10. INTEGUMENTARY AND LYMPHATIC SYSTEMS Flashcards
The structure and function of the integumentary and lymphatic systems. The clinical presentations, investigation procedures and some orthodox treatments of skin and lymphatic system pathologies.
Name the three main layers of the skin
- Epidermis
- Dermis
- Subcutaneous layer (protective adipose tissue)
True or false:
The epidermis contains ample blood vessels and nerve endings
False
What kind of cells make up the epidermis and in which proportions?
90% Kerinatocytes: tough fibrous protein that protects from heat, microbes and chemicals
8% Melanocytes: pigment that contributes to skin colour and absorbs UV light. Two types: eumelanin = brown/black; pheomelanin = reddish/yellow
2% Langerhans cells: immune cells (skin’s surveillance)
What are the two types of melanin in the skin and how are they different?
Eumelanin = brown / black
Pheomelanin = reddish / yellow
Name three accessory structures in the dermis
Sweat glands
Hairs
Sebaceous glands
Nerve endings
In relation to the epidermis, what do the following definitions refer to?
a. A single row of dividing to form new keratinocytes
b. 3-5 layers of cells undergoing apoptosis
c. 25-30 layers of flattened dead keratinocytes
a. Stratum basale
b. Stratum granulosum
c. Stratum corneum
Describe the function of the following components of the dermis:
a. Collagen fibres
b. Elastic fibres
a. Tencile strength
b. Stretch and recoil
Which cells are responsible for the production of collagen and elastic fibres?
Fibroblasts
Which of the following components are located within the dermis?
a. Lymph vessels
b. Sweat glands
c. Sensory nerve endings
d. Stratum corneum
e. Hairs
f. Sebaceous glands
g. Arterioles and veins
h. Fibroblasts and immune cells
i. Freckles
a. Lymph vessels
b. Sweat glands
c. Sensory nerve endings
e. Hairs
f. Sebaceous glands
g. Arterioles and veins
What is the function of Meissner’s corpuscle?
Detection of light pressure
Name two body locations that contain numerous sweat glands
Palms, groin, axillae, soles of feet
Name four functions of sebaceous glands
It secretes sebum that
1. Forms a protective barrier
2. Keeps hair and skin soft
3. Waterproofing
4. Anti-microbial
List four functions of the skin
- Protection
- Thermoregulation
- Vitamin D production
- Sensation
What is the range that is considered as normal body temperature?
36.5 - 37.5 degrees
Name three body locations containing sebaceous glands.
Face, lips, scalp, nipples, glans penis
Explain specifically how sebum can act as an anti-microbial
The fatty acids in sebum inhibit bacterial growth
Describe the function of the arrector pili muscle
The arrector pili connects the hair follicle to the dermis.
When the hair is erect, it traps a layer of air next to the skin (part of thermoregulation)
Explain how age can affect sebaceous gland activity
Activity increases in puberty, decreases with age
Describe THREE ways in which the skin provides protection
- Physical barrier — closely-packed keratinised cells and melanin.
- Sebum — contains fatty acids which inhibit microbial growth.
- Sweat — contains lysozymes, which are enzymes that break down bacteria.
- Desquamation — shedding of skin cells helps remove microbes.
- Nerve sensors — induce protective reflexes.
Name TWO temperature control centres
Temperature control centres are the
hypothalamus and medulla oblongata
(brain stem)
Name the nervous system that controls both sweat gland and blood vessels in thermoregulation
Autonomic nervous system (ANS)
Describe the main difference between ‘hypothermia’ and ‘hyperthermia’
Hypothermia (<35°C) - When core temperature drops below that required for normal metabolism and body functions.
Hyperthermia (>38.5°C ) - When core temperature elevates above 38.5°C.
Which body organ is responsible for producing active vitamin D?
The kidneys
Name TWO minerals that vitamin D promotes uptake from gastrointestinal tract.
Calcium and phosphorus
Name the organ where vitamin D is stored in the body.
The liver
With regards to skin absorption, list THREE examples for:
a. Lipid soluble molecules
b. Toxins
a. Vit A, D, E, K; Some medications; Essential oils; O2 and CO2
b. Acetone,carbon, tetrachloride, lead and mercury, arsenic, poison oak and ivy
With regards to skin excretion, name FOUR products excreted via the skin
• Salt(sodiumchloride).
• Water.
• Urea.
• Ammonia.
Describe how superficial wounds heal
• Basal cells move across the gap until contact inhibition (he cessation of cell division in cells that touch each other) occurs.
• Epidermal growth factor causes multiplication of the basal cells until space is filled.
