1. Tissues (Muscle & Nervous)
Topic 2.3 (Part 1)

2. Tissues
Tissues are the concentration of cells with a similar structure that join together to accomplish a common function.
The many different tissues in the body have been classified into four main types:
1) epithelial
2) connective
3) muscle
4) nervous
Each of these has it own subtypes.
The differences between tissues and how they might appear under the microscope always relates to the particular functions they provide.

3. Tissues Tissue Broad Function Epithelia
Act as protective linings and coverings. In some locations, absorption and secretion are important functions of these lining and covering cells. As secretory cells, epithelia form most glandular structures of the body.
Connective
Serve as connective and supportive tissues that bind and hold body structures together. Specialized fluid connective tissue types serve as liquid media important in transport, exchange, and body defense.
Muscle
Tissues with the unique capability to contract or shorten. This enables muscle types to be involved in functions of support and movement.
Nervous
Nerve cells are specialized for conduction. Nervous tissues therefore serve as the complex telecommunications network of the body. These tissues act in a sensory capacity, to receive, disseminate, and store information collected from receptors. In a motor capacity, nervous tissues provide response potential by controlling effectors such as muscles or glands.

4. Four Types of Tissue

6. Nervous Tissue https://www.youtube.com/watch?v=Wq1XQndqNmA

7. Nervous Tissues
Nerve tissue includes glial cells and neurons. Together they make up the structures of the nervous system-the brain, the spinal cord, and nerves.
Neurons are the nervous system cells that generate, transmit, and receive electrical signals. All neurons receive and conduct electrochemical impulses from one part of the body to another; thus irritability and conductivity are their two major functional characteristics.
A group of supporting cells, called glial cells insulate, support, and protect the delicate neurons, make up the structures of the nervous system-the brain, the spinal cord, and nerves.

8. Nervous Tissue
A class of tissue that has the ability to convey information by electrical signaling.
Nerve tissue is concentrated in the brain and spinal cord, which comprises the central nervous system (CNS). The nerves outside the central nervous system comprise the peripheral nervous system (PNS) .

9. Types and Functions of Glial Cells
Astrocyte (Astroglia): Star-shaped cells that provide physical and nutritional support for neurons: 1) clean up brain "debris"; 2) transport nutrients to neurons; 3) hold neurons in place; 4) digest parts of dead neurons; 5) regulate content of extracellular space
Microglia: Like astrocytes, microglia digest parts of dead neurons.
Oligodendroglia: Provide the insulation (myelin) to neurons in the central nervous system.
Satellite Cells: Physical support to neurons in the peripheral nervous system.
Schwann Cells: Provide the insulation (myelin) to neurons in the peripheral nervous system.

10. Neurons
Neurons usually receive messages from other neurons through short fibers, called dendrites, that pick up messages and carry them to the neuron's cell body.
The axon carries outgoing messages from the cell. A group of axons bundled together makes up a nerve.
Some axons are covered with a myelin sheath. The myelin sheath increases neuron efficiency and provides insulation.

13. Muscle Tissue

14. Muscle Tissue
Highly specialized to contract or shorten, to produce movement.
The distinguishing property of muscle is its ability to generate force on command. All muscle cells use intracellular filaments made of actin and myosin proteins to generate force, and they all require ATP as fuel for contraction.
Types of muscle tissue:
Skeletal muscle
Cardiac muscle
Smooth muscle

15. Muscle Tissue
All muscle cells are long and narrow (elongated) to provide a long axis for contraction, have one or multiple nuclei, and are either striated (stripes) or non-striated.
Muscle fiber is a common descriptive term for muscle cells.  Muscle cells, therefore are also muscle fibers or more specifically myofibers.

16. Functions of Muscle Tissue
Support and movement (Skeletal muscle)
Propulsion of blood through vessels (Cardiac muscle)
Movement of food/body secretions (Smooth muscle)
Thermoregulation (using small smooth muscles attached to feathers or hair shafts; this non-shivering thermogenesis distorts the surface of the skin as the feather/hair shaft is made more erect-goose bumps?)

17. Skeletal Muscle
The most common type of muscle tissue. Skeletal muscle are attached to and pull on bones when they contract, making us move. move.
Skeletal muscle cells are long and thin, have multiple nuclei, and are striated. Skeletal muscle cells are multinucleated because they consist of several cells that have fused together. Muscle cells contain many mitochondria and the characteristic protein filaments(myosin and actin) which are responsible for the muscle contraction.
These muscle can be controlled voluntarily (or consciously).

18. Cardiac Muscle
Is the major tissue of the heart. Striations are visible, it contains one nucleus per cell and is involuntary. The branching cells fit tightly together (like clasped fingers) at junctions called intercalated disks.
The heart acts as a pump and propels blood through the blood vessels. Because the heart never stops working, cardiac muscle must generate ATP continuously, thus cardiac muscle cells have many mitochondria.

19. Smooth Muscle
Smooth muscle, as its name implies appears smooth under a microscope, no striations are visible. The individual cells have a single nucleus and are spindle-shaped (pointed at each end). Smooth muscle is involuntary.
Contracts much slower than skeletal and cardiac.
Smooth muscle is found in walls of hollow organs and blood vessels where contractility and stretch are specific needs:
Stomach, bladder, uterus, blood vessels
Peristalsis-a wavelike motion that keeps food moving through the small intestine.
When smooth muscle contracts, the cavity of an organ alternately becomes smaller (constricts) or enlarges (dilates), propelling substances through the organ.

20. Wolfpack Muscle (Better than Tarheel Muscle)