Category: 12th Zoology

Pneumonia Tuberculosis Symptoms, Treatment

Post author By Mr. Padeepz
Post date September 15, 2018
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Pneumonia

Inflammation of the lungs due to infection is called pneumonia.
Pneumonia is caused by viruses or bacteria.Viral pneumonia is due to
adenovirus, respiratory syncytial virus or a coxsackie virus. The most
common bacterial pneumonia is Pneumococcal pneumonia. Pneumonia may
also be caused by a mycoplasma (an organism that is intermediate between
a bacterium and a virus)

Pneumonia Symptoms and Signs

Symptoms and signs include fever, chills, shortness
of breath and a cough that produces yellow – green sputum and occasionally
blood.

Pneumonia Treatment

The drugs prescribed depend on the causative microorganism.
They may include antibiotic drugs or antifungal drugs. Aspirin or paracetamol
may be given to reduce fever. Oxygen therapy and artificial ventilation may
be required.

Tuberculosis (TB)

It is an infections disease, caused in humans by the bacterium
Mycobacterium tuberculae. It was once common world wide and was a
killer disease. People infected with HIV are highly susceptible to
tuberculosis and the disease is becoming more common again in
communities with high rates of HIV infection.

Tuberculosis Causes

Infection is caused by airborne droplets (produced by coughing
or sneezing). The bacteria breathed into the lungs multiply to form an
infected “focus”. In a high proportion of cases, the body’s immune system
then halts the infection and healing occurs. The infection can also occur in
intestines, bones and kidneys.

Tuberculosis Symptoms

The main symptom includes coughing (sometimes bringing up blood) chest pain, shortness of breath, fever and sweating (at night) poor appetite and weight loss. The main complications of tuberculosis of the lungs
are pleural effusion. (Collection of fluid between the lung and the chest wall).

Regulation of respiration

Post author By Mr. Padeepz
Post date September 11, 2018
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Regulation of Respiration

In the brain the medulla oblongata contains a respiratory center. This
controls breathing. The respiratory center consists of an inspiratory center
and an expiratory center. The axons from the nerve cells of these centres
lead to the intercostals muscle through the intercostals nerves and the
diaphragm via the phrenic nerves.

These nerve fibres transmit impulses to the external intercostal muscles and internal intercostal muscles alternately. The walls of the alveoli have sense endings which are stimulated by changes in the tension of alveolar walls. (Regulation of respiration)

When the alveoli are stretched at the height of inspiration the
receptors send stimuli to the expiratory center of the medulla through the
vagus nerve which inhibits further inspiration. This sequence of events is called
Herring – Breuer reflex. (Regulation of respiration)

In addition the medulla contains a pneumotaxic center which is
connected to the breathing centre and helps to ensure rhythmic breathing.
During inspiration, the inspiratory part of the respiratory center sends
impulses to the pneumotaxic center which responds by sending impulses to
the expiratory part of the respiratory center.

The expiratory center is then activated and so the inspiratory center is inhibited reflexly, respiratory rhythm is controlled in this manner by these centers in the brain. (Regulation of respiration)

Mechanism of Breathing

The process of inspiration and expiration happens due to pressure
changes in the thoracic cavity. The thorax is an airtight compartment bounded
by the sternum in front, the vertebral column at the back, the ribs encircling
the sides and the diaphragm found below.

The rib bones are provided with the two sets of muscles namely external and internal intercostal muscles. By the contraction and expansion of these muscles the volume of the thoracic cavity is reduced or increased. The floor of the thoracic cavity is completely closed by the diaphragm. The act of breathing is performed by expansion and contracton of the thoracic cavity. (Mechanism of Breathing)

Inspiration

Inspiration is the process by which fresh air is drawn into the
lungs. It is an active process. The muscles participating in the inspiration
process are external – intercostal muscles present in between the ribs and
the diaphragm.

During quiet respiration, contraction of external intercostal muscle
causes the ribs to move anteriorly and outwardly. This movement enlarges
the cavity of the thorax by increasing it side to side and in dorso-ventral
dimensions. (Mechanism of Breathing)

The contraction of radial muscles of the diaphragm leads to
flattening of inelastic, dome shaped central part of the diaphragm. As a result
of these muscular movements, the volume of the thoracic cavity is increased.
This causes the air pressure within the lungs to fall below the atmospheric
pressure. So air (tidal air) from outside passes through the air passage into
the lungs to equalize the pressure.

