Exam 2 Flashcards
Name the basic tissue type
- Sheets of cells covering a surface or lining a cavity
- responsible for the major function of most organs
EPITHELIUM
Name the basic tissue type
- Cells and ECM (extracellular matrix) that support and connect other basic tissue in organs
- Includes bone/cartilage/blood
CONNECTIVE TISSUE
Name the basic tissue type
-contractile tissues
MUSCLE
Name the basic tissue type
-Conductive tissues that distribute signals that control various body functions
NERVOUS TISSUE
Nervous system is divided into what? Further division?
1) CNS - central nervous system (Brain and Spinal cord)
2) PNS- peripheral nervous system (cranial, spinal and peripheral nerves)
* *Afferent - brings SENSORY info (about touch, taste, smell, sight and sound) from the periphery TOWARD the CNS
* *Efferent- carries MOTOR info to the periphery FROM the CNS
What are the 2 main cells if the CNS and their function? How are these 2 cells further classified?
1) Neurons - conducting cells (classified based on number of dendrites and axons
* MULTIPOLAR. *UNIPOLAR. *BIPOLAR
2) Glia - non-neuronal supporting cells with different functions
(Smaller than neurons with dark staining nuclei, highly branch, DO NOT CONDUCT)
* ASTROCYTES
*OLIGODENDROCYTES
*EPENDYMAL CELLS
*MICROGLIA
What are the 3 parts of a Neuron?
SOMA
AXON
DENDRITES
Name the part of a neuron
-can be a few or many branched processes that RECEIVE SIGNALS
Smaller branches are spines where synapses form
DENDRITES
**smaller branches on dendrites are DENDRITIC SPINES where SYNAPSES with axons form (the branches INCREASE surface area available for synapse)
What can be found in a neuron SOMA
Cell body (perikaryon) containing cytoplasmic organelles
- LARGE nucleus with prominent nucleolus
- MANY dark staining basophils NISSL BODIES (areas of RER and polyribosomes)
- Golgi, mitochondria, lysosomes, microtubules and neurofilaments
- LIPOFUSCIN- yellow pigment granules
Name the part of a neuron
- long process extending from pole opposite dendrites which CONDUCT SIGNAL as an action potential to a target cell (either another neuron or a muscle)
- Has a hillock near the start and a terminal at the end
AXON
Axon HILLOCK- clear area of CELL BODY, NO NISSL BODIES, near the start of the axon
Axon TERMINAL- small branches at the end of the axon that MAKE SYNAPTIC CONTACT with the target cell
How many types of atonal transport do we have? What are they?
2 types
FAST axonal transport (Anterograde and Retrograde)
SLOW axonal transport (ANTEROGRADE ONLY)
Name the axonal transport
- toward the axon TERMINAL
- 100-400 mm/day
- uses KINESIN
- Vesicles that bud from the golgi can be used as (precursors for NTs, enzymes that make small NTs, plasma membrane proteins)
- Mitochondria
- Tracers (to see where cell body is/target)
FAST Axonal Transport - ANTEROGRADE
Name the Axonal transport
- toward the CELL BODY
- 50-200 mm/day
- uses DYNEIN
- Has ENDOCYTIC VESICLES (trophies factors e.g NGF)
- Mitochondria
- Viruses and toxins (herpes simplex, rabies, polio, tetanus toxin)
- Tracers
FAST Axonal Transport - RETROGRADE
Name the Axonal Transport
- 0.2-0.4 mm/day
- toward the AXON TERMINAL
- HAs CYTOSKELETAL PROTEINS (tubular, actin, neurofilaments)
- Has CYTOPLASMIC PROTEINS (Enzymes, calmodulin)
SLOW Axonal Transport - ANTEROGRADE
** Slow axonal transport has ONLY ANTEROGRADE direction (move TOWARD the AXON TERMINAL)
Axon terminal of a presynaptic cell is filled with what that contains what?
What can these perform?
What are the targets?
- Synaptic vesicles that contain Neurotransmitters
- Perform SYNAPSE
- Targets may be other neurons, muscles or glands
Name the types of neurons based on number of dendrites and axons and GIVE EXAMPLES
1) NUMEROUS branched DENDRITES, SINGLE AXON
2) SINGLE DENDRITE, SINGLE AXON
3) SINGLE BIDIRECTIONAL AXON
1) MULTIPOLAR (All motor neurons and interneurons)
2) BIPOLAR (sensory neurons found in eye, ear, olfactory epithelium)
3) UNIPOLAR/pseudounipolar
* * originally bipolar during development
* * one branch to CNS, other to PERIPHERY
* * cell bodies of SENSORY neurons found in GANGLIA
Tell me about the origin(s) of GLIAL in the CNS
What are the origins of the respective glial cells?
2 MAIN ORIGINS
1) Derived from NEUROEPITHELIAL stem cells
* Oligodendrocytes - produce myelin in the CNS (smaller than astrocytes)
* Astrocytes - Protoplasmic (found in gray matter) and Fibrous (found in white matter)
* Ependymal cells
2) Derived from MONOCYTES
* Microglia- phagocytosis cells similar to macrophages (clean up debris)
The plasma membrane of SUPPORTING CELLS form a PROTECTIVE INSULATION in CNS and PNS.
