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Biomed 1 - Revision Deck > Lecture 10 - Skin and Lymphatic System > Flashcards

Lecture 10 - Skin and Lymphatic System Flashcards

1
Q

3 layers of skin

A
  1. Epidermis
  2. Dermis
  3. Subcutaneous / adipose layer
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2
Q

Epidermis

A
  • Superficial layer of skin
  • Keratinsed epithelium (waterproofing/protection)
  • No blood vessels, no nerve endings
  • Nutrients and oxygen supplied in interstitial fluid
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3
Q

Dermis

A
  • Middle layer
  • Connective tissue
  • Contains accessory structures
    • Sweat glands
    • Hairs
    • Sebaceous glands
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4
Q

Subcutaneous / Adipose Layer

A
  • Insulating and protecting layer of fatty tissue
  • Connects dermis to deeper-lying muscle and bone
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5
Q

Connective tissue

A

Matrix filled with fibers and specialised cells

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6
Q

Epidermis cells

A
  • 90% of epidermal cells are keratinocytes
    • Keratin- tough, fibrous protein that protects from heat, microbes and chemicals
  • 8% melanocytes
  • 2% Langerhans cells - immune
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7
Q

Fingerprints

A
  • Formed in 3rd month of foetal development
  • Downward projections of epidermis into dermis
  • Increase surface area
  • Enhance grip by creating friction
  • Unique to each individual
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8
Q

Layers of epidermis

A
  • Stratum corneum
    • 25-30 layers of flattened dead keratinocytes, shed (desquamated)
  • Stratum lucidum
    • 3-5 layers of dead cells (only in thick skin)
  • Stratum granulosum
    • 3-5 layers undergoing apoptosis (cell death)
  • Stratum spinsosum
    • 8-10 layers new keratinocytes
  • Stratum basale
    • Single row dividing to form new keratinocytes
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9
Q

How often is complete replacement of epidermis

A

40 days

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10
Q

Dermis

A
  • Thickest layer of skin
  • Formed of connective tissue
  • Matrix of collagen and elastic fibres
  • Strength, elasticity (stretch and recoil)
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11
Q

Accessory organs in dermis

A
  • Arterioles and capillaries (thermoregulation)
  • Lymph vessels
  • Sweat glands
  • Hairs
  • Sebaceous glands
  • Fibroblasts
  • Immune cells (macrophages and mast cells)
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12
Q

Where are sweat glans most numerous?

A
  • Palms
  • soles of feet
  • axillae
  • groin
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13
Q

Sweat glands consist of three things

A
  • Gland, duct, pore
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14
Q

Function of sweat glands

A
  • Excretion of urea
  • (excess leads to dehydration and sodium depletion)
  • Evaporate sweat - regulate body temperature
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15
Q

3 nerve endings in dermis

A
  1. Meissner’s corpuscle - sensitive to light pressure
  2. Pacinian corpuscle - sensitive to deep pressure
  3. Free nerve ending - sensitive to pain and temperature
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16
Q

What are hairs?

A
  • Concentric columns of dead keratinsed cells bonded together by proteins
  • ‘arrector pili’ smooth muscle connecting hair follicle to dermis
  • When hair erect - traps layer of air next to skin (thermoregulation)
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17
Q

Sebaceous glands

A
  • Secrete sebum
  • Keeps hair soft
  • Water-proofing for skin
  • Anti-microbial (fatty acids)
  • Face, scalp, lips, eyelids, nipples
  • Increases with puberty, decreases with age
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18
Q

Skin - functions

A
  • Protection
  • Thermoregulation
  • Vit D production
  • Sensation
  • Absorption
  • Excretion
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19
Q

What does skin protect against?

A
  • Chemicals
  • Toxins
  • Trauma
  • Light
  • Microbes
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20
Q

How does skin protect?

A
  1. Physical barrier
  2. Sebum - fatty acids inhibit microbial growth
  3. Sweat - contains lysozymes, break down bacteria
  4. Desquamation - shedding skin cells removes microbes
  5. Nerve sensors - reflexes
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21
Q

Where are the temperature control cells located?