Expiration

Inspiration is followed by expiration. It is a passive process.
Expiration is the process by which air is exhaled or blown out from the lungs.
The expiration results when the volume of the thoracic cavity is decreased
and air pressure in the lung is increased. The expiratory process involves the
following movements.
1. The diaphragm relaxes and rises to resume the original dome shape.
2. The ribs take their original position as a result of contraction of the internal
intercostal muscles.

Gaseous exchange in the alveoli

Once the air is within the lungs the process of gaseous exchange
begins. Capillaries of the pulmonary artery remains close to the wall of the
alveloli. This enhances the exchange of gases.
Oxygen carbon-di-oxide water vapour
Inhaled % 21.00 0.04 variable
Exhaled % 15.7 3.6 saturated

Oxygen and carbon-di-oxide are exchanged across the alveolar
membrane by diffusion from the site of higher to low partial pressure until the
partial pressure of the two regions are equal. This process is a simple
physical one which does not involve any secretary or active transport
mechanism.

In the atmospheric air there is a high concentration of oxygen
20-95% (PO2 140mm Hg) while the proportion of carbon dioxide is low
(0.04%).

The alveolar PO2 is about 100mm Hg and the PO2 of venous blood
is about 40mm Hg. This pressure gradient is sufficient for the transfer of O2.
The PCO2 of venous blood is 46mm.Hg and that of alveolar air is only 6mm.Hg
(1/10th of O2), it is adequate for CO2 transfer by diffusion. CO2 diffuses 20
times faster than O2.

Respiration – Process of pulmonary respiration

Post author By Mr. Padeepz
Post date September 10, 2018
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Respiration

Respiration is a process by which oxygen reaches the body cells and
is utilized by them in metabolism and carbon-di-oxide formed as a waste
product gets eliminated. The real function of respiration is to provide the
energy needed by body cells. Cells obtain energy by metabolizing glucose
utilising oxygen.

Hence they require a constant supply of oxygen. In
addition, the waste products of the metabolic process, namely
carbon-di-oxide must be carried away from the cells. The transport of
oxygen and carbon-di-oxide between lungs and body cells takes place by an
efficient cardio-vascular system.

Process of pulmonary respiration

Respiration includes several processes which are listed below
(i).ventilation is the breathing in of air with more oxygen into the lungs
(inspiration). It is followed by expulsion of air with more of carbon-di-oxide
(expiration).
(ii). Diffusion of oxygen from the alveoli into the blood inside
surrounding capillaries.
(iii). Transport of oxygen by the blood to the heart through the
pulmonary vein.
(iv). Distribution of oxygen by various arteries and their
capillary network to all cells of the body. As the blood passes through tissue
capillaries, it gives up oxygen (and nutrients such as glucose) to the body,
tissues and picks up the waste products of cellular respiration (Carbon-dioxide
and water).
(v). Exchange of the oxygen and carbon-di-oxide between the blood and
body cells. With in body cells glucose and oxygen take part in a complex
series of reactions which provide energy to power the cells. During this
cellular repiration glucose is converted to carbon-di-oxide and water.
(Enzymatic oxidation).

(vi). Transporting blood with carbon-di-oxide. Carbon-di-oxide is carried
back in the blood to the heart then to the lungs where it diffuses into the
alveoli and is breathed out of the body (External respiration).
(vii) Exchanging of carbon-di-oxide with oxygen at the alveolar surface.
(viii) Expiration of air with carbon-di-oxide from the lungs.

Myasthenia Gravis

This disease, affects one in 20,000 persons. It causes the person to
become paralysed because of inability of neuromuscular junction to transmit
signals from the nerve to muscle fibre. The muscles affected include those
used in walking, breathing, chewing, and talking. A characteristic sign of the
disease is drooping eyelids.

Myasthenia gravis most often affects women between the ages of 20 and 30, but it can strike anyone after adolescence. It is believed that myasthenia gravis is an autoimmune disease in which patients have developed antibodies against their own acetylcholine activated ion channels.

These antibodies are produced by thymus gland. If the disease
gets intense enough, the patient dies of paralysis of respiratory muscles. Thedisease can be cured by removal of the thymus and by a blood-cleansing
process, called plasmaphoresis, that removes the destroying antibodies.
About 10 per cent of the victims die.

