Exam 2 Quiz 2 Flashcards
1
Q
Define the peripheral nervous system and list its components
A
-all neural structures outside of the brain and spinal cord
-sensory receptors
-peripheral nerves and associated ganglai
-motor endings (i.e. axon terminal, motor end pate)
-ganglia are a collection of cell bodies in the PNS
2
Q
How are receptors classified
A
-stimulus type
-location
-structural complexity
3
Q
classifications of receptors by stimulus type
A
Mechanoreceptors- light touch, pressure, vibration, stretch and itch (these adapt readily)
Thermoreceptors- changes in temperature
Photoreceptors- light energy (e.g. retina)
Chemoreceptors- chemicals (e.g. smell, taste, changes in blood chemistry)
Nociceptors- pain causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals)
-receptors differ in there locations intensity of stimulus required to generate an impulse of adaptability
4
Q
How do you classify receptors by location
A
-the two classifications are somatic and special
somatic: multiple locations in the body
-pressure temperature, pain touch, body position and movement
-primary somatosensory cortex(post central gyrus)
Special: only in certain areas of the body
-taste, smell hearing, balance, vision
-perception processing in specific cortical regions
5
Q
what is the difference between sensation and perception
A
-sensation: awareness of changes in internal and external environment
Perception: conscious interpretation of those stimulus (applying meaning)
6
Q
list the three basic levels of neural integration in sensory systems
A
- receptor level: sensory receptors (transduction: this is converting to electrical stimulus –> graded potentials)
*graded potentials are the nervous system translation of stimulus
- circuit level: processing in ascending pathways (transmission–> APs)
*transmission is the propagation of action potential across axon
- perceptual level: processing in cortical sensory area
7
Q
How does the central nervous system interpret information based on origin and frequency
A
-the action potentials are transmitted to specific brain regions
-visual stimuli travel via sensory neurons directly to brain areas associated with vision
-all information traveling through these neurons are interpreted as light
-stronger stimuli activate more receptors and trigger greater frequency of impulses in sensory neurons
-activation of a sensory pathway at any point gives rise to the same sensation that would be produced by stimulation of receptors in the body part itself
-acuity is influences b the receptive field size
-each sensory neuron responds to stimulus info only within a circumscribed region of the body surrounding it (receptive field)
-the size of the field varies with density of receptors in region; the more closely receptors are spaced, the smaller the area of the body each monitors
-the smaller the receptive field, the greater its acuity or discriminative ability
8
Q
Define sensory adaptation, what is the advantage of this and which receptors adapt slowly and which ones quickly
A
-sensory neuron stops sending impulses even tough stimulus is still present
advantage: keep track of changes in stimuli while ignoring unimportant stimuli
-certain receptors (olfaction, light touch) adapt quickly while others (pain, joint and muscle) adapt slowly or not at all
-the ones that don’t adapt are pain receptors and thermoreceptors
9
Q
Name the components of a reflex arc
A
-reflexes occur over neural pathways called reflex arcs that have five essential components- receptor, sensory neuron, CNS integration center, motor neuron and effector
10
Q
Describe what each component of the reflex arc does
A
- receptors are the site of stimulus action
- Sensory neurons transmit afferent impulses to the CNS
- integration Center: if it is a simple reflex arc, the n the integration center will be a single synapse in the middle of a sensory neuron and a motor neuron. in more complex reflex arcs, multiple synapses with chains of interneurons are involved
- motor neurons: conducts efferent impulses form the integration enter to an effector organ
- Effector: muscle fiber or gland cell that responds to the efferent impulses (by contracting or secreting)
11
Q
What are inborn (intrinsic) reflexes
A
a rapid, involuntary, predictable motor response to a stimulus
12
Q
learned (acquired) reflex
A
A reflex that results from practice or repetition (like driving)
13
Q
What does the knee jerk reflex test
A
the somatic reflexes is important clinically to assess condition of the NS
14
Q
Compare and contrast stretch & tendon reflexes (hint proprioception)
A
-they both help the nervous system smoothly coordinate the activity of your skeletal muscles
-in order to be able to coordinate the activity of the skeletal muscles the length of the muscle must be known and the tension of the muscle and the associated tendons
-proprioception (where the body is in space) is essential for smooth, coordinated movements
15
Q
what is in charge of detecting the length of the muscles
A
the muscle spindles
16
Q
what is in charge of the tension in the muscle and tendons
A
the golgi tendon organs
17
Q
what is the role of mechanoreceptors and reflexes
A
the mechanoreceptors in skeletal muscle, tendon and joints respond to changes in muscle length, tendon tension and joint position (proprioceptors)
18
Q
Describe the stretch reflex
A
-maintain muscle tone in large postural muscles
-cause muscle contraction in response to increased muscle length (stretch)
-all stretch reflexes are monosynaptic and ipsilateral
19
Q
What nervous systems are involved in conscious control of skeletal muscles
A
-the afferent and somatic efferent nervous systems
-they are also involved in the involuntary mechanisms to control muscles
-most somatic reflexes help us maintain balance/ posture and avoid injury
20
Q
What are the 3 types of muscle tissue?
