The integumentary system

Question 1

What are the 7 functions of the skin?

Answer 1

Protection
Regulation of body temperature
Sensation
Immune defence
Excretion
Vitamin D synthesis
Water regulation
Endocrine function

Question 2

Describe the skins role in protection

Answer 2

It acts as a physical barrier, protecting the body from physical, chemical, and biological hazards such as UV radiation, pathogens, and toxins.

Question 3

Describe the skins role in body temperature regulation

Answer 3

The skin helps regulate body temperature through processes like sweating (evaporative cooling) and vasoconstriction/dilation of blood vessels (heat conservation or dissipation).

Question 4

Describe the skins role in sensation

Answer 4

The skin contains numerous sensory receptors that detect touch, pressure, pain, and temperature, allowing us to perceive and respond to stimuli from the environment.

Question 5

Describe the skins role in immune defence

Answer 5

Specialized immune cells in the skin, such as Langerhans cells and dendritic cells, help protect against pathogens and foreign substances by initiating immune responses.

Question 6

Describe the skins role in excretion

Answer 6

Sweat glands in the skin excrete waste products, such as urea and salts, helping to regulate electrolyte balance and eliminate toxins from the body.

Question 7

Describe the skins role in vitamin d synthesis

Answer 7

When exposed to sunlight, the skin produces vitamin D, which is essential for calcium absorption and bone health.

Question 8

Describe the skins role in water regulation

Answer 8

The skin helps prevent excessive loss of water from the body through its barrier function, helping to maintain hydration and prevent dehydration.

Question 9

Describe the skins role in Endocrine function

Answer 9

The skin produces and releases various hormones and signaling molecules involved in local and systemic physiological processes. Eg. Melatonin, which is involved in regulating circadian rhythms and has antioxidant properties

Question 10

What is the dermis

Answer 10

It is a layer of the skin. It lies beneath the epidermis and is composed of connective tissue. It’s divided into 2 layers: the papillary dermis and reticular demis.

Question 11

What is the dermis composed of?

Answer 11

Blood vessels
Lymphatic vessels
Nerves
Sweat glands
Sebaceous glands
Hair follicles
Immune cells - macrophages, mast cells, fibroblasts

Question 12

What is the function of fibroblasts and where are they found?

Answer 12

In the dermis
They produce collagen and elastin fibers which contribute to the structural integrity and flexibility of the skin

Question 13

What is the function of the papillary dermis and where is it located

Answer 13

Its located just beneath the epidermis and contains finger-like projections called dermal papillae, which interlock with the epidermis and help anchor the two layers together

Question 14

What is the function and location of the reticular dermis

Answer 14

It’s the deeper thicker layer of the dermis, consisting of dense irregular connective tissue that provides strength, support, and elasticity to the skin

Question 15

What is the epidermis

Answer 15

It is the outermost layer of the skin

Question 16

What is the epidermis composed of

Answer 16

Stratified squamous epithelial tissue
It’s made up of several layers
It lacks blood vessels and relies on diffusion from the underlying dermis for nourishment

Question 17

What are the layers found in the epidermis

Answer 17

Stratum basale (or basal layer) - deepest layer
Stratum spinosum
Stratum granulosum
Stratum corneum - outermost layer

Question 18

What is the stratum basale composed of?

Answer 18

Actively dividing cells responsible for replenishing outer layers of the epidermis

Question 19

What is the stratum corneum composed of and where can it be found?

Answer 19

The outermost layer of the epidermis, and is composed of dead keratinocytes (keratinized cells) that provide protection against physical and environmental damage

Question 20

Whats the structure and function of hair?

Answer 20

Structure: Composed of a protein called keratin, arranged in three layers: the medulla (innermost layer), the cortex (middle layer), and the cuticle (outermost layer).

Function:
Protection for the scalp from UV radiation, abrasions, and minor physical trauma.
Insulation - regulates body temperature by trapping heat close to the skin when it’s cold, providing insulation
Sensation - Hair follicles are surrounded by sensory nerves, allowing hair to detect touch, movement, and changes in the environment.
Excretion - Sebaceous glands attached to hair follicles secrete sebum, an oily substance that moisturizes the hair and skin, as well as inhibiting bacterial growth.

Question 21

Whats the structure of a nail?

