Muscular System 1.2

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Questions and Answers

What is the appearance of skeletal myocytes?

Square and rigid

Oval and flexible

Narrow and fibre-like (correct)

Round and bulky

What is the term for the visible banding in skeletal myocytes?

Myofibrils

Striation (correct)

Fibrillation

Sarcomeres

What is the function of sarcomeres in skeletal myocytes?

Muscle contraction (correct)

Muscle relaxation

Muscle growth

Muscle regeneration

What is the characteristic of skeletal myocytes that gives them a 'striped' appearance?

Series of sarcomeres Signup and view all the answers

Why do skeletal myocytes have a fibre-like shape?

Because they are narrow and relatively long Signup and view all the answers

What is the primary function of skeletal muscle?

To move bones of the skeleton Signup and view all the answers

How do skeletal muscles typically attach to bones?

Through tendons Signup and view all the answers

What type of control do skeletal muscles operate under?

Voluntary control with some automatic functions Signup and view all the answers

What is the typical structure of a skeletal muscle?

A belly in the middle with tendons at both ends Signup and view all the answers

What can be changed voluntarily about automatic functions like breathing and swallowing?

Both the rate and depth Signup and view all the answers

What is the main difference between the way we control voluntary and involuntary actions of skeletal muscles?

Voluntary actions can be changed at will, while involuntary actions cannot Signup and view all the answers

What is the role of tendons in skeletal muscles?

To connect muscles to bones Signup and view all the answers

What is the shape of skeletal muscles that allows for efficient movement?

Fibre-like Signup and view all the answers

What is the relationship between skeletal muscles and the conscious mind?

Skeletal muscles operate under a combination of conscious and subconscious control Signup and view all the answers

What is the exception to the typical structure of a skeletal muscle?

Some muscles have only one tendon Signup and view all the answers

What is the primary function of the point of origin of a skeletal muscle?

To provide a stable site for muscle attachment Signup and view all the answers

What happens when the gastrocnemius muscle contracts?

It pulls on the calcaneal tuberosity and helps propel the animal forward Signup and view all the answers

What is the characteristic of skeletal muscles that allows for automatic functions like breathing and swallowing?

Cruise control Signup and view all the answers

What is the role of the belly in a skeletal muscle?

It is the middle portion of the muscle Signup and view all the answers

What is the relationship between the point of insertion and the point of origin of a skeletal muscle?

The point of origin is more stable than the point of insertion Signup and view all the answers

What is the result of the contraction of skeletal muscles?

Movement of the skeleton Signup and view all the answers

What is the mechanism by which muscle fibres move past each other to result in contraction of the muscle?

Little heads on one filament bind to the adjacent filament and then move Signup and view all the answers

What is the analogy that helps to explain the sliding filament theory?

Oars pushing water past the boat Signup and view all the answers

What is the role of the little heads on the myosin filament?

To bind to the adjacent filament and then move Signup and view all the answers

What is the result of the myosin heads binding to the adjacent filament and then moving?

The muscle fibre moves past the adjacent filament Signup and view all the answers

What is the sliding filament theory trying to explain?

How muscles contract and move past each other Signup and view all the answers

What is the outer covering of the entire muscle composed of?

Epimysium Signup and view all the answers

What is the layer of connective tissue that surrounds bundles of muscle fibers called?

Perimysium Signup and view all the answers

Which layer of connective tissue surrounds individual muscle fibers themselves?

Endomysium Signup and view all the answers

What is the structure that connects muscle to bone or other muscles?

Tendon Signup and view all the answers

What is the relationship between the connective tissue layers and the tendons/aponeuroses?

They are continuous with each other Signup and view all the answers

There are __________ layers of dense connective tissue surrounding muscle tissue.

3 Signup and view all the answers

The __________ layer of connective tissue surrounds individual muscle fibers themselves.

endomysium Signup and view all the answers

The __________ layer surrounds multiple bundles of muscle fibers.

epimysium Signup and view all the answers

The connective tissue layers are continuous with the __________ or aponeuroses that connect muscle to bone or other muscles.

tendons Signup and view all the answers

The outer covering of the entire muscle is composed of __________ tissue.

dense connective Signup and view all the answers

The endomysium layer surrounds multiple bundles of muscle fibers.

