Neurons and brain 7.2A Flashcards
What is the Nervous system?
The nervous system is a communication network that controls all the other systems in the body.
Central nervous system (CNS) comprised of the brain and spinal cord. Receives and processes information before initiating a response.
Peripheral nervous system (PNS) branches out to the rest of the body and carries messages to/from the CNS.
What is neurons?
Trillions of nerve cells made up the nervous system.
Neurons transmit electrical messages called nerve impulses around your body at high speeds and in one direction.
What is the Neuron structure
Neurons contain a nucleus, cytoplasm and a cell membrane.
Neurons also have other specialized parts:
Dendrites – receive messages from other nerve cells
Axon – sends nerve impulse away from cell body
Axon terminals – pass the message on to the next neuron
What is an Axon?
The axon is coated in white, fatty cells called Schwann cells that form the myelin sheath
It’s purpose is to insulate the axon and allow the electrical impulses to travel quickly
Types of neurons
Sensory neurons: carry messages from cells in sense organs (eyes, ears, tongue, skin) to the CNS.
Relay connector neurons: transmit messages between neurons in the CNS
Motor neurons: carry messages from the CNS to effectors
Types of Sensory neurons
Sensory neurons have specialized receptors that are sensitive to stimuli
heat/light/sound/ taste/touch
Transmitting along a neuron
Once a neuron has been stimulated, a nerve impulse travels down the axon.
This electrical signal is called an action potential
Transmitting between neurons
Once the nerve impulse reaches the axon terminal, special chemicals neurotransmitters are released into the synapse which is the space between neurons
This stimulates the dendrites of the next neuron
What is in the brain?
In the CNS (brain and spinal cord), the myelinated axons cluster together forming white matter
The cell bodies form grey matter
The human brain contains ~10 billion neurons and has an average volume of 1.2-1.4 L
The brain controls and regulates body functions.
What is MRI
Brains can be imaged through Magnetic Resonance Imaging(MRI)
used to indicate tumors or brain injury
Functional MRI(FMRI) indicates blood flow in the brain and can be used to diagnose stroke or disease.
What is The Cerebrum?
comprises 80% of the brain
Functions:
Processes senses
Complex thought processes
Voluntary movement
The cerebrum is broken into right and left hemispheres, right hemisphere controls movement of the left side of the body
These spheres can work independently, but most tasks require both to work together
Left has more control of logical thinking or language. Right manages emotional, creative, music and art.
What is the cerebral cortex
formed of the outer layer of the cerebrum.
The ridges are called gyri, and the troughs are called sulci
Frontal lobe: controls movement, reasoning, problem solving and emotion.
Parietal lobe: contains the primary somatosensory cortex –processes sense of touch.
Occipital lobe: contains the primary visual cortex –processes visual information.
Temporal lobe: contains the primary auditory cortex – processes sound in left hemisphere and is responsible for language and speech.
What is The Cerebellum
responsible for coordination and balance
What is The medulla / brainstem
The medulla / brainstem is section connecting the brain to the spinal cord.
It is responsible for monitoring vital functions:
breathing
blood pressure
heart rate
Damage to it can be fatal.
Protection of Brain and Spinal Cord
Due to the importance of these structures, both the brain and spinal cord are encased in bone.
The brain is encased in the cranium, spinal cord in the vertebrae.
They are also both suspended in cerebrospinal fluid (CSF) to provide nutrients and absorb shock.
