4. Integumentary System

Question 1

What are components of the integumentary System?

Answer 1

Skin (integument)

hair

nails

oil and sweat glands

Question 2

what are three layers of integumentary system and describe their tissues

Answer 2

• Epidermis
  
  • outer most layer / squamous stratified epithelial tissue
• Dermis
  
  • inner layer / made from CT
  • vasuclar supply, sweat + oil glands, sensory neurons + nerves
• Hypodermis (not part of the skin)
  
  • subcutaneous layer, made from adipose tissue
  • insulation and cushioning

Question 3

What are functions of integumentary system

Answer 3

• Protection -
  
  • mechanical- keratinised stratified squamous cells provide waterproof thick layer
  • chemical- sebacious oil reduces pH (increase acidity) to inhibit bacteria
  • biological - langerhans cells from bone marrow act as phagocytes / trigger immune response
• metabolic function
  
  • produce melanin + vit D
• thermoregulation
  
  • underlying blood vessels- vasodilation / constriction
  • sweat - evaporation
  • hairs
  • subcutaneous fat provides insulation
• Excretion -
  
  • sweat excretes excess salts
• Sensory
  
  • subcutaneous sensory receptors for temperature, pain, pressure
• Blood reservoir
  
  • 5% of blood circulating in underlying dermis
  • blood can be moved to other organs as necessary

Question 4

list 4 different types of cells in epithelium

Answer 4

• Keratinocytes
• Melanocytes
• Langerhans cells
  
  • Merkel (tactile) cells

Question 5

Describe the dermis

Answer 5

made from thick CT

Highy vascularised and has lots of nerve endings, hair follicles, sweat and sebaceous glands

divided into 2 layers

1. Papillary layer (outer)
2. Reticular layer (deep)

Question 6

List the appendages of the skin and a role they each play in homeostasis

Answer 6

• nails
  
  • protective surface on distal end of phalanges
  • homeostasis- act as effectors to scratch an itch
• hair / hair follicles
  
  • insulates body / reduces heat loss
  • homeostasis- thermoregulation, hair acts as an effector with arrector pilli mucles that contract when cold. pull the hair erect
• hair follicles-
  
  • cold / fear stimulates arrector pilli muscles to contract and raise hairs to trap air and increase insulation for body
• sweat glands -
  
  • function to secrete sweat (mainly water) body via evaporation
  • homeostasis- thermoregulation - cool the body via evaporation
• sebaceous glands-
  
  • sebum functions to moisturise and lubricate hair and skin
  • homeostasis- overwashing hair + skin can reduce natural sebum, and cause sebaceous gland to increase production

Question 7

Describe Keratinocytes

Answer 7

• most abundant cell in epidermis
• produce protein keratin, which toughens/ waterproofs teh skin
• produced from deepest layer and migrate to apical layer (as keratinocytes are pushed up, they die and are filled with keratin)

Question 8

describe melanocytes

Answer 8

produce melanin compound, which protects against UV

produced in deep layer and give melanin to keratinocytes to transport to apical layer

Question 9

langerhans cells

Answer 9

produced in BM and migrate to epidermis

phagocytes and activate immune response

Question 10

merkel (tactile) cells

Answer 10

occasionally found in epidermis

associated with sensory nerve endings responding to touch