Physio Test 2 Etc

Front 1

ANS efferent fibers

Back 1

have their cell bodies in the spinal cord, and they
reach the sympathetic ganglia on both sides of the vertebral column.

Front 2

ANS sympathetic system

Back 2

prepares and mobilizes the body in emergency cases
e.g.: during exercise, fear…
Fight or Flight

Front 3

sympathetic stimulation

Back 3

increased heart rate, constriction of the arterioles of the skin and intestine,
(but, dilatation of those of the skeletal muscle), which raises the blood pressure, sympathetic stimulation leads to dilation of the pupils, sphincters close, hair stands and sweating occurs.

Front 4

parasympathetic system

Back 4

conserves and stores the energy
e.g.: during sleep

Front 5

parasympathetic stimulation

Back 5

Decrease in heart rate, pupil constriction, increased peristalsis, increased
glandular activity, sphincters open, bladder wall is contracted.

Front 6

Synapses between neurons are made

Back 6

in the autonomic ganglia.

Front 7

Parasympathetic ganglia are located

Back 7

in or near the effector organs.

Front 8

Sympathetic ganglia are located

Back 8

in the paravertebral chain.

Front 9

preganglionic neurons of the sympathetic nervous system originate

Back 9

in spinal cord segments T1-L3, or the thoracolumbar region.

Front 10

Preganglionic neurons of the parasympathetic nervous system originate

Back 10

in the nuclei of cranial nerves and in spinal cord segments S2-S4, or the craniosacral region.

Front 11

Adrenal Medulla

Back 11

is a specialized ganglion of the sympathetic nervous system.
-Preganglionic fibers synapse directly on chromaffin cells in the adrenal medulla.
-The chromaffin cells secrete epinephrine (80%) and norepinephrine (20%) into the circulation.

Front 12

Pheochromocytoma

Back 12

is a tumor of the adrenal medulla that secretes excessive amounts of catecholamines and with increased excretion of 3-methoxy-4-hydroxymandelic acid (VMA).

Front 13

Postganglionic neurons of both divisions have their cell bodies

Back 13

in the autonomic ganglia and synapse on effector organs (heart, blood vessels, sweat glands

Front 14

Sympathetic: (thoraco-lumbar)
Origin

Back 14

cell bodies lie the lateral horn
of the T1- L2/3 spinal cord.

Front 15

Parasympathetic: (cranio-sacral)
Origin:

Back 15

CN III, CN VII, CNIX and CN X
and S1, S2, S3 (pelvic splanchnic nerve).

Front 16

Adrenergic neurons release

Back 16

norepinephrine as the neurotransmitter.

Front 17

Cholinergic neurons

Back 17

whether in the sympathetic or parasympathetic nervous system, release acetylcholine (Ach) as the neurotransmitter.

Front 18

Peptidergic neurons

Back 18

in the parasympathetic nervous system release peptides such as vasoactive inhibitory peptide and substance P.

Front 19

alpha 1 receptors

Back 19

-are located on vascular smooth muscle of the skin and splanchnic regions, the gastrointestinal (GI) and bladder sphincters, and the radial muscle of the iris.
-produce excitation (contraction ,constriction).

Are equally sensitive to norepinephrine and epinephrine. However, only norepinephrine released from adrenergic neurons is present in high enough concentration to activate alpha 1 receptors.

Front 20

alpha 1 mechanism of action

Back 20

G protein alpha stimulator, Phospholipase C, formation of inositol 1,4,5-triphospate (IP3) and increase in intracellular (Ca+).

Front 21

alpha 2 receptors

Back 21

are located in presynaptic nerve terminals, platelets. Fat cells, and the walls of the GI tract.

-often produce inhibition (relaxation or dilation).

Front 22

alpha 2 mechanism of action

Back 22

G protein alpha inhibitor, inhibition of adenylate cyclase and decrease in cyclic adenosine monophosphate (CAMP).

Front 23

beta 1 receptors

Back 23

are located in the sinoatrial (SA) node, atrioventricular (AV) node, and ventricular muscle of the heart.

-produce excitation (increased heart rate, increased conduction velocity, increased contractility).

