Nervous 2 Flashcards
Nerve Pathways: Pyramidal:
Pyramidal:
Lateral tract
AKA UPPER MOTOR NEURONS
Disorders Characterized by: babinski, hypertonic spasticity, clonus (test at ankle), hyperreflexia, loss of fine motor skills, muscle wasting
Impulses downward through the spinal cord. By means of direct routes and interconnecting neurons in the cord, these nerves eventually excite the alpha motor neurons that control/modulate the fine and gross properties of skeletal muscles during all purposeful movements.
Nerve Pathways: Extrapyramidal:
Extrapyramidal:
Ventromedial tract
AKA LOWER MOTOR NEURONS
Disorders Characterized by: Parkinsonism OR dyskinesias.
Neurons in this tract originate in the brainstem and connect at all levels of the spinal cord. They control posture and provide a continual background level of neuromuscular tone. (Involuntary movements- Balance/Posture)
Reflex Arc
Reflex Arc:
Stimulus
Peripheral receptor
Afferent sensory fiber
Interneuron in spinal cord
Efferent motor fiber
Effector
Afferent neurons enter the spinal cord through the dorsal root
Transmit sensory input from peripheral receptors
Interneurons relay info to different levels of the cord.
Impulses then pass over the motor (efferent) pathway to the effector organ
Dyskinesias
Extra-pyramidal disorder. Dyskinesias
Dyskinesias
patient may make twitching or rolling motions. She cannot control the movements and usually is incapable of sitting still
Tremor
Extra-pyramidal disorder. Dyskinesias
Tremor
Rest tremor occurs when the affected body part is completely supported against gravity.
Action tremors are produced by voluntary muscle contraction.
postural, isometric, kinetic tremors.
Chorea
Extra-pyramidal disorder. Dyskinesias
Chorea
Brief, irregular movements that are not repetitive or rhymic, but appear to flow from one muscle to the next
Myocolonus
Extra-pyramidal disorder. Dyskinesias
Myocolonus
Is continuous flow of involuntary irregular movement. The movements are rapid, jerky, non rhythmic and explosive that flit from portion of the body to another in random sequence.
Tics
Extra-pyramidal disorder. Dyskinesias
Tics
Repetitive, stereotyped, semipurposeful movement.
Patient could willingly suppress them at expense of mounting inner tension
Dystonia
Extra-pyramidal disorder. Dyskinesias
Dystonia
relate to involuntary and abnormal muscle tension that forces patients into awkward and sometimes painful twisted or bent positions.
Akinetic rigid syndrome
Parkinsons. Extra-pyramidal disorder.
The Babinski Sign
The normal response in an adult to stroking the sole of the foot is flexion of the big toe, and often the other toes. Following damage to descending upper motor neuron pathways, however, this stimulus elicits extension of the big toe and a fanning of the other toes.
What is Clonus and how to test it?
oscillatory motor response to muscle stretching
Positive when stretching calf with (via hand on foot) and foot starts shaking in response
Motor unit:
Motor pool:
Motor unit: made of 1 alpha motor neuron + muscle fibers
Motor pool: all alpha motor neurons projecting to a given muscle
Size Principle:
Type 1 fiber
Type 2 fiber
Size Principle: Start small. AKA fast-twitch is recruited last.
Type 1 fiber = slow twitch = endurance, aka red muscles.
Type 2 fiber = fast twitch = power, aka white muscles.
What is the basic functional unit of a muscle fiber?
Sarcomere
Myocyte
Myofibril
Sarcomere
A myocyte is a muscle fiber
A myofibril is a bundle of sarcomeres
Muscle spindles
Outside: Extrafusal fibers
Inside: Intrafusal fibers
Nuclear bag (like a bag in the center)
Nuclear chain (along the fiber like chains)
Innervated by gamma-motor neurons, which change the spindle’s length.
Around intrafusal fibers
Primary spindle afferents (1a):
Secondary spindle afferents (2):
Around intrafusal fibers
Primary spindle afferents (1a): annulospiral, dynamic changes in length (tapping and vibration)
Secondary spindle afferents (2): flower-spray, static changes in length (posture)
Stretching of the intrafusals:
2 ways
Activating gamma motor neurons, shortening ends, stretching center.
