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Questions and Answers
What physiological response creates goose bumps?
What physiological response creates goose bumps?
- Expansion of skin tissue
- Relaxation of the arrector pili muscle
- Contraction of the arrector pili muscle (correct)
- Increased blood flow to the skin
What happens to hair when the arrector pili muscle contracts?
What happens to hair when the arrector pili muscle contracts?
- Hair falls out
- Hair becomes softer
- Hair stands upright (correct)
- Hair bends downward
Why is the arrector pili muscle considered a vestigial structure in humans?
Why is the arrector pili muscle considered a vestigial structure in humans?
- It helps in digestion.
- It no longer functions in humans. (correct)
- It has no historical significance.
- It is used for movement.
How does the arrector pili muscle benefit polar bears in cold environments?
How does the arrector pili muscle benefit polar bears in cold environments?
Under what circumstances does the arrector pili muscle primarily activate in humans?
Under what circumstances does the arrector pili muscle primarily activate in humans?
What is the primary effect of the contraction of the arrector pili muscle?
What is the primary effect of the contraction of the arrector pili muscle?
How does the insulation effect of hair standing up help polar bears?
How does the insulation effect of hair standing up help polar bears?
What is the primary role of the arrector pili muscle in humans?
What is the primary role of the arrector pili muscle in humans?
What component gives skin its toughness and is also found in nails?
What component gives skin its toughness and is also found in nails?
What layer of skin do hair follicles originate from?
What layer of skin do hair follicles originate from?
Which part of the dermis is described as thinner and looser in texture?
Which part of the dermis is described as thinner and looser in texture?
What is the approximate rate of hair growth per month?
What is the approximate rate of hair growth per month?
What type of muscle is the arrector pili muscle classified as?
What type of muscle is the arrector pili muscle classified as?
Which structure extends upward from the hair follicle?
Which structure extends upward from the hair follicle?
What do the cells in hair primarily contain that contributes to their structure?
What do the cells in hair primarily contain that contributes to their structure?
Which layer lies below the dermis and contains fat tissue?
Which layer lies below the dermis and contains fat tissue?
What distinguishes the growth rate of fingernails and toenails?
What distinguishes the growth rate of fingernails and toenails?
What happens involuntarily when the arrector pili muscle contracts?
What happens involuntarily when the arrector pili muscle contracts?
What is the primary component that makes up the nail?
What is the primary component that makes up the nail?
Which layer of the skin is directly connected to the nail root?
Which layer of the skin is directly connected to the nail root?
From which layer do the cells that contribute to nail growth originate?
From which layer do the cells that contribute to nail growth originate?
How do keratinocytes affect nail growth?
How do keratinocytes affect nail growth?
What happens to the keratinocytes as they move towards the nail?
What happens to the keratinocytes as they move towards the nail?
What term is used to describe the layers of skin and associated structures like nails?
What term is used to describe the layers of skin and associated structures like nails?
Why are nails considered part of the epidermis?
Why are nails considered part of the epidermis?
Which of the following statements about the growth of nails is INCORRECT?
Which of the following statements about the growth of nails is INCORRECT?
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Study Notes
Integumentary System Overview
- Integument consists of the skin layers and appendages such as nails and hair.
- Appendages, including nails, are crucial functional structures in the integumentary system.
Nail Structure and Growth
- The nail root, attached to the epidermis, is essential for nail development.
- Nails are formed from keratinocytes in the stratum basale of the epidermis, leading to the upward growth of nails.
- Keratin, a tough protein, makes up nails, providing stiffness and durability.
- Fingernails grow approximately four times faster than toenails.
Hair Structure and Growth
- Hair follicles originate in the reticular layer of the dermis and produce hair shafts that emerge from the skin.
- Hair growth occurs through flattened, keratin-filled epithelial cells, with a growth rate of approximately 0.5 inches (1.25 cm) per month.
- Hair consists of a central shaft that extends through the epidermis.
Dermis Layers
- The dermis contains two layers:
- Papillary dermis (thinner, looser connective tissue).
- Reticular dermis (thicker, denser connective tissue).
Arrector Pili Muscle
- The arrector pili muscle is smooth muscle located in the papillary dermis, controlling involuntary actions.
- Contraction of this muscle results in goosebumps and hair standing on end.
- Goosebumps occur during cold exposure or strong emotions.
Functionality of Arrector Pili
- In animals, such as polar bears, the arrector pili muscle helps trap warm air within a dense coat of hair, providing insulation in cold climates.
- In humans, the arrector pili muscle is considered vestigial, as its function is less significant due to reduced body hair.
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