
(b) osteoblasts and osteoclasts
(c) chondroblasts and osteoclasts
(d) osteoblasts and osteocytes
(iv) In skeletal
muscle, calcium facilitates contraction by binding to
(a) tropomyosin (b) actin.
(c) troponin. (d)
myosin.
(v) Which of the
following statements concerning the role of Ca2+ in the contraction of skeletal
muscle is correct?
(a) The mitochondria act as a store of Ca++
for the contractile process
(b) Ca+2 entry across the plasma membrane is
important in sustaining the
contraction of skeletal muscle
(c) A
rise in intracellular Ca+2allows actin to interact with myosin
d) The
tension of a skeletal muscle fibre is partly regulated by G proteins muscle
(vi) The function of the T tubules in muscle contraction is to
(a) make and
store glycogen
(b) release
Ca2+ into the cell interior and then pick it up again
(c) make
the action potential deep into the muscle cells
(d) to hamper
the the nerve impulse
(vii)
The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes are the:
(a) neuromuscular
junctions (b) sarcomeres
(c) myofilaments (d) Z
discs
(viii) Myoglobin has a special function in muscle tissue.
(a) it breaks down glycogen.
(b) it is a contractile protein
(c) it holds a reserve supply of oxygen
in the muscle
(d) none of these
Short Questions
Q1. Name the
cranial and facial bones
Ans. The 28 Bones of the skull are tabulated
here.
Skull
|
Unpaired Bones
|
Paired Bones
|
Cranium 8
Bones
|
Frontal
Occipital
Sphenoid
Ethmoid
|
Parietal
Temporal
|
Facial bones
(face) 14 bones
|
Mandible
Vomer
|
Maxilla
Zygomatic
Lacrimal
Nasal
Inferior concha
Palatine
|
Auditory ossicle
(ear bones) 6
Bones
|
|
Malleus
Incus
Stapes
|
Q2. What is the
function of the intervertebral discs?
Ans. The inter vertebral discs are protective shock
absorbing pads between the bones of vertebrae. They remain in stable position
with the help of the cartilaginous portion of disc & the gel portion
present among the discs. Any damage to disc or infection than causes disc
defects & disc thus can not keep themselves stable.
Q3. Distinguish
between the anulus fibrosus and nucleus
pulposus regions of a disc.
Ans.
i. Vertebral column is a bony tube made
up of vertebrae, connected with each other by mean of intervertebral
discs.
ii. The discs
act as shock absorber during walking running or jumping etc.
iii. The outer
part of the disc is called annulus fibrosis and its internal part is the
nucleus pulposus.
iv. Slipped
disc or herniation occurs most commonly in those areas of vertebral column
where a mobile part joins a relatively immobile part, on occasions like bending
forward, while lifting a heavy load,
v. In these
areas the posterior parts of annulus fibrosis of the disc ruptures and the
central nucleus pulposus is forced out.
vi. This may press one or more nerve roots
and thus results in the onset of
pain.
Q.4 Briefly
describe the impairment of function seen in
cleft palate.
Ans. Clef palate is the abnormal union of palate bone
during its development as a result of the birth the defect of palate cancers
malfunction for the new born. In speech, eating habits & in swallowing.
Extensive Questions
Q1. Describe the structure of bone.
Ans.
Bone:
i)
Introduction: Bone is a rigid form of connective tissue, which forms the
endoskeleton of vertebrates.
ii) Nature: Bone is a
living hard (resists compression) and strong (resists bending) structure.
iii)
Composition: It consists of a hard ground substance or matrix and cells. In
the adult human, the matrix consists of about 65% inorganic matter (calcium
phosphate, carbonate etc) and about 35% organic substances (protein, collagen).
The cells are embedded in the
matrix.
iv)
structure: The structure of bone is specially designed to withstand
the compression strains falling upon it and to resist pressure.
v) Bone
Cells: Bones are composed of cells for example; osteoblasts (cells
that to help form bone), and osteoclasts (cells that help eat away old bone).
In
addition, bone contains cells called osteocytes, which are mature osteoblasts
that have ended their bone-forming capacity. These cells engage in metabolic
exchange with the blood that flows through the bones.
Osteoblasts:
i. The
osteoblasts are mononucleate cells. Osteoblasts produce a matrix which is
composed mainly of Type I collagen.
ii. They are
also responsible for mineralization of this matrix.
iii. Osteoblasts
are the immature bone cells, and eventually become entrapped in the bone matrix
to become osteocytes- the mature bone cell.