Passively lengthening or shortening of intrafusal fibers
Muscle contraction process
- Excitatory Post Synaptic Potential (EPSP) reaches muscle fibril and AP propagates.
- Sarcolemma release Ca++
- Ca++ binding to TROPONIN exposes binding site.
- Muscle contraction first begins with cross-bridging of actin and myosin.
- ATP is currently bound to myosin
- Release of ATP (ADP and Pi) => POWER STROKE
- New ATP joining = BREAKING CROSS BRIDGE
- Hydrolyzing the ATP => myosin bends again into “cocked”
The first step in the process of a muscle contraction is for Ca++ to bind to _______ so that _________ can slide away from the binding sites on the actin strands.
Troponin, tropomyosin
During the cross-bridge cycle, when is myosin in a high-energy configuration?
Before the power stroke
After the power stroke
Before the power stroke.
This energy is expended as the myosin head moves through the power stroke, and at the end of the power stroke, the myosin head is in a low-energy position. After the power stroke, ADP is released; however, the formed cross-bridge is still in place, and actin and myosin are bound together. As long as ATP is available, it readily attaches to myosin, the cross-bridge cycle can recur, and muscle contraction can continue
Muscle Soreness caused by:
- Minute tears in muscle tissue
- Osmotic pressure changes causing edema around muscle.
- Muscle spasms
- Overstretching/tearing of muscle harness
- Acute inflammation (the later part of working out)
- Alteration in calcium regulation
Notable: lactic acid only causes initial soreness in working out. (30 mins after)
A person runs a 10K and is sore several days afterwards. Is lactic acid the culprit?
No! The soreness is caused by microtears in the muscle tissue and possibly inflammation
Labeled Line Principle
nerve fibers only transmit a single modality of sensation (i.e. crushing and burning both cause pain)
Chemoreceptor examples and where they get their potential from
Taste
Smell
O2 (aortic and carotids)
Osmolality of fluids (supraoptic nuclei)
CO2 (medulla, aortic, carotids)
BG, AAs, Fatty Acids (hypothalamus)
Nocireceptors sense what
Nocireceptors:
Physical damage and pain
Chemical damage and pain
Electromagnetic Receptors are what?
Electromagnetic: Cones & Rods (Cones = Color)
Receptor potentials:
Receptor potentials:
Mechanical deformation (stretch, chemical, temperature, light)
The more stimulus a receptor gets, the less the potential amplitude changes.
Aka high sensitivity but its hard to max it out.
Adaptation:
Adaptation:
Receptor initially responds at a high impulse rate first, then slower, then less or not at all
If you adapt fast, it means a constant stimulus won’t keep triggering potentials. (I.e. if you brush a hair and keep touching it, you stop feeling it)
Tonic Receptors
Tonic Receptors
Continually transmits
Keeps brain aware constantly
Examples:
Muscle spindles
GTOs
Pain receptors
Chemoreceptors
Baroreceptors
Rate/Phasic Receptors
Rate/Phasic Receptors
Transmits only when there is a CHANGE in stimulus
Only when the “rate” changes/”Reactive” receptor
Reacts strongly to change
Examples:
Pacinian corpuscle
Stops transmitting if you keep pressing.
WILL SEND NEW SIGNAL WHEN PRESSURE IS RELEASED.
Nerve Fiber Classifications
A contains:
Key ones to know within type A fibers:
Primary/annulospiral & GTO =
Secondary/flower spray =
Motor spindle =
Pricking pain =
A Contains alpha, beta, gamma, and delta fibers.
Primary/annulospiral & GTO = Aα
Secondary/flower spray = Aβ
Motor spindle = Aγ
Pricking pain = Aδ
Nerve Fiber Classifications
Key ones to know within type C fibers:
ACHING
COLD & WARMTH
CRUDE TOUCH/PRESSURE
Signal Pathways
Divergence
Splitting up a single signal
When it occurs: Lots of fibers to excite leaving the pool.
Signal Pathways
Convergence
Multiple inputs into a single neuron.
