Category: 12th Zoology

The Brain – Fore Brain, Midbrain, Hindbrain

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Post date September 20, 2018
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The Brain

There are more than a thousand million neurons in the adult human
brain. An estimate shows that the cerebral cortex alone has about 102783000
synapses. Thus the brain is a complex organ.

On structural and functional basis the brain can be divided into 3
regions. They are (1). Fore brain, (2). Midbrain, (3). Hind brain.

Fore Brain (Prosencephalon)

This region of the brain comprises Diencephalon and the cerebrum.
The diencephalon is formed of thalamus and hypothalamus.

Thalamus (Fore brain)

It is the largest part of the diencephalon. This region contains a
cluster of nuclei. Most of the sensory inputs are conducted to the cerebral
cortex through the thalamus. Axons carrying auditory, visual and other
sensory informations synapse with specific nuclei of this region. This
region may also influence mood and general body movements due to strong
emotions such as fear or anger.

Hypothalamus (Fore brain)

This region contains small nuclei and nerve tracts. The nuclei called
mamillary bodies are involved in olfactory reflexes and emotional responses
to odours. The funnel shaped infundibulum from the hypothalamus
connects it to the posterior pituitary or neurohypophysis. This region
controls the secretions of the pituitary gland.

The hypothalamus receives inputs from several sensory systems such
as tongue, nose and external genitalia. It is associated with emotional and
mood relationships. It provides a relaxed feeling. Feeling good after a meal,
rage and fear are also due to this region. It also coordinates responses to the
sleep-wake cycle with other areas.

Cerebrum (Fore brain)

It is the largest part of the brain. It weighs about 1400g in males and
1200g in females. Larger brains are normally associated with larger bodies
and not with greater intelligence.

The grey matter on the outer surface of the cerebrum is the cortex. It
forms clusters deep inside the brain called nuclei. The inner part of the brain,
in between the cortex and the nuclei has white matter named as
cerebral medulla.

Cerebral cortex (Fore brain)

The cortex contains several primary sensory areas. These areas
include taste area, primary auditory cortex for processing auditory stimuli,
visual cortex for perceiving visual images and areas for other cutaneous
sensations.

The cortical areas adjacent to the primary sensory centers are called
the association areas. These areas are involved in the process of
recognition. For example the sensory stimulus from the retina of the eye
reaches the visual association area of the cortex. Here the visual
information is compared with past experiences. Further this area has
connections with other parts of the cortex, which influence decisions. Thus
visual information is judged several times. This may be one of the reasons
why two people who witness the same event can present somewhat
different versions of what happened.

The primary motor area of the cortex controls many voluntary
movements, especially the finer motor movements of the hands. Muscle groups
such as facial muscles, that have many motor units have greater innervation. They are represented by a large area of the motor cortex.

Anterior to the primary motor area are the premotor area. It is the
staging area in which motor functions are organized before they are
initiated in the motor cortex. For example, if a person decides to lift a hand,
the neurons of the premotor area are stimulated first. This area determines
the order and the degree to which the muscles must contract.

The prefrontal area provides motivation and foresight to plan and
initiate movements. This area is well developed only in primates and
especially in humans. Our emotional behaviour and mood are controlled by
this area.

The midbrain or Mesencephalon

The roof of this region contains four nuclei. The nuclei form mounds.
They are collectively called corpora quadrigemina. It is formed of 2
superiour colliculi or mounds and 2 inferior colliculi or mounds. The
superior colliculi are involved in visual reflexes. They control eye and head
movements. They aid in visual tracking of moving objects. The inferior colliculi
are involved in hearing.

The hindbrain or Rhombencephalon

This part of the brain comprises Cerebellum, Pons and Medulla
oblongata.

Cerebellum

This region communicates with other region of the CNS through three
large nerve tracts called the cerebellar peduncles.
The cerebellum consists of following three parts Parts Control

1. flocculonodular balance and maintenance
of muscle tone.