-are sensitive to both norepinephrine and epinephrine, and are more sensitive than alpha1 receptors.

Front 24

beta 1 mechanism of action

Back 24

activation G protein alpha stimulator, activation of adenylate cyclase and increase in cAMP.

Front 25

Beta 2 receptors

Back 25

-are located on vascular smooth muscle of skeletal muscle, bronchial smooth muscle, and in the walls of the GI tract and bladder.

-produce relaxation (dilation of vascular smooth muscle, dilation of bronchioles, relaxation of the bladder wall.)

-are more sensitive to epinephrine than to norepinephrine.

-are more sensitive to epinephrine than the alpha 1 receptors.

Front 26

Beta 2 receptors mechanism of action

Back 26

activation G protein alpha stimulator, activation of adenylate cyclase and increase in cAMP.

Front 27

nicotinic receptors

Back 27

are located in the autonomic ganglia of the sympathetic and parasympathetic nervous systems, at the neuromuscular junction, and in the adrenal medulla. The receptors at these are similar, but not identical.

-are activated by Ach or nicotine.

-produce excitation.

-are blocked by ganglionic blockers in the autonomic ganglia, but not at the neuromuscular junction.

Front 28

nicotinic mechanism of action

Back 28

Ach binds to alpha subunits of the nicotinic Ach receptor, The nicotinic Ach receptors are also ion channels for Na+ and K+.

Front 29

muscarinic receptors

Back 29

are located in the heart, smooth muscle, and glands.

-are inhibitory in the heart (decreased heart rate, decreased conduction velocity in AV node).

-are excitatory in smooth muscle and glands (increased GI motility, increased secretion).

-are activated by Ach and muscarine.

-are blocked by atropine.

Front 30

muscarinic mechanism of action

Back 30

Heart SA node: inhibition of adenylate cyclase, which leads to opening of K+ channels, slowing of the rate of spontaneous Phase 4 depolarization, and decreased heart rate

2. Smooth muscle and glands: formation of IP3 and increase in intracellular (Ca2+).

Front 31

ANS brain centers

Back 31

Medulla
-Vasomotor center
-Respiratory center
-Swallowing, coughing, and vomiting centers

2. Pons
-Pneumotaxic center

3. Midbrain
-Micturition center

4. Hypothalamus
-Temperature regulation center
-Thirst and food intake regulatory centers

Front 32

Preganglionic release

Back 32

ACH

Front 33

Postganglionic release

Back 33

Parasympathetic: Ach
Sympathatic:
Norepinephrine (NA)

Front 34

The enviromental signals that can be detected
include

Back 34

mechanical force, light, sounds, chemicals, and temperature.

Front 35

Mechanoreceptors

Back 35

respond to mechanical stimulus
-Pacinian corpuscles
-joint receptors
-Stretch receptors in muscle
-Hair cells in auditory and vestibular systems
-Baroreceptors in carotid sinus

Front 36

photoreceptors

Back 36

-Rods and cones of the retina

Front 37

chemoreceptors

Back 37

Olfactory receptors
-Taste receptors
-Osmoreceptors
-Carotid body O2 receptors

Front 38

Extremes of temperature and pain

Back 38

Nociceptors

Front 39

a-alpha

Back 39

large alpha-motoneuronsConduction velocity: fastest

Front 40

a-beta

Back 40

Touch, pressureConduction velocity: Medium

Front 41

a-gamma

Back 41

gamma-motoneurons to muscle spindles (intrafusal fibers)Conduction velocity: Medium

Front 42

A-delta

Back 42

Touch, pressure, temperature, and painConduction velocity: Medium

Front 43

B conduction velocity

Back 43

preganglionic autonomic fibersConduction velocity: Medium

Front 44

C conduction velocity

Back 44

Slow pain, postganglionic autonomic fibers Conduction velocity: Slowest

Front 45

Receptive field

Back 45

is an area of the body that, when stimulated, changes the firing rate of a sensory neuron. If the firing rate of the sensory neuron is increased, the receptive field is excitatory. If the firing rate of the sensory neuron is *decreased, the receptive field is inhibitory.