Types of muscle contraction

Post author By Mr. Padeepz
Post date September 9, 2018
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Types of muscle contraction

There are 2 types of muscle contraction

1. Isotonic contraction:

It involves muscle shortening as the myofilaments
slide. This contraction produces normal movements, such as bending the
knee, rotating the arms and smiling.

2. Isometric contraction:

It occurs when the myofilaments “spin their wheels”
without moving, causing tension in the muscle. This is due to the muscles that
are pitted against some more or less immovable object.

Isometric and aerobic exercises (types of muscle contraction)

In isometric exercise, muscles are moved through a short distance
against a high resistance, as in pushing or pulling an immovable object.
Isometric exercise is best for developing large muscles, whereas isotonic
exercise has beneficial effects on the cardiovascular system. Isometric
exercise-increases the thickness of the muscle fibres and their ability to store
glycogen.

Exercise :

The muscle inactivity always leads to weakness and wasting of
muscles. Muscles are no exception to the saying “use it or lose it”. Regular
exercise increases muscle size, strength and endurance. There are several
exercises according to the needs and benefits. For example jogging or biking
results in stronger, more flexible muscles with greater resistance to fatigue.
Stamina formation is mainly carried out through aerobic activities, such as
running and swimming.

Benefits of aerobic exercise: Physical exercise is a major contributor to
health and can improve the body in three ways: more efficient heart, and
lungs, improved muscle tone, and more supple joints. It is also essential to
prevent obesity.

Due to regular exercise, blood supply to muscle increases,
it results in supply of more O2. Further aerobic exercises make overall body
metabolism more efficient, improve digestion and enhances neuromuscular
co-ordination. Heart beat enlarges, so that more blood is pumped out with
each beat, fat deposits are cleared from the blood vessels and the lungs
become more efficient in gaseous exchange. These benefits may be temporary
or permanent on the basis of regular and vigorous exercises. Aerobic
exercises do not cause the muscle to increase in size, even though the
exercise may go on for hours.

Aerobic exercises increase the adaptability of muscles and give greater endurance to muscles. To gain good health, it is suggested that a total of at least 20 minutes per day, of moderate exercise, to burn around 200 calories (837 joules) a day, is required. Regular exercise is preferrable to occasional intense sessions.

The bulging of muscles of a body builder or professional weight lifter
results mainly from resistance or isometric exercise in which muscles are
pitted against some immovable, or nearly so, object. Endurance and resistance
exercises produce different patterns of muscle response, it is
important to know what your exercise goals are. Weight lift will not improve
your endurance for a marathon race. At the same time, Jogging will do little
to improve your muscle definition nor will it make you stronger. Proper
exercise for proper goal is necessary.

Mechanism of muscle contraction

Post author By Mr. Padeepz
Post date September 9, 2018
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Mechanism of muscle contraction

Sliding – filament hypothesis

Hanson and Huxley proposed this hypothesis (1955). According to
this hypothesis, the contractile unit of muscle is made up of two types of
filaments i.e., myosin and actin. These filaments during contraction slide over
one another. It has been observed that both at the time of contraction and
stretching, the length of the ‘A band’ remains constant. The length of the ‘I
band’, on the other hand, changes in accordance with the length of the muscle.

Due to this, the Z discs are pulled together. Thus successive sarcomeres are
pulled. This leads to the contraction of the muscle.

ATP as the source of Energy for contraction

For a muscle in action, energy is required. This energy is released by cleaving ATP molecules to ADP+ Pi. Greater amount of work is performed by the muscle, with greater amount of ATP that is cleaved. This energy binds with active site of actin filament to contract.

Neuro muscular Transmission

The muscles are innervated by myelinated nerve fibres that originate from the spinal cord. The nerve ending makes a junction, called neuromuscular junction. The nerve is connected at the midpoint of muscle fibre so that action potential in the fibre travels in both directions. When a nerve impulse reaches the neuro-muscular junction, a substance called acetylcholine is released. The acetylcholine induces muscle fibre for contraction.

Initiation of muscle contraction

Initiation of contraction of skeletal muscle begins with action potentials in the muscle fibres. These elicit electrical currents that spread to the interior of the fibre, where Ca ions are released from the sarcoplasmic reticulum. The Ca ions inturn initiate the chemical events of the contractile process. This overall process of controlling muscle contraction is called excitation.

