BELL RINGER If you were not here yesterday (absent or field trip) check the crate for your work. Use this time to catch up. You are behind. This is all due to me by tomorrow. If you were here yesterday, you have 10 minutes to finish Sections A, B, and C from the worksheets and get checked off with me before we move on with class.

Muscular and Nervous Tissue Chapter 4 Body Structures & Functions

Muscular Tissue Function Contracts to produce movement Movement can be voluntary or involuntary The function of all muscle cells is to contract. As you know, an aggregation of these muscle cells is referred to as muscle tissue. Muscle tissue is found throughout our body and is responsible for: The voluntary movement of our skeleton as well as the involuntary rhythmic beating of our heart and functioning of our intestines. Lastly, it should be mentioned that mature muscle cells do not undergo mitosis. Therefore, depending on the type of muscle tissue, the cells have limited to no capabilities for regeneration. For example, if cardiac muscle tissue is damaged, then the damaged area will not be replaced by new cells but with fibrous connective tissue.

Types of Muscular Tissue 1. Skeletal 2. Smooth 3. Cardiac

Characteristics of Skeletal Muscle Appearance: striated (striped) and column-shaped cells (muscle fibers) Alternating light and dark bands make striations Location: Attached primarily to bones Control: Voluntary (conscious) Contracts quickly, tires easily (fatigable) Allows for wide range of forces to be generated

Skeletal Muscle Tissue - 400X

Smooth Muscle Appearance: spindle-shaped Location: wall of hollow organs example: Intestines, urinary bladder, ureters, blood vessels Control: Involuntary Contracts rhythmically and quickly

Smooth Muscle

Smooth Muscle Tissue - 400X

Cardiac Muscle Has features of both skeletal and smooth muscle - Like skeletal muscle, it has strong contractions and striated appearance - Like smooth muscle, it is under involuntary control and has rhythmic contraction

Appearance: striated and branched Location: heart Function: contraction of heart pumps blood and causes the heartbeat Control: Involuntary

Cardiac Muscle Tissue - 400X

Nervous Tissue The ultimate control of all the organ systems is done by the nervous system. Function: controls and coordinates all bodily functions and responds to internal and external stimuli. THINK… COMMUNICATION!

Nervous Tissue Found: brain, spinal cord, and peripheral nerves The cells that transmit messages (impulses) are called neurons.

Structure of a Neuron Nucleus Dendrites Axon terminals Cell body Myelin sheath Axon Nodes

Neuron Structure Dendrites extend from the cell body and carry impulses from the environment toward the cell body.

Neuron Structure The largest part of a typical neuron is the cell body. It contains the nucleus and much of the cytoplasm.

Neuron Structure The axon is the long fiber that carries impulses away from the cell body.

Neuron Structure The axon is sometimes surrounded by an insulating membrane called the myelin sheath.

Neuron Structure There are gaps in the myelin sheath, called nodes, where the membrane is exposed. Impulses jump from one node to the next.

Neuron Structure Impulses are then passed to the next cell by the axon terminals.