Front 46

Steps in sensory transduction

Back 46

Stimulus arrives at the sensory receptor.( photon of light on the retina, a molecule of NaCl on the tongue).B. Ion channels are opened in the sensory receptor, allowing current to flow.Usually the current is inward, which is depolarization of the receptor.C. The change in membrane potential produced by the stimulus is the receptor potential, or generator potential.

Front 47

tonic receptors

Back 47

are slow adapting (muscle spindle, pressure, slow pain)-respond repetitively to a prolonged stimulus.

Front 48

Phasic receptors

Back 48

rapidly adapting (pacinian corpucle, light touch)-show a decline in action potential frequency with time in response to a constant stimulus.

Front 49

First order neurons

Back 49

are the primary afferent neurons that receive the transduced signal and send the information to the CNS. Cell bodies of the primary afferent neurons are in dorsal root or spinal cord ganglia.

Front 50

second order neurons

Back 50

are located in the spinal cord or brain stem.-receive information from one or more primary afferent neurons in relay nuclei and transmit it to the thalamus.-Axons of second-order neurons usually cross the midline in a relay nucleus in the spinal cord before they ascend to the thalamus. Therefore, sensory information originating on one side of the body ascends to the contralateral thalamus.

Front 51

Third order neuron

Back 51

are located in the relay nuclei of the thalamus. From there, encoded sensory information ascends to the cerebral cortex.

Front 52

Fourth order neurons

Back 52

are located in the appropriate sensory area of the cerebral cortex.The information received results in a conscious perception of the stimulus.

Front 53

Somatosensory system

Back 53

The somatosensory system processes information about touch, pain and temperature.
Mechanoreceptors (for touch)2. Thermoreceptors (temperature)3. nociceptors (pain)

Front 54

dorsal column system

Back 54

From the medulla the second-order neurons cross the midline and ascend to the contralateral thalamus, where they synapse on third-order neurons. Third-order neurons ascend to the somatosensory cortex, where they synapse on fourth-order neurons.
processes sensations of fine touch, pressure, two-point discrimination, vibration

Front 55

anterolateral system

Back 55

processes sensations of temperature, pain, and light touch.-consists primarily of group of fibers, which enter the spinal cord and terminate in the dorsal horn.-second-order neurons cross the midline to the anterolateral quadrant of the spinal cord and second to the contralateral thalamus, where they synapse on third-order neurons.-Third-order neurons ascend to the somatosensory cortex, where they synapse on fourth-order neurons.

Front 56

Destruction of the thalamic nuclei results in

Back 56

loss of sensation on the contralateral side of the body.

Front 57

Fast pain

Back 57

is carried by group A-delta fibers. It has a rapid onset and offset, and is localized.

Front 58

slow pain

Back 58

is carried by C fibers. It is characterized as aching, burning, or throbbing that is poorly localized.

Front 59

Neurotransmitter for nocireceptors

Back 59

substance P

Front 60

Cranial nerve VII

Back 60

the facial nerve, carries taste sensations from the anterior two thirds of the tongue and soft palate.

Front 61

Cranial nerve IX

Back 61

the glossopharyngeal nerve carries taste sensations from the posterior one third of the tongue.

Front 62

3.Also a branch of the vagus nerve

Back 62

carries some taste sensations from the back of the oral cavity (i.e. pharynx and epiglottis).

Front 63

Dendritic endings of these nerves are located around the taste buds and relay sensations of touch and temperature.

Back 63

Taste sensations are passed to the medulla oblongata, where the neurons synapse with second-order neurons that project to the thalamus, from here, third-order neurons project to the area of the postcentral gyrus of the cerebral cortex that is devoted to sensations from the tongue.

Front 64

Salt

Back 64

An ion channel in the taste cell wall allows Na+ ions to enter the cell. This on its own depolarizes the cell, and opens voltage-regulated Ca2+ gates, flooding the cell with ions and leading to neurotransmitter release.

Front 65

sour

Back 65

Sour taste signals the presence of acidic compounds (H+ ions in solution). There are three different receptor proteins at work in sour taste. The first is a simple ion channel which allows hydrogen ions to flow directly into the cell.

Front 66

bitter

Back 66

Bitter compounds act through structures in the taste cell walls called G-protein coupled receptors (GPCR’s). When the bitter compound activates the GPCR, it in turn releases gustducin, the G-protein it was coupled to.

Front 67

sweet

Back 67

Like bitter tastes, sweet taste transduction involves GPCR’s.

Front 68

Ageusia

Back 68

(Loss of taste):You may lose your sense of taste if the facial nerve is damaged.

Front 69

Hypogeusia

Back 69

decreased taste sensitivity)

Front 70

Hypergeusia

Back 70

increased taste sensitivity)

Front 71

sore tongue

Back 71

It is usually caused by some form of trauma, such as biting your tongue, or eating piping-hot or highly acidic food or drink. If your top and bottom teeth don’t fit neatly together, tongue trauma is more likely. Some people may experience a sore tongue from grinding their teeth (bruxism). Disorders such as diabetes, anemia, some types of vitamin deficiency and certain skin diseases can include a sore tongue among the range of symptoms.

Front 72

glossodynia

Back 72

A condition characterized by a burning sensation on the tongue.

Front 73

Benign migratory glossitis

Back 73

This condition is characterized by irregular and inflamed patches on the tongue surface that often have white borders. The tongue may be generally swollen, red and sore. Another name for this condition is geographic tongue. The cause of benign migratory glossitis is unknown.

Front 74

Receptor cells

Back 74

are located in the olfactory epithelium.-are true neurons that conduct action potentials into the CNS.

Front 75

olfactory

Back 75

sensory PP a

Front 76

Anosmia

Back 76

Anosmia is the lack of olfaction, or a loss of the sense of smell.

Front 77

Phantosmia

Back 77

Phantosmia is the phenomenon of smelling odors that aren't really present.

Front 78

Dysosmia

Back 78

When things smell differently than they should.

Front 79

sclera

Back 79

The outer layer of the eye is the sclera, which is a tough white fibrous layer that maintains, protects and supports the shape of the eye. The front of the sclera is transparent and is called the cornea. The cornea refracts light rays and acts like the outer window of the eye.

Front 80

The eye can distinguish two qualities of light:

Back 80

its brightness-its wavelength, for human, the wavelengths between 400 and 750 nanometers are called visible light.

Front 81

choroid

Back 81

The middle thin layer of the eye is the choroid, it is the vascular layer of the eye lying between the retina and the sclera. The choroid provides oxygen and nourishment to the outer layers of the retina. It also contains a nonreflective pigment that acts as a light shield and prevents light from scattering.

Front 82

retina

Back 82

The third or the inner layer of the eye is call the retina. The retina lays over the back two thirds of the choroid coat, which is located in the posterior compartment. The compartment is filled with vitreous humor which is a clear, gelatinous material.
Contains rods + cones

Front 83

rod cells

Back 83

are very sensitive to light and do not see color, that is why when we are in a darkened room we see only shades of gray.

Front 84

cone cells

Back 84

are sensitive to different wavelengths of light, and that is how we are able to tell different colors. It is a lack of cones sensitive to red, blue, or green light that causes individuals to have deficiencies in color vision or various kinds of color blindness.

Front 85

At the center of the retina is the optic disc

Back 85

sometimes known as "the blind spot" because it lacks photoreceptors. It is where the optic nerve leaves the eye and takes the nerve impulses to the brain.

Front 86

fovea centralis

Back 86

The fovea is a pit that has the highest visual acuity and is responsible for our sharp central vision - there are no rods in the fovea.

Front 87

layers of the retina

Back 87

. Pigment epithelial cell-absorb stray light and prevent scatter of light.2. Receptor cells are rods and cones 3. Bipolar cells. The receptor cells (rods and cones) synapse on bipolar cells, which synapse on the ganglion cells.4. Horizontal cells 5. Amacrine cells for circuits with the bipolar cells. 6. Ganglion cells are the output cells of the retina. (*Axons of ganglion cells form the optic nerve).

Front 88

color blindness

Back 88

is the inability to perceive differences between some or all colors that other people can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals.

Front 89

Night blindness

Back 89

may exist from birth, or be caused by injury or malnutrition (for example, a lack of vitamin A). The most common cause of nyctalopia is retinitis pigmentosa, a disorder in which the rod cells in the retina gradually lose their ability to respond to the light.

Front 90

Glaucoma

Back 90

(Intracranial pressure)

Front 91

Visual agnosia

Back 91

is the inability of the brain to make sense of or make use of some part of otherwise normal visual stimulus, and is typified by the inability to recognize familiar objects or faces.

Front 92

Emmetropia

Back 92

normal. Light focuses on the retina

Front 93

hypertropia

Back 93

farsighted. light focuses behind the retina and is corrected with a convex lens.

Front 94

myopia

Back 94

nearsighted. Light focuses in front of the retina and is corrected with a biconcave lens.

Front 95

Astigmatism

Back 95

Curvature of the lens is not uniform and is corrected with a cylindric lens.

Front 96

outer ear

Back 96

Auricle, Ear Canal, Surface of Ear Drum)

Front 97

the middle ear

Back 97

is air-filled.The middle ear includes most of the ear drum (tympanic membrane) and the 3 ear bones ossicles: malleus (or hammer), incus (or anvil), and stapes (or stirrup). The opening of the Eustachian tube is also within the middle ear.

Front 98

Inner ear

Back 98

is fluid-filled.(Cochlea, Vestibule, and Semi-Circular Canals, and a series of ducts called the membranous labyrinth. The fluid outside the ducts is perilymph; the fluid inside the ducts is endolymph.

Front 99

Structure of the cochlea: three tubular canals

Back 99

The scala vestibuli and scala tympani contain perilymph, which has a high Na+.B. The scala media contains endolymph, which has a high K+. –The scala media is bordered by the basilar membrane, which is the site of the organ of Corti.

Front 100

The organ of corti

Back 100

The organ of Corti is located on the basilar membrane. -It contains the receptor cells for auditory stimuli. Cilia protrude from the hair cells and are embedded in the tectorial membrane. -Inner hair cells are arranged in single rows and are few in number.

Front 101

Steps in auditory transduction

Back 101

by the organ of Corti sensory pp b slide 16

Front 102

The base of the basilar membrane

Back 102

(near the oval and round windows) is narrow and stiff. It responds best to high frequencies.

Front 103

The apex of the basilar membrane

Back 103

(near the helicotrema) is wide and compliant. It responds best to low frequencies.

Front 104

sound waves

Back 104

Frequency is measured in hertz (Hz).
-Intensity is measured in decibels (dB)

Front 105

Otitis Media

Back 105

An inflammation of the middle ear segment. It is usually associated with a buildup of fluid and frequently causes an earache

Front 106

Streptococcus pneumoniae and Haemophilus influenzae are

Back 106

the most common bacterial causes of otitis media. As well as being caused by Streptococcus pneumoniae and Haemophilus influenzae it can also be caused by the common cold.

Front 107

Vestibular system

Back 107

detects angular and linear acceleration of the head.-reflex adjustments of the head, eyes, and postural muscles provide a stable visual image and steady posture.

Front 108

nystagmus

Back 108

-An initial rotation of the head causes the eyes to move slowly in the opposite direction to maintain visual fixation. When the limit of eye movements reaches, the eyes rapidly snap back (nystagmus), then move slowly again.-The direction of the nystagmus is defined as the direction of the fast (rapid eye) movement. Therefore, the nystagmus occurs in the same direction as the head rotation

Front 109

post rotary nystagmus

Back 109

occurs in the opposite direction of the head rotation.

Front 110

vertigo

Back 110

dizziness. Vertigo is usually associated with a problem in the inner ear balance mechanisms (vestibular system), in the brain, or with the nerve connections between these two organs.

Front 111

What happens if the person turns the head to the right side.
Vestibular system

Back 111

sensory pp B

Front 112

neurons

Back 112

transmit electrical signals, found in grey matter of CNS and ganglia

Front 113

neuroglial cells

Back 113

support cells): nonexcitable, surround and wrap neurons

Front 114

Characteristics of Neurons

Back 114

Conduct electrical impulses along the plasma membrane
Produce nerve impulse
Produce action potential
Longevity: can live and function for a lifetime
Do not divide: fetal neurons lose their ability to undergo mitosis
High metabolic rate: require abundant oxygen and glucose

Front 115

There are two types of supporting cells in the peripheral nervous system:

Back 115

Schwann cells and satellite cells

Front 116

Schwann cells

Back 116

which form myelin sheaths around peripheral axons.