A
skeletal, cardiac, smooth
21
Q
describe skeletal muscle tissue (what is it attached to, its shape, what it looks like etc)
A
-it is attached to bones and skin
-striated (myofibrils)
-voluntary (conscious control)
-powerful
-single, very long cylindrical, multinucleate cells with obvious striations
22
Q
cardiac muscle tissue
A
-the walls of the heart
-shows uninucleate or bi nucleate striations
-involuntary
23
Q
smooth muscle tissue
A
-Involuntary
-single unit muscle in the walls of hollow visceral organs (other than the heart) multiunit muscle in intrinsic eye muscle, air ways, large arteries
-single fusiform, uninucleate and no striations
24
Q
List four important functions of muscle tissue.
A
-produce movement of bones or fluid (blood)
-maintain posture and body position
-stabilize joints
-generate heat(skeletal muscle)
25
what are the special characteristics of muscle tissue
-excitability: (responsiveness or irritability): receive and respond to stimuli
-contractility: shorten when stimulated
-extensibility: stretch
-elasticity: recoil to resting length
-they can transform chemical energy (ATP into directed mechanical energy (this makes them capable of exerting force)
26
How many arteries, nerves and veins is each skeletal muscle served by
-one artery
-one nerve (with multiple neurons)
-one or more veins
27
why does skeletal muscle have such a rich blood supply
-they need a rich blood supply because they need oxygen and nutrients o produce ATP for contraction
28
how are skeletal muscle fibers organized
-striated by a highly organized internal arrangement
29
what is a skeletal muscle cell
muscle fiber
30
how is a skeletal muscle organized and how long are the fibers
-many parallel muscle fibers bundles by connective tissues
-fibers usually extend entire length of muscle
31
embryonic development
-formed by fusion of many smaller cells called myoblasts
myo=muscle
blasts= primitive cell that forms more specialized cell)
32
Why does it make sense that another feature of skeletal muscle is the abundance of mitochondria
-ATP is needed for muscle contraction (chemical energy--> mechanical energy)
33
what are Myofibrils
-Densely packed, rodlike elements
- 80% of cell volume
-Exhibit striations
-contains myofilaments creating dark A band and light I band
34
Describe the functional role of myofibrils
to produce muscle contraction and relaxation
35
Describe the microscopic structure and the functional role of the sarcoplasmic reticulum, and T tubules of skeletal muscle fibers
-both regulate muscle contraction
-The Sarcoplasmic reticulum regulates intracellular levels of ionic calcium. It stores calcium and releases it on demand when the muscle fiber is stimulated to contract
-Most Sarcoplasmic reticulum tubules run longitudinally along the myofibril
-T tubules increase the muscles fiber surface area
-T tubules also encircle each sarcomere
-Think of the T tubules as a rapid communication or messaging system that ensures that every myofibril in the muscle fiber contracts at virtually the same time
36
Describe the sliding filament model of muscle contraction
-when relaxed: slight overlapping of actin and myosin
-When the nervous system stimulates muscle fibers, the myosin heads on the thick filaments latch onto myosin-binding sites on actin in the thin filaments, propelling actin toward M line
-sarcomeres, muscle cells and whole muscle shortens
-the H zone disappears and the I band shortens
37
Define motor unit
A motor unit consists of one motor neuron and all the muscle fibers it innervates, or supplies
38
Describe the difference between eccentric and concentric contractions
Concentric Contractions: muscle shortens and does work, such as picking up a book or kicking a ball (think of coming together)
Eccentric Contractions: muscle generates force as it lengthens, are equally important for coordination and purposeful movements
-Eccentric contractions occur in your anterior thigh muscles
39
Name the cranial nerves that are involved with the special senses
