Hair Growth Cycle and Anatomy — MCQs
Anagen phase of the hair indicates-
Non-scarring alopecia is associated with all except?
The organ of Corti normally contains:
A 22-year-old woman presents with diffuse hair loss for 1 month. She had a past history of enteric fever 4 months ago. What is the likely cause?
Swarm of bees appearance seen in?
Consider the following regarding the human hair growth cycle : I. Anagen is a phase of active hair growth II. Telogen is a transitional phase III. Catagen is a resting phase Which of the statements given above is/are correct?
What phase of hair growth is primarily responsible for the length of eyebrows?
Rapid, diffuse, excessive hair loss occurring 3 months after childbirth is due to?
The growth phase of hair is
A male presents with alopecia and exclamation mark hairs. Diagnosis?
Hair Growth Cycle and Anatomy Indian Medical PG Practice Questions and MCQs
Question 1: Anagen phase of the hair indicates-
- A. The phase of degeneration
- B. The phase of resting
- C. The phase of activity and growth (Correct Answer)
- D. The phase of transition
Explanation: ***The phase of activity and growth*** - The **anagen phase** is the active growth phase of hair follicles, where cells in the hair matrix rapidly divide and differentiate to form the hair shaft. - During this phase, which can last for several years, hair grows significantly, with the average duration being **2-7 years for scalp hair**. - This is the longest phase of the hair growth cycle, and approximately **85-90% of scalp hairs** are in anagen at any given time. *The phase of degeneration* - This description corresponds to the **catagen phase**, where hair growth ceases and the hair follicle shrinks, signaling the end of the active growth period. - During catagen, the outer root sheath detaches from the dermal papilla, and the hair follicle undergoes controlled regression. - This is a brief phase lasting only **2-3 weeks**. *The phase of resting* - This phase is known as the **telogen phase**, during which the hair follicle is completely at rest, and the old hair is eventually shed. - Telogen is a relatively quiescent period, typically lasting about **3-4 months**, before the follicle re-enters the anagen phase. - Approximately **10-15% of scalp hairs** are in telogen at any given time. *The phase of transition* - This also refers to the **catagen phase**, which serves as a brief transitional period between the active growth (anagen) and resting (telogen) phases. - The term "transition" accurately describes catagen's role as an intermediate stage in the hair growth cycle.
Question 2: Non-scarring alopecia is associated with all except?
- A. Telogen effluvium
- B. Androgenetic alopecia
- C. Alopecia areata
- D. Frontal fibrosing alopecia (Correct Answer)
Explanation: ***Frontal fibrosing alopecia*** - This condition is a form of **lichen planopilaris**, which causes **scarring alopecia** due to destruction of hair follicles and replacement with fibrous tissue. - It results in a **receding hairline** and eyebrow loss, with irreversible hair loss. *Telogen effluvium* - This is a common cause of **non-scarring alopecia**, characterized by diffuse hair shedding triggered by various stressors like illness, stress, or medications. - The hair follicles enter the **telogen phase** prematurely, leading to increased shedding but typically regrowth once the trigger is removed. *Androgenetic alopecia* - Often referred to as **male or female pattern baldness**, this is a form of **non-scarring alopecia** driven by genetic predisposition and androgens. - It causes a progressive miniaturization of hair follicles, leading to thinning hair, but the follicles remain present and capable of producing hair. *Alopecia areata* - This is an **autoimmune condition** that causes **non-scarring hair loss** in patches on the scalp or other parts of the body. - The hair follicles are attacked by the immune system but are not permanently destroyed, allowing for potential regrowth.
Question 3: The organ of Corti normally contains:
- A. A single row of outer hair cells and 3-4 rows of inner hair cells
- B. A single row of inner hair cells and a single row of outer hair cells
- C. A single row of inner hair cells and 3-4 rows of outer hair cells (Correct Answer)
- D. 3-4 rows each of inner and outer hair cells
Explanation: ***A single row of inner hair cells and 3-4 rows of outer hair cells*** - The **organ of Corti**, crucial for hearing, is structurally organized with a distinct arrangement of hair cells to efficiently transduce sound vibrations into electrical signals. - This specific arrangement ensures optimal **sound processing**, with inner hair cells primarily responsible for converting sound and outer hair cells for amplifying and fine-tuning hearing [1]. *A single row of outer hair cells and 3-4 rows of inner hair cells* - This statement reverses the actual arrangement of hair cells in the cochlea, which is essential for correct auditory function. - The **inner hair cells** are primarily responsible for sound transduction and are less numerous than the **outer hair cells**, which are involved in auditory amplification [1]. *A single row of inner hair cells and a single row of outer hair cells* - While there is indeed a single row of **inner hair cells**, the **outer hair cells** are consistently found in multiple rows (typically three to four) [1]. - This misconception underestimates the complexity and amplification role of the outer hair cells in the auditory system. *3-4 rows each of inner and outer hair cells* - This statement is incorrect because the **inner hair cells** are characteristically arranged in a **single row** [1]. - Having multiple rows of inner hair cells would alter their primary function in **sound transduction** and signal generation for the brain.