Describe specifically how deep wounds heal (HINT – think of three phases)
Inflammatory phase:
• Migration of leukocytes to clean up any microbes and foreign tissue.
• Blood clot forms and becomes a scab. Epithelial cells migrate to repair the basement membrane.
Proliferative phase:
• Granulation tissue is formed with the laying of collagen and blood vessels.
• Extensive growth and repair of epithelial cells.
Remodelling phase:
• Can take three weeks to six months. • Scab sloughs off and scar tissue
remains (fibrosis).
Explain the difference between a ‘hypertrophic scar’ and a ‘keloid scar’
- Hypertrophic scar: Stays within the boundary of the wound.
- Keloid scar: Takes up a larger space than the wound (normally raised).
With regards to skin lesions, name the following:
a. A small firm elevated lesion
b. Thick dry rough plaques of thickened skin
c. Small elevated erythematous lesion containing purulent exudate
d. Small flat circumcised lesion of a different colour to normal skin
a. Papule
b. Lichenification
c. Pustule
d. Macule
Describe the difference between an ‘open comedone’ and a ‘closed comedone’
• Open comedone: ‘Blackhead’ (acne vulgaris) — if oil is open to air, it will oxidise > turns dark
• Closed comedone: ‘Whitehead’ If skin has grown over oily material, it remains white.
Using pathophysiology, describe the difference between irritant contact dermatitis and allergic contact dermatitis
1) Irritant contact dermatitis (ICD) is the non-specific inflammatory reaction to a substance contacting the skin. Abrasive chemicals can corrode the epidermis, causing cutaneous ulceration, hands being particularly vulnerable due to frequent occupational exposure to soap (that can abrade the lipids in skin).
- Allergen Contact Dermatitis (ACD) is a Type IV delayed hypersensitivity reaction where sensitisation occurs on first exposure (to various chemicals, rubber, plants, metals). Pruritic, erythematous rash develops at the site on subsequent exposures. Multiple allergens can cause ACD and cross- sensitisation among agents is common.
Describe ONE sign / symptom more suggestive of allergic contact dermatitis.
Pruritic, erythematous rash develops at the site on subsequent exposures. Pruritis is significant, but slower onset of symptoms.
Explain how continued exposure to soap can lead to irritant contact dermatitis?
Frequent occupational exposure to soap can abrade the lipids in skin
Name TWO allergens involved in allergic contact dermatitis.
Various chemicals, rubber (latex), plants, metals.
Describe the difference between ‘phototoxic dermatitis’ and ‘photoallergic contact dermatitis’
Phototoxic dermatitis is a type of Irritant contact dermatitis (ICD) in which topical (eg. perfume / cream) or ingested irritants are activated by exposure to UV rays.
Photoallergic contact dermatitis is a Type IV delayed hypersensitivity reaction (ACD) in which a substance becomes allergenic only after it undergoes structural change triggered by UV light; e.g. sunscreens.
List THREE food allergens which can contribute to atopic eczema
Milk, eggs, soy, wheat, peanuts, fish
List TWO airborne allergens which can contribute to atopic eczema
Dust mites, moulds, pollen
Using pathophysiology, describe the difference between ‘atopic eczema’ and ‘psoriasis’
Atopic eczema is an immune-mediated inflammation of the skin due to the interaction between genetic and environmental factors while psoriasis is a chronic, autoimmune, inflammatory skin disease.
In psoriasis, the stratum basale divides too quickly, making abnormal keratin, with stratum corneum renewal in as little as 7 days (rather than 40). There is also reduced shedding and an accumulation of the stratum corneum, causing silvery scales and flakes on the skin surface.
Explain why lichenification is a sign of atopic eczema in older children.
Lichenification is the result of broken skin on repeated scratching.
Compare location of lesions in atopic eczema and psoriasis.
In atopic eczema, there is typically red scaly lesions on flexor surfaces and cheeks while in psoriasis, lesions are characteristically on extensor surfaces (wrists, elbows, knees) and scalp.
List TWO signs / symptoms of psoriasis
- Red scaly plaques covered with overlapping silvery shiny scales that may bleed.
- Possibly tiny dents in fingernails / toenails.
- Psoriatic arthritis (in 14% of cases).
Name TWO trigger factors in psoriasis
Infection,chemicals,alcohol,stress, anti-malarials, beta-blockers
Name the following condition and identify TWO causes:
“An itchy red, blotchy, raised rash resulting from swelling of superficial skin”
Urticaria.
Causes could include: Medications, food allergies, stings, stress.
Using pathophysiology, describe the difference between ‘acne vulgaris’ and ‘acne rosacea’.
