Muscle Types, Structure, and Function: A Comprehensive Biology Guide

Skeletal Muscle

is striated, attaches to bones, and allows movement of the body. Skeletal muscle is considered voluntary, because it acts under our conscious control.

Smooth Muscle

is not striated. It is arranged in layered sheets and contracts in waves. Smooth muscle contracts involuntarily and is found in internal structures such as arteries and the digestive tract.

Cardiac Muscle

is striated and found only in the heart. This tissue contracts involuntarily.

Epimysium

surrounds the entire muscle and protects and supports muscle structure.

Perimysium

surrounds bundles (fascicles) and provides pathways for nerves and vessels.

Endomysium

surrounds individual muscle fibers and supports capillaries and nerve endings.

Muscle Fiber

contains many myofibrils.

Myofibril

contain sarcomeres, the units that actually contract.

Muscle Cramps

caused by low magnesium and sodium levels, and low blood glucose levels can prevent adequate ATP production.

Rigor Mortis

is a phenomenon that occurs after death, where muscles stiffen due to the lack of ATP.

ATP in Distilled Water

The length is 20 cm and the percent contraction is 0.

Salt Solution with No ATP

The percent contraction is 0.

Skeletal Muscle Belly Structure

is made of bundles called fascicles, which contain many muscle fibers.

Fascicle

contains many muscle fibers (cells).

Sarcolemma

is a cell membrane of a muscle fiber.

Sarcoplasm

is the cytoplasm of a muscle fiber.

Dysium

is connective tissue around a fiber.

Calcium Transport Proteins

In the absence of ATP, it stop pumping calcium into the sarcoplasmic reticulum.

Myosin Binding Sites

on the actin filaments of myofibrils become exposed when calcium leaks out.

Crossbridge

Myosin heads form a _____ and bind to the myosin binding sites on the actin filaments.

Muscle Fatigue

occurs when there is insufficient ATP available to release myosin heads from the binding sites.

Sarcomeres

The basic contractile units of muscle fibers that are designed to shorten and lengthen within a safe range.

Microtears in Myofibrils

Small tears that occur in muscle fibers, which can happen during excessive strain.

Z-discs

Structures that can be torn due to excessive tension, damaging the alignment of myofibrils.

Connective Tissue Damage

Occurs when the endomysium and perimysium, the supporting layers around fibers, tear along with the muscle fibers.

Shivering

Involuntary muscle contractions that occur when the body is cold, helping to maintain homeostasis.

Homeostasis

The process by which the body maintains a stable internal environment, such as temperature.

ATP Breakdown

During this process, about 60-70% of the energy is released as heat, which raises body temperature toward normal.

Thermal Energy

Energy produced by shivering that helps counteract cooling of the body.

Actin-Myosin Overlap

The interaction between actin and myosin filaments that is disrupted during a muscle strain.

Sliding Filament Mechanism

The process by which muscle fibers contract, which can be disrupted by damage to the muscle structure.

Voluntary Muscle Control

The ability to consciously control skeletal muscles.

Involuntary Muscle Control

The automatic control of cardiac and smooth muscles without conscious effort.

Striated Muscle

Muscle tissue that has a striped appearance due to the arrangement of muscle fibers, found in skeletal and cardiac muscles.

Non-Striated Muscle

Muscle tissue that does not have a striped appearance, found in smooth muscle.

Muscle Strain

An injury that occurs when a muscle is overstretched or torn.

ATP

Salt solution with no 2.0

Percent Contraction

0

Makeup of a Muscle

Bone, Tendon, Skeletal Muscle Belly Structure

M. Fascicle

is made of Fibers.

Function of Connective Tissue Membranes

Protects and supports muscle structure.

Actin & Myosin

Proteins that drive contractions.

Troponin

Binds to Ca+, changes shape & moves tropomyosin away.

Damage to Connective Tissue

The endomysium and perimysium often bear a load.