cranial nerves Assignment PDF

Question # 02: Explain the functions of any 06 pairs of cranial nerves.
Your cranial nerves are pairs of nerves that connect your brain to different parts of your head,
neck, and trunk. There are 12 of them, each named for their function or structure.
Each nerve also has a corresponding Roman numeral between I and XII. This is based off their
location from front to back. For example, your olfactory nerve is closest to the front of your
head, so it’s designated as I.
I. Olfactory nerve
The olfactory nerve transmits sensory information to your brain regarding smells that you
encounter. When you inhale aromatic molecules, they dissolve in a moist lining at the roof of
your nasal cavity, called the olfactory epithelium. This stimulates receptors that generate nerve
impulses that move to your olfactory bulb. Your olfactory bulb is an oval-shaped structure that
contains specialized groups of nerve cells.
From the olfactory bulb, nerves pass into your olfactory tract, which is located below the frontal
lobe of your brain. Nerve signals are then sent to areas of your brain concerned with memory and
recognition of smells.
II. Optic nerve
The optic nerve is the sensory nerve that involves vision.
When light enters your eye, it comes into contact with special receptors in your retina called rods
and cones. Rods are found in large numbers and are highly sensitive to light. They’re more
specialized for black and white or night vision. Cones are present in smaller numbers. They have
a lower light sensitivity than rods and are more involved with color vision. The information
received by your rods and cones is transmitted from your retina to your optic nerve. Once inside
your skull, both of your optic nerves meet to form something called the optic chiasm. At the
optic chiasm, nerve fibers from half of each retina form two separate optic tracts. Through each
optic tract, the nerve impulses eventually reach your visual cortex, which then processes the
information. Your visual cortex is located in the back part of your brain.
III. Oculomotor nerve
The oculomotor nerve has two different motor functions: muscle function and pupil response.
Muscle function. Your oculomotor nerve provides motor function to four of the six muscles
around your eyes. These muscles help your eyes move and focus on objects. Pupil response. It
also helps to control the size of your pupil as it responds to light. This nerve originates in the

front part of your midbrain, which is a part of your brainstem. It moves forward from that area
until it reaches the area of your eye sockets.
IV. Trochlear nerve
The trochlear nerve controls your superior oblique muscle. This is the muscle that’s responsible
for downward, outward, and inward eye movements. It emerges from the back part of your
midbrain. Like your oculomotor nerve, it moves forward until it reaches your eye sockets, where
it stimulates the superior oblique muscle.
V. Trigeminal nerve
The trigeminal nerve is the largest of your cranial nerves and has both sensory and motor
functions.
The trigeminal nerve has three divisions, which are:
Ophthalmic. The ophthalmic division sends sensory information from the upper part of your
face, including your forehead, scalp, and upper eyelids.
Maxillary. This division communicates sensory information from the middle part of your face,
including your cheeks, upper lip, and nasal cavity.
Mandibular. The mandibular division has both a sensory and a motor function. It sends sensory
information from your ears, lower lip, and chin. It also controls the movement of muscles within
your jaw and ear.
The trigeminal nerve originates from a group of nuclei — which is a collection of nerve cells —
in the midbrain and medulla regions of your brainstem. Eventually, these nuclei form a separate
sensory root and motor root. The sensory root of your trigeminal nerve branches into the
ophthalmic, maxillary, and mandibular divisions. The motor root of your trigeminal nerve passes
below the sensory root and is only distributed into the mandibular division.
VI. Abducens nerve
The abducens nerve controls another muscle that’s associated with eye movement, called
the lateral rectus muscle. This muscle is involved in outward eye movement. For example, you
would use it to look to the side. This nerve, also called the abducent nerve, starts in
the pons region of your brainstem. It eventually enters your eye socket, where it controls the
lateral rectus muscle.
Q# 3 Explain social organization in insects with examples.

In insects social life has evolved only in two orders, namely, Isoptera (termites) and
Hymenoptera (bees, wasps and ants) which make a nest and live in colonies of thousands of
individuals that practice division of labour and social interaction.
Examples:
SOCIAL LIFE IN TERMITES
Termites were the first animals which started living in colonies and developed a well organised
social system about 300 million years ago, much earlier than honey bees, ants and human beings.
Although termites do not exceed 3-4 mm in size, their queen is a 4 inch long giant that lies in the
royal chamber motionless, since its legs are too small to move its enormous body. Hence
workers have to take care of all its daily chores. Termite queen is an egg-laying machine that
reproduces at an astonishing rate of two eggs per second. Generally the queen of a termite colony
can lay 6,000 to 7,000 eggs per day, and can live for 15 to 20 years. The other
castes, workers and soldiers are highly devoted to the colony, working incessantly and tirelessly,
demanding nothing in return from the society. Soldiers have long dagger-like mandibles with
which they defend their nest and workers chew the wood to feed to the queen and larvae and
grow fungus gardens for lean periods. Nasutes are specialized soldiers which specialize in
chemical warfare. They produce a jet of highly corrosive chemical from their bodies that can
dissolve the skin of enemies and can also help in making galleries through the rocks.
SOCIAL STRUCTURE OF A BEE COLONY
The population of a healthy bee hive in spring and honey flow period may contain 40,000-80,000
individuals but the population declines in winter and extreme summer. There is remarkable order
in the hive and no conflicts are seen among the members. Queen is one and a half times larger
than the workers and is the only fertile female in the hive. Queen keeps the colony together by
secreting a pheromone called queen substance from its mandibular glands. In multiqueen
colonies, young queens after emergence attempt to sting and kill the rival queens.

Question # 04: Explain the importance of animal behavior in ecosystems.
Animal behavior is the bridge between the molecular and physiological aspects of biology and
the ecological. Behavior is the link between organisms and environment and between the
nervous system, and the ecosystem. Behavior is one of the most important properties of animal
life. Behavior plays a critical role in biological adaptations. Behavior is how we humans define
our own lives. Behavior is that part of an organism by which it interacts with its environment.
Behavior is as much a part of an organisms as its coat, wings etc. The beauty of an animal
includes its behavioral attributes. For the same reasons that we study the universe and subatomic
particles there is intrinsic interest in the study of animals. In view of the amount of time that
television devotes to animal films and the amount of money that people spend on nature books
there is much more public interest in animal behavior than in neutrons and neurons. If human
curiosity drives research, then animal behavior should be near the top of our priorities.
While the study of animal behavior is important as a scientific field on its own, our science has
made important contributions to other disciplines with applications to the study of human
behavior, to the neurosciences, to the environment and resource management, to the study of
animal welfare and to the education of future generations of scientists.
A. ANIMAL BEHAVIOR AND HUMAN SOCIETY
1. Many problems in human society are often related to the interaction of environment and
behavior or genetics and behavior. The fields of socioecology and animal behavior deal with
the issue of environment behavioral interactions both at an evolutionary level and a
proximate level. Increasingly social scientists are turning to animal behavior as a framework