Chapter 1: Brain Basics Flashcards
What is the largest part of the brain?
Cerebrum
What is the cerebrum associated with?
Higher order functioning, including the control of voluntary behaviour like thinking, perceiving, planning and understanding language
How can the cerebrum be divided?
Right and left hemispheres
How do the two hemispheres in the cerebrum communicate with each other?
Through a bundle of fibres called corpus callosum
What is the outer layer of the cerebrum called?
Cerebral cortex, also known as gray matter
What fraction of the cerebral cortex is folded into grooves?
Two-third
Why is the cerebral cortex folded into grooves?
To increase the brain’s surface area, allowing for the inclusion of more neurons
What is the frontal lobe responsible for?
- initiating and coordinating motor movements
- higher cognitive skills like problem solving, thinking, planning and organising
- many aspects of personality and emotions
What is the parietal lobe involved in?
Sensory processes, attention and language
What happens when there is a damage to the right side of parietal lobes?
Difficulty in navigating spaces, even familiar ones
What happens when there is damage to left side of parietal lobe?
Ability to understand spoken or written languages may be impaired
What is the occipital lobe responsible for?
Processing visual information like recognising shapes and colours
What is the temporal lobe responsible for?
- processing auditory information and integrating information from other senses
- short term memory through hippocampal formation
- emotional responses through amygdala
What is the hippocampal formation?
A prominent C-shaped structure in the medial temporal lobe
What is the amygdala?
A collection of nuclei found deep within the temporal lobe
What are the key parts of the forebrain?
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
- basal ganglia
- thalamus
- hypothalamus
What is the basal ganglia?
Cerebral nuclei deep in the cerebral cortex
What does the cerebral nuclei do?
Help to coordinate muscle movements and reward useful behaviours
What does the thalamus do?
Prioritise sensory information and pass most sensory information on to the cerebral cortex
What does the hypothalamus do?
Control appetites, defensive and reproductive behaviours and sleep-wakefulness
What does the midbrain consist of?
- two small pairs of hills called colliculi
- clusters of neurons that regulate activity in widespread parts of the central nervous system
What is the use of colliculi?
It is a collection of neurons that play a critical role in visual and auditory reflexes and relaying this type of information to the thalamus
What is the clusters of neurons in the midbrain important for?
Important for mood and reward mechanisms
What does the hindbrain include?
Pons and medulla oblongata and cerebellum
What does pons and medulla oblongata do?
Control respiration, heart rhythms and blood glucose levels
What does the cerebellum’s two hemispheres do?
It helps to control movement and cognitive processes that require precise timing and play an important role in Pavlovian learning
What is Pavlovian learning?
How two stimuli is linked together to produce a learned response in human or animals
What is the spinal cord?
It is an extension of the brain through the vertebral column
What does the spinal cord do?
- receives sensory information from all parts of the body below the head
- relays this sensory information to the brain and its cerebral cortex
- generates nerve impulses in nerves that control the muscles and the viscera
How does spinal cord generate nerve impulses in nerves?
Through reflex activities and voluntary commands from the cerebrum
What are the two great divisions of the nervous system as a whole?
- central nervous system (CNS)
- peripheral nervous system (PNS)
What forms the central nervous system?
Forebrain, midbrain, hindbrain and spinal cord
What is the brain protected by?
Skull
How long is the spinal cord?
17 inches or 43cm
What is the spinal cord protected by?
Vertebral column
What does the peripheral nervous system consist of?
Nerves and ganglia
What is ganglia?
Small concentrations of gray matter
Overall, what is the nervous system like?
Network of gray matter regions interconnected with white matter tracts
What does the peripheral nervous system consist of?
- somatic nervous system
- autonomic nervous system
What is the somatic nervous system made up of?
Neurons connecting the central nervous system with parts of the body that interact with the outside world
What is the somatic nervous system?
It is associated with voluntary control of body movements via skeletal muscles
What is the somatic nerves in the cervical region related to?
Neck and arms
What does the somatic nerves in the thoracic region serve?
Chest
What does the somatic nerves in the lumbar and sacral region interact with?
Legs
What is autonomic nervous system made up of?
Neurons connecting the CNS and internal organs
What does the sympathetic nervous system do?