Question 4: A 22-year-old woman presents with diffuse hair loss for 1 month. She had a past history of enteric fever 4 months ago. What is the likely cause?
- A. Telogen effluvium (Correct Answer)
- B. Androgenic alopecia
- C. Alopecia areata
- D. Anagen effluvium
Explanation: ***Telogen effluvium*** - **Telogen effluvium** is characterized by diffuse hair shedding, often occurring 2-4 months after a significant physiological or psychological stressor, such as **enteric fever**. - The stress prematurely shifts a large number of hair follicles from the **anagen (growth)** phase into the **telogen (resting)** phase, leading to synchronized shedding. *Androgenic alopecia* - This condition presents as a gradual, patterned hair loss, typically characterized by **receding hairline** and thinning at the crown in men. - In women, it often appears as **diffuse thinning** over the crown, but it's not usually acute or triggered by an infection in the manner described. *Alopecia areata* - **Alopecia areata** is an autoimmune condition causing **sudden, well-demarcated patches of hair loss**, not diffuse shedding. - It is frequently associated with other autoimmune diseases, and the hair loss pattern is distinct from the patient's presentation. *Anagen effluvium* - **Anagen effluvium** causes rapid, diffuse hair loss during the **anagen (growth)** phase, often triggered by chemotherapy or radiation. - The onset is typically much faster (days to weeks) after the trigger, unlike the delayed onset seen in this case.
Question 5: Swarm of bees appearance seen in?
- A. Telogen effluvium
- B. Alopecia areata (Correct Answer)
- C. Androgenetic alopecia
- D. Anagen effluvium
Explanation: ***Alopecia areata*** - The "swarm of bees" appearance refers to the characteristic **peribulbar lymphocytic inflammation** seen on scalp biopsy in active alopecia areata. - This finding represents an **immune response targeting the hair follicles**, leading to non-scarring hair loss. *Telogen effluvium* - Histologically, telogen effluvium is characterized by a high proportion of **telogen hairs** in the hair counts and **no significant inflammation** around the follicles. - The "swarm of bees" peribulbar infiltrate is not a feature of telogen effluvium, which is typically a reaction to a systemic stressor. *Androgenetic alopecia* - Androgenetic alopecia is characterized by **follicular miniaturization**, where vellus hairs replace terminal hairs, and a **decrease in the number of hair follicles**. - It does not show the "swarm of bees" peribulbar lymphocytic infiltrate; instead, there might be subtle inflammation or fibrosis in advanced stages but not the dense peribulbar type. *Anagen effluvium* - Anagen effluvium is characterized by the **sudden shedding of hairs in the anagen phase** due to a toxic or inflammatory insult disrupting hair matrix keratinocyte proliferation. - Histology often shows **dystrophic anagen hairs** and damaged hair shafts, but not the specific "swarm of bees" lymphocytic infiltrate seen in alopecia areata.
Question 6: Consider the following regarding the human hair growth cycle : I. Anagen is a phase of active hair growth II. Telogen is a transitional phase III. Catagen is a resting phase Which of the statements given above is/are correct?
- A. III only
- B. I, II and III
- C. I only (Correct Answer)
- D. I and II only
Explanation: ***I only*** - Statement I is **correct**: **Anagen is the active growth phase** of the hair cycle where hair follicle cells in the matrix rapidly divide and differentiate - The hair shaft actively grows during this phase, which typically lasts **2-7 years** and determines the maximum length of hair - **Only statement I is accurate**, making this the correct answer *III only* - This option is incorrect because statement III claims **Catagen is a resting phase**, which is medically inaccurate - **Catagen is actually the transitional/regression phase** (lasting 2-3 weeks) where hair growth stops and the follicle shrinks - The **resting phase is Telogen**, not Catagen *I, II and III* - This option is incorrect because **both statements II and III contain errors** - Statement II incorrectly identifies **Telogen as a transitional phase** when it is actually the **resting phase** (2-4 months) - Statement III incorrectly identifies **Catagen as a resting phase** when it is actually the **transitional phase** - Only statement I is correct *I and II only* - This option is incorrect because **statement II is inaccurate** - Statement II claims **Telogen is a transitional phase**, but Telogen is actually the **resting phase** where the hair remains in the follicle before shedding - The **transitional phase is Catagen**, not Telogen - Only statement I is correct, not both I and II
Question 7: What phase of hair growth is primarily responsible for the length of eyebrows?
