1. Muscle & Nervous Tissues

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Muscle Tissues:
A. General Characteristics
1. Muscle cells (aka, myocytes or muscle fibers), can contract and include three major types.
2. All muscle cells contain two proteins that can slide past each other, called actin and myosin. When they slide past each other, the cell is shortened, and the muscle contracts.

3. You’ll need more rows than this, but you get the idea…
Make a chart like this…Use it for your notes… Simplify / Summarize the details presented here
Muscle Tissues
Tissue
Description
Function
Location
You’ll need more rows than this, but you get the idea…

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B. Skeletal Muscle Tissue
1. Skeletal muscle is attached to bone and can be controlled by conscious effort (voluntary).
2. The cells (aka, muscle fibers, or myocytes) are long and cylindrical, striated (they appear striped due to the regular arrangement of actin and myosin fibers), have many nuclei and contract when a nerve impulse sends them a message from the brain.

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C. Smooth Muscle Tissue
1. Smooth muscle tissue lacks striations (because the actin & myosin fibers are lined up randomly in the cell), it is uninucleate, and it consists of spindle-shaped cells.
2. This involuntary muscle is found in the walls of internal organs, such as the digestive tract, blood vessels, iris of the eye, and urinary bladder.

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D. Cardiac Muscle Tissue
1. Cardiac muscle tissue is found only in the heart and consists of branching fibers that are connected to each other with intercalated disks. These connections allow the contraction to spread across the entire heart simultaneously, making a unified heartbeat.
2. This involuntary muscle has a single nucleus in each cell but appears striated.

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Nervous Tissues:
A. Nervous tissues are found in the brain, spinal cord, peripheral nerves, and in clusters of cells called ganglia.
B. Neurons, or nerve cells, conduct nervous impulses while helper cells, called neuroglia, support and nourish the neurons.
C. Neurons have two main types of extensions: multiple dendrites, which gather incoming messages from other neurons, and a single axon that sends an outgoing message to other neurons.

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Neural Communication:
A. Neurons communicate with both electrical impulses and chemical messages.
B. The electrical impulse occurs along the length of a single neuron – it is properly called an “action potential.” A wave of electric charge flows down the axon from the cell body, sending a signal to the tips of the axon (the “axon terminals”).
C. Chemical messages are sent between different neurons, at the synapse. When an electric impulse reaches the axon terminal, it secretes neurotransmitter molecules which carry the message to the next neuron. The space between neurons that the neurotransmitters must cross is called the synaptic cleft.

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Neuroglia:
A. The nervous system also depends on cells called glia to assist the neurons.
B. While neurons actually communicate with each other, the glia simply help neurons in a variety of ways (although recent evidence suggests they may also play a role in communication).
C. Glial cells support neurons by: helping move nutrients and wastes between neurons and the blood stream, insulating neurons, speeding up action potentials, and more.

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15. Organs
are Made of Tissues!!!
Tissues
Combine into
Organs!!!