Neurons and brain 7.2A Flashcards
What is the Nervous system?
The nervous system controls all body systems through communication.
-Central Nervous System (CNS): Includes the brain and spinal cord; processes information and initiates responses.
-Peripheral Nervous System (PNS): Connects the CNS to the body, transmitting messages to and from it.
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
When a nerve impulse reaches the axon terminal, neurotransmitters are released into the synapse, stimulating the next neuron’s dendrites.
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 detect brain tumors or injuries. Functional MRI (fMRI) measures blood flow and helps diagnose strokes or brain diseases.
What is The Cerebrum?
The cerebrum makes up 80% of the brain and is responsible for:
-Processing senses
-Complex thought
-Voluntary movement
-Divided into right and left hemispheres, the right controls the left side of the body. While they can work independently, most tasks require both.
-The left hemisphere handles logic and language, while the right focuses on emotions, creativity, music, and art.
What is the cerebral cortex
formed of the outer layer of the cerebrum.
Cerebrum is highly folded
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
The brain and spinal cord are protected by bone—the brain by the cranium and the spinal cord by the vertebrae. Both are suspended in cerebrospinal fluid (CSF), which provides nutrients and absorbs shock.