Acne Vulgaris is the blockage of sebaceous / hair follicle ducts.
Acne Rosacea is chronic inflammation of the skin associated with vascular changes, which results in flushing.
Name TWO body locations affected by acne vulgaris
The face and, to a lesser extent, the back and chest.
Explain specifically how diet plays a role in acne vulgaris.
Abundant high glucose foods and dairy in the typical Western diet elevate insulin levels which promote oil production and excess skin cell production in follicles. They also cause the testes (and ovaries)
to produce testosterone.
What is meant by ‘inflammatory acne’?
‘Inflammatory acne’ begins as closed comedones. Distension of the follicle can occur, causing inflammation (red papules).
Define seborrhoea.
Seborrhoea is the excessive discharge of sebum (oily skin).
With regards to acne rosacea, which gender is most affected?
Females
List TWO causes of acne rosacea.
- Exaggerated vasodilatory response to hyperthermia.
- High incidence of gastric Helicobacter pylori found in rosacea patients (88%).
Flushing reaction may be caused by gastrin (gastrin = H. pylori growth). - Environmental (oil, chlorine, UV)
- Cosmetics (e.g. paraffin)
- Medications
- Stress
List TWO signs / symptoms more suggestive of acne rosacea
- Facial flushing — redness across nose and cheeks
- Seborrhoea (oily skin) with papules, pustules.
Name the virus which contributes to warts and verrucae
Human Papillomavirus (HPV 2 and 4)
Describe the lesion of warts
Papular lesions with a coarse roughened surface, usually with a red margin.
Name ONE endocrine pathology associated with skin tags
Hyperinsulinaemia
Explain how autoimmunity can lead to vitiligo
It is hypothesised that an increased number of Langerhans cells (immune cells involved in skin ‘surveillance’) may inhibit the proliferation of melanocytes.
Describe the appearance of vitiligo
Vitiligo is characterised by patches of skin without pigmentation due to the loss of melanocytes.
Explain the difference between first and third degree burns
First degree burns affects only the epidermis. Third degree burns extend through epidermis and dermis into subcutaneous tissue.
Explain specifically how the following complications can arise from burns:
a. Dehydration
b. Hypothermia
c. Renal failure
a. Dehydration occur due to loss of water and plasma through damaged skin surface.
b. Hypothermia — due to impaired thermoregulation and heat loss.
c. Renal failure could occur if the kidneys cannot filter waste from broken-down red blood cells and damaged tissue.
Name TWO ducts that lymphatic vessels drain into.
Lymphatic vessels ultimately drain into the
thoracic duct or the right lymphatic duct.
List TWO functions of the lymphatic system.
- Return proteins, lipids and water from the interstitial fluid to the blood.
- Immunity against harmful organisms.
Name FOUR components of the lymphatic system.
• Lymph fluid (lymph).
• Lymph vessels.
• Lymph nodes.
• Lymph organs (spleen and thymus).
• Lymphoid tissue (e.g. tonsils).
• Bonemarrow.
Name THREE components (not water) in lymph.
• Leukocytes.
• Plasma proteins (from capillaries).
• Fats absorbed from the small intestine.
• Bacteria and cell debris from damaged tissue.
Describe specifically the main difference between the lymphatic system and the cardiovascular system.
The cardiovascular system is a circular and closed system in which the fluid (blood) leaves from and returns to the heart.
In comparison, the lymphatic system is a linear system in which the lymphatic capillaries at the peripheral tissues drain lymphatic fluid.
Lymphatic fluid contains cells, proteins and macromolecules and transports it back to the vascular system.
Describe the function of lymph nodes.
Lymph nodes filter lymph and remove foreign matter such as microbes, cell debris and tumour cells
Name TWO immune cells found in lymph nodes
lymphocytes and phagocytes
Complete the following:
Lymph enters the ___________ vessels. Foreign substances are trapped in irregular channels by ___________ fibres. ___________ destroy foreign substances by phagocytosis. Whilst ___________ destroy remainder by immune response. Filtered lymph leaves via ___________ vessels. Many ___________ vessels, very few ___________ vessels in turn slow down the flow of ___________.
afferent
reticular
Macrophages
lymphocytes
efferent
afferent
efferent
lymph
Name TWO locations containing lymph nodes
Cervical, axillary, inguinal, vertebral column, mesenteric (intestinal)
Explain the difference between ‘red pulp’ and ‘white pulp’ found in the spleen
- White pulp contains lymphocytes and
macrophages. - Red pulp contains all the components of circulating blood.
List TWO functions of the spleen
- Haematopoiesis in foetus.