2. vermis – anterior part motor coordination and muscle tone.
3. vermis – posterior part and fine motor coordination and
lateral hemispheres muscle tone.

Cerebellar disfunction may cause decreased muscle tone, imbalance and lack
of co-ordination.

Pons

This region relays information from the cerebrum to the
cerebellum. It also contains sleep center and respiratory centers. These
centers along with medulla help to control respiratory movements.

Medulla oblongata

It is the most inferior part of the brain stem. It acts as a conduction
pathway for both ascending and descending nerve tracts. The nuclei inside
medulla oblongata function as centers of several reflexes involved in the
regulation of heart rate, blood vessel contractions, breathing, swallowing,
vomiting, coughing and sneezing.

Nervous system

Co-ordination systems Nervous Co-ordination

All living animals maintain a constant inner state, irrespective of
changes happening in the environment. This phenomenon is named as
homoeostasis. It is achieved due to coordination of response. The
coordination is due to the animal body, acting as a self-regulating system
capable of making appropriate responses to stimuli.

The coordinating system of the body contains suitable structures for
detecting stimuli, transmitting information and responding to stimuli. There
are feedback mechanisms that ensure that degree of responses is
related to the intensity and direction of the stimuli.

Mammals have two main coordinating systems, namely the
nervous system and the endocrine system.

Nervous system

The neurons are the basic units of the nervous system. They help in
conducting the stimuli in between the receptor organs – spinal cord, brain
and effector organs.

The neurons conduct the stimulus as electrochemical events. These sequential events involve migration of ‘Na’ and ‘K’ ions outside and inside the neuronal cells. This phenomenon is known as Sodium- Potassium pump. This sequence of electro chemical events is known as the impulse.

The junctions of neurons in nerve pathway are called the synapses.
A synapse is formed between the bulb-like end structure of the axon called
boutons and the cyton or dendrite of the adjacent neuron. At the junction
there is a gap called the synaptic cleft, which is usually about 10 to 20 nm.
At this point, transmission of stimulus happens through transmitter
substances such as acetylcholine.

In the nervous system the bundles of parallel axons of the nervous
tissue having myelin sheath constitute the white matter. Collection of
neurons having unmyelinated axons form the grey matter.
The axons make up the white matter of the CNS for nerve tracts.

They propogate action potentials. The grey matter performs integrative
functions. The outer surface of the brain (cortex) and the central area of the
spinal cord consist of grey matter. Within the brain, collections of grey
matter form centers called nuclei.

Thrombosis

The formation of a thrombus or blood clot within an intact blood
vessel is called thrombosis. Clotting is a normal response that prevents bleeding
when a blood vessel wall is injured. However thrombus formation is
abnormal if it occurs in an intact vessel.

A thrombus within an artery may block the artery preventing blood
and oxygen from reaching the organ or tissue supplied by an artery.
A thrombus that forms within one of the coronary arteries supplying
heart muscle is known as coronary thrombosis. This is the cause for heart
attack .

A thrombus within arteries supplying the brain is known as cerebral
thrombosis. It causes stroke. When a portion of a thrombus clot becomes
fragmented and enters the circulating blood, it is called embolus. Embolus
may block a circulation to vital parts resulting in serious consequences such
as stroke.

Clotting of Blood or Haemostasis

Post author By Mr. Padeepz
Post date September 19, 2018
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Clotting of Blood or Haemostasis

When a blood vessel is damaged, it results in coagulation or clotting
of blood. A blood clot is a network of thread like protein fibers, called
fibrin, that traps blood cells, platelets and fluid.
The clotting depends on several proteins in the plasma. They are
called coagulation factors. Normally these factors are in an inactive state.

After injury they are activated to produce a clot. The activation can happen
in three stages.