CN I: Olfactory Nerve (smell)
CN II: Optic Nerve (vision)
CN VII: Facial Nerve (taste)
CNVIII: Vestibulocochlear Nerve (hearing and balance)
CN IX: Glossopharyngeal (taste)
CN X: Vagus ( taste)
40
Describe the location and structure of taste receptors
-taste depends on chemoreceptors found on the tongue
-taste bud: cluster of 25 taste cells and 25 supporting cells
about 10,000 taste buds
-found mostly on papillae of the tongue
-taste hairs contain chemoreceptors specific for certain chemicals of tastants
-most taste receptors are located along outer of tongue with few receptors in the center of the tongue
41
What do taste buds convert chemical signals from food and drink to
-taste buds convert chemical signals from food or drink dissolved in saliva into Action Potentials
42
what are the five qualities of taste that taste receptors and sensory neurons respond to
-sweet
-sour
-salty
-bitter
umami (savory)
43
Describe the gustatory pathway
-tastant bind to chemoreceptors causing to depolarization and NT release that stimulates...
-Cranial Nerves VII, IX and X carry impulses from taste buds to medulla
-then it goes to the thalamus
-gustatory cortex in the insula
-hypothalamus and limbic system appreciation and hippocampus (memories)
44
relationship between taste and other senses and receptors
-taste is combined with signals from multiple taste receptors allow us to differentiate between hundreds of flavors
-taste is 80% smell
-chewing food releases chemicals from the food that contact olfactory receptors
-thermoreceptors, mechanoreceptors, nociceptors in mouth also influences taste
-temp and texture enhance or detract from taste
45
Describe the location and structure of smell receptors (also how many olfactory chemoreceptors are for different odorants)
-there are olfactory chemoreceptors for more than 1,000 different odorants
-olfactory hairs project into the olfactory epithelium covering inner surface of nostrils
46
Pathway for smell
odorants dissolve in mucus and bind to chemoreceptors on olfactory hairs
-olfactory receptor cells then generate an impulse
-olfactory receptor cells synapse with olfactory neurons in olfactory bulb where the information is partially integrated before being passed to olfactory areas in frontal and temporal lobes
- around 10,000 different smells can be sensed
47
What makes smell different from the other senses?
-messages from the olfactory nerves go directly to the limbic system, without entering the thalamus first
48
Compare and contrast the roles of rods and cones in vision
rods: dim light, shades of grey, peripheral vision receptors
-rods are more sensitive to light than cones but do not provide clear outlines of objects
Cones: bright light, color images and sharp outlines
-remember colorful cones
49
Describe the relationship of cones and wavelength
-blue, red and green cones are named for the wavelength of light that they absorb best
-all other colors come from activation of more than one type of cone at the same time
50
color blindness
-is more common in men
-it is due to a lack of one or more cone cell
51
Photoreceptors (where are the located and what do they do)
-located in the eyes (the retina) and they receive visual information
-photoreception: eye detects visual stimuli by converting light energy to nerve impulses and transmitting them to the brain (this is the transduction for eyes)
52
Pathway of light through the eye
Light enters eye -> cornea -> aqueous humor -> pupil -> lens -> vitreous humor -> neural layer of retina
53
What is the iris
-Controls the diameter of the pupil and how much light enters
-dilates and constricts the pupil
Constrictor pupillae: constricts the pupil
Dilator Pupillae: dilatates the pupil
54
what are Golgi tendon reflexes
-polysynaptic reflexes
-help prevent damage due to excessive stretch/ force by relaxing the muscles
-important for smooth on sent and termination of muscle contraction (coordination of movements)
55
How do golgi tendon organs work?
