Brain and Nerve System Flashcards
The Brain
- Weighs about 1.5 kg
- Sends thousands of messages each second
- Is the control centre
- Enables you to learn
- Stores info
- Performs complex mental tasks
- Controls your actions & feelings
What is the brain protected by
- A bony skull
- Three layers of connective tissues called the meninges
- Cerebrospinal fluid
What are the parts of the brain?
- The cerebrum
- The cerebellum
- The Brain stem
The cerebrum
- Makes up 90% of brain volume
- Is wrinkled to fit more brain into the skull
- Separated into two hemispheres
- Controls memory, speech, thought, conscious actions, sensory perception, and emotion
The cerebellum
- Pink structure that sits at back of brain underneath the cerebrum
- Controls balance and coordinates complex muscle actions
The brain stem
- Connects directly to the spinal cord
- Controls unconsciously/involuntary activities (eg: breathing, heart rate, digestion)
The corpus callosum
a bundle of nerve fibres that connects the left and right hemispheres and allows communication between them
What are the lobes that make up the cerebrum
- Frontal
- Parietal
- Occipital
- Temporal
Frontal Lobe
Involved in:
- Planning and selecting movements
- Memory Formation
- Expressing Emotions
Contains the:
- Primary Motor Cortex
- Broca’s area
Primary Motor Cortex
controls voluntary movement
Broca’s area
speech production
Parietal Lobe
Involved in:
- Touch
- Detecting movements
- Location of objects
- Body Sensations
Contains the:
Primary Somatosensory Cortex
Primary Somatosensory Cortex
Recieves information about what the body is touching and feeling
Occipital Lobe
Involved in:
Vision
Contains the:
Primary vision cortex
Primary visual cortex
Processes visual information
Temporal Lobe
Involved in:
- Hearing
- Memory
- Emotions
Contains the:
Primary Auditory Cortex
Wernicke’s area
Primary auditory cortex
Responsible for the sense of hearing
Wernicke’s area
responsible for speech comprehension
Wernicke’s area
responsible for speech comprehension
Left Hemisphere
- Controls right side of body
- Involved in verbal or language related tasks
- Referred as the logical side
- controls language, involved in tasks that require logic and handles numerical calculations
Right Hemisphere
- Controls left side of body
- Is involved in non-verbal or spatial tasks
- referred as the creative side
- creativity, music and art, facial recognition
The Two Human Nervous Systems
Central Nervous System
Peripheral Nervous System
Central Nervous System
Made up of the brain and spinal cord
The CNS interprets sensory information from the body, makes decisions, and sends commands back to the body
Peripheral Nervous System
Made up of neurons that join the rest of the body to the CNS
It connects the CNS to your muscles, skin, and organs to help you react and move.
Somatic Nervous System
Controls voluntary movement
Input from sense organs
Output to skeletal muscles
It helps you control your muscles consciously and move when you want to.
Autonomic Nervous System
Controls involuntary movement
Input from internal receptors
Output to smooth muscles & glands
It keeps your body running smoothly without you having to think about it.
Sympathetic Nervous System
Activates the fight or flight response during stressful situations
It prepares your body to react quickly to stressful or dangerous situations.
Parasympathetic nervous system
Promotes ‘rest and digest’ activities, helping the body relax and conserve energy
It helps your body relax and recover, bringing everything back to normal after stress.
Flight, Fight, Freeze Response
A state of high arousal where the body rapidly prepares for a burst of vigorous activity when presented with a threatening situation
Fight
Confront the stressor
Flight
Remove ourselves
Freeze
Stay still and try to hide from the stressor
Neurons (nerve cell)
cells that receive and sends impulses throughout the body
What are the three types of neurons that make up the nervous system?
- Sensory Neurons
- Interneurons
- Motor Neurons
Sensory (afferent)
- transmit impulses to CNS from receptors
- impulses arrive at the brain
Interneurons (connector neurons)
- Connects motor & sensory neurons
- Impulses travel through CNS
Motor (efferent) neurons
- transmit impulses from CNS to muscles
- impulses exit the brain
Dendrites
receives messages from other neurons via their receptor sites
Cell body (soma)
contains the nucleus & controls the cell
Axon
sends messages away from the soma to the axon terminal branches
Myelin sheath
insulates axon to help protect it and speed up transmission
Axon terminal branches
passes messages from axon through to the terminal buttons
Terminal buttons
the message becomes a chemical called a neurotransmitter
Synapse
the gap between axon transmitter & next neuron. Neurotransmitter carry the message across the gap.
How is an impulse sent? (Communication within neurons)
Received by the receptor sites on the dendrites and passed to the soma -> an electrical impulse starts in the axon -> travels to the axon terminals -> neurotransmitters in the terminal buttons are released into the synapse
Excitatory
stimulate or activate postsynaptic neurons
Inhibitory
block or prevent postsynaptic neurons from firing
Lock and Key Processes
Each type of neurotransmitter has a chemically distinct shape and when its released by the presynaptic neuron, neurotransmitter searches for the correctly shaped receptor sites on the dendrites of the postsynaptic neurons.
Like a key in a lock or a piece of a jigsaw puzzle, a neurotransmitter’s shape must precisely match the shape of the receptor site on the postsynaptic neuron’s dendrites in order to bind (‘attach’) to its receptors, unlock them and have an effect on the postsynaptic neuron.
Communication between neurons
Neurotransmitters are A chemical substance that cross the ‘synaptic gap’ & reach the dendrites of the next neuron or the effector organ -> this has an effect on the next neuron or organ.
Conscious Response
- a reaction that involves awareness, its a voluntary and intentional response.
- able to exercise some degree of control over it
Unconscious response
- a reaction that does not involve awareness, its an involuntary and unintentional response
- usually unable to exercise control but can learn to exercise some degree of control over certain responses.
Typical Neuron Communication
- Receptor sites receive sensory input
- Sensory neurons carry sensory messages along afferent pathways in the spinal cord to the brain
- The brain coordinates a message
- Interneurons relay the message to motor neurons
- Motor neurons carry motor responses along efferent pathways in the spinal cord to the body
- The effector site has a response
Reflex
reactions that occur without thinking to protect us from damage
Spinal Reflex
an automatic response that is initiated by neurons in the spinal cord, instead of the brain
Typical Neuron Communication for a spinal response
- Receptor site receive sensory input
- Sensory neurons carry sensory message along afferent pathways in the spinal cord
- The interneurons in the spinal cord coordinate a message
- Interneurons relay the message to motor neurons
- Motor neurons carry the motor message along efferent pathways in the spinal cord to the body
- The effector site has a response
