Anatomy & Physiology I: Skin and Muscles

Practice Test: Anatomy & Physiology I (Ch. 5 & Ch. 9) Notes

Multiple Choice

  • Epidermis layer: The layer of the skin composed of stratified squamous epithelium is the Epidermis.
  • Function of melanocytes: The primary function of melanocytes is to absorb UV radiation.
  • Hypodermis composition: The hypodermis is primarily composed of adipose and areolar connective tissue.
  • Goosebumps: Goosebumps are caused by the arrector pili muscle.
  • Voluntary muscle tissue: The type of muscle tissue that is voluntary is Skeletal muscle.

True/False

  • The reticular layer of the dermis is composed primarily of dense irregular connective tissue (False).
  • Apocrine sweat glands are active from birth (False).
  • The sarcomere is the functional unit of muscle contraction (True).
  • Troponin is responsible for covering the active sites on actin in a relaxed muscle (True).
  • The All-or-None Principle applies to the contraction of a single muscle fiber (True).

Fill in the Blank

  • The dermal papillae layer is responsible for fingerprints.
  • The three layers of thin skin from deep to superficial are hypodermis, dermis, and epidermis.
  • The sarcolemma is the plasma membrane of a muscle fiber.
  • The two types of myofilaments in muscle cells are thin (actin) filaments and thick (myosin) filaments.
  • Calcium is stored in the sarcoplasmic reticulum and muscle cell.

Short Answer

  • Sebaceous Glands & Skin Health: Sebaceous glands secrete sebum, which lubricates the skin and hair, preventing dryness and protecting against bacteria.
  • Muscle Contraction Process: Muscle contraction occurs when an action potential travels from the neuromuscular junction, triggering the release of calcium, which exposes myosin binding sites on actin, leading to contraction through the sliding filament model.
  • Muscle Types: Skeletal muscle is striated and voluntary; cardiac muscle is striated and involuntary; smooth muscle is non-striated and involuntary.
  • Severe Burns Consequence: Severe burns can lead to loss of fluid, skin infections, and impaired thermoregulation.
  • Role of ATP in Muscle Contraction: ATP provides the energy required for muscle contraction by powering the cross-bridging process and is needed for relaxation as well by pumping calcium back into the sarcoplasmic reticulum.

Layers of the Skin

  • Epidermis: Stratified squamous epithelium; constantly renewing through cellular turnover.
  • Dermis: Composed of dense connective tissue, highly vascularized; provides structural support.
  • Hypodermis: Also known as the subcutaneous layer; primarily made of adipose tissue, serves as a shock absorber and insulator.

Regions and Functions of Skin

  • Epidermis: Thin and avascular, renewed every 15-30 days.
  • Dermis Structure: Main support structure, contains nerves and blood vessels.
  • Subcutaneous Layer Function: Shock absorber, regulates temperature, varies in thickness.

Skin Cells

  • Keratinocytes: Produce keratin and die as they migrate to the surface.
  • Melanocytes: Produce melanin to protect against UV radiation.
  • Langerhans cells: Provide immune defense.
  • Merkel cells: Function as touch receptors.

Muscle Tissue Types

  1. Skeletal Muscle: Voluntary, striated, multinucleated, involved in movement.
  2. Cardiac Muscle: Involuntary, striated, found only in the heart, responsible for pumping blood.
  3. Smooth Muscle: Involuntary, non-striated, found in hollow organs, low energy requirement.

Muscle Characteristics

  • Excitability: Ability to respond to stimuli.
  • Contractility: Ability to shorten forcefully when adequately stimulated.
  • Extensibility: Ability to stretch without being damaged.
  • Elasticity: Ability to return to its original shape after stretching.

Muscle Functions

  • Produce movement and manipulate environment.
  • Maintain posture and body position.
  • Stabilize joints and generate heat.

Skeletal Muscle Structure

  • Each skeletal muscle is a discrete organ, supplied with blood and nerves.
  • Connective tissue sheaths (epimysium, perimysium, endomysium) play critical roles in muscle function.

Neuromuscular Junction

  • Where nerve cells connect to muscle fibers; essential for muscle contraction signaling.
  • Action potentials lead to calcium release, triggering muscle contraction via the sliding filament model.