Lecture 1 Flashcards
Organs
CNS=
PNS= (2 types)
CNS=Brain & Spinal Cord
PNS=Nerves
-cranial nerves and branches
-spinal nerves and branches
Stroma-
Parenchyma-
Stroma - Support tissue in organs (glia, blood vessels, CT)
Parenchyma - Functional tissue in organs (neurons)
What are tissue cells within organs?
- Neurons (parenchyma)
2. Glia (stroma)
Directional Terms for Brain: Rostral- Caudal- Ventral- Dorsal-
Rostral - anterior
Caudal - posterior
Ventral - inferior
Dorsal - superior
Dendrites and Soma: Afferent/Efferent? Mechanical or chemical stimuli? What ion channels? Graded potential (small or large?)
- Receive afferent mechanical and chemical input/stimuli
- Open mechanical (sensor/receptor) and chemical (neurotransmitter) gated Na+ and K+ ion channels on dendrite and soma to generate a depolarizing change in membrane electrical potential (graded potential)
- Small but proportional to intensity of initial mechanical/chemical stimuli
Axon Hillock:
Where/What is it?
How do grade potentials reach?
All or nothing -
- Region at base of axon connected to soma
- Trigger zone for AP
- Graded potentials from dendrite/soma will reach axon if they sum to threshold = -55mV
- Voltage gated sodium and potassium channels open to generate AP which is all or nothing
- All or nothing: always same intensity over entire distance of neuron
Axon:
What is it?
Afferent/efferent?
- Carries AP
- Efferent output to axon terminals
Axon terminals:
How many per axon?
Does AP travel to all terminals?
What occurs once AP reaches terminal?
- Generally many axon terminals associated with a single axon due to collateral and terminal branching
- Single AP generated by axon hillock reaches all axon terminals
- Voltage gated Ca2- channels open (Ca2- travels into presynaptic neuron) to trigger the release of neurotransmitter
Synapse:
Describe the parts
What do the NT do here?
- Intercellular junction between axon terminal (pre-synaptic membrane) and target cell membrane (post synaptic membrane - usually dendrite/some of next neuron in communication chain)
- NT opens chemical gated channels on post synaptic membrane to generate a depolarization
Axonal Transport:
Fast Anterograde -
(nonstop microtubule transports-)
Kinesin or Dynein?
Fast anterograde - Moves proteins associated with vesicle (peptide NT, enzymes, and membrane proteins) from golgi apparatus in soma to synaptic terminals
- Nonstop microtubule transport = fast transport
- Kinesin
Axonal Transport:
Slow Anterograde -
(stop and go microtubule transports = )
Slow Anterograde = axioplasmic flow
- Moves soluble (non membrane bound/associated) cytoskeletal, proteins from soma to axon terminals
- Stop and go microtubule transport = slow transport
Axonal Transport:
Fast retrograde
(nonstop microtubule transport = )
Kinesin or Dynein?
Fast retrograde
- Moves endocytosis vesivles (recycle membrane, chemical messengers, pathogens) from axon terminals to soma
- Nonstop microtubule transport = but slower than fast anterograde
- Dynein
Axon structural variation leads to variation in signal conduction velocity:
- What two variations?
- Classifications -
Variations:
1. Fiber diameter
2. Thickness of myelin
Classifications:
1. Conduction velocity - type A, B, C from fastest to slowest
2. Fiber diameter - Type I, II, III, IV from biggest to smallest
*Look at chart
Direction of signal transmission starting with Dendrite ->
Dendrite -> soma -> axon hillock -> axon -> axon terminal
3 Types of Neurons function:
1. Sensory
Describe
Name 3 types
- Sensory - axons in peripheral nerves carry afferent signals from sensor/receptors to CNS (brain/spinal cord)
- Special
- Viscero
- Somato
1st Type Sensory Neurons
Special Sensory=
Special Sensory=
- Vision: retina to CN 2
- Auditory: Spiral organ corti to CN 8
- Equilibrium: macula (static) and crista ampullaris (dynamic) to CN 8
- Olfaction: olfactory epithelium to CN 1
- Gustatory: taste buds to CN 7, 9, and 10
2nd Type Sensory Neurons
Viscerosensory =
Single neuron from interoreceptors (unconscious) to subcortical CNS
Ex: diffuse temp
3rd Type Sensory Neurons
Somatosensory =
Single neuron from skin, muscle, and joint (conscious) receptors to cortex
ex: Temp, pain, touch
3 Types of Neurons:
2. Motor
Describe
Name 2 types
- Motor - axons in peripheral nerves carry efferent signals to effectors (muscles and glands)
- Somatomotor - single neuron from CNS to skeletal muscle (voluntary)
- Autonomic motor - 2 neuron pathway from CNS to smooth muscles, cardiac muscle, or glands (involuntary) - Sympathetic - activates fight or flight (lateral horn at T1-L2)
- Parasympathetic - activates rest and digest (lateral horn S2, 3, 4
Types of neurons structural: (name where there are usually found)
Multipolar -
Bipolar -
Pseudo-unipolar -
Multipolar - soma with single axon and multiple dendrites (common in CNS)
Bipolar - soma with a single axon and a single dendrite stalk (common in special sensory organs)
Pseudo - unipolar - single axon with a proximal (efferent) and distal branch (afferent) (found in sensory neurons of dorsal root ganglion)
Types of synapses (3):
Name them and describe
- Axosomatic - axon with soma
- Axodendritic - axon with dendrites
- Axoaxonal - axon with axon
(will modulate effect of NT - their bonding or amount)
Neuron Loops:
Describe pathway
-Negative feedback loop (reflex loops)
Sensor/receptor -> sensory neuron -> control center (brain/spinal cord) -> motor neuron -> effector (muscle/gland)
Neuron Circuits (4): 1. Diverging
Diverging - allows amplification of mass activation of many targets
-Can be in same or to multiple pathways
Neuron Circuits (4): 2. Converging
Converging - increase stimulation or inhibition of postsynpatic neuron (stronger signal with stronger output)
-can be from multiple sources or from single source with many axon terminals