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neuromuscular junction –
- synapse between a motor neuron axon and a muscle fiber.
- in skeletal muscles all axons release acetylcholine to contract a muscle.
- receptors of acetylcholine are nicotinic.
- opposing sets of muscles.
- includes a flexor and extensor
- autoimmune disease where the immune system forms antibodies that attack the acetylcholine receptors at neuromuscular junctions.
- causes weakness and rapid fatigue of skeletal muscles.
fast contraction and rapid fatigue.
slow twitch fibers
less vigorous contractions and no fatigue.
use oxygen during their movements.
using reactions that don’t require oxygen at the time although they need O2 for recovery.
if a group in isolation, individuals develop a group rhythm, even if individuals had other rhythms before.
rely more strongly on these zeitgebers; if not, their effective circadian rhythms are longer than 24 hours
receptor that detects position or movement of a part of the body.
- caused by a stretch; does not produce one
- when a muscle is stretched the spinal cord sends a reflexive signal to contract it (to keep it from overstretching).
receptor parallel to the muscle that responds to a stretch.
golgi tendon organs
respond to increases in muscle tension.
- consistent automatic responses to stimuli
- insensitive to reinforcements, punishments, and motivations.
- restriction of pupil in bright light.
- executed as a whole: once initiated it cant be stopped
- reflexes are ballistic
central pattern generators
- neuroal mechanisms in the spinal cord that generate rhythmic patterns of motor output
- ex: wing flapping, wet dog shake
- fixed sequence of movements.
- ex: animal grooming, typing, piano playing.
- thinking or talking about it interferes with the action.
primary motor cortex
- elicits movements.
- does not send messages directly to muscles; goes to the brainstem and spinal cord first which generate the impulses that go to muscles.
posterior parietal cortex
keeps track of position of the body relative to the world.
- responds to lights, noises, and other signals for a movement and plans movements
- damage: many movements would seem illogical or disorganized
- ex: showering with clothes on.
active during preparations for a movement and less active during movement itself.
supplementary motor cortex
- planning and organizing a rapid sequence of movements in a particular order
- inhibition of a step in a habitual action when you need to do something else
- activated a second or two prior to a movement.
- active both during preparation for a movement and while watching someone else perform the same or a similar movement;
- cells in the insula become active when you see something disgusting.
- begins at least 500 ms before the person’s conscious decision.
- in a study, people report that their decision to move occurred about 200 ms before the movement.
paths from the cerebral cortex to the spinal cord.
lateral corticospinal tract
set of axons from the primary motor cortex, surrounding areas, and the red nucleus.
part of the midbrain responsible for controlling arm muscles.
medial corticospinal tract
axons frm many parts of the cerebral cortex not just primary cortex and surrounding areas.
receives input fro vestibular system.
- purkinje cells
- parallel fibers
- nuclei of the cerebellum
flat 2d cells in sequential plantes parallel to each other.
axons parallel to each other and perpendicular to the planes of the purkinje cells.
nuclei of the cerebellum
clusters of cell bodies in cerebellum
- group of large subcortical structures in the forebrain.
- caudate nucleus
- globus pallidus- damage = jerky movements
- input from cortex goes to caudate nucleus and putamen, output from caudate nucleus and putamen goes to globus pallidus
- from globus pallidas to thalamus and midbrain then to motor and prefrontal cortex.
- important in starting movements but not in movements guided.
- rigidity, muscle tremors, slow movements, difficulty initiating physical and mental activity.
- still intellectually intact just have trouble with movements.
- easier when movements are guided, stairs, a marathon.
- more common among farmers and those who’ve had exposure to herbicides and pesticides.
- people who smoke or drink coffee have less of a chance to develop it.
- precursor to dopamine
- does cross the BBB
- taken as a pill neurons convert it to dopamine, help initially with parkinson’s; does not help with advanced disease.
endogenous circannual rhythm
body clock that prepares for seasonal changes.
endogenous circadian rhythm
body clock that prepares for daily changes.
free running rhythm
rhythm that occurs when no stimuli reset or alter it.
- stimulus that resets the circadian rhythm.
- light is the dominant one for land animals.
- tides are important for marine animals
- exercise, noise, meals, temperature of envir.
disruption of circadian rhythms due to crossing time zones.
suprachiasmatic nucleus or SCN
- biological clock depends on it
- part of the hypothalamus
- naturally produced hormone
- influences both circadian and circannual rhythms.
