muscles and integument

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Questions and Answers

Which type of muscle is under voluntary control?

Skeletal muscle (correct)

Smooth muscle

All types of muscle

Cardiac muscle

What structure connects muscle to bone?

Ligament

Fascia

Tendon (correct)

Aponeurosis

What is the function of cardiac muscle?

Contracts involuntarily to pump blood (correct)

Surrounds organs for protection

Moves the skeleton

Controls voluntary actions

What does the prefix 'myo-' denote in medical terminology?

Muscle Signup and view all the answers

What is referred to as the 'belly' of the muscle?

The thick, central, contractile portion of the muscle Signup and view all the answers

What is the term for the process of losing a large volume of hair at one time?

Telogen effluvium Signup and view all the answers

During which phase does hair growth primarily occur?

Anagen phase Signup and view all the answers

What is the role of melanocytes in hair color?

They generate pigment for color Signup and view all the answers

What is the quiescent phase of the hair growth cycle where hair has reached its maximum length called?

Telogen phase Signup and view all the answers

Which type of melanin is responsible for producing reddish or yellow hair colors in dogs?

Pheomelanin Signup and view all the answers

What is the primary function of the origin in relation to a muscle?

It serves as the most stable attachment point of the muscle. Signup and view all the answers

Which muscle type is responsible for bending joints?

Flexors Signup and view all the answers

What is the role of synergist muscles?

They contract concurrently with the prime mover to aid movement. Signup and view all the answers

What is a characteristic of skeletal muscle cells?

They are multinucleated with nuclei located under the sarcolemma. Signup and view all the answers

Which protein filaments make up the thick filaments in myofibrils?

Myosin Signup and view all the answers

What defines a sarcomere?

The area from one Z line to the next Z line. Signup and view all the answers

What does the I band represent in muscle anatomy?

A lighter band made up of thin actin filaments. Signup and view all the answers

How are muscle names often determined?

Based on their location, shape, or function. Signup and view all the answers

What is the role of acetylcholine in muscle contraction?

It initiates the process of muscle contraction. Signup and view all the answers

What structure surrounds individual muscle fibers?

Endomysium Signup and view all the answers

Which connective tissue layer binds groups of skeletal muscle fibers called fascicles?

Perimysium Signup and view all the answers

What happens when acetylcholine is released into the synaptic space?

An impulse travels along the sarcolemma. Signup and view all the answers

What initiates the muscle contraction process after the nerve impulse reaches the sarcoplasmic reticulum?

Calcium ions are released into the sarcoplasm. Signup and view all the answers

What is a motor unit?

One nerve fiber and all the muscle fibers it innervates. Signup and view all the answers

Which structural layer surrounds groups of fascicles in skeletal muscle?

Epimysium Signup and view all the answers

What role does acetylcholinesterase play in muscle contraction?

It breaks down acetylcholine in the synaptic space. Signup and view all the answers

What is the primary function of arrector pili muscles in animals?

To assist in temperature regulation by changing the angle of hair Signup and view all the answers

What occurs when the sebaceous glands become full?

They rupture and release sebum Signup and view all the answers

Which type of sweat gland in dogs is found in deep layers of fat and connective tissue of the foot pads?

Eccrine sweat glands Signup and view all the answers

What distinguishes apocrine sweat glands from eccrine sweat glands?

Apocrine glands empty into hair follicles while eccrine glands empty onto the skin surface Signup and view all the answers

What role do tail glands play in animals?

Assist in mating behavior and identification Signup and view all the answers

Which type of secretion is primarily associated with sebaceous glands?

Oily, lipid substances Signup and view all the answers

What is the main purpose of the anal glands in animals?

To store and express scents during defecation Signup and view all the answers

What condition may arise from excessive sebum production?

Hair loss due to follicles being clogged Signup and view all the answers

What happens to calcium ions (Ca++) immediately after they are released during muscle contraction?

They are pumped back into the sarcoplasmic reticulum using ATP. Signup and view all the answers

Which phase of a muscle twitch is characterized by the slight delay between nerve stimulus and contraction?

Latent phase Signup and view all the answers

What characteristic defines the all-or-nothing principle in muscle contraction?

Each muscle fiber contracts fully or not at all. Signup and view all the answers

What is the role of creatine phosphate (CP) in muscle contraction?

It recharges ADP into ATP by adding a phosphate group. Signup and view all the answers

How is oxygen stored in muscle tissue?

In myoglobin, a large protein. Signup and view all the answers

What initiates the contraction of cardiac muscle cells?

Impulses from the sinoatrial node (SA node). Signup and view all the answers

How do intercalated discs contribute to cardiac muscle function?

