LO 4 Flashcards
______ is anatomically simple but functionally important sheet like structures called membranes
Skin
______ is another name for the skin and the connective tissue underneath
Integument
_________ is the integument when considered as a body system
Integumentary system
Hair, nails, and skin glands are examples of _________
Skin appendages
Describe membranes
- Thin, sheet-like structure found throughout the body
- Covers and protect internal and external surfaces and organs
- Anchors organs and bones
- Secrete lubricating fluids to reduce friction
What are the 2 major types of membranes in the body?
- Epithelial membranes (2 distinct layers - epithelial tissue and underlying layer of connective tissue)
- Connective tissue membranes - composed largely of various types of connective tissue
What are the 3 types of epithelial membranes?
- Cutaneous membrane - the skin
- Serous membrane - parietal + visceral
- Mucous membrane
Describe the cutaneous membrane (the skin)
- Primary organ of the integumentary system
- Largest and and one of the most visible organs - 16% of body weight
- Made up of superficial layer of epithelial cells + underlying layer of supportive tissue
Describe the serous membrane
- Made of 2 layers:
i. Epithelial layer: thin layer of simple squamous epithelium ii. Connective tissue layer: very thin, glue-like basement membrane (holds and supports the epithelial cells)
Also secretes lubricating fluid to decrease friction
What are the 2 types of serous membrane?
- Parietal - lines the walls of body cavities (e.g. peritoneum in thoracic cavity)
- Visceral - covers organs in body cavities (e.g. visceral pleura on lungs)
Serous membranes can be easily visualized with this analogy
- Fist pushing into a water balloon
- Demonstrates how serious membranes form a double-walled structure containing a thin pocket of fluid (e.g. heart is surrounded by serous paracardium)
Describe 2 serous membrane diseases
- Pleaurisy - inflammation of the serous membranes that line the chest cavity and cover the lungs (i.e. the pleura)
- Peritonitis - inflammation of the serous membranes that line the walls of the abdominal cavity and cover the abdominal organs (i.e. the peritoneum)
Describe mucous membranes
- Line surfaces the open directly to exterior of body (lining of respiratory, digestive, urinary, and reproductive tracts)
- Epithelial portion varies depending on location and function
- Epithelial cells produce mucous to keep the membranes soft and moist
________ is the transitional area where the skin and mucous membranes meet
Mucocutaneous junction (eyelids, nostrils, anus)
Describe connective tissue membranes
- Do not contain epithelial components
- Produce lubricant called synovial fluid
- Examples are synovial membranes between joints and the lining of the bursae (cushion-like sacks found between many moving body parts)
What are the 2 primary layers of the skin?
- Epidermis
- Dermis
Describe the supporting layer of the skin (hypodermis)
- Loose connective tissue
- Fat - insulation from extreme heat, alternative source of energy, protective cushion
Describe the epidermis
- Outer most layer of skin
- Relatively thin sheet of stratified squamous epithelium
- Arranged in up to 5 distinct layers
Describe the stratum germintativum (also called stratum basal or basal layer)
- Is the inner-most layer of the epidermis
- Continuously undergoes mitosis
- New cells are pushed upward through additional layers “strata” of cells - as they approach surface, cells die and their cytoplasm is replaced by keratin
Describe keratin
Tough, water-proof material that provides cells in the outer layer of the skin with an abrasion resistant and protective quality
______ is the outermost layer of the epidermis, also known as the horny layer
Stratum corneum
What are the 5 layers of the epidermis from the outermost down?
- Stratum corneum (horney layer) - thick, dead, keratin-filled cells (layer that sheds)
- Stratum lucidum - only present in thick, hairless skin (e.g. palms)
- Stratum granulosum - where cell first becomes full of keratin
- Stratum spinosum
- Stratum germintativum (stratum basal) - epithelial cells constantly dividing
______ produce melanin and are stimulated by the sun
Melanocytes
We have a totally new epidermis every _________
24-45 days
Describe skin pigment
- Gives skin colour
- Produced in stratum germintativum by melanocytes
- Pigment is called melanin (brown/dark) - primary function to absorb harmful UV radiation from sunlight
Describe the dermal - epidermal junction
- Specialized area between epidermis and dermis
- Like glue holding the two layers together
- Blisters caused by breakdown of this junction
Describe the dermis
- Deeper and thicker than epidermis
- Composed largely of connective tissue
- Cells scattered further apart than epidermis and there are many fibres (collagen and elastic) between cells
What does the dermis contain?
- Nerve endings
- Muscle fibres
- Hair follicles
Sweat and sebaceous glands - Blood vessels