A&P 1: Block 2 Flashcards
1
Q
Accessory structures of the skin
A
hair nails glands muscles nerves
2
Q
Where does the hypodermis layer fall into the layers of skin?
A
Sub-Q layer consisting of areolar and adipose tissue
Not a part of the skin
3
Q
7 specific functions of the skin
A
Thermoregulation Protection Sensation Excretion Synth of Vitamin D Blood reservoir Absorption
4
Q
Epidermis is composed of what type of epithelium?
A
Keratinized stratified squamous epithelium
5
Q
What are the 4 types of cells within the epidermis?
A
Keratinocytes
Melanocytes
Langerhans
Merkel
6
Q
90% of the epidermal cells are ____
A
keratinocytes
7
Q
How/when are keratinocytes formed?
A
When new cells from mitosis fill with keratin
8
Q
Major functions of keratin
A
Tough, fibrous protein that is
waterproof
protects (heat, microbes, chemicals)
UV protection
9
Q
What part of the cell makes melanin?
A
Organelle melanosome within melanocytes
Melanin is brown-black pigment that contributes to skin color and absorbs UV light
10
Q
After melanin is made by melanocytes, where is it transferred to? How does it get transferred?
A
Melanocyte projections extend between keratinocytes and pass melanin granules to them
Melanin granules cluster over nucleus on skin surface side, shields DNA from UV light
11
Q
What is melanin synthesized from?
A
AA tyrosine w/ tyrosinase enzyme
12
Q
Function of Langerhans cells?
What type of cell are they?
A
Immune response to microbes that invade the skin
Immune, dendritic
13
Q
Where are Merkel cells found?
What is their function?
A
Deepest layer of epidermis (Stratum Basale)
Contact w/ tactile discs (Merkel discs), a type of sensory neuron
14
Q
What two structures make up the sensation of touch?
A
Merkel cells
tactile discs
15
Q
What are the layers of skin
A
Corneum Lucidum Granulosum Spinosum Basale
Lucidum- only present on surface areas of a lot of friction (finger tips, soles)
16
Q
Characteristics of the Stratum Basale
A
Deepest layer of epidermis
Mostly keratinocytes, few melanocytes and Merkel cells
17
Q
What are the intermediate filaments of keratinocytes and where is it found?
A
Tonofilaments
Intermediate filament of keratinocytes in the Stratum Basale
Contains pre-cursor protein for keratin synthesis
18
Q
Characteristics of Stratum Spinosum
A
8-10 layers of keratinocytes, few Langerhans
Cells still alive at this layer, some are dividing
Older cells start to flatten here
19
Q
Characteristics of Stratum Granulosum
A
3-5 layers of flattened keratinocytes
Transition marker for deeper living/superficial dead cells
Filled w/ keratin granules
Waterproofing lipids from lamellar granules are here
20
Q
Characteristics of Stratum Lucidum
A
Only on fingertips, soles, palms
3 layers of flat, dead keratinocytes filled with keratin
21
Q
Characteristics of Stratum Corneum
A
Most superficial
25-30 layers of flat, dead cells
Cell interior mostly keratin
Lipids from lamellar granules form waterproof layer here
22
Q
What type of tissues make up the dermis
A
Irregular CT of collagen and elastic CTs
23
Q
What structures are found in the dermis
A
vessels nerves glands (oil and sweat) Hair follicles arrectores pilorum
24
Q
What are the two regions of the dermis?
A
Papillary- superficial
Reticular- deeper
25
Characteristics of the Papillary region of the Dermis
Just deep to stratum basale
| Increases surface area for diffusion, better adhesion to epidermis
26
What receptors are present in the Papillary region of the Dermis
Touch corpuscles- Meissner- touch/light touch
Free nerve endings- no structural specialization- warm, cold, pain, tickle
27
Characteristics of the Reticular Region of the Dermis
Dense irregular CT w/ collagen and elastic
Gives skin it's strength and elasticity
Spaces between fibers filled with adipose, follicles, nerves, oil and sweat glands
28
What layer of the skin provides the skin strength, extensibility and elasticity?
Reticular region
| Collagen and elastic fibers
29
Subcutaneous layer is made of what tissues?
Areolar and adipose
30
What structures are found in the subcutaneous layer?
Fat
Fibers attaching dermis to deeper tissues
Larger vessels
Sensory receptors: Pacinian/lamellated corpuscles- pressure
31
Epidermal ridges aka
fingerprints
32
When do epidermal ridges form in development/
3 and 4th month of fetal development
Contours of underlying papillary region
Forms lines, loops and whorls
33
Where do sweat glands open to on fingertips?
Epidermal ridges
34
Skin color is a combination of what things?
| Which ones are genetically determine?
melanin
carotene
hemoglobin
Amount/expression of melanin and carotene- genetically determined
35
What does melanin provide to skin?
What does increased sun exposure do to these cells?
Amount causes skin color
Increased exposure= increased enzymatic activity of malanosomes, increased melanin production
36
What does Carotene provide to skin?
yellow-orange pigment
| Pre-cursor for Vitamin A
37
What does Hemoglobin provide to skin color?
O2 carrying pigment in RBCs
When Melanin or Carotene are low, epidermis appears translucent
Causes skin to appear pink
38
What are the parts of the skin's hair shaft and root?
Medulla
Cortex
Cuticle
39
What are skin hairs composed of?
Dead, keratinized cells bonded by proteins
40
How do skin hairs grow?
Cell division at base of follicle via mitosis in the hair matrix
41
What is the canal called that skin hairs grow through?
Pilary canal
42
What is the hair bulb made of?