Answer 21

A hard, keratinous plate that grows from the nail matrix, located beneath the skin at the base of the nail. Consists of several parts:
the nail plate (visible portion)
the nail bed (the skin beneath the nail plate)
the nail matrix (the tissue at the base of the nail that produces new nail cells)
the cuticle (the thin layer of skin at the base of the nail plate)
the lunula (the white, crescent-shaped area at the base of the nail).

Question 22

Whats the function of a nail?

Answer 22

Protecting the fingertips and toes from injuries, and trauma.
Gripping and Manipulation
Sensory Function: Nails contain numerous nerve endings that contribute to tactile sensation
Structural support to the soft tissues of the fingertip, helping maintain its shape and integrity.

Question 23

Describe the process of wound healing

Answer 23

Inflammation – where the body generates a mass of chemical agents to promote cell activity

Granulation – where the body promotes the formation of new cells

Regeneration – permanent repair is complete

Remodelling – the impact of scarring is diminished

Question 24

What are the chemical barriers of the skin in relation to protection?

Answer 24

Skin secretions and melanin:
- Acid Mantle (lactic acid in sweat): retards multiplication of bacteria
- Natural antibiotic: human defensin
- UV shield: melanin and hair covering
- Water barrier: glycolipids of the epidermis

Question 25

What are the physical/mechanical barriers of the skin in relation to protection?

Answer 25

Keratinisation: provides a hard impenetrable barrier (tight junctions and desmosomes act as physical barriers)

Question 26

What are the biological barriers of the skin in relation to protection?

Answer 26

Langerhans cells (from bone marrow) when presented with antigens produce immune response. Macrophages (from blood) engulf debris and bacteria

Question 27

Explain how temperature regulation is maintained through homeostasis using the skin

Answer 27

When the external temperature is lower than the skin heat will be lost by convection and radiation. Below 31-32oC sweat glands produce very little sweat. When body temperature rises dermal blood vessels dilate and sweat glands are stimulated to secrete more sweat (upto 12 litres/day), evaporation of the sweat from the skin dissipates body heat. When the body temperature cools dermal blood vessels constrict and this slows heat loss. In addition the erector pili muscles contract and raise the hairs, trapping a layer of air next to the skin as an insulator.

Question 28

What are the two types of sensory cutaneous receptors and what do they respond to?

Answer 28

Meisseners corpuscles in the dermal papillae respond to gentle touch Pacinian corpuscles (in the deeper dermal layer and hypodermis) respond to deep pressure

Question 29

What are the 3 metabolic functions of the skin?

Answer 29

Calcium metabolism, detoxifaction of carcinogens and conversion of steroids

Question 30

Explain calcium metabolisation & the link with vitamin D

Answer 30

Sunlight (UV) converts a precursor of vitamin D (7-dehydrocholestrerol) into another precursor of vitamin D (cholecalciferol) which is released into blood and is converted in the liver/kidneys to active vitamin D. Without vitamin D calcium cannot be absorbed from the digestive tract. In addition vitamin D promotes calcium retention in bone and reduces loss from the kidneys

Question 31

Explain how the skin carries out detoxification of carcinogens

Answer 31

Keratinocyte enzymes can metabolise and render harmless many cancer causing chemicals

Question 32

Explain how the skin carries out conversion of steroids

Answer 32

Keratinocytes can convert cortizone applied topically into hydrocortisone which is an anti-inflammatory

Question 33

Describe the process and steps of inflammation in wound healing

Answer 33

Histamine, cytokine and other inflammatory chemicals released from damaged mast cells Leads to dilation of capillaries which become permeable White blood cells (neutrophils), plasma rich in clotting proteins and antibodies leak from blood vessels Clotting proteins form a clot which plugs wound Outer part of clot dries and forms a scab Debris and damaged tissue phagocytised and carried away in lymph

Question 34

Describe the process and steps of granulation in wound healing

Answer 34

Granulation tissue is a delicate pink tissue and contains thin permeable capillaries which bud from intact capillaries nearby and give the wound a granular appearance Wound contraction occurs as a result of the contraction of fibroblasts Macrophages clear debris. Fibroblasts make new collagen fibres to bridge the gap The ‘patch’ which forms releases bacteria inhibiting substances

Question 35

Describe the process and steps of regeneration in wound healing

Answer 35

Epithelium begins to regenerate. Epithelial cells migrate across granulation tissue just beneath scab (which then detaches)

Question 36

Describe the process and steps of remodelling in wound healing

Answer 36

The skin remodels to diminish the appearance of scarring as far as possible.