Test 3 Review Powerpoint Flashcards
Isotonic contraction
agonist contracts, antagonist releases basis of movement
pulling up, like with a weight weight
isometric contraction
agonist/antagonist contract across joint, stabilizing joint
no movement
structure of skeletal muscle
axons from CNS innervate muscle fibers
actin in sarcomeres
alpha motor neuron
innervates extrafusal muscle fibers
contraction
motor unit
alpha motor neuron and all muscle fibers it innervates
innervation ration
number of muscle fibers innervated by a motor unit
higher is less fine control
lower is more fine control (1:1)
Lower motor neurons (LMN)
-Ventral horn
-Motor neurons that innervate SKELETAL muscle
directly command muscle contraction
-Ventral horn size differs along length of spine, # of motor neurons differ by how many muscles innervated (arms vs stomach)
-
CNS Control of Contraction
Increasing firing rate of alpha
motor neurons
Recruiting more alpha motor neurons from motor neuron pool
Fast motor units
rapidly fatiguing white fibers
low mitochondrial content
slow motor units
slowly fatiguing
red muscle
high mitochondrial content
Excitation of Muscle
-Alpha motor neuron fires AP
-Ach released from alpha motor neuron at NMJ
-Nicotinic channels open
-Na+ rushes through sarcolemma, causing type of EPSP called EPP (end plate potential)
-one EPP depolarizes sarcolemma enough to cause AP
-AP sweeps down sarcolemma through T tubules
-Voltage gated Ca2+ channels in T tubules open
-Ca 2+ spills out of sarcoplasmic reticulum
Releases calcium all over, amplified, bigger response
Contraction of muscle
- Ca2+ binds troponin
- Myosin-binding sites on actin exposed
- Myosin head binds to actin
- Myosin heads rotate
- Myosin heads use ATP to disengage
- Cycle continues as long as Ca2+ and ATP are present
Sarcomere
basic contracting unit of muscle
Relaxation of muscle
-As EPP (end plate potential)s end, sarcolemma and T tubules return to resting membrane potential
-Ca2+ returns to sarcoplasmic reticulum via ATP-driven pumps
-Myosin-binding sites on actin are covered by troponin
Fast process because we can contract fast
Reflexive movement
- controlled by spinal cord and brainstem circuitry
- cannot improve with practice
- initiated by sensory stimulation
Voluntary movement
- controlled by cerebral corex
- can be improved with practice
- initiated by thoughts
Gamma motor neuron
- innervate intrafusal muscle fibers
- adjust tension in muscle spindle
- extrafusal muscle fibers to shorten
- if spinals are slack, can’t report length of muscle so GMN contracts poles of spindle to align and gage stretch
- contraction of two poles pulls on equatorial region, keeping 1a axons active
Myotatic reflex
- stretch reflex
- muscle spindle stretched –> mechanosensitive ion channels, depolarize, 1a afferent activated –> increased AP –> alpha motor neuron activated –> muscle contracts
- monosynaptic arch: one synapse separates primary input from motor output
- muscle length info
golgi tendon organ
- sensor in skeletal muscle, monitors muscle tension/force of contraction
- 1b axons
- muscle tension info
reverse myotatic reflex
- muscle tension increases
- 1b axons synapse on interneurons in ventral horn
- interneurons are inhibitory, protects muscle from being overloaded
- for example, if muscle tension increaes and almost snaps, inhibits motor neurons so that muscle neurons stop contracting
1a
muscle length info
1b
muscle tension info
corticospinal tract
- LATERAL PATHWAY (voluntary movement)
- voluntary movement in humans
- if cut, lose muscle control, rubrospinal can take over and help rebuild general control but lose fine muscle
rubrospinal tract
LATERAL PATHWAY (voluntary movement) important in non primates
tectospinal tract
VENTROMEDIAL (involun movement of proximal and axial muscles)
-orienting response, esp with eyes
vestibulospinal tract
VENTROMEDIAL (invol move of proximal and axial muscles)
-stability of head and back area to keep head
Pontine reticulospinal tract
VENTROMEDIAL (invol movement of prox and axial muscles)
enhances antigravity reflexes
balance
Medullary reticulospinal
VENTROMEDIAL (invol movement of prox and axial muscles)
liberates antigravity muscles
balance
motor area 6: what projects heavily into it?
basal ganglia and cerebellum
motor area 6: where does it project heavily?
