Common Integument Structure Flashcards
What is the deepest structure of the common integument?
Subcutis (aka hypodermis)
2nd deepest structure of common integument?
Skin (cutis)- dermis and epidermis
What is the surface structure of common integument?
Modified skin structures
5 examples of modified skin structures
- Hair follicles and hairs
- Skin glands (inc. mammary)
- Foot pads
- Nails claws and hooves
- Horns and antlers
Subcutis
Loose connective tissue between skin and muscle fascia
Contains white fat (adipose tissue)
Regional Variations in fat and thickness
Muscle attachments- skin movement: tendons into the subcutis
TYPES OF CUTANEOUS MUSCLE: Platysma
Over the neck and face
TYPES OF CUTANEOUS MUSCLE: Frontalis
Over the frontal bone (not in horses)
TYPES OF CUTANEOUS MUSCLE: Cutaneous colli
From sternum and up neck
TYPES OF CUTANEOUS MUSCLE: Cutaneous trunci
covers the side of the trunk
TYPES OF CUTANEOUS MUSCLE: cutaneous omobrachialis
continuation of the cutaneous trunci over the shoulder and arm
TYPES OF CUTANEOUS MUSCLE: preputial muscles
connect the ventral midline to prepuce.
Cutis
Composed of the dermis and the epidermis
Dermis determines skins thickness
The Dermis
(in the cutis) made up of fibrous connective tissue- collagen and elastin
Collagen fibres are oriented in tension lines or Langer’s lines
The Dermis also contains…
- Blood vessels
- Lymphatic vessels
- Nerves
- Sensory receptors
- Hair follicles
- Arrector pili muscles
- Sebaceous and sweat glands
The epidermis
(the surface layer) 4-5 layers of epidermis
keratinocytes (skin cells) are produced in the stratum basale by mitotic cell division
keratinocytes move to surface whilst specialising
Name 5 layers of epidermis
- Stratum basale (deepest)
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum (surface)
Cells in the epidermis
mostly keratinocytes and corneocytes but also:
- melanocytes: pigment cells to protect against sun radiation
- Langerhans cells: immune cells
- Merkels cells : touch receptors
Functions of common integument
PROTECTION: Physical (fat), Radiation (melanocytes) and Epidermal organs (horns and claws)
IMMUNE: physical barrier, immune cells, antimicrobial secretions.
SENSES: receptors, tactile hairs and toruli hairs.
THERMOREGULATION: sweating, hairs, insulation
STORAGE & EXCRETION: fat stores and glands excrete
COMMUNICATION: gland excretions, arrector pili, pigmentation
SELECTIVE PERMEABILITY: respiration, waterproof.
embryonic development- gastrulation
3 germ layers are formed: ectoderm (top), mesoderm, and endoderm (bottom)
These eventually make all animals tissues and organs.
The flat layers role into a hollow tube with ectoderm outside and endoderm inside
embryonic development- neurulation
Notochard causes the neural groove to form
Gives rise to the epidermis
What does each germ layer form?
Ectoderm- epidermal and neural cells
Mesoderm- musculoskeltal system, connective tissues, organs and blood
Endoderm- lining of gut and respiratory system and out pouchings
Where are neural crest cells?
in the ectoderm
Somites and Dermatomes
at a later embryonic stage mesoderm organises itself into blocks called somites
Dermatome- a segment of dermis from one somite: innervated by one single spinal nerve.
Cutaneous Innervation
After exiting vertebrae spinal nerve splits into dorsal and ventral branches
dorsal branches innervate dorsal skin
ventral branches innervate ventral and lateral skin