False Signup and view all the answers

The perimysium layer surrounds the entire muscle.

False Signup and view all the answers

Dense connective tissue surrounds muscle tissue in multiple layers.

True Signup and view all the answers

The epimysium layer surrounds individual muscle fibers themselves.

False Signup and view all the answers

The connective tissue layers are separate from the tendons or aponeuroses that connect muscle to bone or other muscles.

False Signup and view all the answers

Skeletal muscle fibers exert a small force when they contract.

False Signup and view all the answers

Connective tissue layers in skeletal muscles contain only blood vessels and nerve fibers.

False Signup and view all the answers

Skeletal muscles can move freely without being attached to bones or other muscles.

False Signup and view all the answers

The connective tissue layers in skeletal muscles reduce friction caused by gravity.

False Signup and view all the answers

The connective tissue layers in skeletal muscles hold the components of the muscle together and help to join the muscle firmly to its appropriate structures.

True Signup and view all the answers

What is the primary function of the connective tissue layers in skeletal muscles?

To reduce friction and hold the muscle components together Signup and view all the answers

What type of tissue is found in varying amounts in the connective tissue layers of skeletal muscles?

Adipose tissue Signup and view all the answers

What is the significance of the connective tissue layers in skeletal muscles in relation to bones?

They help to join the muscle firmly to its appropriate structures Signup and view all the answers

What is contained in the connective tissue layers of skeletal muscles, in addition to adipose tissue?

Blood vessels and nerve fibers Signup and view all the answers

What is the role of the connective tissue layers in reducing friction in skeletal muscles?

By allowing muscle fibers to move past each other smoothly Signup and view all the answers

What is the primary function of the connective tissue layers in skeletal muscles?

To reduce friction and hold the muscle components together Signup and view all the answers

What is contained in the connective tissue layers of skeletal muscles, besides adipose tissue?

Blood vessels and nerve fibers Signup and view all the answers

Why do skeletal muscle fibers need to be firmly attached to bones and other structures?

Because they exert a large force when they contract Signup and view all the answers

What is the purpose of the connective tissue layers in relation to the movement of skeletal muscles?

To reduce friction and hold the muscle components together Signup and view all the answers

What is the role of the connective tissue layers in reducing friction in skeletal muscles?

They provide a lubricating effect Signup and view all the answers

Skeletal muscle fibers exert a small force when they contract.

False Signup and view all the answers

Connective tissue layers in skeletal muscles contain only blood vessels and nerve fibers.

False Signup and view all the answers

Skeletal muscles can move freely without being attached to bones or other muscles.

False Signup and view all the answers

The connective tissue layers in skeletal muscles reduce friction caused by gravity.

False Signup and view all the answers

The connective tissue layers are separate from the tendons or aponeuroses that connect muscle to bone or other muscles.

False Signup and view all the answers

What is the primary characteristic of dense connective tissue in terms of its elasticity?

It is inelastic Signup and view all the answers

What is the color of dense connective tissue?

White or silvery Signup and view all the answers

What is the function of tendons in the body?

To transfer movement generated by muscles to bones Signup and view all the answers

What is the characteristic of dense connective tissue in terms of its blood supply?

It has a poor blood supply Signup and view all the answers

What is the relationship between the epimysium and tendons?

Tendons are a continuation of the epimysium Signup and view all the answers

What is the primary function of ligaments in the skeletal system?

To hold joints/bones together and allow movement in certain directions Signup and view all the answers

What type of tissue do ligaments consist of?

Tough fibrous connective tissue Signup and view all the answers

What is the main difference between tendons and ligaments?

Ligaments connect muscle to bone, while tendons connect bone to bone Signup and view all the answers

What is the role of ligaments in joint movement?

To hold joints/bones together and allow movement in certain directions Signup and view all the answers

What is the relationship between ligaments and bones?

Ligaments connect bone to bone Signup and view all the answers

What is the main function of ligaments in the skeletal system?