Front 117

satellite cells

Back 117

or ganglionic gliocytes, which support neuron cells bodies within the ganglia of the PNS.

Front 118

There are four types of supporting cells, called neuroglial cells, in the central nervous system.

Back 118

Oligodendrocytes, Microglia, astrocytes, ependymal

Front 119

Oligodendrocytes

Back 119

which form myelin sheaths around axons of the CNS.

Front 120

microglia

Back 120

which migrate through the CNS and phagocytose foreign and degenerated material.

Front 121

astrocytes

Back 121

which help to regulate external environment of neurons in the CNS

Front 122

ependymal

Back 122

cells, which line the ventricles of the brain and the central canal of the spinal cord.

Front 123

Gliosis and glial scar

Back 123

Gliosis is hyperplasia and hypertrophy of astrocytes that occur in reaction to CNS injury.

Front 124

Oligodendrocytes: respond to injury

Back 124

by expanding and vacuolation of their cytoplasm.

Front 125

Tumors of Neuroglia (glioma):

Back 125

Account for about 50% of intracranial tumors. Astrocytomas and glioblastomas are tumors of astrocytes. Gliomas apart from ependymomas are very invasive and grow large with minimal effect on neighboring neurons.

Front 126

Multiple sclerosis (Demyelinating diseases of the CNS

Back 126

an unknown disease, occurs between ages of 20-40 year, demyelination in CNS, usually starts with optic nerve, spinal cord and cerebellum. Axonal degeneration as a result of demyelination and/or early in the course of the disease is part of the disability.

Front 127

Myelin sheath in PNS and CNS

Back 127

the nervous system pp slide 12

Front 128

CSF=Blood

Back 128

Na+
Cl-
HCO3-
Osmolarity

Front 129

CSF< blood

Back 129

K+
Ca2+
Glucose
Cholestrol*
Protein*

Front 130

CSF> blood

Back 130

Mg2+
Creatinine

Front 131

synapses

Back 131

are the sites where two
neurons come into close proximity.
The term also implies to the nerve-muscle
contact as well.

Front 132

various forms of synapses

Back 132

Axodendritic, axosomatic and axoaxonic.
The first two are the most common forms.
Axons can have a terminal expansion or a
series of expansions called bouton de
passage which make several contacts as
they pass through a dendritic tree.

Front 133

types of synapses

Back 133

Chemical (most common)
2- Electrical

Front 134

chemical synapses

Back 134

involve the neurotransmitters
released from a pre-synaptic neuron that becomes attached to a protein (receptor) at post-synaptic membrane.
Chemical synapses are unidirectional.

Front 135

electrical synapses

Back 135

Most synapses in the nervous system are of chemical type with neurotransmitter, but in electrical synapses, there is no chemical
transmitters.

These synapses are Gap junctions formed by specialized channels called Connexons.
These are found in a group of neurons performing an identical function.
These are bidirectional.

Front 136

Parkinsons could be treated

Back 136

to some extent by neurotransmitters.
Dopamine can not cross the BBB. L-dopa can cross BBB.

Front 137

Phenothiazines

Back 137

block Dopamine receptors postsynaptically.

Front 138

serotonin

Back 138

a master neurotransmitter, is manufactured from tryptophan. It is found all over the body and is necessary to modulate the levels of the stress hormones.
PP slide 27

Front 139

dopamine

Back 139

In the brain, dopamine functions as a neurotransmitter, activating the five types of dopamine receptor - D1, D2, D3, D4 and D5, and their variants.

Front 140

Insufficient dopamine biosynthesis in the dopaminergic neurons can cause

Back 140

Parkinson's disease (in which a person loses the ability to execute smooth, controlled movements).

Front 141

abnormally high dopamine

Back 141

action apparently leading to these conditions (schizophrenia).