Stage 1 – Formation of thrombokinase – Damaged tissues release a
mixture of lipoproteins and phospholipids called tissue factor (TF) or
thromboplastin. This factor in the presence of certain factors in the blood
form a complex called prothrombinase or thrombokinase.

Stage 2 – Formation of thrombin – During this stage soluble plasma
protein prothrombin is converted into the enzyme thrombin by
prothrombinase. Prothrombin synthesis in liver requires vitamin K.
Prothrombin
prothrombinase
thrombin
Ca++

Stage 3 – The soluble plasma protein fibrinogen is converted to insoluble
protein, fibrin by thrombin
fibrinogen
thrombin
fibrin
The fibrin forms the fibrous network of the clot.

Blood – Composition of plasma – Blood cells

Post author By Mr. Padeepz
Post date September 19, 2018
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Blood

The blood is a fluid connective tissue. It consists of liquid plasma and
cells. The plasma makes up 55% of the total volume and 45% of cells or
formed elements. The total blood volume in human female is about 4-5 litres
and 5-6 litres in males.

Plasma

The blood plasma is a slightly alkaline fluid. It is straw coloured.

Composition of plasma

Components Functions

1. Water – as a slovent and suspending medium
for blood components.

2. Plasma proteins- Albumin – Osmotic pressure.
Globulins – Antibody formation
Fibrinogen – Blood clotting.

3. Ions – Na, K, Ca, Mg, Cl
2
, – Osmosis, acid-base balance.
Fe, PO

4
, H and HCO
3
– buffer etc.,

4. Nutrients – Glucose, amino – source of energy, building blocks
acids, triglycerides, cholesterol, – enzyme activity.
vitamins.

5. Waste products – Urea, uric – excreted by the kidneys.
acid creatinine, ammonia
Bilirubin – breakdown product of erythrocytes
Lactic acid – product of anaerobic respiration.

6. Gases
Oxygen – for aerobic respiration
CO
2
– waste product of respiration
Nitrogen – inert gas.

7. Regulating substances
Hormones and Enzymes – body functions
Blood cells or formed elements
There are three types of blood cells or corpuscles. They are

1. Red Blood Corpuscles (RBC) or Erythrocytes

These are circular, biconcave and non-nucleated cells. Males have
about 5.2 million erythrocytes per cubic millimeter of blood (range : 4.2-5.8
million). Females have about 4.5 million/mm3 (range 3.6-5.2 million). Each disc shaped RBC is about 7.5 mm in diameter. Their main
component is a pigmented protein, haemoglobin. It gives red colour to the
blood. The haemoglobin transports O2. The oxygenated form of
haemoglobin is called oxyhaemoglobin.
Erythrocytes stay in circulation for about 120 days in males and 110
days in females. They are manufactured in the marrow of bones such as ribs
and vertebrae. They disintegrate in the spleen and liver.

2. White Blood Corpuscles (WBC) or Leucocytes

These are clear cells lacking haemoglobin. They are nucleated cells
exhibiting amoeboid movement. They protect the body against invading
micro-organisms and remove dead cells from the body. There are five types
of leucocytes.
a). Neutrophils – These are the most common type of leucocytes (60-70%)
in the blood. Their nuclei can occur in more than one form. Hence they are
called polymorphonuclear neutrophils (PMN).
b). Eosinophils (0.5-3.0%) – They are motile cells that leave the circulation
to enter the tissues during an inflammatory reaction. During allergy reaction
their number increases.
c). Basophils (0.1%) – They play a role in allergic and inflammatory
reaction. They contain heparin which inhibits blood clotting.
d). Lymphocytes (20-30%) – These are smallest leucocytes. They are more
common in lymphatic tissues namely the lymph nodes, spleen, tonsils and
thymus. Lymphocytes, called B-cells can produce proteins called
antibodies that can get attached to the bacteria and destroy them. T-cells protect us against viruses by attacking and destroying cells in which viruses
are reproducing.
e). Monocytes (1-4%) – These are largest leucocytes. They destroy
bacteria, dead cells and cell fragments. During chronic infection their number
increases.