Maximum strength of contraction

The maximum strength of contraction of a muscle operating at a normal muscle length is about 3.5 Kg / Sq.cm. of muscle.

Changes in muscle strength

When a muscle begins to contract after a long period of rest, its initial strength of contraction may be as little as one half of its maximum strength. It gains strength after 30-50 muscle twitches. Weight lifters apply this to reach maximum capacity.

Muscle Tone

When the muscles are at rest, a certain amount of contraction usually
remains. This residual degree of contraction in skeletal muscles is called
muscle tone. The skeletal muscle tone is the result of nerve impulses from
the spinal cord. These in turn are partially controlled by impulses transmitted from the brain. To some extent, the muscle tone is due to the muscle fibres itself.

Muscle Fatigue ( muscle contraction is diminished)

Prolonged and strong contraction of muscle leads to the state of muscle
fatigue. This is due to muscle glycogen depletion and lactic acid accumulation.
Fatigue probably results from inability of the contractile process and deficient
metabolic process of the muscle fibre.
However, experiments show, that transmission of nerve signals through
the neuromuscular junction can occasionally diminish the prolonged muscle
activity, thus further reducing the power of muscle contraction. It is a well
known fact that non-supply of blood to the muscles leads to almost
complete fatigue within a minute. This is due to non-supply of O2 and
nutrients to the muscles.

Rigor Mortis

Several hours after death all the muscles of the body attain
a state of contracture called Rigor mortis. This is due to complete
depletion of ATP in muscle fibres. The muscle remains in rigor, until the
lysosome enzymes completely destroy all muscle proteins. This will take place
within 15-25 hours after death.

Muscle Pull

Muscle pull is actually a muscle tear. A traumatic pulling of the fibres
produces tear known as strain. This injury can occur due to sudden
stretching of muscle beyond their point of elasticity. While some strains are
the result of high velocity impacts, other types of pull can be due to repetitive movements.

When the muscles are being exerted over a long period of time, they become vulnerable to tearing from a simple change in the position of muscles. Back pain is a common problem, caused by muscle pull.

This may be due to improper posture at the chairs. In these cases, the muscles are tightened over a long time, but the muscles may not tear until something as
simple as reaching for a glass of water occurs.

Muscles

Muscles are elastic in nature. They are capable of contraction in
response to stimulus from the central nervous system.

The muscle cells function like biological machines that convert chemical energy into mechanical work.

The mechanical work involves various movements including vital processes like contraction of the heart and blood vessels.

Approximately 40% of the body is skeletal muscle and almost 10% is smooth
and cardiac muscles.

Structure of a skeletal muscles:

A striated muscle is composed of many fibres arranged in bundles. The diameter of each fibre varies from 10 to 100 microns. The length of fibres ranges from 1 to 20mm. Each fibre is surrounded by a membrane, called the sarcolemma.
Each muscle fibres is made up of 4 to 20 thread-like structures called myofibrils. They are parallel to each other. The myofibrils are 1 to 3 micron in diameter. In between the myofibrils, the sarcoplasm is present. A small segment of the myofibril is called as the sarcomere.

Structure of sarcomere :

When a sarcomere is observed under a microscope, we could see alternative dense ( A band ) and light bands ( I band). The central region of the A band is often less dense and is known as the “H Zone”.

The ‘I band’ is bisected by a dense narrow line, the Z line. Thus each sarcomere includes repeating units between two Z lines in linear order as Z line, I band, A band, I band and next Z line.

Electron microscopic studies have shown that the striations are due
to the regular arrangement of 2 types of protein filaments. ‘A band’ contains
a set of thick filaments formed of the contractile protein myosin. It may
range upto 110 Ao in diameter and 1.5 micron in length.

The second set of thin filaments ( 50 Ao diameter) overlap the long
filaments in ‘A band’. The second set of filaments extend partly in ‘I band’
and partly in ‘A band’. These filaments are formed of a substance called
Actin.

Myosin, actin, tropomyosin and troponin are the four major proteins
which constitute the contractile machinery of muscle fibre. The energy for
muscle action is provided by ATP molecules.

Rickets and Osteomalacia – Orthopedics

Post author By Mr. Padeepz
Post date September 9, 2018
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Rickets and Osteomalacia

Rickets and Osteomalacia are caused due to inadequate mineralisation
of the bones. Our skeletal system stores 98% of the calcium in the human
body and hence calcium metabolism has a major influence on the structure
and growth of bone.