Front 142

Functions of muscle tissue

Back 142

movement Joint stabilization Heat generation

Front 143

skeletal muscle tissue

Back 143

packaged into skeletal muscles
Makes up 40% of body weight. Cells are striated

Front 144

cardiac muscle tissue

Back 144

occurs only in the walls of the heart

Front 145

smooth muscle tissue

Back 145

in the walls of hollow organs. Cells lack striations

Front 146

skeletal muscle

Back 146

Has a nerve and a blood supply.
neuromuscular junction: Where nerve contacts the muscle
Origin on bone is at less movable attachment
Insertion is on more movable attachment
Origin and insertions are by tendon or aponeurosis

Front 147

motor unit

Back 147

Motor unit recruitment is the progressive activation of a muscle by successive recruitment of contractile units (motor units) to accomplish increasing gradations of contractile strength.

A motor unit consists of one motor neuron and all of the muscle fibers it contracts.

Front 148

sarcomere

Back 148

Is the basic unit of contraction of skeletal muscle from one Z line to the next

Front 149

z disc

Back 149

boundaries of each sarcomere

Front 150

thin actin filaments

Back 150

extend from Z disc toward the center of the sarcomere

Front 151

thick myosin filaments

Back 151

located in the center of the sarcomere
Overlap inner ends of the thin filaments contain ATPase enzymes

Front 152

A bands

Back 152

full length of the thick filament, includes inner end of thin filaments

Front 153

H zone

Back 153

center part of A band where no thin filaments occur

Front 154

M line

Back 154

in center of H zone, contains tiny rods that hold thick filaments together

Front 155

I band

Back 155

region with only thin filaments, lies within two adjacent sarcomeres

Front 156

muscle contraction

Back 156

when a nerve cell stimulates a muscle fiber, it sets up an impulse in the
Sarcolemma that signals the Sarcoplasmic reticulum to release Calcium ions.
Released Ca++ diffuses through cytoplasm and triggers the sliding filament
mechanism.
Impulses further conducted by t tubules

Front 157

Sliding filament theory:

Back 157

Myosin heads attach to actin
in the thin filaments
Then pivot to pull thin filaments
inward toward the center of the
sarcomere

Contraction mechanism is activated
by binding of Ca++ to the thin
filaments and powered by ATP.

Front 158

Tn C (troponin C)

Back 158

binds to calcium, initiates muscle contraction

Front 159

Tn T (troponin T),

Back 159

binds troponin complex to tropomyosin

Front 160

Tn I (troponin inhibitor),

Back 160

inhibits actin binding to myosin heads in resting muscle

Front 161

types of muscle fibers

Back 161

extrafusal, and intrafusal

Front 162

extrafusal

Back 162

make up the bulk of muscle.
-are innervated by alpha-motoneurons.
-provide the force for muscle contraction.

Front 163

intrafusal

Back 163

are smaller than extrafusal muscle fibers.
-are innervated by gamma-motoneurons.
-are encapsulated in sheaths to form muscle spindles.
-run in parallel with extrafusal fibers. But not for entire length of the muscle.

Front 164

muscular dystrophy

Back 164

A group of inherited muscle degenerating disease appearing in childhood.
The affected muscles enlarge with fat and connective tissue but the muscle
fibers actually degenerate

Front 165

Duchenne muscular dystrophy

Back 165

Sex-linked recessive inherited disease, males are most exclusively affected,
1/3500 boys, diagnosed between age 2-10, muscle weakens, first pelvic
muscles affected, then muscles of shoulder and head, rarely live over 20 years.
Fibers lack a submembrane protein called dystrophin.

Front 166

myotonic dystrophy

Back 166

Myotonic dystrophy is an inherited disorder in which the muscles contract but have decreasing power to relax. With this condition, the muscles also become weak and waste away. Myotonic dystrophy can cause mental deficiency, hair loss and cataracts.
Onset of this rare disorder commonly occurs during young adulthood. However, it can occur at any age and is extremely variable in degree of severity.

The myotonic dystrophy gene, found on chromosome 19, codes for a protein kinase that is found in skeletal muscle, where it likely plays a regulatory role.