NS Bio 29/30 Flashcards
CNS
brain and spinal cord
PNS
Located outside the CNS, consists of cranial nerves, spinal nerves, and associated ganglia
SNS and ANS
Cranial nerves connect
brain to organs mainly in the upper body (12pairs)
Spinal nerves
connect spinal cord to parts of the body below the head. 31 pairs of spinal nerves.
SNS
Voluntary, carries impulses to skeletal muscles, tendons, and skin
ANS
Involuntary, impulses are transmitted to cardiac muscle, smooth muscle, or glands.
Sympathic, Parasympathetic, and Enteric
Sensory neurons (afferent)
Information from the internal and external environment and transmits them to the CNS.
Motor Neuron (efferent)
relays signals from the brain and spinal cord to muscle or glands cells.
Ganglion
Mass of neuron cell bodies usually found outside the CNS
Neuron
Includes cell body, axon, dendrites. 100 billion +, no mitosis, very poor regen.
Nissl bodies
Rough E.R. in neurons.
Astrocytes
Contain glycogen, star shaped cells, most numerous glial cell. Regulating electrical impulses, provide lactate for nutrition, K+ transport channels, regulate blood flow.
Glial cells
Surround nerons and provide support/protection. Most abundant cells in CNS. E.g. Astrocytes, oligodendrocytes, Schwann cells, microglia, satellite cells, and ependymal cells.
Axon
Extension of neuron that carries nerve impulses away. No neuron has more than a singal axon.
Dendrite/ Soma
Highly branched extensions that bring nerve impulses towards the cell.
Mitochondria in the NS
Most abundant at the axon terminals.
Oligodendrocytes
Make myelin in the CNS
Schwann Cells
Make myelin in the PNS
Blood brain barrier
High density cells that prevent the passage of substances such pathogens, antibiotics, and chemicals.
Multiple Sclerosis
Auto immune. Break down of the BBB of the CNS. T Lymph attach myelin sheath.
Epilepsy
BBB failure that leads to seizures.
Sympathetic NS
Flight or fight
Inc HR, BP, respiration, skeletal muscle blood flow, pupil dilation, stims adernal medulla (epi and norepi),
and glycogenolysis.
Dec intestinal and stomach movements, salivary gland secretion, urine production, and relaxes urinary bladder.
Parasympathetic NS
Rest and digest
Dec HR, BP, blood flow to skeletal muscles, pupil constriction.
Stims intestinal and stomach movements, salivary gland secretions, increase urine production, tenses urginary bladder.
Enteric Nervous System
Entire length of the alimentary tract - esophagus to anus. Controls the secretory and motile functions of our digestive tract.
Makes over 30 nt, 90% of serotonin is made the gastrointestinal tract and a large amount of dopamine too.
Myelin Sheath
Some axons are surrounded by a fatty substance forming an electrically insulating layer. Contains cholesterol, lipids, and about 20% proteins.
CNS and PNS myeline
Gray matter vs White matter
CNS: oligodendrocytes
PNS: Schwann cells
Grey matter: unmyelinated axons
White matter: Myelinated axons.
Nodes of Ranvier
Gaps between adjacent schwann cells. At these nodes, the axolemma is especially permeable to Na+ and K+. Only present when axon is myelinated.
Na+ ion movement to depolarize. Voltage gated sodium ion channels.
Saltatory conduction
Action potentials can hymp between the nodes of R.
In MS the sheath is degraded and saltatory conduction can not occur.
Cerebrum
Largest part of the mature brain (80%).
Cerebral cortex
Outer covering of grey matter. Gray matter contains cell bodies, glial cells, dendrites, and unmyelinated portions axons. Underneath the gray matter lies the myelinated white matter.
Corpus callosum
White matter tract, largest white matter structure in the brain.
Meninges are three membrane brain and spinal cord
Dura mater: outer layer, many nerves and blood vessels, tough and fibrous
Arachnoid mater: middle layer, no blood vessels, thin and delicate
Pia mater: innermost layer, very vascular and intimately attached to brain and spinal cord.
Between the arachnoid and pia mater
Is the subarachnoid space that contains the cerebral spinal fluid.
Each brain hemisphere controls the opposite side of the body.
If a brain tumor is located on the left side of your brain, the right arm or leg could become weak or paralyzed.
The cerebellum
Involved with balance and muscle coordination.
Fine movement, equilibrium, posture, and motor learning.
Basal ganglia which includes the caudate nucleus, putamen, and globus pallidus work with the cerebellum.
Hypothalamus
Link between endocrine and NS. Part of the limbic system, dealing with emotion, motivation, behavior.
ADH, oxytocin, fluid balance, BP, temp, homeostasis, emotions, sex drive, thirst, digestive juices.
Limbic system
Hypothalamus, amygdala, hippocampus (long term memory), and thalamus. Emotions and memory.
Medulla Oblongata
Regs breathing, HR, swallowing, pH detection, and digestion
The Agnathans are jawless fish
They include hagfish and the lampreys which possess fully developed medulla. This part of the brain was very early to evolve.
Thalamus
Relay station. Relays sensory information to proper areas of the brain.