What is this protective insulation called?
What supporting cells form this in CNS and PNS respectively?
There are GAPS in this protective insulation where adjacent cell processes meet.
What are these gaps called? Function?
MYELIN SHEATH
CNS- Oligodendrocytes (myelinate numerous axons)
PNS- Schwann cells (myelinate individual axon)
NODES OF RANVIER - gaps in the myelin sheath where adjacent cell processes meet (propagate AP down the axon length)
Name the Nodes of Ranvier
- region btw adjacent myelin sheaths
- region where cytoplasmic loops of myelinating cell overlap next to the node
- region adjacent to the paranode
- region btw juxtaparanodes of a single myelin sheath
What is the format/arrangement
NODE
PARANODE
JUXTAPARANODE
INTERNODE
** Regions have concentrations of specific ion channels and transporters
IJP-N-PJI (format)
Compare myelination in CNS vs PNS
Unmyelinated axons in PNS?
CNS
—Oligodendrocytes myelinate multiple axons
-Nodes “open”, but may be in contact with astrocytes
-No basal lamina
PNS
- Schwann cell myelinates single axon
- Schwann cell protrusions overlap nodes
- Schwann cell rests on BASAL LAMINA
- Schwann cells can also envelope MULTIPLE UNMYELINATED axons
- Schwann cells enveloping both the myelinated and unmyelinated axons are surrounded by BASAL LAMINA
Name the glial supporting cell
- Largest and most abundant glial cell
- many processes give a STAR shaped appearance
- Large OVAL NUCLEUS
- express the intermediate filament protein GFAP
- END FEET CONTACT - (capillaries and the inner surface of the pia mater, areas of neurons without myelin)
- Control the environment surrounding neurons (part of the BLOOD-BRAIN BARRIER, nutritional support, NT uptake (potassium and glutamate), electrolyte balance)
ASTROCYTES
- In response to injury, cells divide and form scar tissue
- *Form the GLIA LIMITANS
- glia limiting membrane
- impermeable barrier formed by branched processes of astrocytes extending to the basal lamina of the pia mater
- surrounds the brain and the spinal cord
Name the glial cell
- Simple CUBOIDAL To COLUMNAR epithelial cells lining the ventricles of the brain and the central canal of the spinal cord
- Cilia and microvilli on the apical surface
- DESMOSOMES btw adjacent cells
- Basal processes may contact blood vessels or astrocytes
EPENDYMAL CELLS
- *Cilia- facilitate movement of CSF through central canal of spinal cord
- *Microvilli- may have some absorptive functions
Name the glial cell
-Derived form monocytes that migrate to the brain
(Respond to tissue injury and participate in immune response, PHAGOCYTIC)
-SMALLEST glial cells with IRREGULAR SHAPE and dark staining nucleus
MICROGLIA
Describe Neuronal Degeneration and the events that occur in the CELL BODY, DISTAL AXON, PROXIMAL AXON
CELL BODY
- swelling displaces nucleus to periphery
- chromatolysis (dispersion of nissl substances to periphery0
DISTAL AXON (Wallerian degeneration)
- loss of connection to cell body
- Degeneration
- removal of debris
- scar formation
PROXIMAL AXON
- maintains connection to cell body
- Degeneration back 2-3 internodes
During neuronal DEGENERATION :
What Removes debris in CNS and PNS?
What cause Scar formation in CNS and PNS?
Removal of debris
CNS - MICROGLIA
PNS - MACROPHAGES
Scar formation
CNS- fibrous ASTROCYTES proliferate
PNS- FIBROBLASTS form scar
Tell me about Neuronal REGENERATION in CNS and PNS respectively
What prevents regrowth of axon in CNS?
What 2 things help direct axonal sprouts to correct target in PNS?
What is the name of the AXONS that were not able to find their way to the proper sheath to connect to target? PAINFUL when irritated?
CNS
-scar formed by astrocytes prevents regrowth of axon
PNS
-ENDONEURIAL SHEATH (in intact) and SCHWANN cells act as a quite for directing axonal sprouts to correct targets
(laminin and growth factors)
-proliferation of Schwann cells and myelinization of regrowing axon
-eventual reconnection to target
NEUROMA
(Severed ends too widely separated, scar forms barrier)
The CNS is composed of Gray and White mater. Differentiate btw the 2
Which has NEUROPIL?
Which has NO NEURONAL CELL BODIES?
Which has unmyelinated vs myelinated axons?
GRAY MATTER
- OUTER surface of the cerebrum and cerebellum
- central region of the spinal cord
- consist of ; NEURONS (cell bodies and dendrites), UNMYELINATED AXONS, Neuroglia
- NEUROPIL -densely packed region of cell processes
WHITE MATTER
- Primarily; MYELINATED AXONS (some unmyelinated axons), Oligodendrocytes, blood vessels
- NO NEURONAL CELL BODIES
Brain is made up of
Meninges
Cerebral Cortex
Cerebellum
Which is the connective tissue coverings of the brain and the spinal cord?