Germinal layer of cells called matrix
Site of cell division that produces the hair
43
What layer does the hair bulb come from?
Stratum basale
44
What are the ancillary structures of hair?
Sebaceous gland
Smooth muscles
Root plexus
45
What type of cells surround the root hair plexus?
Dendrites
Nerve endings
Generates nerve impulses if hair shaft is moved
Shaft acts like a fulcrum
Sensitive to touch and movement
46
What are the 3 parts of a nail?
Body- visible (lunula- white part of proximal nail)
Free edge
Root- epithelium deep is the nail matrix, mitotic division= growth
47
What are nails made of?
Keratinized epidermal cells
48
When nails grow, new cells push old ones forward along what basale?
Stratum
49
3 functions of sebum?
Prevents drying out
Prevents evaporation
Inhibits bacterial growth
50
What are the two types of sweat glands?
Eccrine- (merocrine) found on most of skin, thermoregulation
Apocrine- hair that develops at puberty (axilla, groin, beard)
51
Define psoriasis
| Where is it commonly found?
keratinocyte division and movement more rapidly than stratum basale/corneum and shed prematurely
Knees, elbows, scalp
52
Virtually all skin cancers are attributed to excessive ___
sun
53
What are the 3 common forms of skin cancer?
Basal cell carcinomas- most common
Squamous carcinoma
Malignant melanomas (least common, most life-threatening)
54
Define albinism
inability to produce melanin
| melanocytes unable to synthesize tyrosinase
55
Define vitiligo
Partial/complete loss of melanocytes from patches of skin (irregular white spots)
May be autoimmune
56
Under lying causes of erythema
redness of skin
```
injury
heat
infection
inflammation
allergies
```
57
Define striae
stretch marks
| scars from dermis tearing
58
Define alopecia
| What are its causes
```
lack of hair (partial or complete)
aging
endocrine disorder
chemotherapy
skin disease
```
59
Define contact dermatitis
inflammation of skin (redness, itching, swelling)
| Caused by exposure of skin to chemicals= allergic reaction
60
What are the two types of wound healing
Epidermal- superficial, only epidermis involved
Deep wound- injury extends to dermis and subcutaneous layer (loss of some function and scar tissue)
61
What are the 4 overall steps of Deep Wound Healing?
Inflammatory
Migratory
Proliferative
Maturation
62
Characteristics of 1st degree burn
Only epidermis
Skin functions remain intact
3-6 day heal time
Sunburn
63
Characteristics of 2nd degree burn
Partial damage to epidermis and dermis
Some skin function lost (blisters)
3-4 wks heal time w/ scarring possibility
64
Characteristics of 3rd degree burn
Epidermis and dermis involvement
Skin function lost
AKA full thickness
65
Rule of 9s
Only for 2nd and 3rd degree burns on adults
66
Define abrasion
skin has been scraped away
67
Define Athletes foot
superficial fungal infection of skin on foot
68
Define blister
serous fluid with epidermis or between epidermis and dermis
69
Define callus
area of hardened/thickened skin
70
Define eczema
inflammation of skin characterized by patches of blister/dry/itch skin
71
Define wart
mass of uncontrolled growth of epithelial cells caused by papillomavrius
72
Define hirsutism
condition of excessive body hair
73
Define laguno
fine,non-pigmented hairs that cover body of fetus
74
Define Terminal Hairs
Secondary characteristic
Coarse, heavily pigmented
Head, eyebrows, eyelashes
75
Define Vellus hairs
fine/pale body hairs that develop during childhood
76
What does cartilage consist of?
Collage (strength) and elastic fibers embedded in chondroitin sulfate (resilience)
77
What are mature cartilage cells called? What space do they occupy?
Chondrocytes= mature
Derived from chondroblasts
Reside in lacunae (little lakes)
78
Most cartilage is covered in irregular CT called ____.
| What developmental shift occurs to this tissue?
perichondrium
| Becomes vascularized, becomes periosteum
79
Cartilage has no nerves except for where?
Perichondrium
80
Why does perichondrium cartilage heal slowly?
lack of intrinsic blood supply and confinement of chondrocytes to lacunae
81
What are the 3 types of cartilage
Hyaline- most abundant
Fibrinocartilage
Elastic
82
Where is Hyaline cartilage located?
Most abundant
End of long bones
Ribs, nose, trachea, bronchi and larynx
Provides smooth surface for movement to occur
83
Characteristics of fibrinocartilage and where is it located
thick bundles of collagen (very tough/strong)
Found as disc shaped segment between bones
84
Characteristics and location of elastic cartilage
Chondrocytes located in threadlike network of elastic fibers
External ear and epiglottis
85
Different functions of red and yellow bone marrow
Red- RBC formation
| Yellow- triglyceride storage (adipose connective tissue)
86
Define diaphysis
Define epiphyses
Define metaphyses
Di- shaft, body of bone
Epi- distal/proximal portion of bone
Meta- connects Di and Epi
87
Where is the epiphyseal plate located?
at metaphyses of growth plate
88
Define articular cartilage
hyaline cartilage covering epiphyses
89
Define periosteum
dense irregular CT that covers bone, EXCEPT articular cartilage
90
Define endosteum
membrane lining marrow cavity
91
Histology break down of bone matrix
don't know %s
25% water
25% collagen
50% hydroxyapatite- (calcium phosphate, calcium carbonate) for hardness/compression strength
92
What are the 4 cells found in bones
All derive from mesenchyme*
mesenchyme- 1st
Osteogenic- stem cells differentiate->osteoblasts
Osteoblasts- secrete bone matrix and become osteocytes
Osteocytes- mature bone cell, regulate bone matrix composition
Osteoclasts- release enzymes for digesting/remodeling bone
93
Regions of bones can by subcategorized into what 2?
Compact- cortical
| Spongy- cancellous, trabecular
94
Compact bones contain units called?
Osteons- Harversian systems formed from concentric lamellae (rings of calcified matrix)
Interstitial lamellae- between osteons, left over fragments of older osteons
95
Where are the outer/inner circumferential lamelle located?
Outer- encircles bone beneath periosteum
| Inner- encircles medullary cavity
96
Define lacunae
| What connects these?
small spaces between lamellae which house the osteocytes
Connected by Canaliculi- channels w/ ECF
97
Where are blood and lymph vessels found within bone tissue?
Central canal
98
Define perforating (Volkmann's) canals
allows transit of blood/lymph vessels to the outer cortex of bone
99
Spongy bone lacks ____
| What replaces them?
Osteons
| Lamellae arranged in lattice of thin columns called Trabeculae
100
Function of Trabeculae?
Spongy bones- support and protect red marrow, helps bones resist stress w/out breaking
101
Define hematopoiesis and where does it take place
blood cell production
| Spongy bone
102
Within each trabecula of spongy bones there are what sub-structures?
Lacunae- osteocyte containing area for bone nourishment via blood circulating through trabeculae
103
What is the name of the process of forming new bones?
Ossification or,
| Osteogenesis
104
What are the 4 situations that bone formation occurs?
Embryo development
Adulthood
Remodeling
Fx repair
105
What are the two different methods of osteogenesis?
Intra-Membrane ossification- (simpler) spongy bone production (can be remodeled into compact)
Endochondral ossification- process where cartilage is replaced by bone (forms both spongy and compact)
106
Give examples of Intra-membranous ossification process
Skull, mandible, clavicle
mesenchyme->develop w/in membrane->NO cartilage stage
Many ossification centers
107
Give examples of Endochondral ossification process
Most bones, especially long bones
Replacement of cartilage by bone
One primary and 2 secondary centers of growth
108
What are the two processes of bone remodeling?
resorption
| deposition
109
Define acromegaly
bones are too thick and heavy
| Too much new tissue
110
Bones can become too soft such as what 2 diseases?
Rickets
| Osteomalacia
111
Steps/process of bone Fx healing
1: 6-8hrs after injury, formation of Fx hematoma from vessels breaking in periosteum and osteons
2/3: formation of callus (wks-6mon), phagocytes remove debris, fibroblasts deposit collagen to form fibrocartilaginous callus
Osteoblasts form bony callus of spongy bone
4: remodeling (several months) spongy replaced by compact, Fx line disappears, evidence remains
112
Function of Vitamin A in growth/remodeling
stimulates osteoblasts activity
113
Function of Vitamin C in growth/remodeling
Collagen synthesis
114
Function of Vitamin D in growth/remodeling
Ca absorption in GI tract
115
Function of Vitamin K/B12 in growth/remodeling
Bone protein synthesis
116
Importance of Ca homeostasis and where is it stored
Synaptic transmission, muscle contraction, blood clotting
| 99% stored in bones
117
Function of parathyroid hormone and bone structure
PH promotes resorption of bone matrix
prevents loss of Ca in urine
Promotes Vitamin D formation
118
Name of Vitamin D and it's main function
Calcitriol- promotes Ca absorption in intestines
119
What is the production site and function of Calcithonin
Produced in parafollicular cells of thyroid gland
| Lowers blood Ca levels by inhibiting reabsorption
120
What are the two main ways Ca blood can be increased?
Release of Ca from bone matrix
| Retention of Ca in kidneys
121
Definition of joints
point of contact between two bones, bone and cartilage, or between bone and tooth
122
Define suture joint
thin layer of fibrous CT
123
Define syndesmoses
more space than suture, more fibrous CT
| Epiphyseal plate
124
Define gomphoses
teeth in sockets of upper/lower jaw
125
What are the components of cartilaginous joints?
Fibrocartilage/hyaline cartilage
No synovial cavity
Little/no movement
126
What are the two types of Cartilaginous joints
synchondroses- primary cartilaginous join; hyaline cartilage connecting bones (may ossify w/ age)
symphyses- secondary cartilaginous; fibrocartilage
127
Characteristics of synovial joints
most moveable
Articular capsule- dense ir/regular
Synovial mem- secretes fluid
May contain articular discs (menisci)
128
List the 4 characteristics of Muscular tissue
irritable
contractable
extensible
elastic
129
What is a single muscle fiber called?
| What is a bundle of muscle fibers called?
myofiber
| Fascicle
130
Define myofibril
organelle in a muscle fiber composed of filaments
131
Define endomysium
Perimysium
Epimysium
What do these 3 join together to form?
Endo- CT surrounding a fiber
Peri- surrounds fascicle
Epi- surrounds entire muscle
Tendons
132
What does eccentric mean
Multi-nucleated (skeletal muscles)
133
Define aponeurosis
*fill in
related to CT and tendons
Slide 7
134
What comprises a motor unit
Somatic motor neuron supplying a group of muscle fibers (1:1)
135
What is a neuromuscular junction
site where neuron contacts the muscle fiber
136
Why are skeletal muscles multi-nucleated?
During embryonic development, myoblasts fuse to form one skeletal muscle fiber
Prevents muscle fibers from being able to undergo mitosis
137
What is the sarcolemma?
| What is the sarcoplasma?
Lemma- plasma membrane of an individual muscle fiber
Plasma- cytoplasm of skeletal muscle fibers
138
Where are sarcoplasm "chocked full"
contractile proteins arranged into myofibrils
139
What is the T-tubule and what are their functions?
Transverse tubules
"cul-de-sacs from outside of fiber towards interior (invaginate from sarcolemma to interior)
Filled w/ interstitial fluid
Propagation of muscle APs
140
Define sarcoplasmic reticulum
Smooth ER of muscle fiber
| Stores Ca ions and releases them during muscle stimulation
141
What is the unique/special protein located in the sarcoplasmic reticulum?
Calsequestrin- Ca binding protein in sarcoplasmic reticulum which enables muscle relaxation to have a Ca concentration 10,000x higher than cytosol
142
Define Terminal Cisterns
| What do the form?
dilated region that flank T-tubules
2 cisterns flanking 1 T-tubule= Triad
143
What is the basic functional unit of a skeletal muscle?
sarcomere: arrangement of filaments between two Z discs
144
Myofibrils are made of smaller structures called?
How many types?
What is their ratio?
Filaments
Thin: actin (contractile) Troponin (regulatory) Tropomyosin (regulatory)
Thick: myosin (contractile)
2 thin:1 thick
145
Filaments inside myofibrils are arranged compartments called ____?
sarcomeres, the basic unit of a myofibril
| Connected at/by Z disc
146
Long chains of sarcomeres are called a ____?
myofibril
147
What structure make up the striation of muscles?
Thick and thin filaments seen in single myofibrils and whole muscle fibers
148
Overlapping of sarcomeres causes zones and bands, what are they?
A band
I band
Z line
M line
H zone
149
Define Z disc
where adjacent sarcomeres abut*
| Center of an I band
150
Define A band
darker zone
| gives length of thick filaments and varying overlap of thin filaments
151
Define I band
only thin filaments
| consist of parts of 2 adjacent sarcomeres
152
Define H zone
center of A band
| only thick filaments
153
Define M line
midline of a sarcomere
154
Thick filament is composed of ____molecules
What do their tails form?
What doe their heads form?
myosin
Tails form thick filaments
Heads (cross bridges): bind/hydrolyze ATP and the products (ADP and phosphate), change shape (to/away from M line) and bind reversibly w/ actin
155
How do proteins link together in thin/thick filaments?
Thin- acting proteins, peal strands
| Thick- myosin proteins, golf clubs bound together
156
What movement in the fine structure allows contraction to begin?
What triggers this?
movement of troponin-tropomyosin complex
Triggered by Ca binding to tropnin
157
Contractile proteins
Regulatory proteins
Structural proteins
Contract- myosin, actin
Reg- troponin, tropomyosin
Structure- titin, myomesin, dystrophin, sarcolemmal proteins
158
Define titin filament and its function
molecule spans half a sarcomere, Z disc from M line
Attaches thick filament to Z disc and M lines
helps sarcomere return to resting strength
159
Function of dystrophin
links thin filaments of sarcomere to integral membrane proteins in sarcolemma
transmits the tensive forces of sarcomere
160
Define Duchenne Muscular Dystrophy
Most common
Gene coding for dystropphin is mutated, results in little/no dystrophin in sarcolemma. Sarcolemma tears easily during contraction leading to rupture and tissue death
161
Where is the AP generated in a muscle cell?
| How does it travel into the muscle fiber?
Neuromuscular junction
| Along entire sarcolemma and down T-tubules to fiber interior
162
Function of neuromuscular junction
synapse between somatic motor neuron and skeletal muscle fiber
163
How is AP carries across a synaptic cleft?
synaptic end close to axon terminal s/ synaptic vesicle filled w/ ACh
ACh carries impulse across
164
Where is the motor end plate and what is it comprised of?
part of sarcolemma opposite of synaptic bulb
comprised of muscle fiber part of NMJ
165
Define junctional folds
ACh receptors, transmembrane proteins in motor end plate residing in deep grooves
166
What happens after ACh binds?
2 ACh opens ion channel in CAh receptor, allowing Na to flow across membrane
Influx of Ca=more pos charge, AP triggered
167
Why is bacterium Clostridium botulinum bad
produces toxin that blocks exocytosis of synaptic vesicle in NMJ
muscular paralysis since ACh is not released, contraction can't occur
168
Explain sliding filament machanism
Exposed myosin binding site on actin (thin filaments), w/ Ca and ATP, thick and thin slide on each other, sarcomere shortened
169
What are the 4 steps of the Sliding Filament Mechansim
1- ATP hydrolysis: myosin heads hydrolyze ATP
2- Attachment: myosin head binds w/ actin, forming cross bridge
3- Power stroke: cross bridge rotate towards sarcomere center
4- Detachment: myosin heads bind ATP, cross bridge detaches from actin (detachment occurs ONLY when ATP bind to myosin heads)
170
How do zones/band length changes during contraction?
H and I: decrease
A: no change, constant
Sarcomere length: decreases
Thick and thin: no change in length
171
Explain contraction process during rigor mortis
3-4 hrs after death
membranes leak Ca, binds w/ Troponin-Tropomyosin, cross bridges attach and complete 1 power stroke
No more ATP production= cross bridges can't detach from actin, produces rigidity
24hrs after death, proteolytic enzymes from lysosomes digest crossbridges
172
Define hypertrophy
increase in muscle fiber diameter
inc organelle number
more myofibrils=more forceful contractions
173
Define hyperplasia
increase in tissue/organ size DUE TO increased cell number
174
What type of muscle growth occurs after birth
hypertrophy of existing muscles
| no hyperplasia, no mitosis
175
What are the 2 primary hormones that stimulate skeletal muscles?
HGH
| testosterone
176
Define myoglobin
red colored protein found only in muscles
similar to HgB (structure, chemistry, function)
Binds O2 and releases for mitochondria during high aerobic respiration
177
What is the use of ATP for muscle contraction?
Na/K pumps- active transport, AP production
Ca ion pumping- active transport, contraction termination
Energizes myosin head in prep for power stroke
178
ATP production is via what 3 things?
creatine phosphate
glycolysis
aerobic respiration
179
What is the sequence of ATP sources during max sustained contraction?
ATP
creatine phosphate
glycolysis
aerobic cellular resp.
180
What are the usual sources of creatine in the body?
Synth in liver, kidneys, pancreas
Derived from milk, red meat and fish
2g/day is needed
excess may cause dehydration and kidney dysfunction
181
The force that a single fiber can produce is primarily dependent on _____?
What is it's frequency?
Rate at which it is stimulated (nerve impulses arriving at the neuromuscular junction)
Frequency- number of impulses per unit time (typically, per second)
182
Define twitch
brief contraction of all muscle fibers in a motor unit
| aka twitch contraction
183
Define use/function of a myograph
| What is it an example of
measures force generated by direct stimulation of either motor neuron/muscle fibers
Transducer- converts one form of energy into another
184
What are the periods of a myograph associated with?
Ca++ movements, stretching and elasticity
185
In reference to myographs, define refractory period
| When does it start and end?
period of time after first stimulus when response to a second stimulus is not possible
Start: stimulation
Ends: early part of contraction period, duration varies
186
Define myograph latent period
Contraction period
Relaxation period
Latent: muscle AP travels over sarcolemma, Ca is released from sarcoplasmic reticulum
Contraction: Ca bind to tropinin, cross bridges form, peak tension develops in muscle fiber
Relaxation: Ca+ actively transported back to sarcoplasmic reticulum, myosin binding sites covered by tropomyosin, myosin heads detach from actin, tension in muscle fibers decrease
187
Define summation
second stimulus occurs after refractory period but before muscle fiber is relaxed, causes second contraction to be stronger than first contraction
More Ca+ is released from sarcoplasmic reticulum
188
What accounts for the initial/apparent gain of strength after starting an exercise routine/program?
more efficient motor recruitment
| not necessarily increased contractile force capability
189
Define motor unit recruitment
number of active motor units is increased according to need
| More neurons activated in spinal cord, more motor units will be stimulated, more muscle tension will be produced
190
What motor units are recruited first/last during contraction?
```
First= smallest/weakest
Last= larger, stronger
```
191
Cardiac muscle contraction lasts _-_x longer than a skeletal muscle contraction
How is this accomplished?
Cardiac= 10-15x
| O2 delivery by coronary circulation to generate ATP through aerobic respiration
192
Cardiac muscle exhibit what unique capability
| How do they maintain this?
autorhythmicity
75/min
Altered by NS and endocrine system
Larger/numerous mitochondria
193
How does smooth autorhythmic muscle generate ATP?
anaerobic respiration (glycolysis)
194
What types of filaments are in smooth muscles?
Thick, thin and intermediate
Intermediate attach to dense bodies (functionally similar to Z discs) found in sarcoplasma and sarcolemma
Contraction of thick and thin generates tension on intermediates, pulls dense bodies and causes shortening
195
What are the two types of smooth muscle?
Single unit smooth- AKA visceral smooth
Multiunit smooth
Distinguished by number of fibers that comprise a motor unit
196
How are the two types of smooth muscle distinguished?
Visceral- smooth muscle fibers connect to one another by gap junctions and contract as a single unit
Multiunit- lack gap junctions and contract independently
197
Exercise induced muscle damage is evident in what phycical/chemical parts of muscle/what structures?
Physical:
Torn sarcolemmas
Damaged myofibirls
Disrupted Z discs
Chemical:
increased blood levels of myoglobin and creatine kinase
198
Define DOMS
Delayed onset muscle soreness
| 12-48hrs later, microscopic muscle damage is major factor
199
Define muscle fatigue
| What does it result from?
inability of muscle to maintain force of contraction after prolonged activity
Changes within muscle fibers: inadequate Ca ion release, depleted creatine phosphate, low O2/glycogen, increased lactic acid and ADP, failure of action potential to release acetylcholine
200
What condition precedes muscle fatigue
Central fatigue- tiredness and sensation to cease activity
201
Define muscle tone
Small tension/contraction in muscle caused by involuntary contractions of motor units
Established by neurons in brain and spinal cord
202
Why is muscle tone important?
Posture, pressure on digestive organs, BP
203
Define flaccid
state of limpness where muscle tone is lost
| Caused by severed motor neurons in skeletal muscles
204
Neuromuscular disease is a disease/damage to what 3 components of the motor unit?
Somatic motor neuron
Neuromuscular junctions
Muscle fibers
Neuromuscular disease encompasses problems at all 3 sites
205
Define Myasthenia Gravis
Autoimmune disease
Causes chronic/progressive damage of neuromuscular junction by producing Abs that bind and block acetylcholine receptors, decreases number of functional receptor at motor end plates
Causes weakness/fatigue and eventual loss of muscle function
206
Define spasm
sudden involuntary contraction of single muscle that is part of a large group of muscles
207
Define cramp
painful spasmodic contraction
| Caused by inadequate blood flow, overuse, dehydration, extended holding/flexion, low electrolytes
208
Define tic
spasmodic twitch made involuntary by muscles that are ordinarily under voluntary control
209
Define tremor
rhythmic, involuntary contraction that produces quivering/shaking
210
Define fasciculation
brief involuntary twitch of an entire motor unit that is visible under the skin
occurs regularly and is not associated w/ movement of affected muscle
211
Define fibrillation
Spontaneous contraction of single muscle fiber that isn't visible under skin but is detectable by electromyography
May cause signaling for motor neuron destruction
212
Define myopathy
Disease or disorder of skeletal muscle tissue
213
Define muscle strain
Forceful stretching/tearing of muscle fibers
| Quadriceps femoris frequently affected
214
Define myalgia
pain in/associated w/ muscles
215
Define myoma
tumor of muscle tissue
216
Define myositis
inflammation of muscle tissue
217
Define myotonia
slow relaxation/decreased ability to relax muscles after voluntary contraction
May be accompanied by increased muscular excitability and contractility
218
Define Myomalacia
pathological softening of muscle tissue
219
What is in the CNS?
| What is in the Peripheral NS?