A
  • Hypothalamus
  • Medulla oblongata
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22
Q

Temperature regulation by the skin (2 mechanisms)

A
  1. Sweat glands - evaporation
  2. Blood vessels - vasodilation/constriction
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23
Q

Thermoregulation

A
  • High body temp - vasodilation of peripheral blood vessels to promote heat loss
  • Low body temp - vasoconstriction to prevent heat loss
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24
Q

Where is heat produced in the body?

A

Liver, muscles, digestive organisms

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25
Q

Hypothermia

A
  • Less than 35 degrees C
  • Death - below 25 degrees C
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26
Q

Hyperthermia

A
  • Above 38.5 degrees C
  • 40 - life threatening
  • 41 - brain death
  • 45 - death
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27
Q

Why is Vitamin D important?

A
  • UV light activates Vitamin D precursor in skin
  • Kidneys convert precursor to calcitriol
  • Calcitriol - hormone to increase uptake of calcium and phosphorus from food into blood
  • Supports bone density
  • Vit D stored in liver
28
Q

What is absorbed through the skin?

A
  • Lipid-soluble molecules - Vit A, D, E, K + Oxygen and carbon dioxide
  • Toxins - mercury, arsenic, poison oak and ivy
29
Q

What is excreted through the skin?

A
  • Salt (sodium chloride)
  • Water
  • Urea
  • Ammonia
30
Q

Wound healing - superficial

A
  • Basal cells move across gap
  • Epidermal growth factor - multiplication of basil cells until space is filled
31
Q

Deep wound healing - Phase 1

A
  • Inflammatory phase
    • leukocytes clean up microbes and tissues
    • clot forms, becomes scab
    • Epithelial cells migrate to repair the basement membrane
32
Q

Deep wound healing - Phase 11

A
  • Proliferation Phase
    • Granulation tissue is formed by collagen and blood vessels
    • Growth and repair of epithelial cells
33
Q

Deep Wound Healing - Phase 3

A
  • Remodelling Phase
    • 3-6 months
    • Scab sloughs off, care tissue remains (fibrosis)
34
Q

2 types of scar tissue

A
  1. Hypertrophic scar - stays within boundary of wound
  2. Keloid scar - takes up larger space than the wound, normally raised
35
Q

Papule

A
  • Small, firm, elevated lesion
  • Circumscribed, solid elevation of skin with no visible fluid
  • Brown, purple, pink or red
  • ‘maculopapular rash’ in measles
36
Q

Pustule

A
  • Small, elevated, erythematous lesion containing pus
  • Purulent material
  • Necrotic inflammatory cells
  • White or red
37
Q

Macule

A
  • Small flat, circumscribed lesion of a different colour to normal skins
  • Change in surface colour, without elevation or depression
38
Q

Nodule

A
  • Palpable elevated lesion
  • Similar to a papule, but bigger and deeper (i.e. rheumatoid arthritis on fingers)
39
Q

Crust

A
  • Collection of dried body fluid (blood plasma and exudate) and dead skin cells (scab)
  • Exudate - any fluid that filters from the body
40
Q

Lichenification

A
  • Thick, dry, rough plaques of thickened skin
  • Visible thickening of epidermis
  • Accentuated skin markings, pronounced lines
  • Bark-like
  • Hallmark of chronic eczema or excessive scratching
41
Q

Erosion

A
  • Shallow, moist cavity in the epidermis
  • Wearing away with loss of superficial epidermis
  • From chemicals, friction, pressure
  • ‘Ulcer’ in diabetes
42
Q

Keloid

A
  • Raised, irregular mass of collagen due to scar tissue formation
  • Abnormal scar tissue that grows beyond the skin boundary
  • Genetic
  • Vaccination site, scratching, burns
43
Q

Comedone

A
  • Blackheads, whiteheads or red bumps
  • Due to excess sebum, keratin and debris forming a plug in the sebaceous duct or hair follicle
  • Hormones (testosterone) cause thicker oil secretions
  • Open comedo - blackhead (oil exposed to air)
  • Closed comedo - Whitehead (skin grows over oil)
44
Q

Classification of burns

A
  • 1st degree - epidermis
  • 2nd degree - epidermis and some dermis
  • 3rd degree - extends into subcutaneous tissue
  • 4th degree - extends into muscles and tendons
45
Q

Burns - complications

A
  • Dehydration
  • Hypothermia
  • Hypovolaemic shock
  • Infection
  • Renal failure (kidneys can’t filter waste from broken down RBCs and damaged tissue)
  • Contractures - skin distortion
46
Q

What is the lymph system?