-they produce muscle relaxation (lengthening) in response to tension
-contraction or passive stretch activities Golgi tendon organs
-afferent impulses transmitted to spinal cord
-contracting muscle relaxes and antagonist contracts (reciprocal activation)
-information transmitted simultaneously to cerebellum is used to adjust muscle tension
56
what detects the change in length/ stretch in a muscle
-muscle spindles
57
What are the 5 special senses?
taste, smell, hearing, balance, vision
58
Describe the general events that convert light into a neural signal (how does the retina convert light into the AP's)
-rods and cones synapse with bipolar cells partially process and integrate information
-bipolar cells synapse with ganglion cells
-action potential travel down ganglion cells axon and leave retina through the optic nerve
-the axon of the ganglion cells become the optic nerve
-at the optic chiasm about 1/2 of the fibers from each eye cross over contralateral side and continue via optic tracts
-signal is sent to thalamus and then primary visual cortex in occipital lobe of cerebrum
59
What is light adaptation?
Light adaption is when you go from darkness into bright light
-large amounts of pigments are broken down instantaneously producing a glare
-pupils constrict and limit the amount of ight that comes into the retina
-dramatic decrease in retinal sensitivity is caused bc the rod function ceases
-cones and neurons rapidly adapt because they are less sensitive
-visual acuity improves over 5-10 minutes
60
What is dark adaptation?
-opposite as light adaptation
-from bright light into darkness
-the reverse of light adaptation
-cones stop functioning in low-intensity light
-pupils dilate
-Rhodopsin (pigment protein in the rods): accumulated in the dark and retinal sensitivity increases within 20-30 minutes
61
sound waves, sound intensity, and loudness
-sounds are waves of compressed air
sound intensity- physical energy property of sound
loudness- subjective interpretation of sound
-both intensity and loudness are related to the amplitude of sound waves
-measured in decibels
62
list the basic parts of the ear
external ear: hearing and terminated at the eardrum
-funnels sound waves
middle ear: hearing, contains auditory ossicles (these are filled with air)
inner ear: hearing and balance; interconnecting fluid filled tunnels and chambers
63
pathway of hearing
Ear canal, tympanic membrane, ear bones, oval window, cochlear fluid/hair cells, brainstem (8th optic nerve)
-soundwaves travel through the ear activating vibration- sensitive mechanoreceptors (hair cells) deep within the ear
-the vibration causes the production of impulses that travel to brain for interpretation
64
Where are hair cells located?
in the cochlear duct
65
conduction deafness
-blocked sound conduction to fluids of internal ear
-caused by impacted earwax, perforated eardrum, or otosclerosis of the ossicles
-inhibits/ prevents the conduction of sound
66
sensorineural deafness
-damage to neural structures at any point from cochlear hair cells to auditory cortical cells
-this is why your ears ring when you come out of a concert (your hair cells are damaged)
67
what are the proprioceptors that we have covered
muscle spindles (stretch) and Golgi tendon organs (relaxes)
68
Define somatic nervous system
-lets you move your muscles voluntarily
subdivision of the motor efferent division of the peripheral nervous system
69
Define autonomic nervous system
second subdivision of the motor efferent division of the peripheral nervous system
-carries out automatic functions/ responses that it receives from the CNS (heart beating, digestion
-it has two subdivisions (parasympathetic and the sympathetic nervous system)
70
what interesting stuff does the ANS do
-supports somatic reactions: for example if we are running our heart rate increases to support metabolic demand
-mediates emotional states: for example when we get made our face gets red, or when you get embarrassed your face gets red
adjusts body states: when ur cold your peripheral vessels constricts
-muscles, organs and glands
71
describes the dual innervation of the ANS divisions
-almost all visceral organs served by both, with mostly opposite effects
-the only ones that aren't dually innervated are the adrenal glands and the skin
72
Describe the parasympathetic nervous system
-it is the first subdiv of the autonomic nervous system
-rest and digest
-promotes the maintenance activities and conserves body energy
73
give examples of body functions while the parasympathetic system is in control
-digestion
-constricted pupils (because the lens accommodates for close vision
-respiratory rates are low
-HR decreases/ Bp is low
74
Describe the things that the sympathetic nervous system does while it is in control
-mobilizes the body during activity
-fight or flight
-digestion stops
-dilated pupils
-HR and BP increases (this means that the bronchioles dilate)
-respiration rate increases(this means that the bronchioles dilate)
-blood flow is directed to the skeletal muscles and the heart
-liver releases glucose
75
How do the somatic and autonomic nervous systems differ?
