Physiology

Question 1

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

Answer 1

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

Question 2

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

Answer 2

periderm
basal layer
dermis

Question 3

What is a scar?

Answer 3

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

Question 4

What is the epidermis?

Answer 4

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

Question 5

What are the four layers of the epidermis?

Answer 5

Basal layer
Prickle cell
Granular layer
Keratin layer

Question 6

What are the features of the basal layer?

Answer 6

• one cell thick
• loss of keratin
• highly metabolically active

Question 7

What are the features of the prickle cell layer?

Answer 7

• larger cells
• lots of desmosomes
• intermediate filaments

Question 8

What are the features of the granular layer?

Answer 8

• thinner
• less nuclei
• 2-3 layers
• filaggrin
• moist maker

Question 9

What are the features of the keratin layer?

Answer 9

• insoluble waterproof

- cornfield envelope made of corneocytes

Question 10

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

Answer 10

• the balance of cells in and out

- controlled by growth factors, cell death and hormones

Question 11

What does HPV do?

Answer 11

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

Question 12

What is a digital artery?

Answer 12

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

Question 13

What are the characteristics of superficial veins?

Answer 13

• small
• thin
• run in superficial fascia
• variable
• drain to deep

Question 14

What are the characteristics of deep veins?

Answer 14

• large
• thick
• deep to deep fascia
• predictable
• run in neurovascular bundles

Question 15

Where does the cephalic vein run?

Answer 15

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

Question 16

Where does the basilic vein run?

Answer 16

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

Question 17

What is the median cubital artery?

Answer 17

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

Question 18

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

Answer 18

dorsal venous network= hand

dorsal venous arch= foot

Question 19

Where does the great saphenous vein run?

Answer 19

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

Question 20

Where does the small saphenous vein run?

Answer 20

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

Question 21

Are the deep veins bilateral or unilateral?

Answer 21

all deep veins are bilateral except the SVC and the IVC

Question 22

What are vena comitantes?

Answer 22

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

Question 23

What does ischaemia lead to?

Answer 23

• decreased arterial perfusion pressure

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

Question 24

What are perforating veins?

Answer 24

they run at angles and have valves for backflow

Question 25

What is superficial fascia?

Answer 25

loose connective tissue and fat which varies in depth | this contains superficial blood vessels

Question 26

What is deep fascia?

Answer 26

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

Question 27

What are the largest sections of fascia?

Answer 27

fascia lata on the thigh | iliotibial tract down lateral leg

Question 28

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

Answer 28

apical axillary lateral axillary cubital

Question 29

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

Answer 29

superficial inguinal deep inguinal popliteal

Question 30

What are the main epidermal cells?

Answer 30

keratinocytes are the main ones | others are melanocytes, langerhans cells and Merkel cells

Question 31

What are the features of melanocytes?

Answer 31

- 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

Question 32

What are the features of Langerhans?

Answer 32

- 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

Question 33

What are the features of Merkel cells?

Answer 33

- these are basal cells that act as mechanoceptors | - cancer of these cells is rare but deadly

Question 34

What are the phases of hair growth?

Answer 34

``` anagen= growing catagen= involuting telogen= resting ```

Question 35

What are nails made up of?

Answer 35

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

Question 36

What is the dermis made of?

Answer 36

collagen for support and is made of fibroblasts

Question 37

What does disrupted lymphatics lead to?

Answer 37

chronic lymphedema which is non-pitting

Question 38

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

Answer 38

- usually somatic sensory | - special receptors are Meissner's (vibration) and Pascinian corpuscles (pressure)

Question 39

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

Answer 39

- 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

Question 40

What role does the skin play in metabolism?

Answer 40

- vit D metabolism - thyroid hormone metabolism - defence against chemicals

Question 41

What are the parts of hair?

Answer 41

- follicle which is an invagination of the epidermis - central medulla with soft keratin - papilla with vascular channels - outer cortex with hard keratin

Question 42

What are the parts of nail?

Answer 42

- 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

Question 43

What are the types of intention wound healing?

Answer 43

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

Question 44

What are the features of keratinocytes?

Answer 44

- epidermal - sense pathogens - make AMPs that kill pathogens - make cytokines and chemokines

Question 45

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

Answer 45

- CD8 are in the epidermis | - CD4 and CD8 are in the dermis

Question 46

What do plamacytoid cells do?

Answer 46

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

Question 47

What do MHC class 1 and 2 do?

Answer 47

- 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

Question 48

What are the factors affecting skin immune response?

Answer 48

- organ transplant: immunosuppression - sunlight: immunosuppression - ageing: decrease ability to detect cancer and to see antigen

Question 49

What cells do vitamin D metabolism?

Answer 49

keratinocytes