What are the layers?
What are the CT types for the different layers?
Which layer is adjacent to nervous tissue?
What acts as shock absorber?
MENINGES
Layers
1) DURA MATER - outer covering of DENSE connective tissue
2) ARACHNOID MATER- middle layer of LESS DENSE CT
* *Has the Sub-arachnoid space (Network of collagen and elastin fibers filled with CSF that acts as SHOCK ABSORBER)
3) PIA MATER - Inner layer ADJACENT TO NERVOUS TISSUE of LOOSE CT (carries blood vessels)
Brain is made up of
Meninges
Cerebral Cortex
Cerebellum
Which has Gray matter, white matter and PYRAMIDAL NEURONS?
Gray matter is composed of how many layers of cells? What are they? WHat is the Outermost/Innermost layer
Which has myelinated axons?
WHere does the name pyramidal come from?
CEREBRAL CORTEX 1) Gray matter -composed of 6 layers of cells **a) molecular layer -OUTERMOST, external granular layer, external pyramidal layer, Internal granular layer, Internal pyramidal layer, **f) multiform layer -INNERMOST -contains many neurons and glia
2) White matter
- internal to the gray matter
- composed of MYELINATED AXONS
3) PYRAMIDAL NEURONS
- smaller ones in external pyramidal layer
- larger ones in internal pyramidal layer
- NAME from PYRAMIDAL SHAPE of the cell body
- dendrites project toward surface
- Axons extend into the white matter
Brain is made up of
Meninges
Cerebral Cortex
Cerebellum
Which has molecular, PURKINJE and granular layer?
CEREBELLUM
3 layers
1) Molecular- OUTERMOST, mostly fibers and a few neurons
2) PURKINJE -middle
* *Purkinje cells (most prominent cell, large cell bodies in a single layer btw the molecular and granular layers, extensively branched dendrites into molecular layer)
3) Granular- Inner, MANY SMALL NEURONS
Orientation of Gray and White mater in SPINAL CORD?
How is this different from the brain?
What does dorsal and central horn of spinal cord contain?
SPINAL CORD
Silver staining
Gray matter - lighter in color (yellow) - MORE INSIDE - CENTRAL CANAL
White matter - darker in color (brown) - MORE OUTER- contains ascending and descending myelinated axons and glia
Posterior/DORSAL horn- SENSORY fibers of DORSAL ROOT GANGLION
Anterior/Ventral horn - Cell bodies and fibers of MOTOR NERVES
BRAIN/CEREBRAL CORTEX
Gray mater- MORE OUTSIDE
White Mater- MORE INSIDE
The nerves and supporting cells that are found outside the CNS are called?
What is this system made up of?
PNS - Peripheral Nervous System
-Made of cranial and spinal nerves and associated ganglia
NAme the layer(s)of Peripheral Nerves
- DENSE CT layer that surround the peripheral nerves and BINDS MULTIPLE FASCICLES together
- THINNER LAYER of CT that surround the BUDLES of AXONS(fascicles)
- THIN LAYER of LOSSE CT that surround EACH AXON and its associated SCHWANN CELL
EPINEURIUM
PERINEURIUM
ENDONEURIUM (vascular CT layer)
Enteric ganglia of PNS is made up of what plexus?
1) AUERBACH’s plexus
- Myenteric (found btw the two layers of the muscularis externa)
2)MEISNER’s Plexus
**controls motility and secretion in the intestinal tract
Skin sensory receptors are composed of;
Free nerve endings, market discs, Krause end bulbs, root hair plexus, MEISSNER corpuscles, PACINIAN corpuscles, ruffing endings
Which are receptive to touch?
Markel discs Krause end bulbs Root hair plexus MEISSNER corpuscles **First 4 are TOUCH ONLY
PACINIAN corpuscles (pressure, vibration, touch)
Skin sensory receptors are composed of;
Free nerve endings, market discs, Krause end bulbs, root hair plexus, MEISSNER corpuscles, PACINIAN corpuscles, ruffing endings
Which are receptive to pressure?
PaCINIAN corpuscles (pressure, vibration, touch)
Ruffini ending (ONLY PRESSURE)
Name the Skin sensory receptor
- Receptive to TOUCH
- Found in the DERMAL PAPILLA of THICK SKIN
- Encapsulated
MEISSNER corpuscles
Name the skin sensory receptor
- Receptive to PRESSuRE, vIbrATION, TOUCH
- ONION appearance
- Found in the HYPODERMIS of THICK Skin
PACINIAN Corpuscles
Name the sensory receptor
Has
- Muscle spindle
- Golgi tendon organ
MUSCLE SENSORY RECEPTORS
Taste sensation is recognized by TASTE BUDS
Taste buds are found in what types of PAPILLAE on the surface of the tongue ?
What are all the types of papillae?
All papillae is covered by what type of epithelium?
Which papilla has no taste buds?
Which is not well developed in humans?
4 Types of PAPILLAE
1) FILIFORM -entire surface of the tongue, small pointed with keratin at tip, NO TASTE BUDS, MOST NUMEROUS, smallest papillae
2) FUNGIFORM -anterior region and tip of tongue, TASTE BUDS found on APICAL surface of PAPILLA, MUSHROOM LIKE shape
3) CIRCUMVALLATE -posterior region, characterized by DEEP FURROW, multiple TASTE BUDS face the furrow
4) FOLIATE -posterior sides of tongue, TASTE BUDS on SIDES of PAPILLA, Not well developed in humans
**All papillae covered in STRATIFIED SQUAMOUS EPITHELIUM
Taste bud structure?
What 3 cells does it contain?
How it works
location of taste buds?
How it works
TASTANTS
-open pore, bind receptors n receptor cells , initiate a signal cascade, release chemical mediator that stimulate afferent nerves
3 CELLS
1) GUSTATORY/TASTE Cells - located with each taste bud, extend the base of the taste bud to the taste pore. Apex of each taste cell has MICROVLLI for absorption
2) SUSTENTACULAR cell
3) BASAL CELLS -undifferentiated, stem cells for the other 2 cells types in taste buds
LOCATION
Tongue (most numerous), soft palate, pharynx, epiglottis
COMponents of Olfaction receptors
Does it have goblet cells? What has goblet cells?
What are the cell types
What is the CT that lines the olfactory epithelium called?
What covers bone of olfactory region?
PSEUDO STRATIFIED olfactory epithelium - found on surface of SUPERIOR CONCHA, adjacent septum and roof of nasal cavity
(NO GOBLET CELLS, NON MOTILE CILIA - function as ODOR receptor)
CELL TYPES
- Apical supportive
- Olfactory cells (BIPOLAR NEURONS)
- Basal cells
- Transition to respiratory epithelium
- **LAMINA PROPRIA -CT underlying epithelium , also covers bone of olfactory region
How does olfaction work through the LAMINA PROPRIA
What secrete the serous fluid?
What warms inspired air?
-UNMYELINATED nerve fibers carry axons of BIPOLAR NEURONS to olfactory bulb.
-**The base of the olfactory cells convert to axons that leave the epithelium by continuing through the basement membrane, converge in the connective tissue below the epithelium to form bundle of nerve fibers that
pass through the ethmoid bone of the skull, and synapse in the olfactory bulb of the brain (olfactory, or cranial nerve I).
- BOWMAN’s GLAND- secrete serous fluid - dissolve odor so they can bind to receptors on the NON-MOTILE cilia of BIPOLAR NEURONS
- BLOOD VESSELS- warm inspired air
Muscle fibers are composed of Skeletal, Cardiac and Smooth Muscle
Name the muscle respectively:
- A single long MULTINUCLEATED cell with FLATTENED NUCLEI on the periphery
- An INDETERMINABLE number of cells joined end to end, each with 1 or 2 ROUNDED NUCLEI
- A single cell with a SINGLE NUCLEUS in the CENTER
- SKELETAL
- CARDIAC
- SMOOTH
Name the Muscle
-VOLUNTARY
-Has Muscle fiber/cells made of bundles of MYOFIBRILS (grp of actin and myosin filaments)
**SARCOPLASMIC RETICULUM (store calcium) -closely associated with group of MYOFIBRILS
-Each fiber surrounded by layer of CT called ENDOMYSIUM
-MOTOR END PLATES are the site of nerve innervations and transmission of stimuli to muscle
-axon terminal of motor end plate has
Neuromuscular Junctions /motor end plates with Ach NT. And AchE to inactive excess Ach
SKELETAL MUSCLE a
For SKELETAL MUSCLE, WHat is the Basic functional unit of a MYOFIBRILS?
- composed of thick (myosin) and thin (actin) filaments and associated proteins
- OVERLAPPING of filaments creates banding pattern of STRIATIONS
What is this basic unit composed of ?
SARCOMERE
**repeated units of sarcomere run the length of the muscle fiber
Structure has; Z to Z line I band A band H zone M line Muscle triad
**SARCOPLASMIC reticulum and MITOCHONDRIA surround each SARCOMERE
Name the sarcomere structure of SKELETAL MUSCLE (line, band, zone,triad etc)
- SARCOMERE (the contractile unit)
- point of attachment for the thin filaments (actin/pink)
- bisects I Bands
Z line
Z line to Z line (SARCOMERE- smallest contractile unit of muscle)
Name the sarcomere structure of SKELETAL MUSCLE (line, band, zone,triad etc)
- light stripe
- Z line and thin filaments (actin)
- ALPHA-actinin protein binds actin filaments to Z line
I BAND - light stripe
**shorten during contraction (also H zone)
Name the sarcomere structure OF SKELETAL MUSCLE (line, band, zone,triad etc)
- dark stripe
- represents the full length of the THICK filaments (myosin/blue)
- Thin filaments overlap
- TITIN PROTEIN anchors MYOSIN filaments to Z line
**located in the MIDDLE of sarcomere
A BAND -dark stripe
**stay same during contraction
Name the sarcomere structure of Skeletal muscle (line, band, zone,triad etc)
- contains THICK filaments
- SIZE CHANGES depending on the state of contraction of the muscle
**on either side of M bands-contain only MYOSIN filaments
H zone/band
**shorten during contraction (also I band)
Name the sarcomere structure of skeletal muscle (line, band, zone,triad etc)
- anchor point of THICK filaments (MYOSIN)
- *middle of A band-represents linkage of myosin filament
M line
Name the sarcomere structure of skeletal muscle(line, band, zone,triad etc)
Located at the A-I junction
- Made of expanded TERMNIAL CUSTERNAE of The SARCOPLASMIC reticulum (SR) and T tubules
- T TUBULE is formed by sarcolemma invaginations into each myofiber
MUSCLE TRIAD
**At each triad, the AP is transmitted from the T tubules to every MYOFIBER and MYOFIBRILS as well as the SR membrane
Skeletal Muscle Organization
1) Groups of several muscle fibers form ?