Rickets

In this case, mineralization of bones is defective. The rickets caused
by nutritional deficiency is called Nutritional rickets . In India, it is a
common problem among the population below the poverty line. It is due to Vitamin D deficiency. It occurs in children below four years. But it can
afflict all age groups who have calcium and D deficiency. Vitamin D is
associated with calcium absorption and deposition.

Lack of calcium and vitamin D causes softening of bones and pliable deformity. In children the symptoms of rickets are bowed legs, knock knees, pigeon chest,
broadening of wrist and ankles, protruberant abdomen, etc.,
The primary prevention of the Rickets, in the child begins by better
nutrient of the pregnant mother, followed by supply of Vitamin D. Cod and
shark liver oil are very good sources of Vitamin D.

Osteomalacia

In adults Vitamin D and Calcium deficiency leads to
osteomalacia. This is characterized by bone pain and tenderness. It causes
brittleness in the bones.

Orthopedics

Orthopedics deals with all bone deformities occurring in children as
well as adults. The deformities may either be congenital or acquired. The
former is caused by developmental abnormalities (teratogenic), the latter is
caused by trauma or infections or by metabolic disorders. The corrective
measures in the management of these disorders involve physiotherapy, splinting
and use of appliances, traction procedure, plaster cast and wedging,
manipulation under anaesthesia, surgical and neurological examination.

Arthiritis

Arthiritis is the inflammation of all the components and structures of
the joints. It involves synovium, articular surfaces and capsule.
Several etiological factors are attributed to the origin of arthirits
(arthritogenesis). They are diet, psycho-somatic illness, infections, diseases
and metabolic abnormalities, etc.,

Types of arthritis

1. Infective arthiritis :- Infections such as Staphylococcal, Streptococcal,
Gonococcal, Rheumatic, Small Pox, Tuberculosis, Syphilitic, Guinea worms,
etc., can cause damages at the joints. It produces pain in joints.

2. Rheumatic arthiritis :- It is a generalized disease affecting the
connective tissues, of the whole body. It focalizes the involvement of musculoskeletal system. It is an inflammation of synovial membrane.
Rheumatic disease is considered to be of auto immune origin. It is due to
immunological disorder against an unknown antigen..

3.Osteoarthiritis (Osteoarthrosis) : – It is a degenerative condition of the
joints, without any inflammatory process. Osteoarthiritis is a progressive
process affecting the articular cartilage of aging joints. It is characterized by
focal degeneration of the articular cartilage. In the later stage, the cartilage
gets eroded and exposing the sclerosed bone.

4.Metabolic arthiritis :- Metabolic arthiritis is due to metabolic
disorders. This is a disease due to an inborn error of Purine metabolism. It
is commonly called gout. This condition is characterized by the deposition
of Sodium Urate crystals (uric acid) on the articular cartilage, synovial
membrane and in the periarticular tissues. Gout is characterized by onset of
pain swelling and reddening of joints.

Pneumonia

Pneumonia Symptoms and Signs

Pneumonia Treatment

Tuberculosis (TB)

Tuberculosis Causes

Tuberculosis Symptoms

Related Topics in Zoology:

Regulation of Respiration

Related Topics in Zoology:

Mechanism of Breathing

Inspiration

Expiration

Gaseous exchange in the alveoli

Related Topics in Zoology:

Respiration

Process of pulmonary respiration

Related Topics in Zoology:

Myasthenia Gravis

Related Topics in Zoology:

Types of muscle contraction

1. Isotonic contraction:

2. Isometric contraction:

Isometric and aerobic exercises (types of muscle contraction)

Exercise :

Related Topics in Zoology:

Mechanism of muscle contraction

Sliding – filament hypothesis

ATP as the source of Energy for contraction

Neuro muscular Transmission

Initiation of muscle contraction

Maximum strength of contraction

Changes in muscle strength

Muscle Tone

Muscle Fatigue ( muscle contraction is diminished)

Rigor Mortis

Muscle Pull

Related Topics in Zoology:

Muscles

Structure of a skeletal muscles:

Structure of sarcomere :

Related Topics in Zoology:

Rickets and Osteomalacia

Rickets

Osteomalacia

Orthopedics

Related Topics in Zoology:

Arthiritis

Types of arthritis

Related Topics in Zoology: