The Skin 2

Question 1

What are the three classifications of nerve fibres?

Answer 1

Motor nerves, sensory nerves, and secretory nerves.

Question 2

What do motor nerves do in relation to the skin?

Answer 2

Motor nerves go to erector pili muscles that attach to hair follicles. The nerve stimulates the muscle to contract (to shorten) and produce movement. Erector pili muscle causes hair to stand upright giving us goose bumps.

Question 3

What do sensory nerves do in relation to the skin?

Answer 3

Sensory nerves are nerve fibres that react to temperature, touch, pain and pressure. They are found in the papillary layer of dermis and are most abundant in the fingertips. Complex sensations such as feeling vibration depends on a combination of nerve endings.

Question 4

What do secretory nerves do in relation to skin?

Answer 4

Secretory nerves go to sweat and oil glands of the skin and stimulate the glands to product sweat and oil.

Question 5

What are the three types of microscopic glands found in the skin?

Answer 5

Sebaceous glands, sweat glands, and ceruminous glands.

Question 6

What are the functions of sebum oil?

Answer 6

Lubricates, keeps hair soft and pliant, keeps skin soft and supple, prevents excessive water evaporation from skin, prevents excessive water absorption through skin, inhibits growth of bacteria, lessens heat loss from surface and protects and maintains acid mantle of the skin.

Question 7

When does sebum secretion increase and why?

Answer 7

Sebum secretion increases during adolescence and is stimulated by increased blood levels of sex hormones.

Question 8

What happens when sebum accumulates in ducts of sebaceous glands?

Answer 8

Frequently sebum accumulates in some of the ducts of sebaceous glands and cause white heads. With oxidation this accumulated sebum darkens causing comedones (blackheads).

Question 9

What do sudoriferous (sweat) glands consist of?

Answer 9

Sweat glands consist of a coiled base in the dermis and a tube like duct which ends at the skin’s surface to form a sweat pore.

Question 10

Where are sudoriferous (sweat) glands most numerous?

Answer 10

Sudoriferous (sweat) glands are most numerous on soles of feet, forehead, and axillae (underarm).

Question 11

What type of waste products are excreted through the sudoriferious glands?

Answer 11

H2O, sodium chloride (salt), urea, and some other substances.

Question 12

What is considered the normal body temperature?

Answer 12

Normal temperature is 98.6 F or 37 C.

Question 13

What are two ways of maintaining body temperature that are found in the skin?

Answer 13

Blood volume to skin and sensible perspiration.

Question 14

When the body temperature is high what does the heart do?

Answer 14

The heart pumps a large volume of blood to the skin, when body temperature is high.

Question 15

What do blood vessels do when we need to get rid of excess body heat?

Answer 15

Blood vessels dilate (get larger) to carry more blood to the skins surface when we need to get rid of excess body heat. When this happens blood vessels come closer to the body’s surface, and heat radiates from skin surface.

Question 16

What happens to blood vessels when the body is cold?

Answer 16

When the body is cold, blood vessels constrict, the vessels then lie closer to the centre of the body and body warmth is conserved.

Question 17

What is sensible perspiration?

Answer 17

Heat energy is consumed to evaporate fluid, therefore temperature drops. Happens even when skin seems dry and some sweat is evaporated immediately cooling the skin. Sweat rolling off the body without evaporating isn’t doing an efficient job cooling the body like it should.

Question 18

What impedes evaporation of sweat on the skin?

Answer 18

Humidity impedes evaporation (not heat).

Question 19

What increases sweat gland activity?

Answer 19

Environmental heat, exercise, emotions, certain drugs, temperature increase due to illness, hormones (hot flashes), food or caffeine - some people react to spicy food.

Question 20

What are the two types of sweat glands?

Answer 20

Apocrine & eccrine.

Question 21

What kind of sweat glands produce scent and what are the ordinary sweat glands?

Answer 21

Apocrine sweat glands are scent producing and eccrine sweat glands are ordinary sweat glands.

Question 22

Where are apocrine glands located?

Answer 22

Apocrine sweat glands open into hair follicles and are limited to a few regions of the body, particularly axilla and genital areas. Inactive in infants and develops with puberty and enlarge premenstrual.

Question 23

Where are eccrine sweat glands located?

Answer 23

Eccrine sweat glands are ducts that corkscrew to skin surface (not into hair follicle). They are everywhere in skin except lips and a few other areas; largest numbers on skin of palms, soles and forehead. Active from birth/not affected by menstration.

Question 24

What is the appearance of apocrine and eccrine sweat?

Answer 24

Apocrine sweat is a complex substance which gives sweat a milky appearance. Eccrine sweat is clear and watery (extremely diluted salt H2O.

Question 25

What makes sweat smell?

Answer 25

Freshly produced sweat is sterile and inoffensive, decomposition by bacteria gives sweat its odour.

Question 26

What are ceruminous glands?

Answer 26

Ceruminous glands are modified sweat glands located in the external ear. Instead of watery sweat, the secrete cerumen (earwax) - a waxy, pigmented substance.

Question 27

Why do older people bruise more easily?

Answer 27

Increased fragility of blood vessels may make bruising more easy.

Question 28

What is the most obvious sign of aging that occurs in the skin?

Answer 28

The most obvious of all age changes occurring in skin are wrinkles. They begin about age 35 and become more prominent around 40 to 50 years old. Wrinkles occur due to loss of skin’s elasticity.

Question 29

What processes slow down in mid life?

Answer 29

Body processes slow down in mid life and cells are not replaced as rapidly.

Question 30

What occurs in the body when it ages?

Answer 30

1. Sebaceous glands become less active
2. Sudoriferous gland activity decreases
3. Increased fragility of small blood vessels

Question 31

What are the functions of the skin?

Answer 31

Protection
Temperature
Multiple sensing devises
Excretes Fluid and Electrolytes (Salts) 
Stores fat
Synthesizes vitamin D
Absorption of certain substances

Question 32

How does the skin provide protection?

Answer 32

• Keratinized cell layer of skin forms a barrier, protecting underlying tissues from invasion of micro-organisms, bars entry of most chemicals and minimizes mechanical injury of underlying structures.
• Melanin deposits deep in epidermis prevent penetration of ultraviolet rays.
• Protects against dehydration - sebum production and tightly packed cells help with this.

Question 33

How does the skin act as temperature regulator?

Answer 33

1. Blood vessels dilate
2. Sweat secretion increases if body temperature is above normal.

• Larger volume of blood in skin and evaporation of sweat on skins surface. This helps decrease blood temperature back to a normal level. If blood temperature level is below normal, skin blood vessels constrict and sweat secretion decreases.

Question 34

How is the skin a multiple sensing device?

Answer 34

The skin dermis contains millions of microscopic sense organs (nerves) which detect stimuli and lead to sensations of heat, cold, pressure, pain and touch.

Question 35

What fluids and electrolytes does the skin excrete?

Answer 35

Sodium and potassium.

Question 36

Where is fat stored in the skin?

Answer 36

In dermis layer (reticular layer) and subcutaneous layer.

Question 37

How does the skin synthesize vitamin D and what does vitamin D help with?

Answer 37

For vitamin D synthesis to occur skin must be exposed to sunlight or ultraviolet rays. Vitamin D helps with absorption of calcium.

Question 38

What can the skin absorb and how much can it absorb?

Answer 38

There is minimal absorption through the skins surface, but it can absorb some creams or topical anaesthetics.