1. Common integument Flashcards
What is common integument and what does it include
The outer barrier of an organism
- subcutis
- skin
- modified skin structures
What is the skin/cutis split into?
epidermis + dermis
give examples of modified skin structures
- Hair + Hair follicles
- skin + Mammary glands
- footpads
- nails/claws/hooves
- Horns and antlers
What is subcutaneous tissue/subcutis and
what does it contain?
The loose connective tissue between the skin and muscle fascia
contains white fat/ adipose tissue
What is the function of subcutaneous tissue/subcutis?
- insulation
- energy source
- padding/protection
Name the 6 cutaneous muscles, where they are and if they are in certain species
- 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
what does the dermis determine and what is it made up of?
Determines the thickness of the skin
Made up of fibrous connective tissue:
- collagen fibres ( 1,3,5)
- elastin fibres
What is the name for how collagen fibres orientate themselves in the dermis?
Tension lines, also known as langer’s lines
What else does the dermis contain other than fibrous connective tissue?
- blood vessels
- lymphatic vessels
- nerves
- sensory receptors
- hair follicles
- arrestor pili muscles
- sebaceous + sweat glands
What are the 5 layers of the epidermis?
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
what is the name for skin cells and where are they produced
keratinocytes
Found in stratum basale
keratinocytes move to the skin surface and differentiate as they go, how long is the general cycle?
20-30 days
What do keratinocytes contains and what is the product needed for?
keratohyalin granules
needed for keratinisation
What is keratinisation?
process where keratinocytes turn to corneocytes
Name the cells found in the epidermis
- Keratinocytes
- corneocytes
- melanocytes (pigment)
- Langerhans (immune cells)
- Merkel cells (touch receptor)
What are the 7 functions of common integument?
- communication/camouflage
- protection
- immune defence
- sensing environment
- thermoregulation
- storage + excretion
- selective permeability
Explain gastrulation
- 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
What develops from what germ layer?
- 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)
Explain neurulation
- epithelial ectoderm thickens and narrows
- wedge shape attaches to notochord in the mesoderm. Neural groove forms
- neural fold merges
- Neural tube is completed and neural crest cells break away
Where do melanocytes develop from?
Neural crest cells in mesoderm
Define somites
mesoderm organises itself into blocks of tissue called somites
Define dermatome
a segment of dermis derived from one somite and therefore innervated by a single spinal nerve
Describe cutaneous innervation
» 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)
What are autonomous zones?
Non overlapping regions supplied by a single nerve
What is the result of regional variations in fat and thickness of the subcutis?
Skin folds, source of breed variation in dogs, and is importanrt when considering the location of injections.
What is the function of cutaneous muscle?
Skin movement