They transmit impulses quickly from cell to cell. Signup and view all the answers

Which type of muscle does not require external stimulation to initiate contraction?

Cardiac muscle Signup and view all the answers

What occurs in visceral smooth muscle when it is stretched?

It contracts more forcefully. Signup and view all the answers

What type of epithelial tissue makes up the majority of the epidermis?

Keratinized stratified squamous epithelium Signup and view all the answers

Which type of cell in the epidermis is responsible for producing the pigment melanin?

Melanocytes Signup and view all the answers

In which layer of the skin does the majority of nutrient supply originate?

Dermis Signup and view all the answers

What is the primary function of Langerhans cells in the epidermis?

Phagocytize microinvaders Signup and view all the answers

Which hormone reduces contractility of smooth muscle during pregnancy?

Progesterone Signup and view all the answers

What primarily composes the subcutaneous layer (hypodermis) of the skin?

Adipose tissue Signup and view all the answers

Study Notes

Muscular System

Muscle is one of the four basic tissues in the body, composed of cells able to contract and expand
Muscles carry out orders from the nervous system, but some, like cardiac and smooth muscle, have preprogrammed activity
Three types of muscle:
- Skeletal muscle: voluntary control, moves the skeleton, striated, somatic nervous system
- Cardiac muscle: involuntary control, found only in the heart, striated, autonomic nervous system
- Smooth muscle: involuntary control, found throughout the body (e.g., eye, stomach, intestines), non-striated, autonomic nervous system
Myo- refers to muscle generally (e.g., myositis)
Sarco- refers to muscle cells (e.g., sarcoplasm)

Skeletal Muscle Structure and Function

Skeletal muscle can be consciously controlled or controlled unconsciously for functions like breathing
Gross anatomy includes:
- Belly: the thick, central contractile muscle portion
- Tendons: fibrous bands that connect muscles to bone
- Aponeuroses: broad fibrous bands connecting muscle to bone or other muscles
- Linea alba: white line running lengthwise between abdominal muscles on the ventral midline

Microscopic Anatomy of Skeletal Muscle

Skeletal muscle cells are long, cylindrical, and multinucleated (with nuclei just under the sarcolemma)
Myofibrils, composed of even tinier protein filaments (actin and myosin), make up most of the muscle fiber interior
Actin (thin filaments) and myosin (thick filaments) are found in repeating units called sarcomeres
Sarcomeres are responsible for muscle contraction

Connective Tissue Layers

Muscles are secured together and to other structures by connective tissues
Endomysium: delicate connective tissue layer surrounding each muscle fiber
Perimysium: connective tissue layer surrounding groups of muscle fibers (fascicles)
Epimysium: connective tissue layer surrounding entire muscles
Tendons and aponeuroses are continuous with these connective tissue layers

Neuromuscular Junction

The site where motor nerve fibers connect to muscle fibers
Nerve fibers contain synaptic vesicles with acetylcholine
Acetylcholine's release initiates muscle contraction
Acetylcholine is then broken down by acetylcholinesterase

Muscle Contraction Mechanics

During contraction, actin and myosin filaments overlap
Myosin filaments ratchet back and forth, pulling actin filaments toward the center of the sarcomere
Contraction occurs via a series of steps requiring ATP, initiated by nerve impulses
Calcium ions are released, which trigger the interactions between actin and myosin filaments, completing the contraction

Chemistry of Muscle Contraction

ATP provides energy for contraction and the return of the muscles to the resting state
Creatine phosphate replenishes ATP to maintain the reactions
Muscle uses glucose and oxygen for energy; when oxygen is not available, lactic acid is produced

Muscle Contraction

Muscle contraction is a coordinated series of individual twitches, the rate and strength of which varies with need
Phases of a muscle twitch include latent, contracting, and relaxation phases

Cardiac Muscle

Cells are smaller and have only one nucleus
Intercalated discs connect cells, allowing coordinated contraction
Contracts without external stimulus
Pacemaker cells (SA nodes) initiate contraction
Dependent on its own impulse conduction system
Nerves only modify contraction rate
Sympathetic: faster & stronger
Parasympathetic: slower & weaker

Smooth Muscle

Found in sheets of cells in hollow organs
Small spindle-shaped with a single central nucleus
Actin and myosin are not arranged in a parallel manner; produces a non-striated appearance
Contracts in response to various stimuli (stretching, hormones, etc.)
Visceral: large rhythmic waves of contraction
Multiunit: requires specific nerve input for contraction

Other Important Muscular Concepts

Muscle memory: nervous system training to control precise stimulation based on activity

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