area 4
roland’s tapping experiment
motor areas of brain
- M1=simple movement
- SMA + M1 complex movement
- SMA thinking about complex movement
premotor area
planning movement
function of motor cortex
M1 neurons code for force and direction of movement
Force
frequency of action potentials
direction
population coding of action potentials
Basal ganglia
willed movement
parts of basal ganglia
caudate nucleus putamen globus pallidus subthalamic nucleus substantia nigra
caudate nucleus
motor processes learning processes (associative, etc) executive functioning
globus pallidus
movement
pacemaker
putamen
regulate movements
learning
subthalamic nucleus
action selection
substantia nigra
rewards, eye movement, motor planning, addiction
Parkinson’s disease
- degradation of neurons in substantia nigra
- depleletion of dopamine, prevents normal motor activity to basal ganglia
- bradykinesia: slowness in movement
- difficulty initiating willed movements
- increased muscle tone and rigidness
- tremors of hand and jaw
process behind parkinson’s (chem)
- depletion of dopamine
- closes funnel that goes through Ventral Lateral Nucleus to SMA (cortex)
- DA inhibits neurons that send inhibitory output
- over excitation in subthalamic nucleus, can’t fire
treatments of parkinson’s
- L-DOPA treatment: activates neuron in putamen, replaces lost DA in striatum
- DBS: stimulates subthalamic nucleus, less excitatory on global pallidus, less inhibition on VL, more excitatory on SMA
Huntington’s disease
- loss of neurons in caudate, putamen, and globus pallidas
- hereditary, progressive, fatal
- hyperkinesia and dskenesia: abnormal movements
- dementia; cognitive, personality
- autosomal dominant
- *chorea: spontaneous, uncontrollable, purposeless movements
- losing inhibitory input, opening funnel to SMA
Cerebellum
- sequence/timing of muscle contractions
- planned, voluntary movement
- multi joint movement
- M1 through VL
Cerebellar disease
DIDAD
- dysmetria: loss of coordination
- Dysdiadochokinesia: inmpaired ability for rapid alternative movements
- Ataxia: loss of full control of body movements
- Intention tremor
hyperreflexia
motor cortex lesions
increased reflexes
hypertonia
motor cortex lesions
increased muscle tone
babinsky reflex
motor cortex lesion (if exists after 12 months
upward flexion of big toe
clonus
motor cortex lesion
rhythmic cycles of contraction and relation after stretch of limb muscle
point to point communication
most neurons
Glu, GABA, peptide NTs
secretory hypothalamus communication
going to various neurons
ANS: sympathetic, parasympathetic
through blood system
diffuse modulary communication
diffuse like secretory
going to various neurons
but doesnt go through blood system
lateral and medial hypothalamus
functions to control homeostasis
periventricular hypothalamus
- functions in circadian rhythms and endocrine system
- superchiasmatic nucleus
- circadian rhythm
- endocrine system
- pituitary
- more innervated with blod vessels: secretory hypothalamus communication
hypothalamic magnocellular cells
- posterior pituitary
- true neural tissue
- oxytocin, vasoprecin (love hormone for prairie voles, in humans, kidneys for water concentration
hypothalmic parvocellular cells
- anterior pituitary
- true gland
- endocrine system
- hormones for puberty: growth, follical stimulating, glutenizing, prolactin (testes, gonads)
- certain mass (obese people=earlier) –> glutenizing –> testosterone and estrogen
sympathetic nervous system
fight or flight
increases heartrate, blood pressure, eyes dilate, rapid breathing
parasympathetic nervous system
calm
rest and digest
digestion, lowers heartrate, lowers blood pressure, return to normal breathing
outputs of CNS from somatic motor fibers
to skeletal muscle
outputs of CNS from ANS (sympathetic and parasymp systems)
to smooth muscle, cardiac muscle, gland cells
sequence of events ins tress response
Amygdala feels stress, increases reaction, signals to hypothalamus
Release corticaltropin
Goes to anterior pituitary (highly innervated with blood vessels)
ACTH has to be released into blood to get to adrenal glands
Cortisal
increased cardiovascular tone in chronic stress
hypertension, atherosclerosis
mobilization of energy in chronic stress
fatigue, diabetes, obesity
suppression of digestion in chronic stress
ulcers
suppression of growth in chronic stress
decrease growth + muscle mass, dwarfism
suppression of reproduction in chronic stress
decreased libido, no ovulation
suppression of immune system in chronic stress
infections
sharpening of cognition in chronic stress
memory impairment
stimulants
- cocaine, amphetamines, etc block NE and DA receptors
- if you take too quickly, NE causes increased heartrate and die
- addiction
ADHD
- DAT transporter works in reverse, increases DA in cleft
- symptoms: inattention, hyperactivity, impulsivity
- knockdown DAT transporters in mice –> hyperactive
- knockout DAT transporters in mice –> extremely hyperactive
Ecstasy (MDMA)
- higher affinity for SERT than 5HT itself
- reverses SERT activity
- long term=loss of serotonin axons