- Blood reservoir.
- Phagocytosis of worn-out defective erythrocytes.
- Immunity: T and B-Lymphocytes
When a spleen is ruptured, explain why it should be removed?
Damage to the thin-walled veins (sinuses) can cause significant haemorrhage and shock and removal is needed to prevent death.
Name ONE body location that can take over the function of the spleen following removal.
The liver and red bone marrow can take over some function, however, immune function is compromised.
Describe how T-lymphocytes mature in the body.
Epithelial cells in the thymus produce ‘thymosin’ which promotes the maturation of T-Lymphocytes (produced in the red bone marrow).
At what age does the thymus start to atrophy?
Atrophy begins in puberty (age 12), declining throughout life and tissue is replaced by fat.
Define MALT
Mucosa Associated Lymphoid Tissue are small aggregations of lymphoid tissue found in areas of the body exposed to the external environment which serves as a ‘first line of immune defence’.
Name TWO body locations where MALT is located
• Adenoids
• Tonsils
• Small intestine and large intestine
Explain how the lymphatic system plays a role in tissue drainage
The lymphatic system is responsible for draining and recirculating extra interstitial fluid and returning it to the bloodstream
Explain how the lymphatic system plays a role in absorption
Lacteals absorb fat-soluble substances & nutrients from the small intestines into the body:
• Dietary fats.
• Fat-soluble vitamins (A, D, E, K)
Name TWO factors that contribute to lymphatic fluid drainage
Lymphatic fluid is drained with assistance of the following:
• Mild, rhythmical contractions of the lymphatic vessels (lymphatic pump).
• Skeletal muscle pump: Movement and exercise drains fluid. Especially in the calf muscles (gastrocnemius and soleus).
• Respiratory pump: During inhalation air pressure drops in the thoracic region. Lymph moves from high to low pressure.
Using definitions, explain the difference between ‘lymphangitis’ and ‘lymphadenitis’
Lymphangitis is the bacterial inflammation of the lymph vessels (usually streptococcus).
Lymphadenitis describes inflammation of lymph nodes, usually due to a bacterial infection.
Explain why lymphangitis can lead to septicaemia
Since lymph drains into the venous system, infection may spread to the blood and lead to septicaemia which then becomes a medical emergency.
Name ONE characteristic sign / symptom of lymphangitis
Swollen, painful red lines below the skin surface along the lymph vessel course.
Explain why protein accumulation occurs in lymphoedema
Obstruction of lymph vessels causes an increase in protein accumulation in the interstitial fluid.
Explain the key difference between ‘Stage one’ and ‘Stage two’ lymphoedema
Stage 1 — Pitting oedema: Increased protein leads to water retention and swelling of soft tissue.
Stage 2 — Fibrosis of vessels: Increased protein results in inflammation and activation of fibroblasts
List TWO signs / symptoms of lymphoedema
• Severe fatigue of affected area.
• Heavy, painful, swollen limb / area (‘pitting oedema’).
• Discolouration of the skin overlying the lymphoedema.
• Recurring skin infections in the affected limb which may lead to thickening and hardening of the overlying skin.
Name ONE primary and ONE secondary cause of lymphoedema
• Primary: Congenital, poorly developed lymphatics.
• Secondary: Damage to the lymphatic system caused by radiotherapy or lymph node removal. Infections e.g. cellulitis.
Name ONE sign / symptom more suggestive of lymphadenitis
Enlarged lymph nodes that are often painful on palpation
Name ONE infectious cause of splenomegaly
Infectious mononucleosis (glandular fever), malaria
Name ONE pathology for each of the following that may cause splenomegaly:
a. Liver disease
b. Blood / lymphatic malignancy
c. Haemolytic anaemia
a. Cirrhosis leading to portal vein hypertension
b. Leukaemia and Hodgkin’s lymphoma
c. Thalassaemia, sickle cell anaemia
List TWO signs / symptoms of splenomegaly
• Abdominal pain.
• Early satiety (due to splenic encroachment).
• Symptoms of haemolytic anaemia due to accompanying cytopenia.
• Palpable mass in left upper quadrant abdominal
Explain specifically how the following factors can optimise lymphatic health:
a. Exercise
b. Removing common allergens
c. High anti-inflammatory and anti-oxidant diet.
a. Lymphatic vessels rely on exercise to ‘pump’ lymph through the body.
b. Removing common allergens from the diet reduces the stress on the digestive and immune systems
c. Eating green leafy vegetables, berries, omega-3 foods, nuts and seeds, turmeric, ginger can lighten the body’s toxic load