3. Blood Platelets or Thrombocytes

These are minute fragments of cells that play a very important role in
coagulation of blood. Their life expectancy is 5-9 days.

Cardio Pulmonary Resuscitation (CPR)

Post author By Mr. Padeepz
Post date September 19, 2018
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Cardio – Pulmonary Resuscitation (CPR)

Cardio pulmonary resuscitation is the administration of the
life – saving measures of external cardiac compression massage and mouth
to mouth resuscitation (Artificial respiration) to someone collapsing with
Cardiac arrest (Cessation of heart beat)
It is vital to restore the circulation of oxygen carrying blood to the
brain as quickly as possible because permanent brain damage is likely to
occur if the brain is starved of oxygen for more than three to four minutes (Cardio pulmonary resuscitation)

Pulse rate

The rhythmic expansion and contraction of an artery as blood is forced
through it (pumped by the heart) is known as pulse.
The pulse can be described in terms of its rate (number of expansion
per minute) its rhythm, strength and whether the blood vessel feels hard or
soft.

The pulse rate is determined by counting the beats in a set period
(minimum 15 to 20 seconds) and multiplying to give the beats per minute.
The pulse rate usually corresponds to the heart rate which varies according
to the persons state of relaxation or physical activity.
Abnormal rhythm may be a sign of heart disorder. If the pulse feels
weak, it may be a sign of heart failure, shock or an obstruction to the blood
circulation. Weak or absent pulse in one or both legs is a sign of peripheral
vascular disease.

EC8393 Important Questions Fundamentals of Data Structures in C

Post author By Mr. Padeepz
Post date September 18, 2018
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EC8393 Important Questions Fundamentals of Data Structures in C

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Sample EC8393 Important Questions Fundamentals of Data Structures in C

1. What is meant by an abstract data type?

An ADT is an object with a generic description independent of implementation details. This description includes a specification of an components from which the object is made and also behavioral details of objects.

2. Advantages and Disadvantages of arrays?

Advantages: Data accessing is faster Array‟s are simple-in terms of understanding point and in terms of programming. Disadvantages: Array size is fixed Array elements stored continuously Insertion and deletion of elements in an array is difficult. (EC8393 Important Questions Fundamentals of Data Structures in C)

3. What is an array?

Array may be defined abstractly as a finite ordered set of homogenous elements. Finite means there is a specific number of elements in the array.

4. What is a linked list?

Linked list is a kind of series of data structures, which are not necessarily adjacent in memory. Each structure contains the element and a pointer to a record containing its successor. (EC8393 Important Questions Fundamentals of Data Structures in C)

5. What is singly linked list?

A singly linked list is a linked list, there exists only one link field in each and every node and all nodes are linked together in some sequential manner and this type of linked list is called singly linked list.

6. What is a doubly linked list?

In a simple linked list, there will‟topoint be on the next element, where as in a doubly linked list, there will be two pointers one to point the next element and the other to point the previous element location. (EC8393 Important Questions Fundamentals of Data Structures in C)

7. Define double circularly linked list?

In a doubly linked list, if the last node or pointer of the list, point to the first element of the list, then it is a circularly linked list.

8. What is the need for the header?

Header of the linked list is the first element in the list and it stores the number of elements in the list. It points to the first data element of the list. (EC8393 Important Questions Fundamentals of Data Structures in C)

9. Define Polynomial ADT

A polynomial object is a homogeneous ordered list of pairs <exponent, coefficient>, where each coefficient is unique. Operations include returning the degree, extracting the coefficient for a given exponent, addition, multiplication, evaluation for a given input. (EC8393 Important Questions Fundamentals of Data Structures in C)

Subject name	Fundamentals of Data Structures in C
Semester	3
Subject Code	EC8393
Regulation	2017 regulation

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12th Zoology

Heart transplantation

Heart transplantation in animals was first achieved
in 1959. The first human heart transplant was performed by Professor Christian
Bernard in South Africa in 1967.

