Physiology Flashcards

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1
Q

What is the embryological origin of the layers of the skin?

A
epidermis= ectoderm 
dermis= mesoderm
melanocytes= from pigment-producing cells in the neural crest
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2
Q

How will the layers of the skin look at 4 weeks?

A

periderm
basal layer
dermis

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3
Q

What is a scar?

A

a loss of appendages as there is connective tissue covering but nothing else

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4
Q

What is the epidermis?

A

stratified squamous epithelium which is made up of mostly keratinocytes containing keratin

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5
Q

What are the four layers of the epidermis?

A

Basal layer
Prickle cell
Granular layer
Keratin layer

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6
Q

What are the features of the basal layer?

A
  • one cell thick
  • loss of keratin
  • highly metabolically active
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7
Q

What are the features of the prickle cell layer?

A
  • larger cells
  • lots of desmosomes
  • intermediate filaments
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8
Q

What are the features of the granular layer?

A
  • thinner
  • less nuclei
  • 2-3 layers
  • filaggrin
  • moist maker
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9
Q

What are the features of the keratin layer?

A
  • insoluble waterproof

- cornfield envelope made of corneocytes

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10
Q

What is the epidermal turnover and what is it controlled by?

A
  • the balance of cells in and out

- controlled by growth factors, cell death and hormones

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11
Q

What does HPV do?

A

it affects keratinocytes and warts are common in children due to deficient skin barrier

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12
Q

What is a digital artery?

A

an end artery in the feet and hands which has no collateral so there can be occlusion leading to infarction or amputation

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13
Q

What are the characteristics of superficial veins?

A
  • small
  • thin
  • run in superficial fascia
  • variable
  • drain to deep
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14
Q

What are the characteristics of deep veins?

A
  • large
  • thick
  • deep to deep fascia
  • predictable
  • run in neurovascular bundles
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15
Q

Where does the cephalic vein run?

A
  • from the dorsal venous network
  • up the lateral limb in deltopectoral groove
  • drains into axillary vein
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16
Q

Where does the basilic vein run?

A
  • from dorsal venous network
  • rises on medial aspect of limb
  • drains into brachial vein
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17
Q

What is the median cubital artery?

A

joins the basilic and the cephalic veins together but this can have variations eg M, H or Y shape

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18
Q

What are the names of the networks in the hand and the foot?

A

dorsal venous network= hand

dorsal venous arch= foot

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19
Q

Where does the great saphenous vein run?

A
  • from dorsal venous arch
  • up medial aspect
  • drains into femoral vein at the femoral triangle
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20
Q

Where does the small saphenous vein run?

A
  • from dorsal venous arch
  • up posterior midline
  • drains into popliteal vein in popliteal fossa
21
Q

Are the deep veins bilateral or unilateral?

A

all deep veins are bilateral except the SVC and the IVC

22
Q

What are vena comitantes?

A

these are veins next to arteries that are forced to pulse by the artery’s force which increases the venous return to the heart

23
Q

What does ischaemia lead to?

A
  • decreased arterial perfusion pressure

- increased venous pressure from the back pressure to the capillaries so there is decreased arterial flow

24
Q

What are perforating veins?

A

they run at angles and have valves for backflow

25
Q

What is superficial fascia?

A

loose connective tissue and fat which varies in depth

this contains superficial blood vessels

26
Q

What is deep fascia?

A

tough sheet of dense connective tissue which is named according to body part

27
Q

What are the largest sections of fascia?

A

fascia lata on the thigh

iliotibial tract down lateral leg

28
Q

Where are the main groups of lymph nodes in the upper limb?

A

apical axillary
lateral axillary
cubital

29
Q

Where are the main groups of lymph nodes in the lower limb?

A

superficial inguinal
deep inguinal
popliteal

30
Q

What are the main epidermal cells?

A

keratinocytes are the main ones

others are melanocytes, langerhans cells and Merkel cells

31
Q

What are the features of melanocytes?

A
  • migrate from neural crest to the epidermis
  • in basal layer below dendritic cells
  • contain melanosomes which move to nearby keratinocytes via dendrites
  • melanin absorbs light and melanin casts protect nuclear DNA in basal cells
32
Q

What are the features of Langerhans?

A
  • these are a type of dendritic cell
  • they have a mesenchymal origin in the bone marrow
  • they are in the prickle cell layer, dermis and lymph nodes
  • they act as APCs and activate T cells
  • BIRBECK granules are their distinguishing feature
33
Q

What are the features of Merkel cells?

A
  • these are basal cells that act as mechanoceptors

- cancer of these cells is rare but deadly

34
Q

What are the phases of hair growth?

A
anagen= growing
catagen= involuting
telogen= resting
35
Q

What are nails made up of?

A

specialised keratins and stem cells that are in the matrix of nails and differentiate to become flat

36
Q

What is the dermis made of?

A

collagen for support and is made of fibroblasts

37
Q

What does disrupted lymphatics lead to?

A

chronic lymphedema which is non-pitting

38
Q

What nerves are in the dermis and what are the special ones?

A
  • usually somatic sensory

- special receptors are Meissner’s (vibration) and Pascinian corpuscles (pressure)

39
Q

What are the three types of skin glands and their features?

A
  • Eccrine: palms and soles, keep cool, excess sweating
  • Sebaceous: lubricated hair follicles, protect from fungus, largest glands, face and chest, cause of acne
  • Apocrine: axilla and perineum, unclear role, odour after secretion
40
Q

What role does the skin play in metabolism?

A
  • vit D metabolism
  • thyroid hormone metabolism
  • defence against chemicals
41
Q

What are the parts of hair?

A
  • follicle which is an invagination of the epidermis
  • central medulla with soft keratin
  • papilla with vascular channels
  • outer cortex with hard keratin
42
Q

What are the parts of nail?

A
  • plate sits on the bed
  • matrix where cells divide and make keratin
  • hyponychium where the free edge of the nail is secured
  • cuticle is an extension of the skin fold
43
Q

What are the types of intention wound healing?

A
  • primary intention is suturing the wound

- secondary intention is leaving the wound to heal on its own

44
Q

What are the features of keratinocytes?

A
  • epidermal
  • sense pathogens
  • make AMPs that kill pathogens
  • make cytokines and chemokines
45
Q

What are the types of lymphocytes in each layer of the skin?

A
  • CD8 are in the epidermis

- CD4 and CD8 are in the dermis

46
Q

What do plamacytoid cells do?

A

are in the dermis and make IFNalpha and are in diseased skin

47
Q

What do MHC class 1 and 2 do?

A
  • MHC class 1: present antigens to cytotoxic T cells and are present on almost all cells
  • MHC class 2: found on APCs and present to T helper cells
48
Q

What are the factors affecting skin immune response?

A
  • organ transplant: immunosuppression
  • sunlight: immunosuppression
  • ageing: decrease ability to detect cancer and to see antigen
49
Q

What cells do vitamin D metabolism?

A

keratinocytes