2) Muscle fibers are covered by ?
3) The outer covering of the fascicles is called the ?
4) Groups of fascicles form?
5) The muscle is covered with CT called the?
1) A Fascicle
2) ENDOMYSIUM
3) PERIMYSIUM
4) muscle
5) EPIMYSIUM
Connective tissue coverings allow penetration of blood vessels and nerves.
What are the CT components of the SKELETAL MUSCLE ?
-TYPE 1 COLLAGEN
- DENSE IRrEGULAR CT
- EPIMYSIUM
- PERIMYSIUM
- LOOSE IRREGULAR CT
- ENDOMYSIUM
CARDIAC muscle cells are joined by what dense junctional complexes to make a FIBER?
What do these junctional complexes contain?
Zig-zag appearance
INTERCALATED DISKS
** consist of fascia adherents, desmosomes and gap junction
GAP junctions
- allow for a rapid spread of stimuli throughout the entire muscle mass)
- Couple all fibers for rhythmic contraction -FUNCTIONAL SYNCYTIUM (ion can diffuse through gap junctions allow contraction stimuli pass through entire muscle mass)
What are the 3 components of a CARDIAC SARCOMERE
Conduction of excitatory impulses to the cardiac sarcomeres is through what component(s)?
1) T tubules -located at Z LINES make DIADS with SARCOPLASMIC reticulum
2) Sarcoplamic reticulum - less well developed, calcium is IMPORTED from outside the cardiac muscle into the SARCOPLASM for contraction
3) Mitochondria - larger and more ABUNDANT (increased metabolic demands on the cardiac muscle fibers for continuous function.
**Conduction of excitatory impulses to the cardiac sarcomeres is through - T TUBULES and SARCOPLASMIC RETICULUM
Name the MUSCLE
- Cells joined by INTERCALATED DISKS to make a fiber
- cross striations from SARCOMERE
- ROUNDED NUCLEI (sometimes 2)
- Has sarcomere
- Connectivity organizes spread of contraction in the interconnected fibers
- Exhibit AUTORHYTHMICITY (spontaneously generate stimuli)
- Spontaneously generate stimuli
- INVOLUNTARY
CARDIAC MUSCLE
How are PURKINJE fibers different from CARDIAC muscle fibers?
How does purkinje fibers which can be found in cerebellum related to cardiac ?
- Thicker and larger than cardiac muscle fibers
- contain greater amount of GLYCOGEN (lighter staining)
- contain FEWER CONTRACTILE filaments
- On either side of the interventricular septum
- Part of conduction (electrical) system of the heart
- *Branch throughout the MYOCARDIUM
- Deliver continuous WAVES of stimulation from the atrial nodes (SA and AV) to the rest of the heart musclulature (via gap junctions)
- stimulation produces VENTRICULAR CONTRACTIONS (systole) -ejection of blood from both ventricular chambers
Name the muscle
- Eosinophilic cytoplasm
- Minimal ENDOMYSIUM
- speckled hot dog CENTRAL NUCLEUS (looks small and circular in cross section)
- Fiber is a SINGLE CELL with a SINGLE NUCLEUS
- NO T TUBULES
- SR not well developed
- ZONULA ADHERENS-binds muscle cells
- Contain gap junctions
- INVOLUNTARY
- contain CAVEOLAE
- Calmodulin
- Contractile mechanism - use DESMIN and VIMENTIN
- actin and myosin but NO CROSS STRIATION
SMOOTH MUSCLE
What is the contractile mechanism of Smooth Muscle ?
- Intermediate filament cable network of DESMIN and VIMENTIN
- Dense bodies bund intermediate filaments and actin to the membrane
- Actin is attached/anchored to the DENSE bodies to develop contractile force (usually actin is attached to Z line in skeletal and cardiac muscle)
Which Component of smooth muscle allow for rapid ionic communication btw smooth muscle fibers (coordinated activity) and provide functional coupling?
GAP JUNCTIONS
Which component of the SMOOTH muscle :
- vesicular invaginations of the cell membrane
- CONTROL influx of CALCIUM into cells following stimulation
- ** same effect has T TUBULE in skeletal and cardiac muscle.