Limiting factors for Heart transplant surgery

1. Problem of timing : A heart transplant is possible only when a suitable
donor heart is available at right time.
2. Problem of fall-back system : If the heart is rejected (attacked by the
body’s immune system) the only hope for the patient is another transplant.
3. Problem in the certification of brain death.
The success of heart transplant lies in allowing doctors to certify brain
death while the heart was beating. Heart is generatly removed for
transplantation from a person certified for brain death by doctors.

Blood Pressure – Intensive of hypertension, Causes, Preventive measures

Post author By Mr. Padeepz
Post date September 18, 2018
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Blood Pressure

Blood pressure is the force exerted by the flow of blood against the
walls of the main arteries while flowing through them. Blood pressure rises
or falls as the heart responds to the varying demands made by the body
during different activities such as exercise, stress and sleep.
Two types of pressure are measured.

Systolic (the highest) is the pressure created, by the ventricular muscle and the elastic recoil of the aorta (main vessel leaving the heart) as the blood flows through it. Diastolic pressure (the lowest) is recorded during relaxation of the ventricles between beats. It reflects the resistance of all the small arteries in the body and the load against which the heart must work. The pressure wave transmitted along the arteries with each heart beat is felt as the pulse.

Blood pressure is measured using a sphygmomanometer. A healthy
adult has a blood pressure reading of about 120/80 mm Hg (120 mm.Hg –
systolic and 80 mm Hg – diastolic). This often rises normally with age to
about 130/90 at 60. Abnormally high blood pressure is known as hyper tension.
Hyper tension is defined as the “Systolic pressure equal to or greater
than 160 mm Hg and (or) the diastolic pressure equal to or greater than 95
mm Hg”. Abnormally low pressure is termed hypotension.

Intensive of hypertension

Hyper tension puts a strain on the heart and blood vessels. Apart
from increasing the risk of having a stroke or developing heart failure or
coronary artery disease, high blood pressure may cause kidney damage and
retinopathy (damage to the retina at the back of the eye).

Causes

Hypertension is linked with obesity and in some people to a high
intake of salt, alcohol, smoking appears to aggravate the effects of
hypertension.

Preventive measures

Alcohol consumption and smoking should be avoided. Obese persons should make an attempt to reduce weight through restriction of food intake and try regular exercise. The dietary intake of animal fat (milk, cream, cheese fatty meat and eggs) should be reduced. A restricted intake of salt is recommended.

The Brain

Fore Brain (Prosencephalon)

Thalamus (Fore brain)

Hypothalamus (Fore brain)

Cerebrum (Fore brain)

Cerebral cortex (Fore brain)

The midbrain or Mesencephalon

The hindbrain or Rhombencephalon

Cerebellum

Pons

Medulla oblongata

Related Topics in Zoology:

Nervous system

Co-ordination systems Nervous Co-ordination

Nervous system

Related Topics in Zoology:

Thrombosis

Related Topics in Zoology:

Clotting of Blood or Haemostasis

Related Topics in Zoology:

Blood

Plasma

Composition of plasma

1. Red Blood Corpuscles (RBC) or Erythrocytes

2. White Blood Corpuscles (WBC) or Leucocytes

3. Blood Platelets or Thrombocytes

Related Topics in Zoology:

Cardio – Pulmonary Resuscitation (CPR)

Related Topics in Zoology:

Pulse rate

Related Topics in Zoology:

EC8393 Important Questions Fundamentals of Data Structures in C

Sample EC8393 Important Questions Fundamentals of Data Structures in C

Heart transplantation

Limiting factors for Heart transplant surgery

Related Topics in Zoology:

Blood Pressure

Intensive of hypertension

Causes

Preventive measures

Related Topics in Zoology: