Skin, Subcutis, Gastrulation and Cutaneous Innervation Flashcards
What is the common integument made up of?
Subcutis (fascia and cutaneous muscle), skin (dermis and epidermis) and modified skin structures (e.g. hairs, skin glands, claws, hooves, footpads, antlers, horns)
What is subcutaneous tissue and what is its function? What are some other names for it?
Loose connective tissue made of adipose tissue (white fat). Important for insulation, padding and is a source of energy. AKA, subcutis, hypodermis
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
Cutaneous muscle over the neck and face is known as?
Platysma
Cutaneous muscle over the frontal bone is known as?
Frontalis
Cutaneous muscle that spreads from the sternum to the neck is known as?
Cutaneous colli
Cutaneous muscle that covers the side of the trunk is known as?
Cutaneous trunci
Cutaneous muscle that continues from the shoulder to the arm is known as?
Cutaneous omobrachialis
Cutaneous muscle that connects the ventral midline to the prepuce is known as?
Preputial muscles
What is the cutis composed of?
Dermis and epidermis
What is the dermis made up of?
Fibourous connective tissue-collagen and elastin fibres, also contains blood vessels, lymphatic vessels, sweat and sebaceous glands, sensory receptors, nerves, hair follicles, arrector pilli muscles
What are the 5 layers of the epidermis from bottom to top?
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
What is the function of the stratum basale?
Attachment to dermis, production and proliferation of keratinocytes
What is the function of the stratum spinosum?
Contains desmosomes, which act as cell adhesive. Desmosome junctions look ‘spiny’ under a microscope
What is the function of the stratum granulosum?
Contain keratinocytes, and accumulate keratohyalin granules which help to form a waterproof barrier (contain lipids)
What is the function of the stratum lucidum?
A clear layer only found in thick skin e.g toepads, as it lowers the effect of friction on skin. Also allows the skin to stretch
What is the function of the stratum corneum?
The outermost skin barrier, preventing unwanted materials entering body. Few desmosomes here, dead skin cells slough off
What are keratinocytes?
Major cell type of the epidermis
What are corneocytes?
Differentiated keratinocytes
What are melanocytes?
Pigment cells that protect against UV radiation
What are Langerhans cells?
Immune cells
What are merkel’s cells?
Touch receptors
7 main functions of the skin?
1) protection 2) immune defence 3) sensing environment 4) thermoregulation 5) storage and excretion 6) communication/camouflage 7) selective permeability
What are the three germ layers involved in gastrulation?
Ectoderm, mesoderm and endoderm
Explain the general process of gastrulation.
The three germ layers lie flat-ectoderm on top, mesoderm in the middle and endoderm on the bottom. A specialised part of the mesoderm (notochord) causes the ectoderm above it (neural plate) to fold on itself. Neural crest cells (on the edge of the neural plate) meet in the middle, forming a hollow tube-the neural tube-which will give rise to the CNS.
What does the ectoderm give rise to?
The epidermis (epidermal cells) and neural cells-Central Nervous System
What does the mesoderm give rise to?
Connective tissue (subcutis), musculoskeletal system, blood
What does the endoderm give rise to?
The gut, organs, respiratory system
What are somites?
Blocks of cells from the mesoderm that will eventually differentiate into dermis, skeletal muscle, cartilage, tendons, and vertebrae.
What are dermatomes?
Segments of dermis derived from one somite, in which sensory nerves derive from a single spinal nerve root
What is cutaneous innervation?
The area of the skin which is supplied by a specific cutaneous nerve.
What are autonomous zones and why are they important in veterinary medicine?
Non-overlapping regions of innervation, suppiled by a single nerve. They are important for successful local anaesthesia, as well as diagnosing peripheral (extremity) nerve lesions
