Muscle Physiology Quiz

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Questions and Answers

What describes the muscle that directly opposes the action of the prime mover?

Fixator

Antagonist (correct)

Synergist

Agonist

Which type of muscle stabilizes joints to allow for other movements?

Prime movers

Synergists

Fixators (correct)

Antagonists

What is the term for the region from one Z line to the next Z line in a muscle fiber?

Sarcomere (correct)

Myofibril

A band

I band

Which of the following is a thick contractile filament in muscle fibers?

Myosin Signup and view all the answers

Which muscle type is responsible for bending joints?

Flexors Signup and view all the answers

What type of muscle fibers are long, thin, and multinucleated?

Skeletal muscle fibers Signup and view all the answers

Which band in muscle fibers is made up of thin actin filaments?

I band Signup and view all the answers

What role do synergists play in muscle movement?

Enhance the effectiveness of the prime mover Signup and view all the answers

What is the primary role of acetylcholine in muscle contraction?

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

Which connective tissue layer surrounds individual muscle fibers?

Endomysium Signup and view all the answers

What occurs at the neuromuscular junction?

Nerve fibers connect to muscle fibers with no attachment. Signup and view all the answers

What is the function of the sarcoplasmic reticulum during muscle contraction?

To store and release calcium ions. Signup and view all the answers

Which sequence correctly describes the initiation of muscle contraction?

Nerve impulse → Release of acetylcholine →Muscle contraction. Signup and view all the answers

What does a motor unit consist of?

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

What role does ATP play in muscle contraction?

Provides energy for the contraction process. Signup and view all the answers

What is the function of acetylcholinesterase at the neuromuscular junction?

To break down acetylcholine after contraction. Signup and view all the answers

What is the main function of the root hair plexus?

To serve as a touch receptor Signup and view all the answers

Which layer of the hair is responsible for its structural strength?

Cortex Signup and view all the answers

What occurs to the epithelial cells of the matrix as they divide?

They become keratinized Signup and view all the answers

How are compound follicles characterized in terms of hair strands?

Multiple strands emerge from a single epidermal orifice Signup and view all the answers

What is the outermost layer of the hair called, and what is its primary function?

Cuticle, to prevent hairs from matting Signup and view all the answers

What is a key characteristic of the stratum basale?

It contains actively dividing keratinocytes. Signup and view all the answers

Which cell type is NOT typically found in the stratum spinosum?

Merkel cells Signup and view all the answers

What unique feature is characteristic of the stratum granulosum?

It has 2-4 layers of diamond-shaped keratinocytes. Signup and view all the answers

Which of the following statements about the stratum lucidum is true?

It appears as a clear layer in thick skin. Signup and view all the answers

Which statement best describes the stratum corneum?

It is composed of multiple layers of dead keratinocytes. Signup and view all the answers

What is the significance of the dermal papillae found in the papillary layer?

They anchor the epidermis to the dermis. Signup and view all the answers

Which of the following layers of the dermis accounts for approximately 80% of its thickness?

Reticular layer Signup and view all the answers

What role do Meissner’s corpuscles play in the papillary layer of the dermis?

They function as touch receptors. Signup and view all the answers

What is the significance of making incisions along tension lines in skin?

To prevent gapping of wounds Signup and view all the answers

Which of the following statements is true regarding the subcutaneous layer?

It is rich in blood and lymphatic vessels. Signup and view all the answers

How does melanin granule dispersion affect pigmentation?

It is influenced by melanocyte-stimulating hormone. Signup and view all the answers

What are carpal pads primarily associated with?

Weight distribution in the animal Signup and view all the answers

Which of the following is true about the nasal planum in dogs?

It has polygonal plates arranged closely together. Signup and view all the answers

What are chestnuts in horses a remnant of?

The first digit's carpal pads Signup and view all the answers

What unique feature do cutaneous pouches have that is significant in sheep?

They have tubular glands. Signup and view all the answers

What is the role of ATP in muscle contraction?

