Nerves Flashcards
4 types of tissue in the human body
Nervous, epithelial, connective, muscle
Overall function of the nervous system
Communication, regulates internal events, memory, external behaviour, sensations, perceptions, emotions
Function of organs of the nervous system
receive and process internal/external information, and send signals to initiate a response. Organs include brain, spinal cord, receptors of sensory organs.
2 main divisions of the nervous system
CNS (brain and spinal cord) and PNS (all other nervous tissue outside the CNS and ENS)
2 functional systems within PNS
Somatic and autonomic / visceral NS
Function of CNS
Integrates, processes and coordinates sensory input and motor commands
Function of somatic nervous system
Regulates voluntary control over skeletal muscle
Function of autonomic NS (ANS)
Controls automatic activities like heart rate and breathing
Divisions of ANS
Parasympathetic and sympathetic divisions
Function of sympathetic NS (division of ANS)
Can act on smooth muscle, cardiac muscle, glands and adipose tissue when immediate action is required during the fight or flight response. Can increase the rate of functions.
Function of parasympathetic NS (division of ANS)
Rest and digest - regulates less urgent processes such as digestion, waste disposal, production of bodily fluids etc by control of smooth muscle, cardiac muscle and glands. Regulates the baseline rate of processes.
2 types of cells in the nervous system
neurones which are embedded in a mass of (neuro)glial cells
Function of neurones / nerve cells
They are the functional unit of NS which are specialised for intercellular communication
Function of glial / neuroglial cells
Support, protect, provide nutrients and immune function to neurones.
Which part of the PNS carries sensory information to the CNS
Afferent division
Which part of the PNS carries motor commands from the CNS to effectors?
Efferent division
Why do neurons have a high metabolic rate?
High energy demand required to generate and propagate AP
Basic structural features of neurons
dendrites, large cell body, single axon, terminal boutons
What are dendrites?
Highly branched processes that extend away from the cell body. They receive information from synapses / receptors and convey it to the cell body.
Features of the neuron large cell body
Large and prominent nucleolus (ribosome synthesis), nissl bodies, numerous mitochondria.
What are nissl bodies?
Clusters of RER surrounded by free ribosomes. Located in cell body of neurons.
Why do neuron cell bodies have a granular appearance and stain darkly?
High density of nissl cell bodies and other organelles
What is grey matter?
Area in CNS where cell bodies of neurons are located
What is white matter?
Area in CNS where the myelinated axons are
What gives grey matter its distinctive colour?
High density of nissl bodies present in neuronal cell bodies.
Structure and function of axons
Long processes extending from the cell body that are specialised to rapidly propagate APs toward axon terminals.
Which neurons have myelinated axons?
All neurons in the CNS, Some neurons in PNS.
Where are terminal boutons located?
Foot of branches in the axon terminal
Function of terminal boutons
they are communication junctions that form synapses with other neurons / effector organs. Location where electrical signal is converted into a chemical signal in the form of a neurotransmitter.
Functional property of all neurons
Excitability
Why are neurons excitable cells?
Due to small difference in charge between inside and outside of cell which enables the generation of an AP
What are neuroglia?
Highly branched cells occupying space between neurons.
4 neuroglial cells found in the CNS
Ependymal cells, astrocytes, microglia, oligodendrocytes
2 Neuroglial cells found in the PNS
Schwann cells and satellite cells
What cell type are ependymal cells?
Simple ciliated cuboidal epithelium
Where are ependymal cells located?
Lining fluid-filled cavities in the brain (ventricles) and spinal cord
What feature do ependymal cells display in place of a basement membrane?
They taper into long processes that merge with the underlying tissue (astrocytes)
Function of ependymal cells
Move cerebrospinal fluid (CSF) and regulate its composition (using cilia and microvilli)