- pineal gland secretes it mostly at night.
- able to reset biological clock.
endocrine gland located posterior to the thalamus.
- extended period of unconsciousness caused by head trauma, stroke, or disease.
- person cannot be woken up.
- little but steady brain activity.
- no response to stimuli
- typical coma lasts weeks resulting in either death or healing.
- person alternates between periods of sleep and moderate arousal
- breathing is more regular, painful stimulus produces autonomic responses of increased heart rate, breathing and sweating.
- can last for months or years.
- no sign of brain activity and no response to any stimulation.
- brain death after 24 hours of no activity.
minimally conscious state
- occasional brief periods of purposeful actions and a limited amount of speech comprehension.
- can last for months or years.
combination of EEG and eye movement records.
characteristic of relaxation, not all wakefulness
- waves during a burst that lasts at least half a second.
- oscillating interactions b/t cells in the thalamus and cortex.
sharp high amplitude wave most common in stage 2.
slow wave sleep
stages 3 and 4.
- REM sleep
- deep in some ways and light in others.
- associated with rapid eye movement.
- heart rate, BP, breathing rate more variable.
- neurons receive input from many sensory systems and generate spontaneous activity of their own.
- maintains arousal during wakefulness and increases it in response to new or challenging tasks.
- stimulation wakes someone who is sleeping.
- silent during sleep.
- anything that stimulates it strengthens the storage of recent memories.
orexin or hypocretin
- neurotransmitter released by hypothalamus
- not necessary for waking up but is for staying awake.
- drops when you sleep.
distinctive pattern of high amplitude electrical potentials.
- activity triggers onset of REM sleep.
- damage = muscles are not relaxed during REM sleep.
trouble falling asleep.
waking up and cant go back to sleep for a long time.
waking up earlier than needed.
impaired ability to breathe while sleeping
- attack of muscle weakness while person remains awake.
- e.g. collapsing
- sleep attacks
- sleep paralysis
- hypnagogic hallucinations – sensation of falling in bed.
- lack the hypothalamic cells that produce and release orexin.
REM behavior disorder
moving around vigorously during REM periods, acting out dreams possibly.
experiences of intense anxiety from which a person awakens screaming in terror.
enzyme necessary to digest lactose.
conditioned taste aversion
occurs reliably after just a single pairing of food with illness.
food an animal swallows leaks out through a tube.
cranial nerve X conveys info about stomach stretching.
convey info about nutrient contents of the stomach.
- CCK limits meal size in two ways
- closes the sphincter muscle between the stomach and the duodenum, and stimulates the vagus nerve to tell the hypothalamus to release a neurotransmitter rthats a shorter version of CCK.
- enables glucose to enter the cells except for brain cells
- when insulin is high cells receive glucose easily
- when insulin in low, cells need more to receive glucose.
stimulates the liver to convet some of its stored glycogen to glucose to replenish low supplies in the blood.
- limited to vertebrates
- the more fat cells the more leptin.
- signals the brain about the body’s fat reserves.
- in hypothalamus
- has a set of neurons sensitive to hunger signals
- has a set of neurons sensitive to satiety signals.
- receptors in the paraventricular nucleus important for limiting food intake
- deficiencies lead to overeating.
- hunger hormone
- decreases appetite
- enhances learning
- increases persistence in seeking food after prolonged food deprivation.
- responds to incentive or rewrd properties of a meal.
- controls insulin secretion and alters taste responsiveness.
- damage = trouble digesting food
damage =leads to overeating and weight gain
- Controls movement in hands, fingers, and toes.
- Damage means loss of fine motor movements.
activation synthesis hypothesis
a dream represents te brains effort to make sense of sparse and distorted info.
- Axons do not cross to contralateral side, controls bilateral movement of the neck, shoulder, and truck (movements with these are done with both sides always).
- Damage impairs walking, turning, bending, standing up and sitting down.
Pontomesencephalon (part of reticular formation)
Area maintains arousal in wide regions of forebrain (hypothalamus, thalamus, basal forebrain)
- Structure in the pons
- Activity interrupts REM sleep
Amylases (from salivary glands)
(from stomach, small intestine) for proteins (e.g. pepsin)
(from small intestine) for fat
master area that picks up on both hunger and satiety signals from the body. (e.g. CCK).
activity increases various behaviors related to feeding.
inhibits the lateral hypothalamus.
initiates and regulates satiety.