It is used to recharge ADP back into ATP. Signup and view all the answers

Which phase of a muscle twitch occurs immediately after the nerve stimulus?

Latent phase Signup and view all the answers

What is the function of myoglobin in muscle tissue?

It stores oxygen within muscle cells. Signup and view all the answers

How are cardiac muscle contractions initiated?

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

What changes occur in smooth muscle during parturition?

Progesterone decreases, enhancing contractions. Signup and view all the answers

What is the main characteristic of smooth muscle compared to skeletal muscle?

Smooth muscle exhibits involuntary control. Signup and view all the answers

What happens to muscle fibers during anaerobic metabolism?

They generate lactic acid as a by-product. Signup and view all the answers

Which structure helps to connect cardiac muscle cells?

Intercalated discs Signup and view all the answers

Which layer of the skin contains blood vessels?

Dermis Signup and view all the answers

What is the main role of keratinocytes in the epidermis?

Producing keratin. Signup and view all the answers

What type of muscle fiber can undergo the most significant shortening?

Smooth muscle fibers Signup and view all the answers

What is a key feature of muscle fibers' contraction under the all-or-nothing principle?

All fibers reach maximum force upon stimulation. Signup and view all the answers

Where are melanocytes primarily located in the skin?

In the deepest epidermal layers. Signup and view all the answers

Study Notes

Anatomy and Physiology I - The Muscular System

Muscle is one of the four basic tissues in the body, composed of cells that can shorten and lengthen.
Muscles carry out commands from the nervous system (except cardiac and smooth muscle).
Three types of muscle:
- Skeletal muscle: voluntary, moves the skeleton, striated, somatic nervous system.
- Cardiac muscle: involuntary, only found in the heart, striated, autonomic nervous system.
- Smooth muscle: involuntary, found throughout the body (e.g., eyes, lungs, stomach, intestines, bladder, reproductive tract), non-striated, autonomic nervous system.
Myo- refers to muscle (e.g., myositis is muscle inflammation).
Sarco- refers to muscle cells (e.g., sarcoplasm is the cytoplasm of a muscle cell).
Skeletal muscle can be controlled consciously, but also has an "automatic" feature to control/regulate functions like breathing.
Gross anatomy:
- Belly: thick, central, contractile portion of the muscle.
- Tendons: fibrous bands connecting muscle to bone.
- Aponeuroses: broad fibrous bands connecting muscles to bone or other muscles.
- Linea alba: white line running lengthwise between abdominal muscles on the ventral midline.

Anatomy and Physiology I - Muscle Action

Movement is caused by pulling on attachment points.
Prime movers (agonists): muscles primarily responsible for movement.
Antagonists: muscles that oppose the prime mover to control movement.
Synergists: muscles that assist the prime mover in a specific action.
Fixators: muscles that stabilize joints to allow other movements to occur.

Anatomy and Physiology I - Muscle Names

Muscles names may be based on several factors, e.g., shape, location, direction of fibers, number of heads, or attachment sites.

Anatomy and Physiology I - Microscopic Anatomy

Skeletal muscle cells (fibers) are long, cylindrical, and multinucleated.
Myofibrils are composed of contractile proteins (actin and myosin).
Myofibrils are made up of sarcomeres (repeating units)
Sarcomeres are the basic contractile units that cause shortening of the muscle.
The parts of the sarcomere include: I band, Z band, A band
These components work together to create the contraction in skeletal muscles.

Anatomy and Physiology I - Connective Tissue

Endomysium: surrounds individual muscle fibers.
Perimysium: surrounds groups of muscle fibers (fascicles).
Epimysium: surrounds the entire muscle.
These connective tissues help hold the muscle together during contraction.

Anatomy and Physiology I - Neuromuscular Junction

The site where the ends of motor nerve fibers connect to muscle fibers.
Neurotransmitters initiate the process of muscle contraction.
Acetylcholine is the neurotransmitter used to initiate the contraction of skeletal muscle, it is quickly broken down by acetylcholinesterase.
The impulses from motor nerve fibers travel through the T tubules and cause released Ca2+ ions to initiate contraction.

