ANHB1101 Lecture Notes - Lecture 26: Subcutaneous Tissue, Sebaceous Gland, Smooth Muscle Tissue
3 Jun 2018
School
Course
Professor
Lecture 26
Monday, 9 May 2016
8:55 am
Skin
Skin (integument):
• Organ
• Large surface area - ranges from 1.5/2m2
• Weight between 4 and 5 kg
• Functions
o Protection
o Temperature regulation
o Sensation
o Metabolic functions
o Blood reservoir
o Excretion
Structure of Skin:
• Epidermis } main (w/ dermis)
• Dermis
• Subcutaneous layer - not actually part of the skin
• Epidermis/dermis - 1-2mm thick
• Skin on the dorsal surfaces of the body tend to be darker, thicker, hairier and
less well-innovated than the ventral surfaces
• Epidermis + dermis are bound tightly together
• Epidermis is epithelium - no blood vessels
• Dermis is mainly fibrous CT
• Loose CT underneath epidermis - can be folded to increase surface area
Epidermis:
• Epithelium - stratified squamous
• Lots of cell replacement
• Strong junctions between cells - desmosomes and tight junctions
• Thick and thin skin - histological descriptions
• Defining characteristics = epidermal layer
o Thin skin - thinner epidermal layer
o Thick skin - thicker epidermal layer
• Locations
o Thick skin - only on the palms of hands and soles of feet
o Thin skin - all over the rest of the body
• Cells - keratinocytes - most numerous cells
• Change as the layers go up
o Bottom - cuboidal with active mitosis
o Upper layers - active, secreting glycolipid and keratin, cells start to die
• Thick skin - no hair or spacious glands
find more resources at oneclass.com
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Document Summary
Large surface area - ranges from 1. 5/2m2: organ, weight between 4 and 5 kg, functions, protection, temperature regulation, sensation, metabolic functions, blood reservoir, excretion. Loose ct underneath epidermis - can be folded to increase surface area. Melanocytes: manufacture melanin, distributed out to the keratinocytes. Lots of blood vessels and nerves - nerve endings go into epidermis: glands - sweat glands -> form from epidermis, structures from epidermis - nails, hair follicles. Touch receptor: for light touch, dermal side of the epidermal/dermal junction. Epidermal derivatives: formed from down-growths of epidermis, sweat glands, sebaceous glands, hair follicles, nail beds, nails, usually situated into dermis or hypodermis. Length and appearance influenced by sex hormones lives: grows 1mm every 3 days, follicles live for 6-8 years. Structure of hair: sebaceous glands associated with hairs, produce oily sweat which helps make hair shiny and skin supple, all hairs have a bit of smooth muscle associated, hair is dead but base of hair has a nerve.
