The integumentary System Flashcards
What is the epidermis?
Outer layer of the skin
What are the layers of the skin?
- Epidermis
- Dermis
- Subcutaneous
How often does the epidermis regenerate?
4-6 weeks
What is the role of the epidermis?
Act as a barrier to the environment
Prevent penetraction by irritands and allergens
Prevent loss of water
How does the epidermis get nutrients and remove waste?
Through basement membrane
Relies on the dermis
What are the 4 cells in the epidermis?
- Keratinocytes
- Melanocytes
- Langerhans
- Merkel
What are karatinocytes?
Responsible for the production of keratin
Responsible for the water-resistant properties of skin
Prevent entry of foreign matter
What are melanocytes?
Produce the pigment called melanin which is responsible for skin pigment and preventing skin damage from the sun
What are langerhans?
Part of the immune system from red bone marrow
Regulate immune reactions in the skin
What are merkel cells?
Capable of detecting touch
Name the 5 layers of the epidermis
- Statum basale
- deepest level of the epidermis
- border between epi and dermis
- new cells are constantly produced, pushing older cells up until they reach the surface - Stratum spinosum
- have spine line projections and are tightly packed
- provides stregnth and flexibility - Stratum granulosom
- contain granules, form a water-resistant lipid, protect the body for loss of fluid and entry of microbes
- cells lose their nucleus which is called keratinisation.
- skin is tougher and stronger - Stratum lucidum
- 5 layers of flat, dead skin cells
- no nuclus and tightly packed
- provide a barrier to fluid loss - Stratum corneum
- dead scale-like layers that overlap
- covered in lipids as a protective barriers
provides structural strength
- always being rubbed off
- provides a barrier to light, head, microbes, chemicals and injury
What is the dermis?
Second layer of the skin
What is the role of the dermis?
Provides support
Transports nutreints to the epidermis
What is the dermis made of?
Collogen
Fibroblasts
Elastins
Macrophages
Mast cells
White blood cells
What is embedded in the dermis?
Blood vessels
Nerves
Lymph vessels
Smooth muscles
Sweat glands
Hair follicles
Sebaceous glands
Draw and label the skin
What are the functions of the skin?
- Sensation
- Theromoregulation
- Protection
- Excretion and absorption
- Synthesis of vitamin D
Describe the function of sensation
Receptor sites in the skin that sense change in the environment
Describe the function of theromoregulation
Changes in the size of blood vessels
As temp rises, blood vessels dilate to get hot blood to the surface to cool down and vis versa
Sweat glands secrete water and evaporation cools the skin
Pockets of air get trapped between hair when they stand up and cause insulation
Why is thermoregulation important?
It can impact enzyme function
Describe the function of protection
Melanin protects agasint UV
Eliminating waste through pores helps prevent build-up of harmful substances
Preventds fluids escaping
Regulates fluid through swear
Prevents harmful substances entering the body
Sebum has antibac chemicals
Macrophases destory bacteria and viruses
Describe the function of excretion and absorption
Substances are excreted through the skin
Skin can also absorb substances
What is hair?
Growths of dead keratin
What are the functions of hair?
- Inhibit heat loss
- Heart becomes trapped between hair
- Hair on the head can protect the scalp from the sun
- Hair on eyelashes and brows guards the eyes
- Hair in nose protects from inhalation of forein material
What is the function of skin glands?
Thermoregulation
Release of pheromones
What are nails?
Tightly packed, dead, keratinised cells
What is the function of nails?
Protect the end of finger and toes
What are the 3 types of wound healing?
- Primary
- Union of edges - Secondary
- wound is left open and heals by conraction and epithelisation
- Heals from bottom up - Tertiary
- Delayed primary closue
What are the phases of wound healing?
- Haemostasis
- Inflammation
- Proliferation
- Epithelisation
- Maturation
Describe haemostasis (stage 1 of wound healing)
Vasoconstriction occurs so blood flow is reduced
When platelets come into contact with exposed collagen they release chemical messagers that stimulate a clotting cascase
Platelets adhere to vessel walls, creating a fibrin clot
Describe inflammation (stage 2 of wound healing)
Histamine is released from mast cells which cause vasodilation and increase capillary permeability
Exudate made of serous fluid, white blood cells and plasma protein covers the wound bed
Describe proliferation (stage 3 of wound healing)
Consists of granulation which is a loose matrix of fibrin, collagen and other substances
Capillaries bid from venules in close proximity to the wound and extend into the wound site
Myofibroblasts cause contraction of the wound to reduce surface area
Describe epithelisation (stage 5 of wound)
Macrophages release growth factor which stimulations the proliferation and migration of epithelial cells.
New cells originate from the wound margin and move over in a leap frog style
They stop by contact inhabitatio, when cells are sourrounding the cell
Describe maturation (stage 5 of wound)
This is the formation of scar tissue
Inflammatory material is removed, leaving collagen fibres which are reorganised to give maximal strength
Gradulation tissue is replated by stronger avasular scar tissue
What generates scar tissue?
Fibroblasts