-their effectors
-their efferent pathways
-target organ responses to neurotransmitters
76
what are effectors of the somatic nervous system
-the skeletal muscles (because they are voluntary)
77
what are the effectors of the autonomic nervous system
-the projections go virtually everywhere
-cardiac muscle
-smooth muscle(almost everywhere, found in blood vessels and viscera)
-glands
78
what is the efferent pathway of the of the somatic nervous system
-the CNS--> muscle
-one, thick, heavily myelinated somatic motor fiber
-uses saltatory conduction
79
what is the efferent pathway of the ANS
-ANS pathway is a two neuron chain
-preganglionic neuron (in the CNS) has a thing, lightly myelinated preganglionic axon (still uses saltatory conduction)
-postganglionic neuron in autonomic ganglion has an unmyelinated postganglionic axon that extends to the effect organ (uses continuous conduction)
80
What is a ganglion?
collection of neuron cell bodies in the PNS
81
Neurotransmitter and Effects of the somatic nervous system
-all somatic motor neurons release acetylcholine (ACh)
-effects are always stimulatory
82
Describe the process of neurotransmitters passing through the preganglionic and post ganglionic fibers and their effects (this is for the ANS)
Preganglionic fibers release ACh
Postganglionic fibers release norepinephrine or ACh at effectors (depends if the fibers are from the parasympathetic or sympathetic nervous system)
Effect is either stimulatory or inhibitory, depending on type of receptors
83
Describe the cholinergic fibers and receptors
-release or receive ACh, respectively
-associate with ACh always
84
Describe Adrenergic fibers and receptors
-release or receive norepinephrine respectively
-always associate with norepinephrine
-norepinephrine comes from adrenal medulla and epinephrine
85
Describe cholinergic receptors
-there are two types of receptors bind ACh
Nicotinic: ligand gated (ionotropic because it directly causes ion movement)
-the ligand is ACh
Muscarinic: metabolic receptor (G-proteins linked) second messenger system
-these are named after drugs that bind to them and mimic ACh effects
86
Describe Nicotinic Receptors
-they are found on the motor end plates of skeletal muscle cells (N1) in somatic NS
-all ganglion neurons (sympathetic and parasympathetic) (N2)
-hormone- producing cells of adrenal medulla
-effect of ACh at nicotinic receptors is always stimulatory/ excitatory
87
Describe Muscarinic Receptors (where are they found on and what effects does ACh have on them)
Found on: all effector cells stimulated by postganglionic cholinergic (release ACh) fibers
-postganglionic parasympathetic fibers (limited postganglionic SNS fibers- to skin and vessels)
in the parasympathetic branch both ganglions secrete ACh onto muscarinic receptors
-when ACh binds to them it can either be inhibitory or excitatory but it depends on the target organs receptor type
88
Describe the subdivisions so the Adrenergic Rectors
-there are two types
-Alpha 1 and 2
-Beta 1 and 2
-the effects of norepinephrine depends on subclass of receptors on target organ
-it can be excitatory or inhibitory
89
describe beta 1 adrenergic receptors
-always associate with the heart
-it also affects the kidneys and the adipose tissue
-increases the heart rate and strength, it also stimulates the renin release by the kidneys
90
describe beta 2 adrenergic receptors (think of relaxation)
-associate with the lungs and most other sympathetic target organs
-also affects the blood vessels serving the heart, liver and skeletal muscle
-effects are mostly inhibitory; it dilates blood vessels and bronchioles
-relaxes sooth muscle walls of digestive and urinary visceral organs
-also relaxes the uterus
91
Describe Alpha 1 adrenergic receptors
-found on blood vessels in the mucosa
-affects almost all of the sympathetic target organs except the heart
-excitatory response
-it constricts the blood vessels (vasoconstriction) and the visceral organ sphincters, dilates pupils of the eyes
92
describe alpha 2 adrenergic receptor