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CNS= Brain and Spinal cord
PNS= cranial nerves (12 pairs)
spinal nerves (31 pairs)
Peripheral nerves (numerous)
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220
What components make up the entire nervous system?
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Brain
Spinal cord
Spinal nerves
Ganglia
Enteric plexuses
Sensory receptors
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221
Define sensory nerves
Detect changes internally/externally
Carry sensory info from receptor to brain/spine
Afferent neurons
222
Define integrative nerves
Analyze and store info, makes decisions
| Most are interneurons- short neurons in brain, spine and ganglia
223
Define motor nerve
Respond to decisions
Carry info from brain/spine to effectors (muscle/gland)
Efferent neurons
224
Define somatic nerve
Sensation from body wall, limbs, head, special senses
| Motor control of skeletal muscle
225
Dfine autonomic nerve
Sensation from internal organs
| Motor control of smooth and cardiac muscle and glands
226
Define enteric nerve
Sensation of GI tract
| Motor control of smooth muscles and glands of GI tract
227
Difference between neuron and ganglion
Nerve: association/bundle of neuronal axons in PNS
Ganglion: group of neuronal cell bodies in PNS and associated tissues
228
Define tract
association/bundle of neuron axons in CNS
229
Define nucleus
bundle of unmyelinated nerve cells in CNS
230
Define plexus
Nerve network in PNS
| Can also apply to network of veins/lymph vessels
231
Define neuron
Electrically excitable
| Adapted to produce/transmit AP
232
Define neuroglia
NS cells that support, nourish and protect neurons
More neuroglia than neurons
233
What are the basic parts of the neuron
Cell body
| Fibers- axon, dendrites
234
What is the axoplasm
| What is the axolemms
plasm- axon cytoplasm
| lemma- axon plasmalemma
235
What organelles do neurons have?
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Nucleus
Cytoplasm
Lysosome
Golgi
Mitochondria
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Nissi bodies- clusters of RER
236
What are the special functional adaptations of neurons
Dendrites- little trees, receiving portion of neuron. Short, tapered, highly branched
Axon- propagates impulse to next neuron/muscle/nerve
Can reach up to 3ft long
Do not replace, no mitosis
237
Define axon hillock
small hill
| elevation in cell body that axon arises from
238
Where does the AP originate from?
Trigger zone of neuron
| Junction of hillock and initial segment
239
What is the first part of the neuron called?
| What happens if axon is cut?
initial segment
| distal fragment dies
240
What organelles do axons have?
| What organelle is not found in axons?
Mitochondria
Microtubules
Neurofibirls
RER, no protein synth. Takes place in cell body
241
Define telodendria
| How do the terminate?
Axon terminals
Synaptic end bulbs
Varicosities- string of swollen bumps
242
What are the 2 components of the neuron cytoskeleton?
Neurofibrils- intermediate filaments, provide shape/support to cell
Microtubules- tubulin, move material between cell body and axon
243
Define slow axonal transport
one way only from cell body -> terminals
| transports to growing/regenerating axons
244
Define fast axonal transport
2 way transport
Microtubules are used as tracks/motors
Transports organelles and materials to form axolemma membranes, synaptic bulbs and vesicles
245
Define structural classification
Based on number of axon/dendrite processes extending from cell body
246
Define multipolar neuron
Several dendrites, only one axon
Located in brain and spinal cord
Composes vast majority of neurons in human body
247
Define bipolar neuron
One dendrite, one axon
Convey special senses signals
Located in retina, inner ear and olfactory area of brain
248
Define unipolar neuron
Pseudounipolar neuron
One process: from body -> central branch that functions as axon
Employed as sensory neurons that convey touch and stretch info from extremeties
249
Define neuroglia
Non-excitable support cells
Smaller and more numerous than neurons
Compose half of CNS volume, will occupy space lost during injury/disease
250
Which neuroglias are found/located in the CNS?
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
251
Where are neuroglia located in the PNS?
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Schwann cells (neurolemmocytes)
Satellite cells
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252
Function of astrocytes
Regulate ECF composition in CNS
Help form BBB
Absorb excess neurotransmitter
Influence neural synapse formation
253
Function of oligodendrocyte
Myelinate axons in CNS
254
Function of microglial cells
Phagocytes of CNS
255
Function of ependymal cells
Line brain ventricles
Produce/monitor/aid in CSF circulation
For BBB/CSF barrier
256
Function of Schwann cells
Myelinate axons in PNS
257
Function of satellite cells
Second type of PNS neuroglia
| Structural support and regulate materials between neuronal cell bodies and intersticial fluid
258
Difference in replication of nervous system cells
Neurons- no mitosis
| Neuroglial cells- do mitosis
259
Define glioma
brain tumor of glia
| includes astrocytomas, oligodendrogliomas, and schwannomas
260
What two cells perform myelination?