A

Network of tissues, vessels and organs that work together to move ‘lymph’ back into the circulatory system

47
Q

Lymph system consists of:

A
  • Lymph fluid (lymph)
  • Lymph vessels
  • Lymph modes
  • Lymph organs (spleen and thymus)
  • Lymphoid tissue (e.g. tonsils)
  • Bone marrow
48
Q

Lymph system functions

A
  • Return protein, lipids and water from interstitial fluid to the blood
  • Immunity against harmful organisms
49
Q

Lymph drains into what two ducts?

A
  • right lymphatic duct
  • thoracic duct
50
Q

What is lymph?

A
  • Watery fluid similar to blood plasma but with less plasma proteins
  • Same composition as interstitial tissue
51
Q

Lymph contains:

A
  • Water
  • Leukocytes
  • Plasma proteins (seeped out of capillaries)
  • Fats (absorbed from small intestine)
  • Bacteria and cell debris (from damaged tissue)
52
Q

Lymphatic vessels are what type of tube?

A
  • Blind-end tubes - one-way structure
  • Located in the spaces between cells
53
Q

Lymphatic vs cardiovascular system

A
  • Cardiovascular system
    • circular, closed
    • blood leaves from and returns to heart
  • Lymphatic system
    • linear
    • Lymphatic capillaries drain lymphatic fluid
    • Lymphatic fluid contains cells, proteins and macromolecules - transports back to vascular system
54
Q

What is the function of lympatic nodes?

A
  • Filter lymph
  • Remove foreign matter - microbes, cell debris, tumour cells
  • 600 bean-shaped
  • Filled with immune cells (lymphocytes, phagocytes)
55
Q

Lymph enters modes via

A

Afferent vessels

56
Q

Filtered lymph leaves via

A

Efferent vessels

Many afferent, few efferent - slows down flow of lymph

57
Q

5 locations containing most lymph nodes

A
  • Cervical
  • axillary
  • inguinal
  • vertebral column
  • mesenteric (intestinal)
58
Q

What is the term referring to swelling of lymph nodes?

A

lymphadenopathy

59
Q

Spleen contains two types of pulp

A
  1. White pulp - lymphocytes and macrophages
  2. Red pulp - components of circulating blood
60
Q

Spleen functions:

A
  1. Haematopoiesis (in foetus)
  2. Blood reservoir
  3. Phagocytosis of worn-out defective erythrocytes
  4. Immunity: T and B-lymphocytes
61
Q

What can compensate for ruptured/removed spleen?

A
  • Liver and red bone marrow can take over some functions
  • But immune function is compromised
62
Q

Thymus function

A
  • Immune development
  • Antibody production in early life
  • ‘thymosin’ promote maturation of T-lymphocytes (produced in red bone marrow)
  • T-cells leaving thymus via blood migrate to lymph nodes and lymphatic tissues where they colonis
  • Atrophy begins puberty (age 12), replaced by fat
63
Q

MALT

A
  • Muscosa Associated Lymphoid Tissue
  • First line of immune defense
  • Small aggregations of lymphoid tissue found in areas of the body exposed to external environment
  • Adenoids, tonsils, small and large intestine (especially appendix)
64
Q

Lymphatic System Functions

A
  • Tissue drainage
  • Absorption (lacteals absorb fat-soluble substances - dietary fat, vitamins A, D, E, K)
  • Immunity - production/maturation of lymphocytes - lymph nodes, spleen, thymus
    *
65
Q

What mechanisms assist with lymphatic draining

A
  • Lymphatic pump - mild contractions of lymphatic vessels
  • Skeletal muscle pump - movement drains fluid
  • Respiratory pump - during inhalation air pressure drops in thoracic region, lymph moves from high to low pressure

Biomed 1 - Revision Deck (9 decks)

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