found on membrane of adrenergic axon terminals, the pancreas, and blood platelets
-inhibits NE release from adrenergic terminals
-inhibits insulin secretion by pancreas
-promotes blood clotting
93
Describe the effects of Atropine
-anticholinergic (blocks ACh receptors)
-blocks muscarinic receptors (postganglionic PNS)
-used to prevent salivation during surgery and to dilate the pupils for examination
94
describer the effects of over the counter drugs for colds, allergies and nasal congestion
-stimulates alpha 1 so it vasoconstricts to mucosae
95
Describe Beta Agonists and Beta Blockers
-agonists typically affect Beta 2--> they dilate the lung bronchioles in asthmatics
-beta blockers typically affect Beta 1--> causes heart rate to reduce, cardiac output and hypertensions (also arrythmias)
96
What are the exceptions to the SNS and PNS responses (also postganglionic neurons and the involvements of ACh and NE)
-SNS is not always excitatory and PSNS is not always inhibitory and SNS and PSNS do not always oppose each other
-you have to think about how their effects could help their body based on the scenario
-postganglionic neurons often have more than one receptor (nicotinic and muscarinic enhancing modulation
-multiple neurotransmitters possible (co transmission_ ACh or NE are not always involved
97
what are myofilaments
-they are arranged in the sarcomeres (thick myosin) filaments and thin (actin) filaments
98
What are sarcomeres and what are their features? (M Line, Thick and thin filaments, and H zone)
-smallest functional unit of muscle fiber
Thick filaments: length of A band
-Thin filaments: length of I band and partway into A band
-M line: line of protein myomesin that holds adjacent thick filaments together
-H zone: lighter mid region where filaments do not overlap
99
describe the ultrastructure of thick filaments
-each thick filament consists of many myosin molecules whose heads protrude at opposite ends of the filament
-has actin binding sites that bind to acting and pull it
100
describe the ultrastructure for thin filaments
-a thin filament consists of two strands of actin subunits twisted into a helix plus two types of regulatory proteins (troponin and tropomyosin)
tropomyosin: prevents binding to myosin
Troponin is important for muscle contractions
101
what are the requirements for skeletal muscle contraction
Activation: neural stimulation at a neuromuscular junction in a somatic motor neuron. Activation causes excitation and excitation leads to contraction
Excitation- contraction coupling: muscle cells are also excitable
-generation and propagation of AP along the Sarcolemma (membrane )
-final trigger: a brief rise in the intracellular Ca++ levels (this is how we get out calcium)
102
Describe the events that happen in the Neuromuscular Junction
-AP arrives at the axon terminal of motor neuron
-voltage gated Ca2+ channels open and Ca2+ enters the axon terminal and binds to synaptotagmin
-Ca2+ entry causes some synaptic vesicles to release their contents (acetylcholine) via exocytosis
-Acetylcholine diffuses across the synaptic cleft and binds to nicotinic receptors in the sarcolemma
-ACh binding opens ion channels that allow simultaneous passage Na+ into the muscle fiber and K+ out of the muscle fiber
-ACh effects are terminated by its enzymatic breakdown in the synaptic cleft by acetylcholinesterase
-the ion channels are nicotinic because they bind with ACh
103
Describe how the generation of an action potential on sarcolemma is similar to EPSP
local depolarization: endplate potential
-there is more of a NA influx and then K+ efflux
Generation and propagation of an AP: end plate potential spreads to adjacent membrane areas and triggers and AP that propagates along sarcolemma
Repolarization: fiber is n refractory until repolarization is complete and it cannot be stimulated until refractory is done
-ionic conditions of resting state are restores by sodium potassium pumps
104
What is the site in which the action potential excites the muscle fiber
The neuromuscular junction
105
What are junctional folds?
