1(A) The human brain controls nearly every aspect of the human body ranging from physiological

functions to cognitive abilities. It functions by receiving and sending signals via neurons to
different parts of the body. It functions by receiving and sending signals via neurons to different
parts of the body. The human brain, just like most other mammals, has the same basic structure,
but it is better developed than any other mammalian brain. The brain, along with the spinal cord,
constitutes the central nervous system. It is responsible for thoughts, interpretation and origin of
control for body

Parts of Human brain 1. Cerebrum or forebrain 2. Midbrain The brainstem 3. Pons varolli 4.
Medulla oblongata 5. Cerebellum 6. hindbrain Cerebrum: The Parts of the Central Nervous System
It is the largest part of the brain and occupies anterior and middle part of the cranial cavity. It is
divided by a deep cleft into right and left cerebral hemispheres. Deep within the brain, the
hemispheres are connected by a mass of nerve fibres called corpus callosum. The superficial part
of the cerebrum is composed of nerve cell body, forming cerebral cortex. The cerebral cortex
shows many enfolding of varying depth. The exposed areas of the fold are called as gyro or
convolutions and are separated by sulci or fissure. The convolutions help in increasing surface area
of the cerebrum. Each hemisphere of the cerebrum is divided into the following lobes:

. 1. Frontal lobe: It is associated with parts of speech, planning, reasoning, problem-solving and
movements.

2. Parietal lobe: Help in movements, the perception of stimuli and orientation

3. Occipital lobe: It is related to visual processing. 4. Temporal lobe: This region is related to
perception and recognition of memory, auditory stimuli and speech. the cerebral cortex is the layer
of the brain often referred to as grey matter because it has cell bodies and synapses but no myelin.
The cortex (thin layer of tissue) is grey because nerves in this area lack the insulation or white fatty
myelin sheath that makes most other parts of the brain appear to be white. The cortex covers the
outer portion (1.5mm to 5mm) of the cerebrum and cerebellum. The cortex consists of folded
bulges called gyri that create deep furrows or fissures called sulci. The folds in the brain add to its
surface area which increases the amount of grey matter and the quantity of information that can
be processed. Medullary body – is the white matter of the cerebrum and consists of myelinated
axons. Commissural fibres – conduct impulses between the hemispheres and form corpus
callosum. Projection fibres – conduct impulse in and out of the cerebral hemispheres Association
fibres – conduct impulses within the hemispheres. Basal ganglia – masses of grey matter in each
hemisphere that are involved in the control of voluntary muscle movement. Functions of the
Cerebrum Nervous System Mental activities involved in memory, intelligence, sense of
responsibility; thinking, reasoning, moral sense, and learning. . Sensory perception, including the
perception of pain, temperature, touch; sight, hearing, taste and smell. Initiation and control of
voluntary muscle contraction. The brain consists of two types of tissues: grey matter and White
matter. 1. Grey matter mainly consists of various types of cells, which make up the bulk of the
brain. 2. White matter is primarily composed of axons, which connect various grey matter areas of
the brain with each other. The exterior portion of the cerebrum is called the cortex or the cerebral
mantle. The cortex is extremely convoluted, due to which, it has a large surface area. The
cerebrum also includes: 1. Sensory areas: To receive the messages. 2. Association areas: These
areas integrate the incoming sensory information. It also forms a connection between sensory and
motor areas. 3. Motor areas: This area is responsible for the action of the voluntary muscles.
 The heart serves as the body’s pump, propelling oxygen-rich blood to tissues and organs while
simultaneously receiving oxygen-depleted blood for reoxygenation. This cyclical process ensures
the body meets its metabolic demands efficiently.

Right Side of the Heart

Superior and Inferior Vena Cava (SVC and IVC): Deoxygenated blood enters the right atrium
through these veins. Right Atrium: Blood accumulates in this chamber before contracting and
pushing blood through the tricuspid valve. Tricuspid Valve: This one-way valve prevents the
backflow of blood into the right atrium. Right Ventricle: After going through the tricuspid valve,
deoxygenated blood enters the right ventricle for contraction to push it towards the lungs.
Pulmonary Valve: From the right ventricle, blood pumps through this valve into the pulmonary
artery. Pulmonary Artery: This artery carries deoxygenated blood to the lungs for oxygenation.

Left Side of the Heart

 Pulmonary Veins: Oxygenated blood returns to the heart from the lungs through these veins,
entering the left atrium.

 Left Atrium: Blood travels through this valve from the left atrium to the left ventricle.

 Mitral Valve (Bicuspid Valve): Oxygenated blood enters the left ventricle through this one-way
valve.

 Left Ventricle: The left ventricle, the thickest chamber, pumps oxygenated blood through the rest
of the body.

 Aortic Valve: From the left ventricle, blood pumps through this valve into the aorta.

