6. Nervous System Flashcards
Stimuli
changes in the environment to which organisms respond and react
response
reaction of the organism due to the stimulus
receptors
special cells in our body that can detect different stimuli
effectors
special organs in the bodt that bring about responses
what are the 5 receptors in our body and where are they
Photo receptors - eyes
Olfactory receptors - nose
Gustatory receptors - tongue
Auditory/ Balance receptors - ears
Skin receptors
Coordination
the process of adjusting the body for changes in the external and internal environment by interconnecting the receptors and effectors
nervous coordination
controlling and coordinating the various functions of your body through nervous system is known as nervous coordination
chemical coordination
controlling and coordinating body functions through hormones is known as chemical coordination
which system carries out chemical coordination
endocrine system
hormones
chemical substances known as hormones (chemical messengers) work inside your body
what are the two parts of the nervous system
Central nervous system
Peripheral nervous system
what is the central nervous system made of?
brain, spinal cord, relay neurons
what is the CNS also called
Body’s command centre
what is the peripheral nervous system made of
network of nerves
what is the main function of the peripheral nervous system
to connect parts of the body to the central nervous system
what is the peripheral nervous system also called
information highway
what does the peripheral nervous system consist of
somatic nervous system (skeletal muscles, voluntary actions)
autonomic nervous system (involuntary actions)
what are nerve cells
group of specialized cells which help in communication and coordination of various responses in our bodies by linking different parts of a complex network
functions of nervous system
- keeps us informed of changes in our surroundings
- enables us to think, remember and reason to find solutions to our problems
- controls and harmonizes voluntary functions
- regulates involuntary functions
set of bones around the brain
skull/ cranium
bony cage which protects the spinal cord
vertebral column
what controls the autonomic nervous system
medulla oblangata
nerve impulse
electrical signal that carries information to and from the brain and travels along a nerve
myelin sheath
fatty white substance which covers the axons; main purpose is insulation
synapse
junction between two neurons i.e dendrites of one neuron and axon of the immediately next neuron is called synapse
axon
long tube like projection arising outwards from cell body
Cell body is also called
soma/cyton
cell body consists of
cytoplasm and nucleus
dendrites
long and thin cytoplasmic projections stretching out from the soma
2 functions sensory neurons
recieve messages from receptors
carry impulses to the brain and spinal cord
function of motor neurons
transmit impulses from brain and spinal cord to effectors to initiate response
function of relay neurons/interneurons/association neurons
serve as links between sensory and motor neurons and conduct impulses between them
what is the brain (2)
highest coordinating centre in the body
complex organ which controls thought, memory, emotion, motor skills, etc and all other processes to regulate the body
3 statistics on the brain
(adult brain) weighs 1.35 kg
consumes 25% of total oxygen in body
contains 80% water
what are the meninges
three membranous coverings which cover the brain
what is the function of meninges
cover the brain and spine
cushion, nourish and protect the brain and spine
cerebrospinal fluid
space between the meninges is filled with a special watery fluid
what does cerebrospinal fluid do
collect waste material from the neurons of the brain
three parts of the brain
- cerebrum
- cerebellum
- medulla oblongata
5 (structure) points on the cerebrum
- anterior/front part of the brain
- divided into right and left hemispheres
- hemispheres are separated by a deep groove
- outer surface is full of fold (more space to pack in neurons)
- walls of each hemisphere have two internal regions: outer cortex and inner medulla
what is grey matter
- outer cortex contains the cell bodies of the neurons and appears grey-ish
- hence, it is called grey matter
what is white matter
- inner medulla contains the axons of the neuron
- appears white and hence is called white matter
sheet of fibres that joins the two cerebral hemispheres together
corpus callosum
what does corpus callosum do
transfers information from one hemisphere of the brain to the other
functions of the cerebrum (5)
- controls all voluntary activities
- intelligence, consciousness, willpower
- association areas which enable us to think, plan, invent, memorise etc
- sensory areas where the sensory info is received
- site of our faculties such as learning, reasoning, memory, emotions, personality, development, etc.
what does cerebellum mean
small brain
where is the cerebellum located
below cerebrum, near the back of the skull
what do pons do
they join the two cerebellar hemispheres together, forming a bridge below them
what is the function of the cerebellum (4)
- maintains body’s posture and balance
- helps us learn new movements
- coordinated both the voluntary and involuntary action of the body
- muscular movement is coordinated by the cerebellum
where is the medulla oblongata
lowest part of the brain, base of skull, Infront of cerebellum
function of medulla oblongata (2)
- controls all involuntary functions like heartbeat, breathing, sneezing, vomiting, heart rate, swallowing etc
- an injury to the medulla oblongata leads to instant death as the internal organs stop functioning
what is spinal cord
bundle of nerves arranged in a cylindrical fashion with a narrow hollow cavity in the centre called the central canal
what is the central canal filled with(1) and why is it important (2)
- cerebrospinal fluid
- acts as a shockproof cushion
- is a medium through which food, waste products, and respiratory gases are exchanged b/w brain and spinal cord
spinal cord is connected to rest of the body via
nerves
what is different about the arrangement of white and grey matter in spinal cord
arrangement is reversed
white matter on the outside, grey matter on the inner side
what functions does the spinal cord perform (3)?
- controls reflex actions that take place below the neck
- conducts messages from diff parts of the body to the brain
- conducts messages from brain to effectors (muscles and glands) as response
reflex action
an action or movement not controlled by conscious thought and done without thinking
what are nerves
enclosed, cable like bundle of axons
what do nerves do
provide a path for the electrical impulse from the central nervous system to be transmitted to different parts of the body
three types of nerves
sensory nerves ( contain axons of sensory neurons)
motor nerves (contain axons of motor neurons)
mixed nerves (contain axons of both)
two types of nerves based on origin
cranial and spinal
cranial nerves (3)
- emerge from the brain
- 12 pairs
- may be sensory, motor or mixed nerves
spinal nerves (3)
- emerge from the spinal cord
- 31 pairs
- mixed nerves (control muscles)
