The Integumentary System

Question 1

What are the 2 main layers in the skin?

Answer 1

The epidermis and dermis.

Question 2

What are keratinocytes (in epidermis)?

Answer 2

These are the main cell type, ‘born’ deep in epidermis and evolve (differentiate), produce keratin.

Question 3

What are melanocytes (in epidermis)?

Answer 3

-in deepest layer of epidermis
-secrete melanin

Question 4

What is melanin and its purpose?

Answer 4

This is a dark protective pigment and is secreted to keratinocytes (acts as a suncream for them).

Question 5

What are Merkel cells (epidermis)?

Answer 5

These are specialised sensory cells, light touch and textures.

Question 6

What are dendritic cells (epidermis)?

Answer 6

-These ingest invaders and foreign materials (rip to pieces)
-Activate immune defences of the body (presented with parts of bacteria so they know how to fight it).

Question 7

What is the order of epidermal layers?

Answer 7

-Straum corneum
-Stratum lucidum
-Stratum granulosum
-Stratum spinosum
-Stratum basale

Question 8

What are features of stratum corneum?

Answer 8

This is the roughest, 20-30 sheets and have dead keratinocytes (always sloughing off).

Question 9

What are features of stratum lucidum?

Answer 9

This is a clear layer of keratinocytes (only in thick skin).

Question 10

What are the features of stratum granulosum?

Answer 10

Contains living keratinocytes- as you get deeper through layers, cells are younger.
Cells start to specialise.

Question 11

What are the features of stratum spinosum?

Answer 11

This is the layer where mitosis is active.

Question 12

What are the features of stratum basale?

Answer 12

This is a single layer of columnar cells.

Question 13

What happens to the shape of cells and nuclei as you go through the layers.

Answer 13

At the bottom, they are taller (columnar) and then gradually flatten and more disc shaped.

Question 14

What is the meaning of sloughing?

Answer 14

This is shedding dead surface cells from the skin.

Question 15

What does the dermis layer contain?

Answer 15

-collagen
-elastic fibres
-blood vessels
-nerve endings
-sweat glands
-hair follicles

Question 16

What is the papillary layer of the dermis?

Answer 16

This contains collagen, elastin and blood vessels and enhances sensory (areolar tissue).

Question 17

What is the reticular layer of the dermis?

Answer 17

This contains heavy bundles of collagen (dense tissue)- gives the skin strength.

Question 18

Why is protection a function of the skin?

Answer 18

-physical barrier and immune system for infection
-protects from dehydration and physical damage (trauma or light).

Question 19

Why is temp regulation a function of the skin?

Answer 19

-vasodilation- flood skin with warm blood which is then removed by evaporators
-too cold= hair follicles stand up and trap a layer of air on the skin

Question 20

What is the function of the eccrine sweat gland?

Answer 20

This releases sweat to the surface of the skin and produces antibodies.

Question 21

Why is secretion a function of the skin?

Answer 21

-contains sebaceous oil gland which produces sebum (slightly acidic to help control bacteria on skin surface)
-apocrine gland (yellow oily sweat- milky sweat)

Question 22

Why is the cutaneous sensation a function of the skin?

Answer 22

-free nerve endings respond to damage of skin
-hair plexus (bare nerves) associated with hair root structure and sensory (tells what’s happening with hairs)
-pacinian corpuscle respond to vibration (pressure sensing).

Question 23

What is skin colour determined by?

Answer 23

-Hb (red pigment in blood)
-melanin (more in more heat so offer more protection so darker)
-carotene