- folds of sarcolemma beneath synaptic cleft
- Contains both ACh receptors and enzyme
(Acetylcholinesterase: AChE) that breaks down Ach
106
What releases norepinephrine?
released by most sympathetic postganglionic axons (adrenergic fibers)
107
the events of excitation-contraction coupling that lead to cross-bridge activity.
-AP leads to sliding of myofilaments (contraction)
-AP is propagated along sarcolemma to T Tubules (remember that T-tubules talk to myofibrils and they do deep into the muscle cells)
-voltage sensitive proteins next to the 2 cisterns stimulate Ca2+ release from sarcoplasmic reticulum
-therefore Ca2+ is necessary for contraction
108
Go into detail about how calcium interacts with troponin
-action potential is propagated along the sarcolemma and down the T tubules
-calcium ion are released
-calcium binds to troponin and removes the blocking actions of tropomyosin
-contraction begins (ATP is required)
109
Describe the cross bridge cycle
-continues as long as Ca2+ and adequate ATP are present
-cross bridge formation- high energy myosin head attached to thin filaments (myosin head has to be raised so they bind, pull and release the actin)
-working power stroke- myosin head pivots and pulls thin filament toward M line (this is the actual movement)
- the detachment happens when the ATP attached to myosin head
-cocking of myosin head- energy from hydrolysis of ATP cocks myosin head into high energy state again
110
what are the three phases of muscle contractions
-excitation at the neuromuscular junction
-excitation contraction coupling
-cross bridge cycling
111
What are the 2 regulatory proteins of the excitation contracting coupling sequence and what are they associated with?
tropomyosin and troponin
-associate with the thin filaments
112
what is the function of tropomyosin
Blocks the myosin-binding site on actin, preventing contraction
113
what is the function of troponin
binds calcium and is site of movement - moves tropomyosin away from actin
114
what role does Calcium play in the Excitation Contraction Coupling and how does this allow the sarcomeres to contract
-all actin has a myosin binding site but it is blocked by Tropomyosin when there is no Ca present
-Ca ions that are released from the two cisternae bind troponin
-troponin changes shape and in a way that shifts tropomyosin away from the myosin binding sites on actin
-Once the binding sites are exposed, the myosin heads can bind to them, forming cross bridges between the thick and thin filaments.
-Muscle contraction can now occur through cross bridge cycling
115
what is the function of the Z discs
-Connects a sarcomere to the next sarcomere; center of an I band
-anchors the thin filament
116
what are the thick filaments anchored to
M line
-it also marks the center of the sarcomere
117
What is the H zone?
