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Questions and Answers
What is the primary function of hair on the scalp?
What does the structure of the hair bulb primarily contribute to?
Which of the following statements about nails is incorrect?
Which part of the hair determines its curliness?
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Where is hair densely distributed on the human body?
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What role do eyelashes and eyebrows primarily serve?
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What is the primary function of the papillary layer of the dermis?
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What type of receptor are Pacinian corpuscles?
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Which cells are found in the stratum basale layer of the epidermis?
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The hair root is encased within which types of sheath?
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What components are primarily found in the dermis of the skin?
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What is the primary role of the hypodermis?
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Which of the following best describes arrector pili muscles?
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What is the function of Meissner’s corpuscle?
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The reticular layer of the dermis is characterized by which of the following features?
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How do hair follicles contribute to sensory perception?
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What is the primary function of ligaments in the skeletal system?
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Which part of the human skeleton contains the highest number of bones?
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How many total bones are in the adult human skeleton?
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Which type of tissue is cartilage classified as?
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What is the role of the thoracic cage in the human skeleton?
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Where is cartilage primarily found in the human body?
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Which of the following is not a component of the skeletal system?
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How many bones make up the vertebral column?
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Which type of bone is typically longer and found in the limbs?
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What shape are short bones typically classified as?
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What is the overall prevalence of sarcopenia among Japanese community-dwelling older adults?
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Which age group is primarily associated with the increased reduction in lower limb muscle cross-sectional area?
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Flat bones are generally related to which of the following?
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How are bones classified according to their size and shape?
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What structural change in muscle composition is typically observed with aging?
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Which type of muscle fiber is most significantly reduced with age?
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Which of the following is NOT an example of flat bones?
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What characteristic is commonly associated with long bones?
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What is the effect of aging on the total number of muscle fibers?
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What factor is associated with increased intramuscular adipose tissue in older inpatients?
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Which type of bone would you NOT find in the ankle?
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Flat bones can be found in which of the following locations?
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What is the typical contribution of lean muscle mass to total body weight in young adults?
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How does muscle strength change with age?
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Study Notes
Epidermis Layers
- Stratum spinosum is several layers thick, cells have dark nuclei and spiny projections.
- Stratum basale is the deepest layer of the epidermis and is a single layer of actively dividing cells.
- Keratinocytes, melanocytes, and Merkel cells are present in the stratum basale.
Dermis
- Found below the epidermis, composed of elastic and collagenous fibers.
- Contains sweat glands, sebaceous glands, nerve endings, and hair follicles.
- Composed of two layers:
- Papillary layer is composed of loose connective tissues with many blood vessels.
- Reticular layer is deeper and thicker than the papillary layer and is composed of dense and stretchable connective tissues.
- Papillae are fingerlike projections in the papillary layer that bring blood vessels near the epidermis and help to hold the two layers together.
- The arrangement of the papillae determines fingerprints.
Hypodermis or Subcutaneous Layer
- Not a part of the skin but connects the dermis to other organs.
- Stores fat, is a shock absorber, and anchors the skin to underlying structures.
Specific Appendages inside the Skin Layer
- Arrector pili muscles cause goosebumps.
- Sensory nerve fibers protect the body and are sensitive to temperature.
- Hair follicles contain nerve endings allowing a person to feel hair movement.
- Sebaceous glands associated with each hair follicle produce oil to condition hair and skin.
- Pores lubricate the skin.
- Meissner’s corpuscles in the dermis monitor the duration and extent of touch.
- Pacinian corpuscles are pressure sensitive receptors.
Hair
- Found everywhere in the body except palms, soles, lips, penis, and parts of the female genitalia.
- Dense distribution of hair on the scalp, face, pubic area, and underarms.
- Functions for protection:
- from injury, sunlight, and heat loss (scalp hair)
- from foreign particles (eyebrows and eyelashes)
- from airborne particles (hairs in the nostrils).
- Also functions as a sexual attractant.
- Composed of the shaft, root, and bulb.
- The shaft determines the curliness of the hair: round shaft (straight hair), oval shaft (wavy hair), and flat shaft (kinky hair).
- The bulb is the enlarged base of the follicle.
- The root is encased in an internal or epithelial root sheath (derived from the epidermis), and an external or connective root sheath (derived from the dermis).
Nails
- Composed of hard plates of highly keratinized cells.
- Formed from the stratum corneum of the epidermis.
- Cover and protect the dorsal surface of the fingernails and toenails.
- Help in grasping and picking small objects.
Overview of Skeletal System
- Bones are classified according to size and shape:
- Long bones are typically longer.
- Short bones are generally cube shaped.
- Flat bones are thin, flattened, and usually curved.
- Irregular bones have complex shapes.
The Skeletal System Consists of More Than Bones
- The human skeleton is made up of bones, ligaments, and cartilage.
- Ligaments are bands of dense and fibrous connective tissue that are essential for joint function.
- Cartilage is more flexible than bone but stiffer than muscle, found in the larynx, nose, between vertebrae, and at the ends of bones.
The Adult Human Skeleton Is Made Up of 206 Bones
- Skull - 22 bones
- Shoulder Girdle/Upper Extremities - 64 bones
- Thoracic Cage - 25 bones
- Vertebral Column - 33 bones
- Pelvic Girdle/Lower Extremities - 62 bones.
Age-Related Changes in Muscle Structure
- Lean muscle mass contributes up to 50% of total body weight in young adults, but this decreases to 25% by 75 to 80 years.
Typical Muscle Changes with Age
- Reduced muscle mass and increased fat mass.
- Reduced lower limb muscle cross-sectional area, beginning in early adulthood and accelerating after age 50.
- Decline in the number of muscle fibers, primarily affecting type II fast-twitch glycolytic fibers.
Sarcopenia
- Prevalence in Japanese community-dwelling older adults is 9.9% overall (9.8% among men, and 10.1% among women).
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Description
Test your knowledge on the layers of the skin, including the epidermis, dermis, and hypodermis. This quiz covers the structure and functions of these layers along with specific cell types and their roles. Perfect for students studying human anatomy and physiology.