Summation
Signal Pathways
Reciprocal
When one inhibits, the other contracts
Common in muscles
The Process of Hearing
- Sound causes Tympanic Membrane to move.
- Malleus, Incus, Stapes conducts sound to the oval window.
- Vibrations enter at oval window, specifically the scala vestibuli and make fluid move along.
- Higher frequency = a wave with more oscillation
- Hair cells get moved by the vibrations
- Nerve fibers get stimulated by hair cells
7 .Nerve fibers depolarize the cochlear nerve.
3 semicircular canals control equilibrium.
Utricle:
Saccule:
Ampulla:
Sterocilia:
3 semicircular canals control equilibrium.
Utricle: horizontal in an upright position.
Saccule: vertical in a lying down position.
Ampulla: rotational movement
Sterocilia: Found on hair cells, detects acceleration and deceleration
Main 2 PREvertebral ganglia:
Sympathetic or Parasympathetic?
Main 2 PREvertebral ganglia:
Celiac (stomach to anus)
Hypogastric (Bladder)
Sympathetic
Sympathetic Anatomy
Origin of sympathetic nerve fibers:
Origin of sympathetic nerve fibers: T1 to L2.
Sympathetic Anatomy
Order of preganglionic neurons:
Start in the
- Start in the LATERAL HORN.
- Anterior root
- Spinal nerve
- EXITS VIA WHITE RAMUS
- Sympathetic chain
A. SYNAPSE AT THE SAME LEVEL
B. GO UP/DOWN
C. GO DIRECTLY
4 Cranial Nerves are parasympathetic:
4 Cranial Nerves are parasympathetic:
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X (vagus) - 75% of all nerve fibers
Origin of parasympathetic nerve fibers:
Origin of parasympathetic nerve fibers:
Cranial nerves - III Cranial, VII Facial, IX glossopharyngeal, X Vagus
AND S2 & S3. (IMPORTANT)
Unique: Most preganglionic parasympathetic go where?
Unique: Most preganglionic parasympathetic go STRAIGHT TO THEIR ORGAN.
Postganglionic parasympathetic neurons are in where?
Postganglionic parasympathetic neurons are IN THE WALLS OF THIER ORGANS
Sympathetic
All preganglionic =
Most postganglionic sympathetic neurons are_____
Except for________
All preganglionic = cholinergic
Excite postganglionic
Most postganglionic sympathetic neurons are adrenergic
Except cholinergic for
Sweat glands
Piloerector muscles of hairs
Very few blood vessels
Parasympathetic
All preganglionic =
All postganglionic =
All preganglionic = cholinergic
Excite postganglionic
All postganglionic = cholinergic
Adrenergic Receptors (Alpha and Beta)
Alpha: Alpha1 and Alpha2
Beta: beta1, beta2, beta3
Norepinephrine from nerve fiber
Norepinephrine and epinephrine from adrenal gland
The effects of these depend on the receptors in the organs
If they are all beta receptors, epinephrine will be the more effective excitant.
Receptor types
Acetylcholine activates 2 types
Nicotinic
Muscarinic
Nicotinic
Found in the autonomic ganglia at the synapse between Preg. and Postg of both Symp. and Paras
Muscarinic
Muscarine = poison from toad stools
Found on all effector cells that are stimulated by the postg. cholinergic neurons of either para or symp.
.
Receptor types
Sympathetic
Adrenergic
Sympathetic
Adrenergic
α1
Peripheral vasculature smooth muscle
α2
Spinal cord
Acts to regulate sympathetic input from CNS to
PNS
β1
Cardiac and smooth muscle
β2
Bronchial tree, visceral organs
Receptor types
Parasympathetic
Cholinoreceptors
Nicotinic
Ganglions
Skeletal muscle
Muscarinic
Located on target visceral organs
DUMBBELS
Defacation
Urination
Miosis
Bradycardia
Bronchospasm
Emesis
Lacrimation
Salivation
Sympathetic Stimulation:
Albuterol inhalers provide immediate relief of acute asthma symptoms by binding to the _______ receptors on the smooth muscles of the bronchioles, causing them to dilate. Symptom relief lasts up to 3 to 4 hours.
Alpha 1
Alpha 2
Beta 1
Beta 2
Beta 2
