The Tissue level of Organization Chpt. 4 MUSCLE & NERVOUS TISSUE

MUSCLE & NERVOUS TISSUE

Muscle tissue

Specialized for contraction/ produces movement; three types:

• Skeletal muscle

• Cardiac muscle

• Smooth muscle

Skeletal muscle

type of muscle tissue; Large muscles responsible for body movement;

– Consists of long, thin cells called muscle fibers

– Cells do not divide

– New fibers are produced by divisions of myosatellite cells

– Striated voluntary muscle; filaments in organized repeating patterns, form striations

Cardiac muscle

type of muscle tissue; Found only in the heart

– Cells form branching networks connected at intercalated discs; allows for rapid movement; has gap junction

– Regulated by pacemaker cells; cause the contraction

– Striated involuntary muscle

Smooth muscle

type of muscle tissue; Found in walls of hollow, contracting organs, like blood vessels/organs

– Cells are small and spindle shaped

• Cells can divide and regenerate; like after injury

– Nonstriated involuntary muscle

Myosatellite cells

muscle stem cells within skeletal muscles tissue; new muscle fibers are made through the division when activated to repair/replace

Nervous tissue

– Specialized for conducting electrical impulses; from one region of body to another

– Concentrated (most nervous tissue) in the brain and spinal cord

Types of cells in nervous tissue

1. Neurons

2. Neuroglia (supporting cells)

Parts of the Neuron

nervous tissue; longest cell in the body, and it can’t divide; includes:

• cell body (palm)

• dendrites (fingers with info)

• axon (nerve fiber) (arm)

Cell body

body of a neuron; has the nucleus & nucleolus

Dendrites

part of a neuron;

• Short branches extending from the cell body

• Receive incoming signals; gets info from other neurons

“to dendrite, away to axon”

Axon

part of a neuron; only one axon; also known as (nerve fiber)

• Long, thin extension of the cell body (like a tail)

• Carries outgoing electrical signals to their destination

• info→ dendrite→axon→other cells

Neuroglia

(supporting cells); part of nervous tissue; take care & deal w/ everything here

• maintain physical structure (framework) of tissues

• repair tissue framework after injury

• perform phagocytosis (engulf unwanted substances)

• provides nutrient to neurons

• regulate the composition of interstitial fluid surrounding neurons

• separate and protect neurons