Brain

●​ weighs about 1.36 kg, is located inside the cranial cavity, where the
bones of the skull surround and protect it.
●​ The approximately 100 billion neurons of the brain form the main
control center of the body.
●​ The brain and spinal cord together form the central nervous system
(CNS), where information is processed and responses originate.
●​ The brain, the seat of higher mental functions such as
consciousness, memory, planning, and voluntary actions, also
controls lower body functions such as the maintenance of respiration,
heart rate, blood pressure, and digestion.’

Broadly divided into three main sections:

The forebrain, midbrain, and hindbrain
​ Forebrain:​
This is the largest and most complex part of the brain, responsible for
 higher-level cognitive functions. It is divided into three main parts, that
are the cerebrum, thalamus and hypothalamus.
●​ Cerebrum: The largest part of the forebrain, responsible for
conscious thought, memory, and sensory processing. The
cerebrum is divided into two halves by a deep furrow. These
halves are the left and right hemispheres. Corpus callosum
connects the two hemispheres.
➢​Cerebral Cortex: The outer layer of the cerebrum,
involved in higher-level functions like language,
reasoning, and problem-solving.
➢​Lobes: The cerebrum is further divided into four
lobes: frontal, parietal, temporal, and occipital,
each with specialized functions.
●​ Diencephalon: Located deep within the brain, it includes the
thalamus, hypothalamus, and other structures involved in sensory
relay, hormone regulation, and emotional processing.
●​ The thalamus acts as a central relay station for sensory and motor
signals, relaying them to the cerebral cortex, while the
hypothalamus plays a crucial role in regulating essential bodily
functions, linking the nervous and endocrine systems, and
maintaining homeostasis.
​ Midbrain:​
Connects the forebrain and hindbrain, playing a role in motor control,
auditory and visual processing, and alertness.
​
​ Hindbrain:​
Located at the base of the brain, it includes the cerebellum, pons, and
medulla oblongata, which are vital for balance, coordination, and basic
life functions.
●​ Cerebellum: Primarily involved in motor coordination, balance, and
posture. Eg.picking up a pen.
●​ Pons: Connects the cerebellum to the rest of the brain and plays a
role in sleep, breathing, and other vital functions.
●​ Medulla Oblongata: Regulates Involuntary actions like breathing,
heart rate,vomiting and blood pressure.
Spinal Cord
●​ It is a long, thin mass of bundled neurons that carries information
through the vertebral cavity of the spine beginning at the medulla
oblongata of the brain on its superior end and continuing inferiorly to
the lumbar region of the spine.
●​ It is around 45 cm (18 in) in men and around 43 cm (17 in) long in
women.
●​ In the lumbar region, the spinal cord separates into a bundle of
individual nerves called the cauda equina (due to its 440
resemblance to a horse’s tail) that continues inferiorly to the sacrum
and coccyx.
●​ The white matter of the spinal cord functions as the main conduit of
nerve signals to the body from the brain.
●​ The grey matter of the spinal cord integrates reflexes to stimuli.
Nerves
●​ Nerves are bundles of axons in the peripheral nervous system (PNS)
that act as information highways to carry signals between the brain
and spinal cord and the rest of the body.
●​ Each axon is wrapped in a connective tissue sheath called the
endoneurium.
●​ Individual axons of the nerve are bundled into groups of axons called
fascicles, wrapped in a sheath of connective tissue called the
perineurium.
●​ Finally, many fascicles are wrapped together in another layer of
connective tissue called the epineurium to form a whole nerve.
●​ The wrapping of nerves with connective tissue helps to protect the
axons and to increase the speed of their communication within the
body.

Meninges
●​ The meninges are the protective coverings of the central nervous
system (CNS).
 ●​ They consist of three layers: the dura mater, arachnoid mater, and pia
mater.

Dura mater:
●​ The dura mater, which means “tough mother,” is the thickest,
toughest, and most superficial layer of meninges.

Arachnoid mater:
●​ The arachnoid mater, which means “spider-like mother,” is much
thinner and more delicate than the dura mater.

Pia mater:
●​ The pia mater, which means “tender mother,” is a thin and delicate
layer of tissue that rests on the outside of the brain and spinal cord.

