The Nervous System Flashcards
Define Nerves
The body’s wiring, sending and receiving electrical impulses from all parts of the body. A network allowing communication, coordination and interaction of body tissues and systems and between the body and external environment.
What is the order of the Central Nervous System?
- Central Nervous system (CNS)
- Peripheral Nervous System (PNS)
2A. Sensory nerves
2B. Effector Nerves
Bi. Somatic
Bii. Autonomic
From autonomic is the sympathetic and Parasympathetic
What is the characteristics of a Neuron?
Soma (cell body)- which contains the nucleus Dendrites Axon Myelin Axon Terminal
What is the join between the nerves called?
Synapse
What is the central nervous system made of?
Brain and Spinal cord. Made of >100 billion neurons.
Why do neurons normally look grey?
From lack of Myelin
What are the main parts of the brain called?
Cerebrum, cerebellum, diencephalon and brain stem
What is the cerebral cortex?
The outer region is the conscious brain.
What is the Cerebrum sectioned into?
4 outer lobes and 1 inner lobe
What are the specialised neurons called?
Reticular formation
What is the role of the brain stem in conduction?
All information from body to brain and vice versa travel via brain stem.
Define Sensory pathways
From the body, they are ascending pathways that relay pain, temperature, touch, etc.
Define Motor Pathways
Pathways descending to the body.
What is the integrative functions undertaken by the brain stem?
Involved in cardiovascular system control, respiratory control, pain sensitivity control, alertness, awareness and consciousness.
Where is the spinal cord located?
Within the spinal vertebrae
How does the spinal cord create the PNS?
It branches out between each vertebrae
What is grey matter?
Unmyelinated axons
What is white matter?
Myelin sheath wrapped around axon of neuron
How many pairs of nerves are there in the Peripheral Nervous system?
43 pairs
12 cranial pairs
31 spinal pairs
What is the Somatic Nervous System?
Voluntarily controlled movements
What is the Autonomic Nervous System?
involuntary movements, e.g. heart rate, blood pressure etc.
Define Sympathetic
Fight or flight response, Speeds up heart rate etc.
Define Parasypathetic
Slows down heart rate etc, rest and recovery
Define Motor unit
A single motor neuron and all the muscle fibres it innervates.
Why are fine motor movements harder for large muscles?
They usually have one motor movement to hundred of muscle fibres. When one contracts, they all contract.
Why are fine motor movements easier for small muscles?
Fine motor control is easier for smaller muscles as one motor neuron can be responsible for innervating just a few muscles fibres.
Why are neurons called excitable tissue?
They convert stimuli to electrical signal.
Which side are cell membranes on neurons more negative when are rest?
the inside
What is the potential difference between the sides called?
Resting membrane potential
What is the membrane said to be?
Polarised
How is this difference created?
A difference in concentration of potassium ions and sodium ions, inside and outside.
What is the sequence of the imbalance maintained during Resting Membrane Potential?
- Cell membranes are more permeable to potassium ion than sodium ions.
- Sodium- Potassium actively pumps two potassium ions in for every three sodium ions pumped out.
Therefore more positively charged ions outside.
What is Action Potentials?
Opening membrane channels that allow positively charged ions through can occur in small regions. When a segment of an axon’s sodium ion gates are open, it cannot respond to another stimulus until the gradient imbalance is restored causing the signal to travel only one way.
What does the synapse connect?
Neuron to neuron
What does the motor end plate connect?
Neuron to muscle fibre, Neuromuscular junctions.
What is before the synapse?
Presynaptic terminal
What does the presynaptic terminal contain?
Vesicles filled with neurotransmitter
How is the action potential transferred across the synapse?
The vesicles release the neurotransmitter across the synaptic cleft. These molecules bind and activate receptors on the post synaptic membrane triggering depolarisation.
Define Neuromuscular junction
Depolarisation enters sarcomere via t tubule membranes
What is the sequence of Contraction action?
When the signal reaches inside the myofilaments, the electrical charge causes the sarcoplasmic reticulum to release large quantities of stored calcium ions into sarcoplasm.
The Calcium attaches to troponin which wraps the actin molecule. This causes tropmyosin to move, revealing binding sites for the cross bridges to attach.
Define reflex reactions
Actions that happen without conscious control that stem from the inhibitory neuron in the spinal cord.