Schwann-PNS
| Oligodendrocytes- CNS
261
Define myelin
| What is their function?
multi-layered complex of lipids and proteins (layers of plasma membranes)
Prevent loss of electrical signal and speeds nerve impulse conduction
262
What type of cell is a Schwann cell?
neurolemmocyte
263
Myelination cells can be associated w/ unmyelinated cells. What is required for myelination?
Glial cell to wrap its plasma membrane around the axon several times, covers 1mm
264
Define neurolemma
Outer nucleated cytoplasmic layer of Schwann cell which encloses myelin sheath
Found only around axons in PNS
265
How are unmyelinated axons associated w/ Schwann cells?
Axons lay in grooves on surfaces of Schwann cells, no myelin sheath and no neurolemma
266
What happens to the nucleus of the Schwann cell during the myelination process?
Neurolemmocyte nucleus ends in the neurolemma (outer nucleated cytoplasmic layer of the Schwann cell)
267
Define Nodes of Ranvier
Only located on nerve fibers supplied by potentially myelin-producing cells
Gaps between myelinating cells
Found in both C/PNS
268
What does a nerve fiber consist of?
Axon and myelin sheath
| Endoneurim surrounds nerve fiber (this includes Schwann cells)
269
How is myelination in the CNS achieved?
Oligodendrocytes- can myelinate several segments of one axon or myelinate several axons
270
What structure is not present in CNS myelination?
Neurolemma, oligodendrocyte cell body and nucleus do not envelop axon
271
What is the difference between gray and white matter in CNS?
White: predominantly filled w/ myelinated tract fibers, white due to myelin
Gray: predominantly filled w/ neuronal cell bodies, Nissi bodies provide gray color since there is no myelin
272
What are the two types of electrical signals used by neurons to communicate?
AP: (nerve impulses), for short and long term communication, :all or none"
Graded potential: short distance/localized communication. A/effects generation of AP, not "all or none"
273
AP and graded potentials depend on what two features of the plasma membrane?
Existence of a resting membrane potential
Specific ion channels
274
Where is voltage measured?
Across plasma membrane, relative to outside of the cell
275
Where are the nodes of a microelectrode placed?
Recording: inside neuron
Reference: ECF
276
If opposite charges are separated in space, what is the potential?
Their attractive force= potential
| Measured in Volts
277
Define current
Flow of charged atoms or molecules
Electrical current: flow of e-
Body: current means flow of ions
278
What gives the cells the property of electrical excitability?
Ion channels in plasma membrane of neurons and muscle fibers
279
Types of ion channels and their characteristics
Leakage: randomly open/close; more for K+ than Na+; resting membrane is more K+ permeable
Ligand gated: bound to by ligand, controls open/close
Mechanical gated: open in response to mechanical stimuli (tension due to pressure)
Voltage gated: open/close in response to changed in membrane potential
280
Define resting membrane potential
Voltage difference across plasma membrane when neuron is NOT signaling
Membrane is polarized
281
How is resting membrane potential reported?
| What is the range and average (mV) of the potential?
Reported as the potential of INSIDE of membrane relative to OUTSIDE of membrane
Range: -40mV - -90mV w/ -70 average
282
What causes the resting membrane potential?
Anion build up in cytosol
| Cation build up in ECF
283
What ions are in higher concentration in ECF?
| What ions are in higher concentration in the ICF?
ECF: Na and CL
ICF: K, organic phosphates, aa and proteins
284
Resting membrane is ___-___x more permeable to _ than to _
50-100x
K+ than to Na
Cl is in between
285
Membrane is impermeable to all of what molecule?
negatively charged intracellular molecules
286
What two channels produce graded potentials in response to stimuli?
Ligand gated
| Mechanical gated
287
What does "graded" mean in graded potential?
Size of the change in the membrane potential varies in proportion to strength of stimulus (all-or-none)
288
How far to graded potentials travel?
Short distance then diminishes to zero
289
Define hyperpolarization
| Define depolarization
Hyper: membrane is more polarized (more negative)
Depol: less polarized (less neg, more pos)
290
Depolarization opens what ion channels?
Repolarization opens what ion channels?
Resting state has what channels open/close?
Na+, depolarization to -55mB threshold
Opens K+, closes Na+
Resting: K+ closed
291
What effect does Ca+ have on the electrical state of a channel protein?
Pos charge of Ca+ increases voltage level required to open the gate
292
What happens during calcium ion deficit
Ca deficit, Na channels activated by very little change of membrane potential
Nerve fibers become highly excitable, sometimes w/out provocation and not remaining in resting state
293
Why is calcium ion deficit dangerous?
Low Ca= muscle contraction/cramps, tetany
Tetanic contraction of respiratory muscles can be fatal
294
Where is the trigger zone of nerve impulses?
Axon hillock
295
Define propagation
| What is it dependent upon?
aka conduction
nerve impulse movement down neuron to axon terminals
Dependent on positive feedback
296
What are the types of conduction?
Continuous: step by step depol/repol of adjacent segments
Saltatory: special mode occurring only along myelinated axons, faster and more energy efficient
297
Where are voltage gated channels concentrated?
Nodes of Ranvier
298
How do neurons produce their ATP?
Mostly: aerobic metabolism of glucose
299
How is most of the brain's energy consumption used?
Sustaining electrical charge of neurons
300
Effect of axon diameter through A, B and C fibers
A: Large, myelinated
B: medium, myelinated
C: small, unmyelinated
301
What two mechanisms enable stimuli of different intensities to be registered?
Frequency
| Number of sensory neurons activated
302
How does intensity perception get conveyed into impulses?