- A. Anagen phase (Correct Answer)
- B. Telogen phase
- C. Catagen phase
- D. Exogen phase
Explanation: ***Anagen phase*** - The **anagen phase** is the **active growth phase** where hair follicles rapidly produce hair cells, determining the maximum length hair can achieve. - Eyebrows have a much **shorter anagen phase** (months) compared to scalp hair (years), which explains why they don't grow very long. *Telogen phase* - The **telogen phase** is the **resting phase** where the hair follicle is dormant and no further growth occurs. - Hair in this phase is mature and will eventually shed, but this phase does not contribute to hair length. *Catagen phase* - The **catagen phase** is a **transitional phase** where hair growth stops, and the follicle shrinks in preparation for the resting phase. - This phase marks the end of active growth, so it does not contribute to increasing hair length. *Exogen phase* - The **exogen phase** is a sub-phase of telogen, where **hair shedding** occurs. - This phase is about the release of old hair, not the production or increase in length of new hair.
Question 8: Rapid, diffuse, excessive hair loss occurring 3 months after childbirth is due to?
- A. Telogen effluvium (Correct Answer)
- B. Anagen effluvium
- C. Alopecia areata
- D. Androgenetic alopecia
Explanation: ***Telogen effluvium*** - This condition is characterized by an excessive shedding of **club hairs** from the hair follicle, typically occurring 2-4 months after a significant stressor such as **pregnancy and childbirth**. - During pregnancy, high estrogen levels increase the number of follicles in the anagen (growth) phase; after delivery, estrogen drops, and many follicles simultaneously enter the **telogen (resting) phase**, leading to synchronized shedding. *Anagen effluvium* - This type of hair loss is rapid and severe, occurring when a significant percentage of **hair follicles** in the **anagen phase** are abruptly stopped from growing. - It is often seen with **chemotherapy, radiation therapy**, or exposure to toxins, which damage actively dividing hair matrix cells. *Alopecia areata* - This is an **autoimmune condition** where the body's immune system attacks hair follicles, leading to distinct, typically **round patches of hair loss**. - It can affect any hair-bearing area and is not directly linked to hormonal changes post-pregnancy. *Androgenetic alopecia* - Commonly known as **male or female pattern baldness**, this is a genetic condition influenced by androgens, characterized by a progressive **miniaturization of hair follicles**. - It presents as a characteristic pattern of thinning, such as a receding hairline or thinning at the crown, and is not typically a rapid, diffuse postpartum event.
Question 9: The growth phase of hair is
- A. Progen
- B. Metagen
- C. Anagen (Correct Answer)
- D. Telogen
Explanation: ***Anagen*** - The **anagen phase** is the active growth phase of hair follicles, where hair grows rapidly and continuously. It can last from 2 to 7 years. - During this phase, cells in the hair bulb divide rapidly to produce new hair fibers, pushing older hairs up and out. *Progen* - **"Progen"** is not a recognized term for a phase of hair growth in scientific or medical literature. - This term does not correspond to any known stage in the hair follicle cycle. *Metagen* - **"Metagen"** is not a valid or recognized term for any phase of human hair growth. - The life cycle of hair involves distinct phases such as anagen, catagen, and telogen. *Telogen* - The **telogen phase** is the resting phase of the hair cycle, during which hair follicles are inactive, and hair growth ceases. - This phase typically lasts for about 3 months, after which the hair is shed, and the follicle re-enters the anagen phase.
Question 10: A male presents with alopecia and exclamation mark hairs. Diagnosis?
- A. Alopecia areata (Correct Answer)
- B. Tinea capitis
- C. Telogen effluvium
- D. Androgenic alopecia
Explanation: ***Alopecia areata*** - **Alopecia areata** is characterized by sudden, non-scarring hair loss that can affect any hair-bearing area, including the scalp. - The presence of **exclamation mark hairs** (hairs that are narrower closer to the scalp) is a classic dermatoscopic finding in alopecia areata and is highly suggestive of the diagnosis. *Tinea capitis* - **Tinea capitis** is a fungal infection of the scalp often presenting with scaling, erythema, and broken hairs, but typically not "exclamation mark hairs." - It may cause **patchy alopecia** but is usually associated with inflammation and sometimes pustules. *Telogen effluvium* - **Telogen effluvium** is a diffuse, non-scarring hair shedding that occurs after a stressful event, leading to widespread thinning rather than localized patches. - It primarily involves an increase in the number of hairs in the **telogen (resting) phase** and does not typically feature exclamation mark hairs. *Androgenic alopecia* - **Androgenic alopecia**, or male/female pattern baldness, is characterized by a gradual, patterned hair loss due to genetic and hormonal factors. - It involves the miniaturization of hair follicles and progressive thinning, but it does not present with **exclamation mark hairs** or discrete patches of complete hair loss.
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