CAVEOLAE
Differentiate btw smooth and striated muscle (skeletal and cardiac)?
Which has sarcomere?
Which has actin and myosin?
Which has SR/ T-Tubules?
Regulation?
- Actin and myosin but NO SARCOMERE in SMOOTH MUSCLE (Actin connects to IF cytoskeleton and dense bodies - connect to SARCOLEMMA)
- SR but NO T TUBULES
- can be innervated but also REGULATED by ; Hormones, stretch, spread from cell to cell by GAP JUNCTIONS
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Location of nuclei
*Categorize in order of Multiple nuclei (Peripheral) Central nuclei (1 or 2), central nuclei (single)
SKELETAL
CARDIAC
SMOOTH
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Which is has SARCOMERE structure? Which does not?
Has Sarcomere
SKELETAL
CARDIAC
No Sarcomere
SMOOTH MuSCLE
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Which HAS/NO INTERCALATED DISC
HAS INTERCALATED DISC
CARDIAC MUSCLE
NO Intercarlated disc
Skeletal
Smooth
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
What has branches?
Has BRANCHES
CARDIAC MUSCLE
NO branches
Skeletal
Smooth
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Which has cell-cell GAP JUNCTION
GAP JUNCTIONS
CARDIAC
SMOOTH
NO GAP Junction
Skeletal
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Which has T TUBULE
HAS T TUBULES
SKELETAL
CARDIAC - larger
NO T tubules
Smooth
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Has SR
SARCOPLASMIc reticulum
-How does it affect calcium?
ALL have SARCOPLASMIC RETICULUM, nucleus and Mito
SKELETAL- yes
CARDIAC- less well developed
SMOOTH- less well developed
**CARDIAC and SMOOTH muscles can’t sure enough CALCIUM for uninterrupted contraction due to less developed SR
SUMMARY TABLE OF skeletal, cardiac and smooth muscle
Has mitochondria?
ALL HAVE MITOCHONDRIA, nucleus and SR
MITO
Skeletal muscle
Cardiac - larger and MORE ABUNDANT
Smooth
In skeletal muscle for example, the actin and myosin filaments are bound to proteins that help them bin to the Z line.
What are the proteins that help ACTIN bind to Z LINE ?
Whatcha help MYOSIN bind to Z LINE
A(alpha) - Actinin -Bind actin to Z line
TITIN - bind myosin to Z line
What is the determination/differentiation of skeletal muscle (myogenic) cells ?
State the process from STEM CELL TYPE to end product
- TOTIPOTENT stem cell differentiate into 3 germ layers (Ectoderm, mesoderm and endoderm)
- MESODERM stem cells can differentiate into adiboplasts, myoblasts and chondroblast
- single cell MYOBLASTs can then differentiate fo form multinucleated MYOTUBE (when the extracellular conc of growth/transcription factors drop below critical threshold)
**Cells that differentiate into MUSCLE no longer divide
What determines if myoblasts cells became myogenic/skeletal muscle?
Give examples?
TRANSCRIPTION FACTORS
- MyoD
- myogenin
- myf-5
- MRF-4/Herculin/myf-6
Describe the structure and function of myoD?
WHat do the 2 regions help with?
What binds proteins?
What binds DNA?
What is the DNA sequence called? Where is it seen most?
STRUCTURE
- nuclear phosphoprotein
- bHLH region (BASIC HELIX-loop-helix)
FUNCTION?
- HELIX (HLH) region of myoD form DIMER with E2 family proteins (*E2A - E12, E47, E2-2,HEB)
- BASIC region of myoD BIND DNA better (10x) as heterodimer
**DNA sequence called E-box (present in most MUSCLE SPECIFIC ENHANCERS in multiple copies))
Describe the process of transcription activation in skeletal muscle physiology?
How many Ebox must be bound?
What will happen to the muscle genes that have no E-boxes?
- MyoD complexes must bind to 2 or more upstream E-BOXES
- some muscle genes have no Ebox but are still regulated by myogenic intermediate proteins
- SPECIFIC binding to activate transcription (has to be BASIC region)
- MyoD initiates chromatin remodeling in regulatory regions of muscle-specific genes
MyoD is one of the transcription factors that determines if cells become myogenic?
What can cause NO activation of transcription?
What region f MyoD does specificity reside in?
Binding has to be SPECIFIC to activate transcription
- fusing BASIC region of MyoD to non-muscle HLH region leads to dimer via HLH, specific binding to DNA and ACTIVATION of muscle genes
- if you SWITCH basic regions of proteins, you will see dimerization and binding but NO ACTIVATION
***SPECIFICITY of myogenic activation resides in the BASIC REGION
MyoD, MRF4, Myf5 and myogenin and transcription factors that determine the role of myogenic proteins.
At what stages are they determining factors?
MyoD and Myf5 - EARLY
Myogenin and MRF4- Late
A 9 month old is brought to the hospital by his concerned parents because he can do push ups and can lift 7 lbs weights.