Osteocytes:
i. They are
mature bone cells.
ii. They cease
to generate mineralized matrix.
iii. Osteocytes
have many extensions that reach out to meet osteoblasts and other osteocytes
for the purposes of communication.
vi. They are
responsible for the maintenance of bone and calcium.
v. They also
regulate the bone's response to stress and mechanical load.
Osteoclast:
i. Osteoclasts
are large, multinucleated cells that remove bone tissue by removing its
mineralized matrix and breaking up the organic bone.
ii. This
process is known as bone resorption.
iii. They are
equipped with phagocytic-like mechanisms similar to circulating macrophages.
Q2. Describe major
divisions of human axial skeleton
Ans. Axial Skeleton:
Axial skeleton consists of skull, vertebral column and
cular skeleton ribs.
1.
Skull:
i. The skull
consists of cranium (or facial bones), ear bone (or auditory ossicles) and
hyoid bone.
ii. The primary function of skull is the
protection of brain. The human
skull is composed of 22 bones, besides 6 tiny ear
bones and one hyoid bone.
iii. At the
time of birth several of the bones of the cranium are not completely formed.
iv. If the
bones of cranium were completely formed at the time of birth, great difficultly
would have been experienced in the birth canal.
2. Vertebral
Column:
i. The vertebral column forms
a more or less rigid rod.
ii. It extends
through the length of the trunk on the dorsal side and form the backbone.
iii. It houses
and protects the spinal cord.
iv. It is a
place of attachment of pelvic and pectoral girdle.
v. In man,
there are 33 vertebrae.
vi. Seven
cervical vertebrae in the neck region; in the thorax region 12 thoracic
vertebrae; in the lower back region 5 lumber vertebrae; in the sacral region 5
sacral vertebrae (to which
the pelvic girdle is attached )
and at the
end of the vertebral column is the coccyx or tail bone which
consists of 4 small fused vertebrae.
vii. The coccyx
is man's vestige of a tail.
3. Ribs:
i. In man there are twelve
pairs of ribs, one pair articulating with each of the thoracic vertebrae
forming a cage that encloses the heart and lungs.
ii. Ten pairs
of ribs are connected anteriorly with the sternum.
iii. Seven
pairs out of these ten pairs are directly connected with the sternum and are
known as 'true ribs, while the other three pairs are indirectly connected with
the sternum through costal arch and are known as 'false ribs'.
iv. The lower
two pairs of ribs are not attached in front and are known as the “floating
ribs”.
Q3. What are types of fractures? Describe the repair process of a simple fracture.
Ans. Bone fractures:
i. A fracture is the medical term for a
broken bone.
ii. They occur
when the physical force exerted on the bone is stronger than the bone itself.
So bones break when they cannot withstand a force or trauma applied to them.
iii. Simple
fracture: Closed (simple) fractures are those in which the skin is intact.
iv. Compound
fracture: The fracture is an open (compound) fracture if the bone ends
penetrate the skin and form a wound.
Repair of a fractured bone:
i. A fracture
is treated by reduction, the realignment of the broken bone ends.
ii. In closed
or external reduction, the bone ends are coaxed into position by the
physician's hands. In open (internal) reduction, the bone ends are secured
together surgically with pins or wires.
iii. After the
broken bone is reduced, it is immobilized by a cast to allow the healing
process to begin.
iv. For a
simple fracture the healing time is six to eight weeks for small or
medium-sized bones in young adults, but it is much longer for large,
weight-bearing bones and for bones of elderly people (because of their poorer
circulation).
v.Stages; Repair in
a simple fracture involves four major stages;
Heamatoma formation:
i. When a
bone breaks, blood vessels in the bone, and perhaps in surrounding tissues, are
torn and hemorrhage occur.
ii. As a
result, a heamatoma, a mass of clotted blood, forms at the fracture site.
iii. Soon, bone
cells deprived of nutrition die, and the tissue at the site becomes swollen,
painful, and inflamed.
Fibrocartilaginous callus formation:
i. Within a
few days, several events lead to the formation of soft granulation tissue, also
called the soft callus.
ii. Capillaries
grow into the hematoma and phagocytic cells invade the area and begin cleaning
up the debris.
iii. Meanwhile,
fibroblasts and osteoblasts invade the fracture site and begin reconstructing
the bone.
iv. The
fibroblasts produce collagen fibers that span the break and connect the broken
bone ends, and some differentiate into chondroblasts that secrete cartilage
matrix.
v. Within this
mass of repair tissue, osteoblasts begin forming spongy bone, but those
farthest from the capillary supply secrete an externally bulging cartilaginous
matrix that later calcifies.
vi. This entire
mass of repair tissue, now called the fibrocartilaginous callus, splints the
broken bone.