To hold joints/bones together and allow movement in certain directions Signup and view all the answers

What is the structure of ligaments composed of?

Tough fibrous connective tissue Signup and view all the answers

Which ligament is commonly injured in both humans and dogs?

Anterior cruciate ligament Signup and view all the answers

What is the primary difference between ligaments and tendons?

Ligaments connect bone to bone, while tendons connect muscle to bone Signup and view all the answers

What is the role of ligaments in facilitating joint movement?

They restrict movement to specific directions Signup and view all the answers

What is the main function of ligaments in the skeletal system?

To facilitate movement in certain directions Signup and view all the answers

Where are smooth muscles typically found in the body?

In the walls of hollow organs and in small discrete groups Signup and view all the answers

What is the main difference between tendons and ligaments?

Tendons connect muscles to bones, while ligaments connect bone to bone Signup and view all the answers

What is the characteristic of smooth muscles that allows them to carry out unconscious, internal movements?

They are involuntary and controlled by the autonomic nervous system Signup and view all the answers

What is the structure of ligaments composed of?

Tough fibrous connective tissue Signup and view all the answers

Ligaments are similar in structure to muscles and connect bone to bone.

False Signup and view all the answers

Smooth muscle is found in distinct structures like skeletal muscles and the heart.

False Signup and view all the answers

The anterior cruciate ligament (ACL) is a type of smooth muscle.

False Signup and view all the answers

Ligaments allow for movement in all directions in a joint.

False Signup and view all the answers

Multi-unit smooth muscle is found in the walls of some hollow organs.

False Signup and view all the answers

Study Notes

Skeletal Muscle Overview

Skeletal myocytes (muscle cells) are long and narrow, resembling fibers, and are striated, displaying a striped appearance due to bands called sarcomeres.
Skeletal muscles are generally attached to the skeleton through tendons, allowing for movement of bones.
Most skeletal muscles attach to bones with tendons at both ends, featuring a central belly.
Control of skeletal muscle is primarily voluntary, though some actions (like breathing and swallowing) occur subconsciously.

Skeletal Muscle Attachments

Muscles have two key attachment points:
- Origin: The more stable, less mobile attachment point during contraction.
- Insertion: The more mobile attachment point that experiences significant movement.
Example: The gastrocnemius muscle originates from the femur and inserts at the calcaneal tuberosity, allowing for knee flexion and tarsus extension.

Muscle Contraction Mechanism

The Sliding Filament Theory describes muscle contraction via the movement of myosin heads binding to adjacent fibers, facilitating their sliding past one another.
Dense connective tissue surrounds muscle fibers in three layers:
- Endomysium: Surrounds individual muscle fibers.
- Perimysium: Encases bundles of fibers (fascicles).
- Epimysium: Covers the entire muscle, connecting with tendons or aponeuroses.

Connective Tissue Functions

The connective tissue layers stabilize muscle structure and reduce friction during contraction.
These layers accommodate blood vessels and nerve fibers, supplying the muscle.
Skeletal muscle fibers generate significant force upon contraction, requiring firm attachment to bones.

Properties of Dense Connective Tissue

Inelastic and non-stretchable, with high tensile strength oriented in one direction.
Exhibits a white/silvery appearance and possesses a poor blood supply.

Tendons and Ligaments

Tendons: Tough connective tissues connecting muscles to bones, continuing from the epimysium, facilitating movement transfer from muscle to bone.
Ligaments: Similar to tendons but connect bone to bone, providing joint stability and directional movement.
Example: Anterior cruciate ligament (ACL) is a common injury site for both humans and dogs.

Smooth Muscle

Smooth muscle is responsible for unconscious bodily functions and is found throughout the body rather than in distinct structures.
Exists in two forms:
- Visceral Smooth Muscle: Large sheets in the walls of hollow organs.
- Multi-Unit Smooth Muscle: Small, discrete groups of cells.

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Description

Test your knowledge of skeletal muscle cells, including their unique fibre-like shape, striated appearance, and the role of sarcomeres in muscle contraction. Learn about the characteristics of skeletal myocytes and how they function.