1. Common integument

Question 1

What is common integument and what does it include

Answer 1

The outer barrier of an organism
- subcutis
- skin
- modified skin structures

Question 2

What is the skin/cutis split into?

Answer 2

epidermis + dermis

Question 3

give examples of modified skin structures

Answer 3

• Hair + Hair follicles
• skin + Mammary glands
• footpads
• nails/claws/hooves
• Horns and antlers

Question 4

What is subcutaneous tissue/subcutis and
what does it contain?

Answer 4

The loose connective tissue between the skin and muscle fascia
contains white fat/ adipose tissue

Question 5

What is the function of subcutaneous tissue/subcutis?

Answer 5

• insulation
• energy source
• padding/protection

Question 6

Name the 6 cutaneous muscles, where they are and if they are in certain species

Answer 6

• PLATYSMA: over neck and face
• FRONTALIS: over frontal bone * absent in horses
• CUTANEOUS COLI: sternum and neck * best developed in horses
• CUTANEOUS TRUNCI: side of the trunk
• CUTANEOUS OMOBRACHIALIS: continuation of trunci over the shoulder and arm *ruminants + horses
• PREPUTAL MUSCLE: connecting ventral midline to the prepuce

Question 7

what does the dermis determine and what is it made up of?

Answer 7

Determines the thickness of the skin
Made up of fibrous connective tissue:
- collagen fibres ( 1,3,5)
- elastin fibres

Question 8

What is the name for how collagen fibres orientate themselves in the dermis?

Answer 8

Tension lines, also known as langer’s lines

Question 9

What else does the dermis contain other than fibrous connective tissue?

Answer 9

• blood vessels
• lymphatic vessels
• nerves
• sensory receptors
• hair follicles
• arrestor pili muscles
• sebaceous + sweat glands

Question 10

What are the 5 layers of the epidermis?

Answer 10

• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum

Question 11

what is the name for skin cells and where are they produced

Answer 11

keratinocytes
Found in stratum basale

Question 12

keratinocytes move to the skin surface and differentiate as they go, how long is the general cycle?

Answer 12

20-30 days

Question 13

What do keratinocytes contains and what is the product needed for?

Answer 13

keratohyalin granules
needed for keratinisation

Question 14

What is keratinisation?

Answer 14

process where keratinocytes turn to corneocytes

Question 15

Name the cells found in the epidermis

Answer 15

• Keratinocytes
• corneocytes
• melanocytes (pigment)
• Langerhans (immune cells)
• Merkel cells (touch receptor)

Question 16

What are the 7 functions of common integument?

Answer 16

• communication/camouflage
• protection
• immune defence
• sensing environment
• thermoregulation
• storage + excretion
• selective permeability

Question 17

Explain gastrulation

Answer 17

• The formation of the 3 germ layers:
  ectoderm- top/outside layer
  mesoderm - middle layer
  endoderm - bottom layer/ inside tube
  These eventually make up all the animals’ tissues and organs

Question 18

What develops from what germ layer?

Answer 18

• Ectoderm: epidermal and neural cells
• mesoderm: musculoskeletal system, connective tissues, organs and blood
• Endoderm: the lining of the gut + respiratory system + outer pouching ( liver, pancreas)

Question 19

Explain neurulation

Answer 19

1. epithelial ectoderm thickens and narrows
2. wedge shape attaches to notochord in the mesoderm. Neural groove forms
3. neural fold merges
4. Neural tube is completed and neural crest cells break away

Question 20

Where do melanocytes develop from?

Answer 20

Neural crest cells in mesoderm

Question 21

Define somites

Answer 21

mesoderm organises itself into blocks of tissue called somites

Question 22

Define dermatome

Answer 22

a segment of dermis derived from one somite and therefore innervated by a single spinal nerve

Question 23

Describe cutaneous innervation

Answer 23

» After exiting the vertebra, the spinal nerve splits into dorsal and ventral branches/rami
» The dorsal branches generally supply the dorsal cutaneous nerves innervating the dorsal body skin
» The ventral branch supplies the ventral and lateral cutaneous nerves innervating the ventral and lateral body skin
» The limbs are also supplied by spinal nerves
» Regions can overlap (multiple nerves receiving skin sensation)

Question 24

What are autonomous zones?

Answer 24

Non overlapping regions supplied by a single nerve

Question 25

What is the result of regional variations in fat and thickness of the subcutis?

Answer 25

Skin folds, source of breed variation in dogs, and is importanrt when considering the location of injections.

Question 26

What is the function of cutaneous muscle?

Answer 26

Skin movement