Test show mutation in a signaling protein
What protein is this?
How does it affect muscle growth?
What does it inhibit?
How is it activated?
MYOSTATIN mutations
- MYOSTATIN is a member of the TGFb family of SIGNALING proteins
- It is a negative regulator of muscle growth (mutations can lead increase in muscle mass)
- INHIBIT myoblast proliferation and progression from G1 to S
- MyoD binds to E box in myostatin promoter and activate myostatin transcription
How does change in myostatin affect muscle cells/mass
- Gain of function/Overexpression of myostatin lead to fewer muscle cells (Hypotrophy)
- Loss o function/Underexpression of myostatin lead to increased muscle cells (hypertrophy)
**Myostatin works to INHIBIT muscle growth/cells/mass
Skeletal muscle is able to repair itself after damage by recruitment of?
How?
Location?
Composed of?
SATELLITE CELLS
- recruited to SUPPLY MYOBLASTS for repair and regeneration
- located on SURFACE OF MUSCLE FIBER, beneath the basal lamina
- for 2-7% of muscle nuclei in healthy individuals
- normally quiescent until needed
- increase muscle mass after exercise
Skeletal muscle is able to repair itself after damage by recruitment of?
How are these cells recruited?
What is the normal state before need?
SATELLITE CELLS
Normally quiescent until needed
- process activated by IMMUNE RESPONSE to injury
- satellite cells start dividing (form new muscle fibers and reconstitute pool of satellite cells)
- migrate to site of injury
- follow normal differentiation pathway
What happens to muscle mass after exercise?
Describe the process?
How does satellite cell come into play?
What regulates satellite cell activity? How?
Muscle mass INCREASES after exercise
- hypertrophy of existing cells
- weight training damages muscle (micro trauma)
- activates satellite cells (cells start dividing and repair damage which would INCREASE the size and thickness of muscle fiber)
- growth factors and hormones REGULATE satellite cell activity (increase in protein synthesis and glucose uptake)
- TESTOSTERONE stimulate release of hormones - have direct regulatory effect on satellite cells
Actin Myosin Tropomyosin Troponin TITIN Nebulin
All components of what?
What happens here?
MUSCLE SARCOMERE
**Where contraction occurs
Myosin is a component of muscle SARCOMERE.
What are the 3 component of myosin
What properties does myosin have and how does it relate to its function -contraction?
1) 2 heavy chains
- each has a globular head (has ATPase) and a filamentous tail (alpha helical tail)
2) 2 light chains
- 2 pairs- essential light chain on top, regulatory light chain below
3) Crossbridges
- component of head region
- project laterally from the thick filament
- LINK between thick and thin myofilaments
- *Has BIOLOGICAL PROPERTIES
- acts as ATPase which release chemical energy for contraction
- binds to actin
- both properties located in GLOBULAR HEAD
Name the component of muscle sarcomere?
- lies in the groove between the two strands of actin
- has a regulatory function and provides structural rigidity to ACTIN
TROPOMYOSIN
Troponin is one of the components of muscle sarcomere.
It is made up of a complex of 3 proteins.
Where is TROPONIN located?
Name the type of troponin
- serves to bind troponin to TROPOMYOSIN
- contains 2 high and 2 low affinity for CALCIUM
- INHIBITS interaction btw actin and myosin
Troponin is located at the end of TROPOMYOSIN molecule
- TROPONIN T
- TROPONIN C
- TROPONIN I
Name the component of muscle sarcomere
- one molecule extends from M line to Z disc
- acts as spring to keep MYOSIN filaments centered in sarcomere and maintain resting tension that allows muscle to snap back in overextendened
TITIN
Name the component of muscle sarcomere
- associated with actin
- regulated the assemble and alignment of acting filaments (keep it in place)
NEBULIN
WHat is the role of CALCIUM in muscle contraction/relaxation?
- in relaxed muscle, level of free cytosolic CALCIUM is low
- in stimulated muscle, INTRACELLULAR CALCIUM levels increase substantially
- CALCIUM binds to TROPONIN C to change conformation of complex
- when stimulation stops, CALCIUM levels decrease and dissociate from regulatory protein and muscle RELAXES
Movement of what mediates the activity of muscle excitation and contraction?
What are the events called?