Anatomy and Physiology I - Mechanics of Contraction

During a relaxed phase, actin/myosin slightly overlap.
Myosin filaments ratchet back to contract and pull actin filaments towards the center of the myosin filament, shortening the sarcomere

Anatomy and Physiology I - Chemistry of Muscle Contraction

ATP is used to provide energy for muscle contraction.
Creatine Phosphate (CP) acts as a backup energy source.

Anatomy and Physiology I - Muscle Contraction Phases

Latent phase: brief delay between stimulus and contraction.
Contraction phase: muscle shortens in response to stimulus.
Relaxation phase: muscle returns to resting length.

Anatomy and Physiology I - Muscle Memory

Muscle memory is the nervous system training to improve the synchronization of muscle contractions.

### Anatomy and Physiology I - Cardiac Muscle

Cardiac muscle cells are smaller than skeletal muscle cells and have one nucleus per cell.
Intercalated discs: connect cells and allow for coordinated contraction.
No external stimuli needed for contraction, but the rate is determined by the fastest cell.
Impulses spread from cell to cell, coordinated by conduction system (starts in the sinoatrial (SA) node).
Sympathetic nerves speed up/strengthen and parasympathetic nerves slow down contraction.

Anatomy and Physiology I - Smooth Muscle

Found in sheets or groups, non-striated, involuntary.
Cells have fusiform (spindle-shaped) structure, with one nucleus.
Actin and myosin filaments arranged diagonally, giving a non-striated appearance.
Cells can contract in response to stretch (visceral muscle) or specific nerve signals (multiunit smooth muscle).
No need for external stimulation for contraction(ex. visceral smooth muscles in the gut).
Sympathetic nervous decreases and parasympathetic increases activity.

Anatomy and Physiology I - Integument (Skin)

Outer covering of the body, composed of four types of tissue.
Epidermis and dermis are the major layers.
Epidermis: outermost layer (keratinized stratified squamous epithelium).
Keratinocytes: predominant cell type.
Melanocytes: produce melanin (pigment).
Langerhans cells: immune function.
Merkel cells: touch sensation.
Dermis: underlying layer (fibrous connective tissue).
Hypodermis/subcutaneous layer: deep connective tissue layer, adipose tissue for insulation.
Sweat glands (apocrine and eccrine): regulate body temperature.
Sebaceous glands: secrete sebum (oils) to lubricate hair and skin
Hair follicles (hair shaft, bulb): structure for hair growth, nerve endings for sensory input to the skin.

Anatomy and Physiology I - Hair

Hair is crucial in maintaining temperature, sensory input.
Divided into three types of hairs (depending on the function and sensitivity).
- Guard hairs: primary (longer, straighter, thicker)
- Secondary hairs: shorter, softer (wavy, bristled).
- Tactile hairs: (whisker hairs), are specialized for touch and sensory input.

Anatomy and Physiology I - Sebaceous Glands

Found in most body areas, except palms of hands/soles of feet.
Secrete sebum (oil), lubricating hair and skin.
Prevents skin drying, plays a role in skin's waterproofing, antimicrobial action.

Anatomy and Physiology I - Sweat Glands

Eccrine sweat glands: most numerous, regulate body temperature.
Apocrine sweat glands: concentrated in axillae, pubic region, and areola; their function and secretions are often associated with sexual development.

Anatomy and Physiology I - Nasolabial Planum

Also known as the nasal planum.
Composed exclusively of the three epidermal layers.
This is a specialized structure primarily found in sheep, cattle and goats.

Anatomy and Physiology I - Anal Glands

Musk/scent glands located near the anus.
Act as a reservoir for secretions.
Primarily released during defecation/fear.
May be affected with infections.

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Description

Test your knowledge on muscle physiology with this quiz that covers key terms and functions of various muscle types. From the role of prime movers to muscle fiber types, this quiz ensures a comprehensive understanding of muscular anatomy and movements.