Integumentary system

Question 1

Name the 3 layers of the skin

Answer 1

epidermis, dermis and hypodermis

Question 2

Explain the role of the epidermis

Answer 2

It is a stratified epithelium that contains keratinocytes which produce keratin fibres, they are tied together by desmosomes which create a long sheet that provides the epidermis with strength. The epidermis also acts as a physical barrier preventing entry of pathogens (primary defense)
The epidermis contains: keratinocytes, Merkel cells, melanocytes and dendritic cells

Question 3

What is a desmosome

Answer 3

They are cell junctions which fuse cells together in tissues exposed to mechanical forces

Question 4

Function of melanocytes

Answer 4

Are specialised cells involved in the production of melanin, (skin pigmentation) it acts as a sunscreen for keratinocytes and protects us from UV rays

Question 5

Function of merkel cells

Answer 5

These cells are associated with nerve endings as they are involved in touch, texture and light response

Question 6

Function of dendritic cells

Answer 6

These are antigen presenting cells (APC), they digest pathogens, rips them apart. They are a primary defense and activate the immune system, found deep within the skin

Question 7

Name the layers of the epidermis from top to bottom

Answer 7

Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale

Question 8

Function of the basal membrane in the epidermis

Answer 8

It pushes the older dead cells to the top to be sloughed

Question 9

Function of the stratum spinosum

Answer 9

They produce keratin from keratinocytes found in this layer, they also contain Langerhans cells which engulf and digest bacteria

Question 10

Function of stratum granulosum

Answer 10

Consists of 4-6 layers of cells, they start to spread/flatten out, keratin is accumulated. Acute lamellae help keratin become waterproof

Question 11

Function of stratum corneum

Answer 11

Consists of 20-30 layers of cells, thickest layer, these cells are programmed to die, as they become keratinised. This causes them to become very resistant to chemicals, water and mechanical pressures. Forms a solid physiological and biological barrier

Question 12

Define & explain the process of sloughing

Answer 12

Sloughing is the shedding of cells, a normal part of the skin cycle, 50000 skin cells are lost per minute
This is a protective feature as we lose bacteria, flora from the skins surface. This is how the body physically cleans itself
occurs every 21-45 days

Question 13

Describe the structure of the dermis layer

Answer 13

It contains: BV’s, elastic fibres, collagen, nerve endings, sweat glands and hair follicles
Has a papillary layer which provides a large SA of diffusion of nutrients, enhances the sense of touch
the reticular layer of the dermis provides elasticity and flexibility to the dermis (elastic & collagen fibres)

Question 14

What are the main functions of the skin?

Answer 14

-primary defense
-physical barrier for bacteria, chemicals, water and mechanical pressures
-thermoregulation
-prevents UV damage
-secretion of sebum to waterproof skin

Question 15

Purpose of sweating

Answer 15

Sweating allows the body to cool itself, to lower body temp, hair erector muscles relax and so hair lies flat. sweat is secreted from eccrine gland, water in the sweat then evaporates off skin surface, providing a cooling effect. Sweat also produces antibodies on skins surface in attempt to control microbiome

Question 16

Purpose of vasodilation

Answer 16

Dilation of the blood vessels occurs when we need to lower our body temperature, therefore blood flows closer to the surface, giving a flushed appearance, and allows heat to diffuse. The hypothalamus sends a signal to the subpapillary plexus to relax allowing blood to flow closer to surface

Question 17

Purpose of vasoconstriction

Answer 17

This occurs to conserve heat, blood flows further from skin surface, hair erector muscles contract and hair follicles are pulled up, trapping a layer of warm air close to the skin

Question 18

Purpose of secretion

Answer 18

sebaceous glands produce sebum, an oily fatty substance (pH of 4-6), slightly acidic to control bacteria on skin surface, antibacterial membranes are also released to disrupt bacteria & growth

Question 19

What is the apocrine gland and it’s function

Answer 19

A form of sebaceous gland that secretes a milky yellow substance, activates during puberty in armpits and genital regions, they produce pheromones, give maturity

Question 20

Explain the cutaneous sensation

Answer 20

These are free nerve endings that respond to damage to the skin.
Hair plexus can tell us what is proximal to the skin, they can sense movement & vibration
The Pacinian corpuscle found deep within responds to vibrations/pressures

Question 21

Explain the sensory homunculus

Answer 21

It is a model used to refer to the distribution of nerve endings found on the body, with most being found in the hands and lips

Question 22

Gives examples of non-verbal communication that the skin causes

Answer 22

• blushing
  -sweating
  -pheromones
  -odor/stress odor

Question 23

Describe and explain the Stratum lucidium

Answer 23

A thick non-hairy layer of the skin that has 2-3 translucent layers, found in the bottom of the hands and feet. It contains flat & dead keratinocytes as well as Pacinian corpuscles. Lying above the stratum granulosum, thickens the skin in specific areas

Question 24

Factors affecting skin colour

Answer 24

• melanin
  -carotene
  -haemoglobin

Question 25

Define cyanosis

Answer 25

This is poor circulation which leads to a bluish colour of the skin

Question 26

Define jaundice

Answer 26

Jaundice is a yellowish pigment to the skin, caused by bilirubin in breakdown of RBC, build up causes a yellow colour that indicates liver/kidney failure

Question 27

Define albinism

Answer 27

a lack of melanocytes, less production of melanin, giving pale complexion

Question 28

Define a Haematoma

Answer 28

Occurs when tissue suffers damage, blood vessels break and blood flows into the tissues, Hb is broken down