CALCIUM
**events that describe CALCIUM movements in muscle cells is called
EXCITATORY-CONTRACTION COUPLING
Process of E-C coupling
- nerve excite motor end plate to depolarize and cause AP in T-tubular system of sarcolemma
- T-tubules contain VGCa channels (DHP or Dihydropyridine) that mediate long lasting Ca2+ currents -channel act as VOLTAGE SENSOR
- WHen T-tubules depolarize, calcium is released from terminal cisternae of SR
- calcium release from SR takes place with separate calcium channels (RYANODINE receptor 1 or RyR1)
- SR Ca2+ channel comes in close proximity to DHP channel proteins in T-tubule membrane
- conformation changes in DHP channels cause RyR1 channels to open through protein-protein interaction
- Ca2+ are recaptured by SERCA (sarcoendoplasmic reticulum calcium ATPase) in SR and returned to terminal cisternae
WHat is the affinity/interaction btw actin myosin and how does change in the presence/absence of other factors
MYOSIN has a VERY HIGH affinity for ACTIN and would very TIGHT bonds in ABSENCE of TROPOMYOSIN and ATP
- ATP dissociate myosin-actin complex by binding to myosin
- AT REST, tropomyosin lies on the outside groove btw actin chains and blocks interaction of actin and myosin
- When CALCIUM enter SARCOPLASMIc and binds to Troponin C, conformational change occurs in tropomyosin
- tropomyosin molecule moves and exposes active sites on actin
- shift enables nearby myosin crossbridges to attach to actin active sites
Describe the cycle of the Sliding filament model of muscle contraction
4 steps
1) cycle starts with MYOSIN tightly bound to ACTIN, When ATP binds MYOSIN, actin is released
(MA)+ ATP = (M-ATP) + A
2) ATPase on the globular head of MYOSIN myofilament hydolyzes ATP to ADP and Pi
**conformational change occurs and Myosin now in high energy conformational state
**release of Ca2+ exposes binding site on actin and energized myosin head binds to actin
3) Pi dissociate
4) ADP dissociate
* *release of Pi and THEN ADP causes myosin head to turn causing ratchet movement
What happens after Pi and ADP dissociate in the last 2 stages of the sliding filament model of skeletal muscle
What shortens the sarcomere? WHat is this called?
- The release of Pi and ADP cause myosin head to turn in ratchet movement
- This translocated actin filaments toward the M line of sarcomere, pulling Z bands toward each other- This would shorten the sarcomere - POWER STROKE
- contractile proteins remain tracked until another ATP molecule binds to myosin
- cyclic myosin-actin interactions will continue until Ca2+ ions are removed from SARCOPLASM
- *USEFUL ANALOGY/SUMMARY
- ATP cocks myosin trigger
- formation of actin-myosin complex pulls the trigger
- energy stored in cocking the trigger is released
In the absence of ATP in the sliding model, WHat will happen to actin and myosin?
WHat is this called?
What is the main source of energy in skeletal muscle contraction?
RIGOR MORTIS -dead people
**ACTIN remains BOUND to MYOSIN and can’t be released
-ATP CLEAVAGE - main source of energy for contraction
Name the channel
- responsible for large resting chloride conductance of skeletal muscle
- stabilizes resting membrane potential preventing false action potentials
- important in REPOLARIZING membrane following contraction
CHLORIDE CHANNEL (ClC-1)
There are 3 types of contraction
Name this
- single A.P case release ENOUGH Ca2+ to fully initial contraction
- However, Ca2+ are REMOVED from sarcoplasm so RAPIDLY that muscle cell don’t have enough time to develop maximum force
TWITCH CONTRACTION
There are 3 types of contraction
Name this
How does summation contraction work and how is it different from other contraction?
What will summation contraction result in?
SUMMATION contraction
- absolute refractory period of motor nerve is much SHORTER than TWITCH contraction
- This can enable a SECOND stimulus to be applied to muscle cell before relaxation is complete (Basicaly 2 TWICHES together)
- additional Ca2+ is release to sarcoplasm before all the previously released Ca2+ is Removed by SR
**RESULT in -:
INCREASE in intracellular Ca2+
INCREASE in number of crossbridges formed
INCREASE in amount of tension developed
There are 3 types of contraction
Name this
- When rate of stimulation of motor nerve INCREASES to a point where there is LITTLE or NO relaxation evident
- Level of TENSION reaches MAXIMUM PLATEAU
- Continuous signal/contraction/Tension
TETANUS CONTRACTION
Describe the process of SKELETAL MUSCLE RELAXATION
- NO more AP generated at NMJ so SARCOLEMMA returns to its RESTING electrical potential as does entire T TUBULE system and SR membrane
- myosin remains in high energy conformational state but NOT BOUND to actin
- sarcoplasmic calcium then pumped back into SR cisternae by extremely active ATP-driven calcium pump SERCA
- Ca2+ has higher affinity for pumps than for troponin C
- SR contains calsequestrin, a glycoprotein that binds Ca2+ ions and which acts to reduce SR concentration of free Ca2+
small pool of ATP present in muscle but is continually replenished by ?
- what catalyze the phosphorylation of ADP to ATP? WHat does it use?
- What is metabolized in muscle during contraction to provide what to use to generate ATP? Via what 2 mechanisms?
WHat are the 3 sources to generate ATP?
Which is most ABUNDANt?
-CREATINE PHOSPHATE
- CREATINE PHOSHOKINASE using creatine phosphate
- *first source used to generate ATP
-GLYCOGEN in muscle provide GLUCOSE
**Via GLYCOSIS (second source to generate ATP)
and OX.PHOS (third and MOST ABUNDANT source of ATP)
Which basic type of contraction is this:
- Muscle DECREASES in length against opposing load, such as lifting weight up
- keep a constant tension
- muscle contracts, shortens and creates enough force to move the load
CONCENTRIC ISOTONIC contraction