-thick filaments only, thats why it looks lighter
118
what is different from the Action potentials for muscle fibers and for neurons
-in the AP's for muscle fibers, the RMP is -90
-there is no hyperpolarization or sodium potassium pump
119
Describe Motor Units and the relationship it has with contraction
-1 motor neuron and all of the muscle fibers it innervated
-they modulate force production
-the muscle will not contract unless stimulated by a motor neuron
120
Describe small motor units
-small nerve fibers, fine movements (fingers, eyes)
121
Describe large motor units
-larger nerve fibers, in large weight bearing muscles (thighs, hips)
122
how do motor units contract to prevent fatigue
-they contract asynchronously
123
How do muscle fibers spread through the muscle
-muscle fibers from 1 motor unit are spread throughout muscle so a single motor unit causes weak contraction of entire muscle
124
list the types of requirement
Type 1
Type 2a
Type 2x
125
Describe the Muscular Hypertrophy
-increase in muscle size
-increased fiber size due to more myofibrils
-aerobic exercise
-increases vascularity of muscle (grows more capillaries)
-greater hypertrophy of fast twitch fibers
-gets more dense bc there is more myosin and action
126
Describe muscular Atrophy
-decreased muscle size
-Type 2 fibers disintegrate first
-decreased fiber size or loss of muscle fibers
-also caused by disuse
127
Describe the level of organization in the muscle
Whole muscle (wrapped in epimysium)
muscle fascicle (wrapped in perimysium)
muscle fiber (also called muscle cells and they are wrapped in endomysium)
-myofibril (specialized intracellular structure)
-thick/ thin filaments
-myosin and Actin
128
Differentiate between isometric and isotonic contractions
Isometric- Same length but increasing tension (eg. wall sit)
Isotonic- same tension and same amount of resistance, changes length (eg. training)
129
what are graded muscle responses
-variations in the degree or strength of muscle contraction in response to demand
-required for proper control of skeletal movement
-Muscle contraction can be graded (varied) in two ways: Frequency of the stimulation and number of motor units stimulated
130
what is anaerobic metabolism and what fibers use them
-generating chemical ATP without using oxygen
-this is for type 2 fibers because they fatigue faster
-happens in the cytosol
131
what is aerobic metabolism
-generating chemical ATP with Oxygen and it happens in the mitochondria
-for Type 1 fibers
132
Describe Type 2 fibers ( category of activities, type of sports, metabolism, blood supply, energy release, mitochondria and myoglobin)
Category activities: strength
Type of athletes/ sports: sprinters
Type of Metabolism: anaerobic
Amount of blood supply: fewer blood vessels
Amount of energy release: small amount and it's quick
Amount of mitochondria: less mitochondria
Amount of myoglobin: less myoglobin because there is less Oxygen
-fast twitch fibers
133
why is myoglobin important?
carries oxygen and stores it in the blood
134
Describe the events that happen in the generation and propagation of an action potential in a skeletal muscle
-the end plate potential is generated at the neuromuscular junction. this causes a wave of depolarization that spreads to the sarcolemma
-the depolarization of the sarcolemma opens voltage gated Na+ channels, Na+ enters and eventually an AP is generated. The Ap spreads through the rest of the sarcolemma and opens the rest of the voltage gated Na+ channels. The AP continues to propagate
-the repolarization is when the sarcolemma is restored to its resting state. Na+ voltage channels close and K+ channels open and diffuses out
135
What happens when Ca+ is no longer being used
it gets pumped back into the sarcoplasmic reticulum and tropomyosin covers the myosin binding site again
136
Describe the events of cross bridge cycling
1. Cross Bridge Formation: Cycle starts when excitation contraction coupling leaves myosin in binding site exposed
-myosin binds and the cross bridge is formed
-myosin is in a high energy state
-the myosin head has a binding side for ATP that is currently being used by ADP and inorganic phosphate
Power Stroke: the inorganic phosphate detaches. This causes the myosin head to pivot and move the thin filament towards the M line
-ADP leaves and causes myosin head to be in a low energy state
-the myosin head is still attached to actin
Cross bridge detachment: myosin head remains attached until ATP attached to myosin head until ATP binds. Myosin head remains in low energy state
-Myosin head reactivates: When ATP is hydrolyzed by the ATPase and converts the ADP and an inorganic phosphate
-energy that was released during hydrolyses recharges the myosin head, putting it in a high energy state
-cycle repeats when binding happens
137
Describe Type 1 fibers (categories of activities, type of sports, metabolism, blood supply, energy release, mitochondria and myoglobin)
Categories of activates: endurance
Type of sport: marathon
Type of Metabolism: Aerobic
Amount of blood supply: many blood vessels
Amount of energy release: large amount, you get fatigued slowly
Amount a mitochondria: a lot
Amount of Myoglobin: a lot
