Exam 2 Flashcards
Organs of CNS
Brain and Spinal Cord
Organs of PNS
Cranial Nerves, Spinal Nerves, Ganglia, Enteric Plexuses, Sensory Receptors, Motor Receptors
Sensory Neurons
Detect stimuli; convey info to CNS
Association/ Integration Neurons
Integration of sensory info and decision making
Motor Neurons
Motor output; carry info from CNS to effectors and organs
Reflex Arcs
Rapid autonomic responses
Types of reflex arcs
Somatic - stim. skeletal muscle
Autonomic/ Enteric - stim. smooth & cardiac muscle, endocrine and exocrine glands, adipose tissue
Types of nervous tissue
Neurons and neuroglia
Neurons
Circuitry connecting all regions of body to nervous system
Neuroglia
Support, nourish, and protect neurons
Which type of nervous tissue continues to divide mitoticaly?
Neuroglia
Which tissues possess electrical excitability?
Neurons and muscle tissue
Membrane potentials
Electrical signals that travel along cell membrane
Types of membrane potentials:
Graded potentials and action potentials
Graded potentials:
Short distance and variable voltage (diminishes with distance)
Action potentials:
Long distance and constant voltage
3 main parts of neuron
Dendrites, cell body, and axon
Synapse
Site of communication between neurons and other cells/glands
Types of Synaptic Cells:
- Between two neurons
- Neuromuscular synapse
- Neuroglandular synapse
Neurotransmitters
Chemical messengers passing between chemical synapses - excitatory or inhibitory
Structural classifications of neurons
- Multipolar - cell body in CNS
- Bipolar - areas of special senses
- Unipolar - cell podies in ganglia of PNS, right outside spinal cord
Types of Multipolar Neurons
Purkinje (cerebellum) and Pyramidal (cerebral cortex) cells
Electrical synapse
Gap junctions between cells; ion channels made of connexons. In smooth muscle and cardiac muscle.
Chemical synapse
Synaptic cleft between cells; chemical messenger passes through.
Differences between electrical and chemical synapses
Electrical is faster and two-way communication; Chemical is one-way communication; Chemical uses neurotransmitters.
Na+ and Ca+ influx cause:
Depolarization; AP generated
K- and Cl- influx cause:
Polerization; AP not generated
Spatial Summation
Sum of AP from multiple synapses of presynaptic neurons
Temporal Summation
Sum of AP from single synapse/location, but many times in succession
Types of Glia in CNS
- Astrocytes
- Microglia
- Oligodendrocytes
- Ependymal Cells
Types of Glia in PNS
- Schwann Cells
2. Satellite Cells
Astrocytes Functions
Branching provides strength, maintain permeability (BBB), secrete chemical in embryo affecting development, aid nerve impulses, role in learning/memory.
Oligodendrocytes
Myelin sheath of the CNS
Microglia
Phagocytes in the CNS; remove debris, microbes, and damaged tissue
Ependymal Cells
Line ventricles of brain and spinal cord; produce CSF and create blood-CSF barrier
Schwann Cells
Myelin sheath of PNS and axon regeneration
Satellite Cells
Surround cell bodies of neurons in PNS ganglia (unipolar cells)
Saltatory Conduction
Nerve impulse “jumps” node to node; faster and more efficient
Continuous Conduction
NO MYELIN SHEATH - entire axon continuously depolarized; less efficient and slower
4 Neural Circuits
- Diverging
- Converging
- Reverberating
- Parallel
Plasticity
Capability to change, grow, and repair; Sprouting, new proteins, and changes to synaptic contacts
Sprouting
Growth of new dendrites to make new connections
Neurogenesis
Growth of new neurons from stem cells – Only in hippocampus of humans
