Lab 5 - Muscle and Nerve Tissue Flashcards
what does muscle as a tissue type originate from?
the mesodermal layer of the embryo
most prevalent type of muscle, how is skeletal muscle attached
Although most skeletal muscle is connected to bones via tendons,
there are a few areas in the body where this is not the case (e.g. tongue, parts of digestive and
urinary tracts, larynx).
where do skeletal muscle cells arise from and what do they look like
Skeletal muscle cells arise from fusion of precursor cells during development, so they are
multinuclear, and most skeletal muscle cells are quite large.
where is cardiac muscle found, what is their size compared to skeletal
Cardiac muscle is only found in the heart and parts of the venae cavae
Although cardiac muscle cells are large cells, they are not
nearly as large as skeletal muscle fibres.
what does the cardiac muscle cell nucleus look like
Cardiac muscle cells usually have a single nucleus but are
occasionally binucleate, and they have short, blunt ended branches.
how are cardiac muscle cells held to their neighbours
Cardiac muscle cells are held to
their neighbours by junctional complexes known as intercalated discs. These consist of regions
very similar to adhesion belts and desmosomes of epithelial cells, as well as gap junctions that allow
communication between adjacent cells
what is the main visceral muscle in the body and where is it found
Smooth muscle is the main visceral muscle of the body. It is found in the wall of blood vessels as well as hollow organs (e.g. digestive tract, urinary tract, uterus).
smooth muscle cell nucleus and cell shape
Smooth muscle cells are the
smallest of the three types of muscle and have a single nucleus. The cells are fusiform in shape, but their most distinguishing feature is a lack of striations (hence ‘smooth’).
why do smooth muscle cells lack straitions
because their contractile myosin and actin filaments are arranged like a meshwork instead of in
regular arrays of sarcomeres.
what characteristics do all muscle cells have and what happens during that
All muscle cells have the characteristics of excitability and contractility. When muscle cells contract they shorten in length.
Since muscle cells are held together by connective tissue, the muscle tissue as a whole tends to contract and relax in a coordinated fashion. Contraction and relaxation leads to
movement: of body parts for skeletal muscle, of blood for cardiac muscle, and of organ contents for smooth muscle. Depending on the type of muscle, the internal cytoskeletal arrangement responsible for contraction may differ, but all muscle cells contract because thick myosin filaments slide along thin actin filaments in the presence of Ca 2+ and ATP. Likewise, while the various
mechanisms for controlling muscle cell contraction differ between the types of muscle, in all cases a signal of some sort leads to increased levels of Ca 2+ in the cytoplasm, triggering this contractile event.
how can the distribution of nerve tissue in the body be divided
The distribution of nerve tissue in the body can be divided anatomically into the central nervous system (CNS, brain and spinal cord) and peripheral nervous system (PNS, everything outside of the CNS, including nerves and ganglia). It can also be divided functionally into voluntary and involuntary/autonomic nervous systems, and the autonomic nervous system is functionally (and somewhat anatomically) divided further into the sympathetic and parasympathetic nervous
system. A final way of thinking about the nervous system is sensory (input or afferent) and motor (output or efferent)
what is nerve tissue made up of
nerve tissue is made up of nerve cells or neurons and support cells
or glial cells (glia)
location of neuron cell bodies in CNS vs PNS
highly regulated - they are only found in grey matter in the CNS, and in ganglia in the PNS
main types of glial cells in the grey matter
The main types of glia in
the grey matter are astrocytes and microglia, but their exact identity cannot be determined in H & E specimens.
what glial cells are found in white matter
astrocytes, microglia and oligodendrocytes, which associate with the nerve fibres and produce the myelin sheath that gives white matter its name