Cerebrospinal Fluid
●​ The space surrounding the organs of the CNS is filled with a clear
fluid known as cerebrospinal fluid (CSF).
●​ CSF is formed from blood plasma by special structures called choroid
plexuses.
●​ The choroid plexuses contain many capillaries lined with epithelial
tissue that filters blood plasma and allows the filtered fluid to enter the
space around the brain.

Some notable Point:-​

●​ Glucose is the primary source of energy for the brain, providing the
fuel necessary for its proper functioning.
●​ EEG - A number of electrodes are applied to your scalp. It helps
diagnose a number of conditions including epilepsy, sleep disorders
and brain tumours.

Q. Which part of the human brain controls the involuntary action of

vomiting?
RRC Group D 23/08/2022 (Evening)
(a) Midbrai
(b) Hindbrain
(c) Spinal cord
(d) Forebrain
Sol.(b) Hindbrain

Q. Which of the following is composed of nerve fibres that mediate reflex

actions and that transmit impulses to and from the brain?
RRB NTPC CBT - I (30/12/2020) Morning
(a) Heart
(b) Rib cage
(c) Spinal cord
(d) Muscles
Sol.(c) Spinal cord

Q. The EEG (electroencephalogram) test is conducted for diagnosing

ailments of which of the following organs?
RRB NTPC CBT - I (31/07/2021) Morning
(a) Brain
(b) Stomach
(c) Lungs
(d) Heart
Sol.(a) Brain

Q. In mammals, the corpus callosum connects -

RRB JE 27/06/2019 (Evening)
(a) Bone to muscle
(b) The two optic lobes
(c) The two cerebral hemispheres
(d) Bone to bone
Sol.(c)
Q. Which human organ weighs about 1.4 kg and 0.85 litres of blood passes
through it every minute ?
RRB JE 28/06/2019 (Evening)
(a) Heart
(b) Brain
(c) Kidneys
(d) Lungs
Sol.(b) Brain

Q. Which of the following is the main thinking part of the human brain?
RRB ALP Tier - I (10/08/2018) Afternoon
(a) Mid- brain
(b) Cerebellum
(c) Fore-brain
(d) Hind-brain
Sol.(c) Fore-brain

Q. Which of the following is not a voluntary action?

RRB ALP Tier - I (13/08/2018) Evening
(a) Closing of fist
(b) Beating of heart
(c) Moving a chair
(d) Taking an object
Sol.(b) Beating of heart.

Q. Involuntary actions in human beings such as blood pressure, salivation

and vomiting are controlled by the:
RRB ALP Tier - I (20/08/2018) Morning
(a) Pons
(b) Hypothalamus
(c) Spinal cord
(d) Medulla
Sol.(d)
Q. The ________ is responsible for precision of voluntary actions and for
maintaining the posture and balance of the body.
RRB ALP Tier - I (29/08/2018) Afternoon
(a) Cerebrum
(b) Cerebellum
(c) Spinal cord
(d) Mid-brain
Sol.(b) Cerebellum

Q. Which part of the brain regulates breathing?

RRB ALP Tier - I (31/08/2018) Morning
(a) Fore-brain
(b) Cerebellum
(c) Mid-brain
(d) Medulla
Sol.(d) Medulla

Q. Our brain mainly depends on which of the following food?

Higher Secondary 02/08/2022 (Shift - 2)
(a) Fat and proteins
(b) Glucose and amino acids
(c) Only fat
(d) Only glucose
Ans:d

Q. Which of the following is NOT a part of the hind-brain?

SSC MTS 07/10/2021 (Evening)
(a) Pons
(b) Medulla
(c) Cerebellum
(d) Hypothalamus
Ans:d

Q. Which part of the brain is instrumental in making it possible for a person

to perform an activity such as picking up a pencil from the floor?
SSC CPO 24/11/2020 (Morning)
(a) Hypothalamus
(b) Cerebellum
(c) Cerebrum
(d) Cranium
Ans:b

Q. The__________ in the human body controls every activity that you

perform.
SSC CPO 12/03/2019 (Evening)
(a) Respiratory system
(b) Nervous system
(c) Digestive system
(d) Reproductive system
Ans:b