Lecture 16 Flashcards
What are the 3 types of muscles
- Smooth Muscle
- Cardiac Muscle
- Skeletal Muscle
What are the characteristics of smooth muscle
• Walls of most viscera, blood vessels and skin • Not under conscious control • Autonomic • Not striated
What are the characteristics of cardiac muscle
- Wall of heart
- Not under conscious control
- Autonomic
- Striated
What are the characteristics of skeletal muscle
- Usually attached to bones
- Under conscious control
- Somatic
- Striated
what are the two broad types of smooth muscle
- Multiunit
2. Visceral
What is an multiunit type smooth muscle
– represents functionally independent smooth muscle cells which are often innervated by a single nerve terminal and which never contract spontaneously (e.g. smooth muscle in the walls of blood vessels).
What are visceral type smooth muscles
– represents bundles of smooth muscle cells
connected by GAP junctions, which
contract spontaneously if stretched beyond
a certain limit (e.g. smooth muscle in the
walls of the intestines).
What are the Skeletal muscle consists of very long tubular cells,
muscle fibres
Is skeletal muscle fibres single nucleated
No, many peripherally placed nuclei
What are skeletal muscle fibres usually prepared in
cross-striations
What are skeletal muscle innervated/supplied by
somatic nervous system
What is voluntary muscle
made up of skeletal muscle
What is the I-band in contractile apparatus of muscle
actin filaments
What is the A-band in contractile apparatus of muscle
myosin filaments which may overlap with
actin filaments
What is the H-band in contractile apparatus of muscle
zone of myosin filaments only (no overlap
with actin filaments) within the A-band
What is the Z-band in contractile apparatus of muscle
zone of apposition of actin filaments
belonging to two neighbouring sarcomeres
(mediated by a protein called alpha-actinin)
What is the M-band in contractile apparatus of muscle
- band of connections between myosin
filaments (mediated by proteins, e.g. myomesin, Mprotein).
Where does actin filaments of the last sarcomeres extend to
into cytoplasmic specialisations
associated with zonula
adherens-like membrane
specialisations.
What is type 1 of muscle fibre
• Predominantly red muscle cells. • Comparatively thin and contain large amounts of myoglobin and mitochondria. • myosin with low ATPase activity • Contraction is slow and sustained. e.g. in the control of posture.
Is type one muscle fibre contraction fast
no
What is type II muscle fibre
• Predominantly found in white muscles • Thicker and contain less myoglobin. • ATPase activity of the myosin isoform in white fibres is high, and contraction is fast. • Type IIA fibres (red). Type IIB/IIX fibres (white) contain only few mitochondria.
What is type II muscle fibre predominantly found in
white muscles
Is contraction of type II muscle fibres fast
yes
Is myoglobin abundant in type II muscle fibre
no
Is type I or type II muscle fibre thicker
type II
What are muscle spindles
are sensory
specialization of the
muscular tissue.
What is musle spindle made of
A number of small specialised intrafusal muscle fibres (nuclear bag fibres and nuclear chain fibres) are surrounded by a capsule of connective tissue.
What happen to the muscle spindle when the muscle is stretched
muscle spindle are stretched, sensory nerves are stimulated, and a change in contraction of the muscle is perceived.
What muscle cell does Cardiac muscle, the myocardium consist of
consists of muscle cells,
cardiomyocytes, with one centrally placed nucleus.
Where is the nuclei of cardiomyocyte located
Nuclei are oval, rather pale and located centrally in the muscle
cell which is 10 - 15 µm wide.
What does cardiac muscle cell exhibit
cross-striation
How is cardiac muscle cell excitation mediated
by rhythmically
active modified cardiac muscle cells
Why cardiac muscle called involuntary
striated muscle.
Cardiac muscle is innervated by the autonomic nervous system,
which adjusts the force generated by the muscle cells and the
frequency of the heart beat
What is the last Z-line of myofibrils replaced with in the cardiac muscles
the last Z-line of the myofibril
within the cell is “replaced” by the intercalated disk of
the cell membrane). Extensive GAP junctions.
What is Fascia adherens
– Anchor actin to nearest sarcomere
What is macula adherens
– desmosome
– Stop separation during contraction
What is Gap junction for
– Allow action potentials to spread between
cells
What is purkinje fibres for
• Conduct stimuli faster than
ordinary cardiac muscle cells
(2-3 m/s vs. 0.6 m/s).
Where are purkinje fibres located
A bundle of Purkinje fibres extends from the atrioventricular node, pierces the fibrous body, divides into left and right bundles, and travels, beneath the endocardium, towards the tip (apex) of the heart.
Are purkinje fibres thicker than ordinary cardiac muscle cells
yes
Are nervous tissue anatomically divided and how
Anatomically divided
– central nervous system
– peripheral nervous
system
Where is the central nervous system
• Brain and spinal
cord
What are the two major classes of central nervous cells
Two major classes
of cells
– Neurones
– glia
What is the shape on neurones
– Long processes extending from cell body (perikaryon) – Dendrites receptive surface – Axons one per cell – Emerge from axon hillock – Transmitting proces
How many axon does each neurones have
one
What is the shape of Astrocytes (astroglia)
Astrocytes (astroglia)
– Star shaped cells
Where does Astrocytes (astroglia) process contact often with
Processes often in
contact with blood
vessels
What is the role of Astrocytes (astroglia)
– Mechanical and
metabolic support
– Scar forming cells of
CNS
What are the types of Glia
- Astrocytes (astroglia)
- Oligodendrocytes
- Microglia
- Ependymal cells
What is the characteristics of oligodendrocytes
– Form myelin sheath around axons in CNS – May surround several axons
What is the Characteristics of microglia
– Same derivation as
monocytes
– Tissue damage they
become phagocytic
What is the characteristics of epindymal cells
– Line ventricles of brain and central canal of spinal cord – Often ciliated – Simple cuboidal or low columnar
How are Epedymal cells organized
– Simple cuboidal or
low columnar
What are all the nervous tissue outside brain
• It consists of groups of neurones (ganglion cells), called ganglia, feltworks of nerve fibres, called plexuses, and bundles of parallel nerve fibres that form the nerves and nerve roots.
What are Nerve fibres, which originate from neurones within the CNS and pass out of the CNS in cranial and spinal nerves called
efferent or
motor fibers.
What are Nerve fibres which originate from nerve cells outside the CNS but enter the CNS by way of the cranial or spinal nerves called
afferent or
sensory nerve fibres.
What is a schwann cell
Nerve fibre. Axon and its
nerve sheath.
What is the structure that schwann cells forms
Schwann cells form a sheath around one axon and surround this axon with several double layers (up to hundreds) of cell membrane.
What is the reason for the structure of the schwann cells
Insulates the axon,
improves its ability to
conduct.
What is ganglia
aggregations of nerve
cells (ganglion cells)
outside the CNS
What are ganglion cells surrounded by
a
layer of flattened
satellite cells
What many nucleus does smooth muscle have
1
Why does M band not shrink
full of protein, which is why its darker
What is muscle-tendon junction
position where muscle are tethered to a tendon or bone
How many nerve are connected to muscle fibre
1 at a neuromuscular junction
does Type
IIB/IIX fibres (white) contain
few mitochondria.
yes
What does intercalated dics tell you
its a cardiac muscle cell
What are neurones usually stained as
very light bodies, except when in H&E
What can Scar forming cells of
CNS cause
blocking signal transfer, may cause spinal cord injury
Where are oligodendrocyte found in forming a myelin sheath around axons
in the central nervous system
Where are schwann cells found in forming a sheath around axons
peripheral nervous system
Why are the axon insulated
prevent leakage of information