Tay Sachs
We see neurons destroyed in the brain and spinal cord. Autosomal recessive disease in which a defect in a lysosomal enzyme is seen. Elevated ganglioside (lipid).
Choroid plexus
Network of cells that produce CSF in the ventricles of the brain. Plexus consist of ependymal cells.
Microglia
Phagocytic cells located in the CNS. 5% of glial cells.
Stroke
Cut off blood flow to an area of the brain, deprivation of O2. Trouble speaking, numbness of arm, leg, or face, visual problems, headaches, trouble walking.
TIA/ Transient ischemic attack
Mini stroke. When a clot of debris blocked the flow of blood to your brain
Synapse
Junction where one neuron communicates with another neuron.
Presynpatic cell
Stores nt such as Ach in vesicles. Cane be muscle, neuron, or even a gland.
Postsynaptic cell
Cell that has the receptors that bind to the specific nt.
Resting membrane potential is -70mV
Negatively charged with respect to the interstitial fluid on the outside.
[K+] inside > [Na+] inside
[Na+] outside > [K+]inside
Resting voltage potential
More K+ is on the inside, while more Na+ outside.
3Na+ out; 2 K+ in. Excess + charge outside the cell.
Negatively charge molecules such as proteins are more abundant inside the neurons. Cl- also reside more on the interior.
Action Potential
All or none. Voltage gated Na+ channels which bring the potential to a positive value. -70mV to 40mV = depolarization.
Voltage gate channels
Transmembrane proteins. They are usualy ion specific.
Na+, K+, Ca2+, Cl-.
The size of the action potential does not depend on the strength of the stimulus.
Minimum threshold for mammalian neurons
-55mV
Hundreds of action potentials can occur each second.
The greater the stimulus, the more action potentials can be generated.
Speed is constant along the axon
If you increase the stim, you generate more action potentials but the speed and amplitude of the A.P. will not change.
The signal is conducted from the axon of the _____ cell to the ______ of the postsynaptic cell.
Presynatpic cell, dendrite.
The message is unidirectional.
Refractory period types
Absolute: No stimulus, no matter how strong can elicit another A.P.
Relative: A very strong stimulus would elicit an A.P.
The larger the diameter of an axon…
the faster the impulse can move along the axon.
Neurotransmitters example
Ach, Dopamine, Serotonin, Norepinephrine, GABA< Glycine
Acetylcholine
Many functions including learning and memory enhancement
Dopamine
Many functions including keeping focused and paying attention; pleasure
Serotonin
Depression can result from deficiency
Norepinephrine
Involved with mental alertness and memory
GABA
Body’s inhibitory nt, keeps you calm without anxiety. Alcohol is thought to mimic the effect of GABA in the brain.
Glycine
Works with GABA to dec anxiety among other functions.
Norepinephrine
Both a hormone and a neurotransmitter
PNS uses mainly
Acetylcholine as it’s nt. SNS uses both epinephrine and norepinephrine.
Dopamine is a catecholamine
Mainly a neurotransmitter.
Endorphins
Natural body analgesics. Also neuropeptides. Besides dec perception to pain, they produce a euphoric or happy feeling.
Neuropeptides
Used by nerve cells for communication. Can bind to cell surface receptors.
Cnidaria
Include hydra and sea anemone which contain a loose mesh of nerve cells called a nerve net. Interacts with sensory and contractile cells.
Arthropods
Small but intricate NS. Possess a brain and ventral nerve cord. Some have larger diameter axons than in humans.
Flatworms/ Planaria
Nerve net, long nerve cords connected to cerebral ganglia. Bilateral nervous system.
Echinoderms
Sea star, sea urchins, cucumbers, and sand dollars.
No brains but nerve running from mouth to arm/body.
Radial symmetry and CaCO3 shell.
Sponges
Only multicelled animal that lacks a NS. No nerve or sensory cells. Hermaphrodites
Reflex
Automatic, unconscious responses
Reflex arc
Receptor, sensory neuron, reflex center, motor neuron, effector.
Spinal cord
Gray matter: Neurons, shape of a butterfly
White: Axons, containing spinal tracts, sensory and motor.
Spinal cord roots
Dorsal root: transmits sensory information.
Ventral root: Motor root and carries info towards the limbs and organs.
Dorsal
Ventral
Sensory, Afferent
Motor, Efferent
If potassium, K+, channels open, K+ would diffuse outward.
Hyperpolarization is often caused by
1) K+ move out
2) Cl - move in
Hyperpolarization acts to
Inhibit action potentials. After peak of A.P., a hyperpolarization repolarized the membrane potential to its resting value.
Stim -> ______-> _____-> Hyperpolarization
Depolarization, Repolarization
EPSP
Excitatory Postsynaptic Potential. Increase in permeability of the postsynaptic membrane for Na+.
IPSP
Inhibitory postsynaptic potential. Increase in permeability of for K+ and Cl-.
Temporal Summation
Involves single synapse, one after another ESPS
Spatial Summation
Multiple synapses, ESPS occur at the same time
Axon hillock
Intergrating center if the sum allows for an A.P.