- depression, anxiety, disturbed sleep, substance abuse disorders, mood
sexual differentiation
mullarian ducts (f) preset for humankind TDF mullarian ducts dev into oviducts wolffian ducts into vas deferens
male sexual dev
XY chromosomes TDF testes AMH means no mullarian ducts, instead wollfian (seminal vesicles, prostate glands, etc) male brain, and male external genitalia
female sexual dev
no tdf, ovaries, no AMH, mullarian ducts (inner vagina, uterus, fallopian tubes), outer genitalia, female brain
gonadal intersexuality
- “true hermaphroditism”
- gonads have both ovarian and testicular tissue
- majority are infertile
- external genitalia variable
- female structure usually predominate
- most identify as women
turner’s syndrome
- XO female
- neck webbing
- short, barrel chest
- no ovaries
- no gonadal hormones
- infertile
- no testosterone
- problems with visual/spatial/mathematical tasks
kleinfelter’s syndrome
- XXY male
- intersexuality
- “pseudo hermaphroditism”
- tall, small testes, gynecomastia
- feminine body contours
- low testosterone leves
- language skills impaired
Complete AIS (androgen insensitivity syndrome)
- XY male
- intersexuality
- “pseudo hermaphroditism”
- normal prenatal testosterone levels
- mutation in androgen receptor
- shallow vagina, undescended testes
- no male or female internal genitalia
- taller than most females
- caused by absent or non functional androgen receptors
Partial AIS
XY Male
Mutation in androgen receptor
Semenya olympics
Congenital Adrenal Hyperplasia (CAH)
- XX Female
- intersexuality
- “pseudo hermaphroditism”
- defect in production of enzyme cortisol
- hyperplasia of adrenal cortex
- increased cortisol precursor steroids that get converted to androgens
- masculinize female genitalia
- behaviorally masculinized, likely to be sexually attracted to women
- if untreated, infertility
Second wave of hormones
- puberty
- hypothalamus: GnRH (gonadotrpin-releasing hormone)
- activates anterior pituitary (LH and FSH)
- Females: ovaries, estrogen, breasts
- Males: testes, teststerone, male genitalia
Estrodiol
estrogen
monthly on period
increase in synthetic spines in hippocampus
to choose mate, increased cognition
right hemisphere 2% larger
straight men
lesbians
hemispheres are nearly same size
straight women
gay men
sexually dimorphic nucleus (SDN)
inah 3 INH 3 in humans
sexual orientation
women have more widespread of cells, diffuse
Dimorphisms
- ) differences in density, size of cells, # of axons and synapses (amygdala, symmetry of hemispheres, cerebral cortex etc)
- ) microscopic/molecular differences (size and number of nerve cells, synapses, brain circuits, hormone receptors, neurotransmitters)
Male cognition
- navigate with compass direction
- mental rotation
- judgment of line orientation
- more aggressive, competitive
female cognition
- navigate with landmarks
- verbal fluency
- reading facial expression
- memory of object location
same sex attraction
- early play patterns predict sexuality
- women exposed to high androgens more likely to be gay
- prenatal hormones, so conversion therapy doesn’t work
otoacoustic emissions
- men roughly equal
- straight women have most
- bi and gay women less than straight
Glascow coma scale
content: cerebral cortex
VS
arousal (RAS): brainstem modulatory systems
EEG
measures voltages generated by excitation of many neurons in cerebral cortex
depends on
1. number of neurons
2. synchronous activity
Synchronous activity of neurons
pacemaker (thalamus)
high freq
high amplitude
sleep
seizure activity
runaway excitation of brain circuitry
-> pathologically synchronous activity (high freq high amp)
very synchronous
-upset in balance of synaptic excitation and inhibition
treatment for seizures
-GABA agonist
promote inhibition mediated by GABA
-in seizures, sodium channels try to stay open for longer, more sodium enter, hyperexcitable
–> block Na+ channels
Stage 1 of sleep
- transitional sleep (eyes make slow rolling movements, drowsy)
- lightest
- only few minutes
Stage 2 of sleep
- EEG is irregular, short bursts
- sleep spindles diminish brain’s sensitivity to sensory stimuli (thalamic pacemaker)
- k complex keeps person asleep
stage 3 of sleep
- 20-25% delta waves
- delta wave
- high amplitude, low freq
stage 4 of sleep
- increase in delta waves
- deepst stage of sleep
- changes most during life
- decreases with age, ending after 60 years
REM sleep
- sympathetic system
- no muscle tone, paralyzed body
- beta rhythms
- brain incredibly active (dreaming is random activation of circuits that are easily accessible)
- newborn has mostly REM, decreases with age
- paradoxical sleep (waking EEG, but not easily aroused)
Bottlenose dolphin
- microsleeps
- sleeping with one brain hemisphere
Neurotrans in response to sleep (increase or decrease in firing rate?)
Increase: NE, 5-HT, Ach
decrease: dopamine
sleep in brain processing, memory, creativity
- novel solutions to complex problems
- 3x creativity
- synaptic connections are linked and strengthened
Hypocretin
dog falling asleep
arousal
mutation in receptor, narcolepsy, blocked
