4th, 1

What are the four primary tissue types?

Epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

Into what three types is muscle tissue divided?

Cardiac muscle, smooth muscle, and skeletal muscle.

What are the characteristics of cardiac muscle?

Cardiac muscle is striated, has a single nucleus, and has automaticity (it contracts on its own in the heart).

What does automaticity mean?

Automaticity means the muscle is in charge of itself and contracts without conscious control.

What are the characteristics of smooth muscle?

Smooth muscle has no striations, is involuntary, has a single nucleus, and is the smallest of the three muscle fiber types.

What are the characteristics of skeletal muscle?

Skeletal muscle is striated, voluntary, multinucleated, and has the largest cells called muscle fibers.

What are the functions of muscle tissue?

Movement, maintaining posture and body position, protection, stabilizing joints, guarding entrances and exits of the body, and thermoregulation.

What does muscle tissue do for movement?

Muscle tissue produces movement of the body.

How does muscle tissue help maintain posture and body position?

It keeps the body upright and resists gravity.

Why is gravity mentioned under muscle function?

Because muscles continuously work to oppose gravity and maintain posture.

How does muscle tissue provide protection?

It protects internal organs.

How does muscle tissue stabilize joints?

It helps hold joints in position and prevents excessive movement.

What does it mean that muscles guard entrances and exits of the body?

Muscles control the opening and closing of body passages.

What is thermoregulation?

Regulation of body temperature.

How do muscles help with thermoregulation?

They generate heat.

What are the four characteristics of muscle tissue?

Excitability, contractility, extensibility, and elasticity.

What is excitability?

The ability to receive and respond to a stimulus.

What is contractility?

The ability to shorten forcefully when stimulated.

Which tissue has contractility?

Only muscle tissue.

What is extensibility?

The ability to be stretched beyond its resting length.

What is elasticity?

The ability to return to resting length after being stretched.

During what week of embryonic development does skeletal muscle begin to develop?

During the fourth week.

Which cells migrate during skeletal muscle development?

Mesenchymal cells.

What do mesenchymal cells become?

They differentiate into myoblasts.

What are myoblasts?

Immature muscle cells.

How is a skeletal muscle fiber formed?

Hundreds of myoblasts fuse together to form one skeletal muscle fiber.

What are satellite cells?

Muscle stem cells.

What happens to some myoblasts?

They become inactive (quiescent) and are called satellite cells.

What is the function of satellite cells?

They become activated and divide to produce new myoblasts for muscle repair.

What are muscles attached to bones by?

Tendons.

What type of connective tissue are tendons made of?

Dense regular connective tissue (CT).

What type of connective tissue is the periosteum of bone made of?

Dense regular connective tissue (CT).

Why is the connection between a tendon and a bone so strong?

The fibers of the tendon and the periosteum are woven together, creating a very tight connection.

How are muscle cells organized?

They are highly organized in levels, similar to Russian nesting dolls.

What is Level 1 of muscle organization?

The entire muscle (the whole organ).

What covers the entire muscle?

The epimysium.

What type of connective tissue is the epimysium made of?

Dense regular connective tissue.

How is the epimysium connected to the tendon?

Its dense regular connective tissue fibers are woven into the dense regular connective tissue of the tendon.

What is Level 2 of muscle organization?

Fascicles.

What are fascicles?

Bundles of muscle fibers.

What covers each fascicle?

The perimysium.

What is the Latin meaning of the word “fascicle”?

Bundle.

What is Level 3 of muscle organization?

The individual muscle fiber (muscle cell).

What covers each muscle fiber?

The endomysium.

What type of connective tissue is the endomysium?

Dense regular connective tissue.

What is Level 3+ of muscle organization?

Myofibrils.

What is a myofibril?

A bundle of contractile proteins called myofilaments.

What are myofilaments?

Contractile proteins that allow muscles to contract.