The Nervous System Flashcards
How heavy is the brain?
1.5kg
What does the nervous system consist of?
Brain, spinal cord and peripheral nerves
What are the types of cells in the brain?
Neurons and glial cells
What are the three main types of neurons?
- Sensory neurons
- Motor neurons
- Interneurons
What do sensory neurons do?
They are connected to receptors specialised to detect and respond to different attributes of the internal and external environment
What do motor neurons do?
They control the activity of muscles and are responsible for all forms of behaviour including speech
What type of neuron exist in the greatest quantity?
Interneurons
Where are interneurons?
Situated between the sensory and motor neurons
What do interneurons do?
Mediate simple reflexes and responsible for highest functions of brain
What do glial cells do?
Support neurons
What do neurons consist of?
- Cell body
2. Processes: axons & dendrites
What do axons do?
Transmit information from neuron on to others
What do dendrites do?
Receive information being transmitted by axons of other neurons
What is something both processes (axons and dendrites) do?
Participate in specialised contacts called synapses
How are neurons organised?
They are organised in complex chains and network that are pathways where information in nervous system is transmitted
How are brain and spinal cord connected to sensory receptors and muscles?
Through long axons that make up peripheral neerves
What are the functions of spinal cord?
- Simple and complex reflexes
2. Forms a highway between body and brain for information to travel in both directions
What distinguishes human brain with others?
- large size of human brains in relation to body size
- enormous increase in number of interneurons over course of evolution, making humans have a wide choice of reactions to environment
What do the brain consist of ?
Brain stem and cerebral hemispheres
What are the three parts of brain stem?
- hind-brain
- diencephalon
- mid-brain
What is hind-brain?
Extension of spinal cord
What do hind-brain consist of?
Contains networks of neurons that constitute centres of control of vital functions like breathing and blood pressure
What do cerebellum do?
Control and timing of movements
What do midbrain contain?
Groups of neurons that use predominantly a particular type of chemical messenger but all project up to cerebral hemispheres
What do midbrain do?
Regulate the activity of neurons in higher centres of brain to mediate functions like vision, hearing, motor control, sleep and wake cycles, attention
What are the two areas in diencephalon?
Thalamus and hypothalamus
What do the thalamus do?
Relay impulses from all sensory systems to cerebral cortex which in turn send messages back to the thalamus
What does the hypothalamus?
Control functions such as eating and drinking and regulate release of hormones in sexual functions
What does cerebral hemisphere consist of?
- basal ganglia (core)
- cerebral cortex
What role does the basal ganglia play?
Central role in initiation and control of movement
What is cerebral cortex?
Outer layer of brain
What do the cerebral cortex do that enable it to house a large number of neurons?
It has folds that weave in and out to enable a large surface area for sheets of neurons
What is the most highly developed area of the brain in humans?
Cortical tissue
What part of the brain in human is 4 times bigger than in gorillas?
Cortical tissue
How is movement controlled by the cortex?
Pathways from sensory receptors to the cortex and from cortex to muscles cross over from one side to another, this movements of the right side of the body are controlled by left side of cortex and vice versa
How are the left and right cerebral cortex connected?
They are connected by a large fibre tract called corpus callosum
What do the cerebral cortex required for?
Voluntary actions, language, speech and higher functions like thinking and remembering
Which part is required for speech?
Left hemisphere for most people