 Aorta: The aorta, the largest artery, carries oxygenated blood to all parts of the body.
 1(B) Respiratory Tract

The respiratory tract in humans is made up of the following parts:

 External nostrils – For the intake of air.Nasal chamber – which is lined with hair and mucus
to filter the air from dust and dirt.Pharynx – It is a passage behind the nasal chamber and
serves as the common passageway for both air and food.Larynx – Known as the soundbox
as it houses the vocal chords, which are paramount in the generation of sound.Epiglottis –
It is a flap-like structure that covers the glottis and prevents the entry of food into the
windpipe.Trachea – It is a long tube passing through the mid-thoracic cavity.Bronchi – The
trachea divides into left and right bronchi.Bronchioles – Each bronchus is further divided
into finer channels known as bronchioles.Alveoli – The bronchioles terminate in balloon-
like structures known as the alveoli.Lungs – Humans have a pair of lungs, which are sac-like
structures and covered by a double-layered membrane known as pleura.
Air is inhaled with the help of nostrils, and in the nasal cavity, the air is cleansed by the
fine hair follicles present within them. The cavity also has a group of blood vessels that
warm the air. This air then passes to the pharynx, then to the larynx and into the trachea.

The trachea and the bronchi are coated with ciliated epithelial cells and goblet cells
(secretory cells) which discharge mucus to moisten the air as it passes through the
respiratory tract. It also traps the fine bits of dust or pathogen that escaped the hair in the
nasal openings. The motile cilia beat in an ascending motion, such that the mucus and
other foreign particles are carried back to the buccal cavity where it may either be coughed
out (or swallowed.)

Once the air reaches the bronchus, it moves into the bronchioles, and then into the alveoli.

The functions of the human respiratory system are as follows:

Inhalation and Exhalation

The respiratory system helps in breathing (also known as pulmonary ventilation.) The air
inhaled through the nose moves through the pharynx, larynx, trachea and into the lungs.
The air is exhaled back through the same pathway. Changes in the volume and pressure in
the lungs aid in pulmonary ventilation.

Exchange of Gases between Lungs and Bloodstream

Inside the lungs, the oxygen and carbon dioxide enter and exit respectively through
millions of microscopic sacs called alveoli. The inhaled oxygen diffuses into the pulmonary
capillaries, binds to haemoglobin and is pumped through the bloodstream. The carbon
dioxide from the blood diffuses into the alveoli and is expelled through exhalation.

Exchange of Gases between Bloodstream and Body Tissues

The blood carries the oxygen from the lungs around the body and releases the oxygen
when it reaches the capillaries. The oxygen is diffused through the capillary walls into the
body tissues. The carbon dioxide also diffuses into the blood and is carried back to the
lungs for release.
Introduction of respiratory system The respiratory system is the network of organs and
tissues that help you breathe. It includes your airways, lungs and blood vessels. The
muscles that power your lungs are also part of the respiratory system. These parts work
together to move oxygen throughout the body and clean out waste gases like carbon
dioxide. Functions of Respiratory System The respiratory system has many functions.
Besides helping you inhale (breathe in) and exhale (breathe out), it:  Allows you to talk
and to smell.  Warms air to match your body temperature and moisturizes it to the
humidity level your body needs.  Delivers oxygen to the cells in your body.  Removes
waste gases, including carbon dioxide, from the body when you exhale.  Protects your
airways from harmful substances and irritants. PARTS OF RESPIRATORY SYSTEM The
respiratory system has many different parts that work together to help you breathe. Each
group of parts has many separate components. Your airways deliver air to your lungs. Your
airways are a complicated system that includes your:  Mouth and nose: Openings that pull
air from outside your body into your respiratory system.  Sinuses: Hollow areas between
the bones in your head that help regulate the temperature and humidity of the air you
inhale.  Pharynx (throat): Tube that delivers air from your mouth and nose to the trachea
(windpipe).  Trachea: Passage connecting your throat and lungs.  Bronchial tubes: Tubes
at the bottom of your windpipe that connect into each lung.  Lungs: Two organs that
remove oxygen from the air and pass it into your blood.

From your lungs, your bloodstream delivers oxygen to all your organs and other tissues.
Muscles and bones help move the air you inhale into and out of your lungs. Some of the
bones and muscles in the respiratory system include your:  Diaphragm: Muscle that helps
your lungs pull in air and push it out.  Ribs: Bones that surround and protect your lungs
and heart. When you breathe out, your blood carries carbon dioxide and other waste out
of the body. Other components that work with the lungs and blood vessels include: 
Alveoli: Tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes
place.  Bronchioles: Small branches of the bronchial tubes that lead to the alveoli. 
Capillaries: Blood vessels in the alveoli walls that move oxygen and carbon dioxide.  Lung
lobes: Sections of the lungs — three lobes in the right lung and two in the left lung. 
Pleura: Thin sacs that surround each lung lobe and separate your lungs from the chest wall.
Some of the other components of your respiratory system include:  Cilia: Tiny hairs that
move in a wave-like motion to filter dust and other irritants out of your airways. 
Epiglottis: Tissue flap at the entrance to the trachea that closes when you swallow to keep
food and liquids out of your airway.  Larynx (voice box): Hollow organ that allows you to
talk and make sounds when air moves in and out.