Bony callus formation:
i. Within a
week the fibrocartilaginous callus is gradually converted to a bony (hard)
callus of spongy bone.
ii. Bony
callus formation continues until a firm union is formed about two months later.
Bone remodeling:
i. Beginning
during bony callus formation and continuing for several months after, the bony
callus is remodeled. The compact bone is laid down to reconstruct the shaft
walls.
ii. The final
structure of the remodeled area resembles that of the original unbroken bony
region because it responds to the same set of mechanical stressors.
Q4. Compare smooth, cardiac, and skeletal muscles.
Ans.
Types of muscles:
Based
on their location, three types of muscles are skeletal, cardiac, and smooth.
1. Skeletal Muscles:
i. Location: Skeletal
muscles are attached to and cover the bony skeleton.
ii.
Striations: Skeletal muscle fibers are multinucleated, the longest
muscle cells having obvious stripes called striations and are under voluntary
control.
iii. Working
power: They can contract rapidly, but get tire easily and must
rest after short periods of activity, or fatigued. Nevertheless, it can exert
tremendous power.
iv. Function
(a) Skeletal muscles are also remarkably adaptable. For
example, hand muscles can exert a force of a fraction of an ounce to pick up a
dropped paper clip and the same muscles can exert a force of many pounds to
pick heavy loads like a bucket full of water.
(b) Skeletal
muscles are primarily involved in locomotory actions and changes of body
postures.
2. Cardiac Muscles:
i . Location: Cardiac
muscles occur only in the heart where they constitute the bulk of the heart
walls.
ii.
Arrangement: Cardiac muscle cells are arranged in a characteristic branching
pattern.
iii. Nature: Like skeletal muscle cells, cardiac muscle cells are striated, but are
involuntary and have single nucleus.
iv. Working
power: Cardiac muscles usually contract at a fairly steady rate set
by the heart's pacemaker, but neural controls allow the heart to “shift into
high gear” for brief periods.
v. Function:
Rhythmic
contraction of cardiac muscles in atria and ventricles of the heart pump blood
throughout the body.
3. Smooth
Muscles:
i. Location: Smooth muscles
are found in the walls of hollow visceral organs, such as the stomach, urinary
bladder, respiratory passages, and blood vessels.
ii) Shape: Smooth muscle cells are spindle shaped.
iii) Natural: They have one
centrally placed nucleus per cell. They have no striations, and are not
subjected to voluntary control.
iv.
Function: Voluntary muscles control the movement of substances
through hollow organs.
Q5. Explain the ultra-structure of human skeletal muscles.
Ans.
Structure of Skeletal Muscles:
i. Location: The skeletal
muscles are attached to the skeleton.
ii. Muscle fibres: The skeletal muscle consists of muscles bundle, which are further
composed of huge elongated cells called muscles fibre.
iii. Natural
of ii. Muscle fibres: These
muscles fibres are cylindrical, unbranched and with a diameter of 10 –100μm.
iv. Sarcoplasm: Each fibre
consists of a semi fluid matrix, the sarcoplasm or cytoplasm, containing many
nuclei and a large number of mitochondria.
v. The nuclei
are located near the periphery of each fibre.
vi. Each fibre is surrounded by a membrane
sarcolemma.
vii.
T-tubule: The sarcolemma of muscle fibre cell penetrates deep into
the cell to form hollow elongated tube, the transverse tubule, T-tubule.
viii. lumen (a)
of T-TubeThe lumen of which is continuous with the extracellular fluid.
(b) The T-tubule
and terminal portion of the adjacent envelope of sarcoplasmic reticulum (a
modified type of endoplasmic reticulum that store calcium) form triads at
regular intervals along the length of the fibril.
(c). The nerve
impulse is carried through the T-tubule to the adjacent sarcoplasmic
reticulum.
ix. Colour
of fiber: Fibre may be red, due to the presence of the myoglobin- an oxygen
storing pigmented protein.
xii. Composition of fiber: It also contain large
amount of stored glycogen.
xi. Myofibrils: The sarcoplasm of the fibre contains many contractile
elements called myofibrils, which are 1 –2μm in diameter.
xii.
Structure of myofibrils: Each myofibril has alternate light and
dark bands, which give the fibre its “striped” appearances.
It is
because of this, that the skeletal muscles are also called striated or striped
muscles.
Q6. Explain the sliding filament theory of
contraction using appropriately
labeled diagrams of a relaxed and a
contracted sarcomere.
Ans. Muscles
Contraction:
i.
Contractility: Contractility or the ability to contract is a fundamentals
characteristic of living substance.
ii. Use of c
Contractility: It is essential to all kinds of movements,
except growth and cytoplasmic streaming.
iii. Sliding
filament Hypothesis: The currently popular model of muscle fiber
contraction is called the sliding filament hypothesis
(a)
Discovery: It was proposed by H .E.
Huxely and A. F. Huxely.
They
observed that when the muscle contracts, the thick and thin filaments of the
muscles fibre slide past each other but are not changed in length.
(b)
Statement: According to this model, the release of calcium ions from
the sarcoplasmic reticulum causes a reorientation of certain components in the
thin actin filaments, permitting them to bind with extensions (heads) from the
thick myosin filaments.
Each
myosin head then binds and splits an ATP molecule and the energy released
powers the head forward to the next binding component on the actin filament.
As this
occurs, the actin filament moves one "notch" past the myosin
filament.
viii. As long
as calcium ions and ATP are available in the cytoplasm, the myosin heads
continue to "crawl" along the actin filaments, thereby contracting
the sarcomere and muscle.
Recovery: Muscle Fibre Relaxation:
i. When the
electrical impulses reaching a muscle fibre cease, the sarcoplasmic reticulum
begins to re-accumulate the calcium ions by active transport.
ii. Once most
of the calcium is sequestered in the sarcoplasmic reticulum sacs, which takes
only milliseconds, the binding between the myosin heads and the actin filaments
can no longer occur.
iii. As a
result, the thick and thin filaments slide past one another, returning to their
relaxed state of minimal overlap.
iv. The
sarcomeres (and muscle fibres) once again achieve their maximal length and
stretchability.
Control of Muscle Contraction:
i. The
contraction of a muscle fibre is normally an all-or- none phenomenon.
ii. Once it is
stimulated, a muscle fibre will contract to a set length, regardless of
intensity of the stimulus above the threshold level.
iii. The
question then arises: If fibre contraction is an all-or- none phenomenon, how
do we manage the fine control of muscular activity that permits us to lift a
pencil on one occasion and a bowling ball on another?
iv. Part of the
answer has to do with the physical relationship between motor neurons and
muscle fibres.
v. The axon of
a motor neuron has many branches, each branch terminating at a single muscle
fibre. Thus, depending on how many branches it has, one neuron can stimulate
several to many different muscle fibres.
vi. All the
muscle fibres triggered by a single neuron contract simultaneously as a single
motor unit.
vii. Since a
particular muscle may consist of many motor units, the total amount of muscle
contraction depends on the number of motor neurons conducting impulses to their
motor units in that muscle. If many neurons carry impulses at once, many motor
units within the muscle will contract.
viii. This
causes a stronger over all contraction of the muscle than if only a few motor
units are activated.
Q7. Describe the structure of a sarcomere and
indicate the relationship of the
sarcomere to the myofilament.
Ans: Sarcomere(i)
Myofibrils
consist of smaller contractile units called sarcomere.
ii
Structure: In each sarcomere a series of dark and light bands are evident along
the length of each myofibril.
(b). The dark
bands are A band (anisotropic) and the light band are I band (isotropic).
(c). Each A band
has a lighter strip in its midsection called H-zone (hele for bright) which
inturn is bisected by M –line (medial line).
(d) The I band
have midline called Z –line (zwish meaning between). A sarcomere is the region
of a myofibril between two successive Z –line.
iii) Relationship of sacrcomere to myofilametn(i) The region of myofibril is the
sarcomere, which is the functional unit of the contraction process in the
muscles.
(ii). Each
myofilament is made up of central thick filament surrounded by thin filament,
which are linked together by cross bridges. The thick filament contains a
protein, myosin.
(iii). Thin filament is composed of a protein actin as
its main component besides it also has tropomyosin and troponin proteins.
(iv) The myosin
and actin help in contraction of the muscles.
(v) Thick
filament has a tail terminating in two globular heads, which are also called as
cross bridges and these link thin and thick filaments during contraction.
Analyzing and
interpreting
Q1. Identify
the bones of the pelvic girls, pectoral girdle, arms and leg by using the model
of human skeleton.
Ans.
Q2. Compare
the structure of skeleton, smooth and cardiac muscles with the help of prepared
slides.
Ans.
Q3. Draw a diagram
of sarcomere and label its parts.
Ans.
Q4. Justify
how the main functions of the skeleton are to act as a system of rods and levers,
which are moved by the muscles.
Ans. Muscles and bones act
together to form levers. A lever is
a rigid rod (usually a length of bone)
that turns about a pivot
(usually a joint). Levers can be used so that a small force
can move a much bigger force. This is called mechanical
advantage.
There are four parts to
a lever – lever arm, pivot, effort and load. In our bodies:
- bones act as lever arms
- joints act as pivots
- muscles provide the effort forces to move loads
- load forces are often the weights of the body parts that are moved or forces needed to lift, push or pull things outside our bodies.
Levers can also be used
to magnify movement, for example, when kicking a ball, small contractions of
leg muscles produce a much larger movement at the end of the leg.
Levers are able to give
us a strength advantage or a movement advantage but not both together.
Q5. Justify
why do the muscles pull but do not push.
Ans. Skeletal muscles move bones by pulling on them. Because we control
this movement, they are called voluntary muscles. Muscles can pull but not
push, so skeletal muscles are often arranged in pairs that pull bones in
opposite directions.
The body has some 640
skeletal muscles, accounting for about 40 percent of body weight. Skeletal
muscles are attached to bones by tough fibrous connections called tendons.
Initiating
and Planning
Q1. Relate
the bipedal posture of man with his skeleton and musculature.
ANS. Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs,
or legs.
Science, Technology and
Society Connections
Q1. Name
the techniques for joint transplantation.
Ans. 1.Meniscus transplant:
The meniscus is the cartilage in
the knee which
separates the thigh bone (femur) from the lower leg bone (tibia). A meniscus
transplant consists of taking out a worn or damaged meniscus and replacing
it with a new one from a donor. The meniscus to be transplanted is taken from a
cadaver, and,
as such, is known as an allograft. Meniscal transplantation is technically
difficult, as it must be placed accurately and secured to the tibial plateau.
As of 2012, only a few surgeons have significant volume of experience in
meniscus transplantation world wide
2. Microvascular joint transplantation with epiphyseal growth
Q2. Justify
the use of calcium in teenage and twenties can be a preventive action against
osteoporosis.
Ans. Osteoporosis is a disease of the bones. It
happens when we lose too much bone, make too little bone or both. As a result, our
bones become weak and may break from a minor fall or, in serious
cases, even from simple actions, like sneezing or bumping into
furniture.
Osteoporosis means “porous bone.” If we look at healthy
bone under a microscope, we will see that parts of it look like a honeycomb. If
we have osteoporosis, the holes and spaces in the honeycomb are much bigger
than they are in healthy bone. This means our bones have lost density or mass
and that the structure of our bone tissue has become abnormal. As our
bones become less dense, they also become weaker and more likely to break.
No doubt use of calcium in teenage and twenties can be preventive
action against oestiopores because calcium in early years strengthens bones.
How Calcium Helps Prevent Osteoporosis
Calcium makes bones strong. In fact, bones and teeth
contain 99% of the body's total calcium, with the remaining 1% in intracellular
and extracellular
fluids. Bones act as a storehouse for calcium, which is used by the body and
replaced by the diet throughout a person's life. If enough calcium is not
consumed, the body takes it from the bones. If more calcium is removed from the
bones than is consumed in the diet, the bones become fragile and weak as a
person gets older, leading to osteoporosis and fractures.
Osteoporosis prevention begins during childhood and
adolescence by getting enough exercise and the proper nutrients, including
calcium and vitamin D. However, adults can help prevent osteoporosis in the
same ways.
The importance of calcium in developing and
maintaining bone mass (bone density) varies throughout a person's life. At
times of rapid and significant bone growth (during the teenage years) or rapid
bone loss (after age 50 years), calcium is more important. Therefore, to reduce
the risk of osteoporosis, calcium intake should be the highest during
adolescence and after 50 years of age.
Q3. Reason
out the rigor mortis.
ANS. Rigor mortis (Latin: rigor
"stiffness", mortis "of death") is one of the
recognizable signs of death,
caused by chemical changes in the muscles after death, causing the limbs of the corpse to become
stiff and difficult to move or manipulate. In humans, it commences after about
three to four hours, reaches maximum stiffness after 12 hours, and gradually
dissipates from approximately 24 hours after death.
A few
hours after a person or animal dies, the joints of the body stiffen and become
locked in place. This stiffening is called rigor mortis. Depending on
temperature and other conditions, rigor mortis lasts approximately 72 hours.
The phenomenon is caused by the skeletal muscles partially contracting. The
muscles are unable to relax, so the joints become fixed in place.
More
specifically, what happens is that the membranes of muscle cells become more
permeable to calcium ions. Living muscle cells expend energy to transport
calcium ions to the outside of the cells. The calcium ions that flow into the
muscle cells promote the cross-bridge attachment between actin and myosin, two
types of fibers that work together in muscle contraction. The muscle fibers
ratchet shorter and shorter until they are fully contracted or as long as the
neurotransmitter acetylcholine and the energy molecule adenosine triphosphate
(ATP) are present. However, muscles need ATP in order to release from a
contracted state (it is used to pump the calcium out of the cells so the fibers
can unlatch from each other). ATP reserves are quickly exhausted from the
muscle contraction and other cellular processes. This means that the actin and
myosin fibers will remain linked until the muscles themselves start to
decompose.
Rigor
mortis can be used to help estimate time of death. The onset of rigor mortis
may range from 10 minutes to several hours, depending on factors including
temperature (rapid cooling of a body can inhibit rigor mortis, but it occurs
upon thawing). Maximum stiffness is reached around 12-24 hours post mortem.
Facial muscles are affected first, with the rigor then spreading to other parts
of the body. The joints are stiff for 1-3 days, but after this time general
tissue decay and leaking of lysosomal intracellular digestive enzymes will
cause the muscles to relax. It is interesting to note that meat is generally
considered to be more tender if it is eaten after rigor mortis has passed.
Q4. Relate
improper posture to bone/joint problems.
Ans..
Extra Questions
Q1. What do you know about cartilage?
Ans.
Cartilage:
1. Introduction: Cartilage is a type of connective
tissue consisting of cells called chondrocytes and a tough, flexible matrix
made of type II collagen.
2. Properties: Unlike other connective tissues, cartilage does
not contain blood vessels and the chondrocytes are supplied by diffusion.
Because of
this, it heals very slowly.
3. Early emplacement by bones: Although the
human skeleton is initially made up of cartilages and fibrous membranes, most
of these early supports are soon replaced by bones.
4. Location: A few cartilages that remain in adults are
found mainly in regions where flexible skeletal support is needed.
Types: There are three types
of cartilage tissue in human body:
a. hyaline, b. elastic c. fibrocartilage.
Q2. Explain Structural classification of joints?
Ans. Structural classification of joints is based on the
material binding the bones together and whether or not a joint cavity is
present. There are three types of joints, the fibrous, cartilaginous, and
synovial joints.
1. Fibrous joints:
1. Introduction: In fibrous joints, a thin layer of
fibrous connective tissue holds the
bones firmly in position.
2. Joint Cavity: There is no
joint cavity between the bones.
3. Immovable nature: In general fibrous joints are
immovable.
4. Function: Fibrous joints are formed between the bones
of skull, between sacrum and iliac of pelvic girdles, and between the bones of
pelvic girdle.
5. Oceurence: These
joints provide strength and support for the body, and have protective role for
the delicate structures.
ii. Cartilaginous joints:
1. Introduction: Cartilaginous joints are connected entirely by fibrocartilage
or hyaline cartilage.
2. Joint cavity: Joint
cavity is absent.
3. Gliding
movement: Bones
can glide over each other to a limited extent.
4. Occurrence: Cartilage
forms a flexible connection so that these joints
allow slight movement.
5. Function: Such joints are formed between vertebrae,
and between wrist and ankle bones.
Synovial joints:
1.
Nature: Synovial joints are those in which the articulating bones
are separated by a fluid-containing joint cavity (synovial cavity).
2. Free movement: This
arrangement permits freedom of movement, and all synovial joints are freely
movable.
(3) Ligaments: Synovial
joints are reinforced and strengthened by a number of band like ligaments.
1. These
ligaments hold the bones in position.
2. Based on the shape of their particular surfaces, the synovial
joints have different structural plan.
3. This
structural plan determines the type of movement allowed.
4. Types: The synovial joints can be classified
into two major categories; hinge and ball and socket joints.
Hinge joints: (a)
1. Structure: In hinge joints, a cylindrical projection of one bone fits
into a trough shaped surface on another.
2. Function: These joints
permit movement in one plane that is, permit
(a) flexion and
extension only.
(b) Hinge
joints are capable of bearing heavy loads.
Examples: Examples are
elbow and knee joint.
Ball-and-Socket Joints: (b)
1. Nature: In ball-and-socket joints the spherical
or hemispherical head of one bone articulates with the cuplike socket of
another.
2. Free movement: These joints are
the most freely moving synovial joints.
Example: The shoulder
and hip joints are examples.
Q3. Explain the disorders of skeleton?
Ans.
Although human skeleton is hard and strong, yet deformities
do occur resulting in reduced movement or complete immovability. Deformities of
skeleton may be genetic, hormonal or due to the effects of nutrient deficiency
(a) Disc slip:
1. Location: The discs are protective shock-absorbing
pads between the bones of the spine (vertebrae).
2. Intervertebral disc: The discs of the spine are also referred to as
intervertebral discs.
Although they do not actually "slip," a disc may
split or rupture.
Effected: (a) This can cause the disc cartilage and nearby
tissue to fail (herniate), allowing the inner gel portion of the disc to escape
into the surrounding tissue.
(b) This leaking jelly-like substance can place pressure on the spinal
cord or on an adjacent nerve to cause symptoms of pain either around the
damaged disc or anywhere along the area controlled by that nerve.
This
condition is also known as a herniated disc.
(c) The most frequently affected area is in the lower back, but any
disk can rupture, including those in the neck.
(4) Factors involved slip or causes: Factors
that lead to a slipped disc include aging with associated degeneration and loss
of elasticity of the discs and supporting structures; injury from improper
lifting, especially if accompanied by twisting or turning; and excessive strain
forces associated with physical activities.
(b) Spondylosis:
1. Introduction: Spondylosis (spinal osteoarthritis) is
a degenerative disorder that may cause loss of normal spinal structure and
function.
2. Causes: Although aging is the primary cause, the
location and rate of degeneration is individual.
3. Effected areas: The degenerative process of spondylosis
may affect the cervical (neck), thoracic (mid-back), or lumbar (lower back)
regions of the spine.
(c) Sciatica:
1. Introduction: Sciatica refers to pain, weakness,
numbness, or tingling in the leg.
2. Causes: It is caused by injury to or pressure on
the sciatic nerve.
This nerve starts in the lower
spine and runs down the back of each leg.
Common causes of sciatica
include:
Slipped disc, piriformis
syndrome (a pain disorder involving the narrow muscle in the buttocks), pelvic
injury or fracture and tumors.
(d) Arthritis:
i) Introduction: The arthritis is joint inflammation and it can affect
joints in any part of the body.
ii) Causes: Arthritis is the
leading cause of disability in those over the age of 65
(3) Symptoms: some of the symptoms of arthritis are:
ô Joint pain and
swelling.
ô Stiffness particularly in the mornings.
ô The feeling of warmth around a joint.
ô Redness of skin around the joint.
ô Inability to move the joint easily.
Some of the causes of arthritis are broken bone, infection
in the area, an autoimmune disease and general wear and tear on joints.
Q4. What do you
know about joint injuries? Explain.
Ans: Introduction:
1. A
dislocated joint is a joint that slips out of place.
2. It occurs when the ends of bones are forced away from their
normal positions.
3. When a
joint is dislocated, it no longer functions properly.
4. A severe dislocation can cause tearing of the muscles, ligaments
and tendons that support the joint.
b) Symptoms: Symptoms include; swelling, intense Pain, and
immobility of the affected joint.
c). Causes: i)The most common causes are a blow, fall,
or other trauma to the joint.
(ii). In some
cases, dislocations are caused by a disease or a
defective ligament.
(iii) Rheumatoid
arthritis can also cause joint dislocation.
(d) Treatment: A dislocated joint usually can only
be successfully 'reduced' into its normal position by a trained medical
professional.
Surgery may be needed to repair or tighten stretched
ligaments.
(i) Sprain:
1. Introduction: A sprain is
an injury to a ligament.
2. Injured parts: Commonly
injured ligaments are in the ankle, knee, and wrist.
The ligaments can be injured by being stretched too far from
their normal position.
The ligaments are to hold skeleton together in a normal
alignment so ligaments prevent abnormal movements.
However, when too much force is applied to a ligament, such as
in a fall, the ligaments can be stretched or torn.
The sprain
should be rested.
3) Treatment: Sprains can be usually treated with treatments
such as icing and physical therapy.
Dressings, bandages, or ace-wraps should be used to immobilize
the sprain and provide support.
Q5. What do you know about “Energy of Muscle Contraction”.
Explain muscle Problem?
Ans. Energy of Muscle Contraction:
1. Muscle
contraction needs energy.
2. The immediate source of energy for the muscle contraction is ATP,
stored in the muscle cells.
3. An enzyme ATPase, in the muscle cells breaks ATP to ADP, thus releasing
energy for muscle contraction.
4. But much part of the energy comes from carbohydrates or glucose,
stored as glycogen in the muscle cells.
5. When muscle contraction begins, glycogen is converted into
glucose, which is then broken down to form ATP.
6. The muscle
contraction then uses this ATP.
7. We know that in violent exercise, such as running, much energy is
needed.
8. Apparently not, but the muscles cells of all vertebrates have a
reserve of high-energy phosphate compound, called phosphocreatin.
9. During periods of intensive muscular activity, the phosphocreatin
is broken into creatin and a high-energy phosphate group.
10. This group then unites with ADP to form ATP.
11. Of the total energy expended in muscles contraction, only about35%
is utilized for the performance of work; the remaining is liberated in the form
of heat, which is employed to maintain body temperature.
12. In cold weather the production of heat can be increased through
voluntary muscular activity (walking, rubbing hand together etc) or involuntary
by shivering.
13. Conversely, in warm weather, muscular activity is deliberately
decreased to reduce heat production.
Q 6 What do you know about cramps?
Ans
Cramps:
1. Introduction: Muscle cramps are sudden, involuntary
contractions or spasms in one or more muscles.
2. Time of Infection: They often occur after exercise or at night,
lasting a few seconds to several minutes.
3. Temporary contractures: Writer's cramp is a
familiar example of temporary contractures.
4. Causes: Muscle cramps
can be caused by nerves that malfunction. Other
causes are, straining or overusing a muscle, dehydration, lack of minerals in
diet or the depletion of minerals in body, and not enough blood getting to
muscles.
Q7 What do you know about Muscle fatigue?
Ans
Musle fatigue
1. Introduction: Muscle fatigue is a condition of the
muscle in which its capacity to produce maximum contraction is reduced even
though the muscle still may be receiving stimuli.
2. Causes (a) Availability of ATP declines during
contraction and a total lack of ATP results in contractures states of
continuous contraction because the cross bridges are unable to detach.
(b). Although excessive intracellular accumulation of lactic acid (which
causes the muscles to ache and raises H+) alters contractile proteins,
other ionic imbalances also contribute to muscle fatigue.
(c) In general, intense exercise of short duration produces fatigue
rapidly via ionic disturbances, but recovery is also rapid.
(3) Recovery: In contrast to short-duration exercise, the
slow-developing fatigue of prolonged low-intensity exercise may require several
hours for complete recovery.
Q 8What do you know about Tetany?
Ans
TETANY
1. Introduction: Tetany is a symptom characterized by
muscle cramps, spasms or tremors.
2. Time of action: These
repetitive actions of the muscles happen when muscle contracts uncontrollably.
3. Occurrence: Tetany
may occur in any muscle of the body, such as those in face, fingers or calves.
4. Time of muscle cramping: The muscle
cramping associated with tetany can be long lasting and painful.
5. Causes: A common cause of tetany is very low
levels of calcium in the body.
Q9 What isTetanus?Explain.
Ans
TETANUS
1. Introduction: Tetanus is infection of the nervous system with the potentially deadly bacteria Clostridium tetani.
1. Introduction: Tetanus is infection of the nervous system with the potentially deadly bacteria Clostridium tetani.
2. Causative agent: Spores of the bacteria C. tetani live in the soil
and are found around the world. In the spore form, C. tetani may remain
inactive in the soil, but it can remain infectious for more than 40 years.
3. Infection time: Infection
begins when the spores enter the body through an injury or wound.
4. Tetanospasmin: The spores release bacteria that spread
and make a poison called tetanospasmin.
This poison blocks nerve signals from the spinal cord to the
muscles, causing severe muscle spasms.
The spasms can be so powerful that they tear the muscles or
cause fractures of the spine.