Skeletal Muscle

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Skeletal Muscle
Long, cylindrical, unbranched cells with
striations and multiple peripheral
nuclei Voluntary Movement facial expression,
posture, breathing, speech, swallowing and
excretion
Cardiac Muscle
Short branched cells with striations and
intercalated discs one central nucleus per cell
(usually) Involuntary Found in the heart
Smooth Muscle
Short fusiform cells nonstriated with only one
central nucleus Involuntary Swallowing, GI tract
functions, labor contractions, control of
airflow, erection of hairs control of pupil
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Nervous Tissue
Nervous Tissue made of two cell types, neurons
and glial (supporting cells) cells Function to
generate electrical signals and conduct these
signals to other neurons, muscles, or
glands Central nervous system (brain and spinal
cord), peripheral nerves and sensory tissues
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Apoptosis
Apoptosis programmed cell death Not the same as
Necrosis, which is tissue death Unneeded cells
are given the command to die and they go through
a series of steps ending in them being
destroyed. Implicated in some autoimmune
diseases (eg. Hashimoto's thyroidosis)
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Apoptosis
Apoptosis programmed cell death. This is also
the way that embryos are sculpted into the adult
form
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Apoptosis

• Regulated by multiple chemical signals
• Some signals say die
• Some prevent apoptosis from occurring

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Apoptosis
Once suicide signal is given 1. Chromatin in
nucleus condenses 2. Cell pulls away from its
neighbors 3. Shrinks and then breaks up into
blebs 4. The membrane-bound blebs are eaten by
neighboring cells/immune system cells
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Stem Cells
Totipotent Earliest embryonic cells, can develop
into ANY cell type Pluripotent After Day 4 of
development, cells begin to specialize and are
then considered to be Pluripotent They can still
act as stem cells, but are more limited in what
they can become Multipotent stem cells in a
tissue which can differentiate and give rise to
the cell types within that tissue Example Adult
stem cells in bone marrow which give rise to
blood cells
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Hemopoiesis

At
Tot
Adult stem cells in bone marrow give rise to
blood cells