integumentary system

Question 1

what is involved in the integumentary system?

Answer 1

• skin
• hair
• nails
• exocrine glands

Question 2

what do the exocrine glands do?

Answer 2

• secrete substances onto an epithelial surface
• secrete products directly into the bloodstream

Question 3

facts about the skin:

Answer 3

• the skin is only a few mm thick
• largest organ in the body
• average person’s skin weighs around 10 lbs and has a surface area of almost 20 square feet

Question 4

what is the structure of the skin?

Answer 4

• the skin forms the interface between the internal and external environment and is therefore crucial as both a sensor and effector in homeostasis

Question 5

what are the functions of the skin?

Answer 5

• senses, touch, pain, pressure and temperature
• thermoregulation
• protection
• energy storage
• production of vitamin d

Question 6

explain the function of the skin ‘protection’

Answer 6

• the skin acts as a barrier
• the skin covers the whole body and it provides protection from physical damage, dehydration, variations in temperature, chemicals, radiation and microbes

Question 7

describe the protection from mechanical damage

Answer 7

• this is done by insulating and cushioning the deeper body organs
• examples o mechanical damage are bumps and cuts
• when a person is bumped, the uppermost layer of the skin toughens or hardens the cell
• the toughening of the cells is due to the presence of keratin in the upper layer of the skin
• pressure and pain receptors in the skin send impulses to the CNS to alert an individual to possible damage

Question 8

describe the protection from chemical damage

Answer 8

• acids and bases, when exposed to the body at high levels, can cause extreme damage to the internal organs
• due to the presence of tough keratinised cells, damage to internal organs is prevented

Question 9

describe the protection from bacterial damage

Answer 9

• its difficult for microbes to penetrate the skin’s dry, dead outer cells
• the skin secretes urea, salt and water (acidic) when a person sweats, thus, inhibiting bacterial growth
• phagocytes are also located in the skin which are responsible for ingesting foreign substances and pathogens
• bacterial penetration to deeper body tissues is prevented
• the sebaceous glands produce oils which also helps to kill microbes

Question 10

describe the protection from UV radiation

Answer 10

• the colour of the skin depends on the presence of the pigment melanin
• melanin is produced by the melanocytes and is good at protecting the boy from the damaging effects of the sunlight or UV damage

Question 11

describe the protection from thermal damage

Answer 11

• when the body is exposed to extreme heat or cold the receptors located in the skin alerts the nervous system of the tissue-damaging factors
• the brain, in response, sends impulses to the site of possible damage for the body’s compensatory mechanism

Question 12

how does the skin regulate in physiology

Answer 12

• thermoregulation via sweat and hair
• osmoregulation via sweat

Question 13

what is subcutaneous fat?

Answer 13

• beneath the dermis is a layer of adipose tissue (fat)
• fat is made when excess food is eaten
• stored fat is used for energy when food is laking
• you can survive for only about one day on stored glycogen
• with stored fat, you can survive for weeks

Question 14

what is the synthesising vitamin d

Answer 14

• human skin can make large amounts of vitamin d when lots of the skin is exposed and the sun is high in the sky
• UVB rays cause modified cholesterol molecules in the skin to be converted to vitamin d

Question 15

what happens when the sun is bad?

Answer 15

• exposure to too much UVA and B can cause skin cancer
• UVB = burns
• UVA = tans

Question 16

what are other functions of the integumentary system?

Answer 16

PREVENT BODY FROM DRYING OUT:
- the sin’s outermost part, the epidermis, contains a waterproofing glycolipid and keratin in order to prevent water loss from the body surface

ACT AS MINI-EXCRETORY SYSTEM:
- the perspiration contains urea, uric acid and salts

Question 17

explain how hyper and hypo thermia is caused

Answer 17

• prolongued exposure to high temoeratures can lead to hyperthermia
• if the body’s core temperature rises above 40 degrees, its thermoregulatory mechanisms break down
• when this happens, positive feedback occurs and the person’s body temperature can spiral out of control
• a core body temperature of 43 degrees and higher usually causes death
• if the person’s core body temperature falls below 35 degrees, a person may suffer from hypothermia
• the body’s thermoregulatory mechanisms fail and positive feedback occurs leading to a further decrease in temperature

Question 18

what is the role of the hypothalamus

Answer 18

• where the thermoregulatory centre is located
• detects internal temperature changes and sends impulses to muscles and glands

Question 19

what happens when the body is too hot?

Answer 19

1. VASODILATION
   — arterioles dilate (enlarge) so more blood enters skin capillaries and heat is lost
2. SWEATING
   — sudorific glands secrete sweat which removes heat when water changes state
3. PILORELAXATION
   — this means the hairs flatten
4. STRETCHING OUT
   — by opening up, the body has a larger surface area

Question 20

what happens when the body is too cold?

Answer 20

1. VASOCONSTRICTION
   — arterioles get smaller to reduce blood going to skin, keeping the core warmer
2. SHIVERING
   — rapid contraction and relaxing of skeletal muscles
   — heat produces by respiration
3. PILOERECTION
   — hairs on skin stand up
4. CURLING Up
   — making yourself smaller so there’s a smaller surface area