Mobilises energy and resources during times of stress and arousal
What does parasympathetic nervous system do?
Conserves energy and resources during relaxed state, including sleep
How are messages carried throughout the nervous system?
Through neurons
What is a neuron?
A specialised cell designed to transmit information to other nerve cells, muscle or gland cells
What does each neuron consist of?
Cell body, dendrites and axon
What does the cell body contain?
Nucleus and cytoplasm
What are axons like?
They extend from cell body and give rise to many smaller branches before ending at nerve terminals
What are dendrites like?
They extend from the neuron cell body and receive messages from other neurons
What are synapses?
Contact points where one neuron communicates with another
What are dendrites covered with?
Synapses formed by ends of axons from other neurons
What happen when neurons receive or send messages?
They transmit electrical impulses along their axons
What are many axons covered with?
Myelin sheath
What does myelin sheath do?
Accelerate the transmission of electrical signals along the axon
What is the myelin sheath made of?
Specialised cell called gila
What are gila that make sheath called?
Oligodendrocytes and in the peripheral nervous system, Schwann cells
What is the number of gila compared to neurons?
The brain contains ten times more gila than neurons
What is the function of gila?
Transport nutrients to neurons, clean up brain debris, digest parts of dead neurons and help hold neurons in place
What do nerve impulses involve?
The opening and closing of ion channels
What are ion channels?
They are selectively permeable, water-filled molecular tunnels that pass through the cell membrane and allow ions to enter or leave the cell
What does the flow of ions in ion channel result in?
It creates an electrical current that produce tiny voltage changes across the neuron’s cell membrane
What does the ability of a neuron to generate an electrical impulse depend on?
The difference in charge between the inside and outside of the cell
What happens when a nerve impulse begins?
There will be a dramatic reversal in the electrical potential that occurs on the cell’s membrane as the neuron switches from an internal negative to a positive charge state
What is the dramatic reversal in electrical potential that occurs on the cell membrane called?
Action potential
How can neurons fire impulses very rapidly?
The action potential potential passes along the axon’s membrane at speeds up to several hundred miles per hour which allows neuron to fire impulses multiple times every second
What happens when the voltage change reaches the end of an axon?
It triggers the release of neurotransmitterd
How are neurotransmitters released?
Neurotransmitters are released at nerve terminals, diffuse across the synapse and bind to receptors on the surface of target cell
What are target cells?
Often another neuron or possibly a muscle or gland cell
What does each receptor on a target cell have?
A distinctively shaped region that selectively recognises a particular chemical messenger
How does the neurotransmitter fit into the specially shaped region in each receptor of the target cell?
In like a lock and key system
What happens when a neurotransmitter is in place in region in receptor?
The interaction alters the target cell’s membrane potential and triggers a response from the target cell
What are the potential responses of a target cell when a neurotransmitter is in place?
- generation of action potential
- contraction of muscle
- stimulation of enzyme activity
- inhibition of neurotransmitter release
What is the first neurotransmitter identified?
Acetylcholine (ACh)
Acetylcholine is released by what kinds of neurons?
- neurons connected to voluntary muscles, causing them to contract
- neurons that control the heartbeat
How is ACh synthesized in axon terminals?
When action potential arrives at nerve terminals, electrically charged calcium ions rush in and ACh is released into the synapse where it attaches to ACh receptors on the target cell, ACh is then broken down by enzyme acetykcholinesterase and resynthesized in the nerve terminal
What happens when ACh attach to receptor in voluntary muscles?
It opens up sodium channels and cause muscles to contract
What is myasthenia gravis?
A disease characterised by fatigue and muscle weakness
What causes myasthenia gravis?
Antibodies that block one type of ACh receptor
What are the main drugs used to treat Alzheimer’s disease?
Drugs that inhibit acetylcholinesterase and increase ACh in the brain
What are amino acids?
Building blocks of proteins
What can certain amino acids serve as?
Neurotransmitters in the brain
Which amino acids serve as neurotransmitters in the brain?
Glycine and gamma-aminobutyric acid (GABA)
What do glycine and GABA do
Inhibit the firing of neurons
What is the activity of GABA increased by?
Benzodiazepines and anticonvulsant drugs