Frequency: light touch= low frequency
Number: firm pressure stimulates more pressure neurons
303
What stimulus does not generate an AP?
sub-threshold stimulus
304
Define synapse
junction between two neurons
| junction between neuron and an effector (muscle or gland)
305
What are the 3 common types of chemical synapses
Axodendritic- axon to dendrite
Axosomatic- axon to soma
Axoaxonic- axon to axon
306
Difference between electrical and chemical synapse
Electrical: physically touch, AP moves through as ions flow
Chemical: do not touch, neurotransmitter bridges gap and allows AP to travel
307
How are action potentials conducted between adjacent cells?
Gap junctions
| Hundreds of connexons per gap junction connect cytosol
308
Where are electrical synapses found?
Heart muscle fibers
| Visceral smooth muscle
309
Neurotransmitters that cause hyperpolarization of the postsynaptic membrane are ______
inhibitory
310
Excitatory postsynaptic potential typically result from opening of what kind of channels?
ligand-gated CATION channels
| Na, K and Ca
311
Does one EPSP initiate a nerve impulse?
No, but becomes more excitable and more likely to reach threshold since it's partially depolarized
312
Difference between EPSP and IPSP
IPSP: opening of ligand gated ANION channel for Cl or ligand gated K
313
What would happen if a neurotransmitter was not removed from a synaptic cleft?
Continuous influence of postsynaptic neuron/fiber/gland
314
How are neurotransmitters removed?
Diffusion
Degradation- Acetylcholine broken down to acetyl and choline by acetycholinesterase
Cell uptake: reuptake if taken by same cell that released; uptake if taken back by cell that didn't release originally
315
Define neurotransmitter transporters
Membrane proteins that accomplish neurotransmitter uptake
316
Define Spatial summation
Neurotransmitter builds up and released simultaneously by presynaptic end bulbs
317
Define Temporal Summation
Neurotransmitter buildup and released by single presynaptic end build many times in succession
318
Look at slide 17
Analyze
319
What are the two classes of neurotransmitters?
Small molecule
| Neuropeptides
320
What are the small molecule neurotransmitters?
```
Acetylcholine
Amino acids
Biogenic amines
ATP/purines
Nitric oxide
```
321
What kind of junctions does ACh open?
@ neuromuscular junctions, opens ligand-gated CATion channels
322
Where is ACH released from?
Many PNS neurons
| Some CNS neurons
323
What are the two most common excitatory examples of amino acids?
Most common inhibitory?
Glutamate (glutamic acid)
Aspartate (aspartic acid)
Inhib: aminobutyric acid (GABA) and glycine
324
Where are exogenous amines absorbed?
Directly by intestines
325
Biogenic amines as neurotransmitters are generally associated with ____
and produce what kind of stimulus
Brain
Excitatory or inhibitory
Naming and categories, not BioChem heavy
326
What are the classical monoamine neurotransmitters
Histamine- arousal/attention and pro-inflammatory
Serotonin- sensory perception, temp regulation, mood/sleep and appetite
Catecholamine neurotransmitters
327
What are the catecholamine neurotransmitters
Dopamine- emotional response, addiction, pleasure, skeletal muscle tone/contraction
Norepinephrine- wakening from deep sleep, dreaming, mood regulation
Epinephrine- used by brain neurons
328
Where is norepinephrine made?
adrenal medulla
329
Where is NO gas made?
Endothelial cells in vessel walls
Lipid soluble, diffuses->smooth muscles causing vasodilation
Produced on demand
330
Characteristics of neuropeptides
Short chain AA linked by peptide bonds
In both CNS and PNS
Excitatory and inhibitory
Formed in neuron body, packed in vesicles, transported to axon terminals
As hormones, regulate physiological responses
331
What are the opioid peptides?
Enkephalins
Endorphins
Dynorphins
Body's natural pain killers
332
Define neural circuit
billions of neurons in CNS that are a functional group that process specific kind of information
333
Define simple series circuit
One presynaptic neuron, stimulates one post-synaptic neuron which stimulates another
334
Define diverging circuit
AP diverges which amplifies original signal
| Sensory signals
335
Define converging circuit
AP convergence
More effective stimulation/inhibition
Motor neuron->skeletal muscles
336
Define reverberating circuit
Branches from subsequent stimulate neurons loop back and form a circuit
Can last seconds->hrs
Breathing, waking up, short-term memory
337
Define parallel after-discharge circuit
One input w/ one output neuron and variable intermediate neurons
338
Define plasticity
NS ability to change based on experience and need
339
How can neurons change during plasticity?
New dendrites
Synthesize new proteins
Nature/number of synapses
340
How can PNS perform repair/regeneration?
Dendrites and myelinated axons can undergo repair if cell body remains intact and myelinating Schwann cell is still active
341
How does the sheath of Schwann conduct repairs?
Neurolemma forms regeneration tube to guide/stimulate axon regrowth
342
In myelinated axons, voltage gated channels are concentrated around what structures?
Nodes of Ranvier
343
What happens if the myelin sheath is destroyed?
Current can't spread as far and can't reach next group of voltage-gated channels
344
Two disease examples of myelin destruction
Guillain-Barre Syndrome: PNS (result of bacteria infection)
| Multiple Sclerosis: CNS (autoimmune)
345
Epileptic seizures are commonly called what other name?
| What is their most common cause?
electrical storm
| Brain damage at birth
346
What is rabies considered a fatal disease?
Virus reaches CNS by fast axonal transport
347
How do local anesthetics produce their desired effect?
Block opening of voltage gated Na channels, prevents transmission of pain signals
