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Digestive And Integumentary System (Integumentary System (Skin Layers: …
Digestive And Integumentary System
Integumentary System
Skin Functions:
Maintain homeostasis
Provide a protective covering
Slow down water loss from deeper tissues
House sensory receptors
Synthesize various biochemicals
Excrete small quantities of waste
Skin Layers:
Epidermis (Outer layer)
Dermis (Inner layer)
Hypodermis (Subcutaneous layer)
Cell division increases where skin is rubbed or pressed regularly
Epidermis:
Lacks blood vessels
5 Layers Of The Epidermis:
Stratum Corneum (Uppermost) - Dead cell layer
Stratum Lucidum - Dying cell layer; not in all body skin
Stratum Granulosm - Mature cells
Stratum Spinosum - Maturing cells
Stratum Basale (Innermost) - New cells
(Most of body areas only have 4 layers)
Stratum Lucidum is the thickened skin of the palms and soles
Stratum Basale anchors the epidermis and the dermis and seperates the two layers
Melanocytes:
Specialized cells in the epidermis (Produce melanin)
Lie in the deepest layer of the epidermis
Can be a site of skin cancer
Contain long, pigment containing cellular extensions that pass upward between epidermal cells
Extensions transfer melanin granules
Melanin:
A dark pigment that provides skin color
Absorbs UV radiation in sunlight, preventing mutations in DNA of skin cells and other damaging effects
Skin Color:
Due largely to melanin
More melanin = Darker skin
(Darker people don't have more melanocytes, their melanocytes just produce more melanin!)
Enviromental and physiological factor also affect skin color
Dermis:
Thicker than the epidermis
Nerve cell processes
Hair follicles
Sebaceous glands
Sweat glands
Dermal blood vessels supply nutrients to all skin cells
Hypodermis:
NOT a true layer of the skin
Found beneath the skin/dermis
Masses of loose connective and adipose tissues that bind the skin to the underlying organs
Neurons (Sensory Receptors) In Skin:
Four basic types - Pain, light touch, deep pressure and temperature
Hair Follicles:
Present on all skin surfaces
(Except for palms, soles, lips, nipples, and parts of external reproductive organs)
Extend from the skin surface into the dermis and contain the hair root
Hair is composed of dead epidermal cells
Sebaceous/Oil Glands:
Contain groups of specialized epithelial cells and are usually associated with hair follicles
Secrete oily mixture (fatty material and cellular debris) called sebum through small ducts into the hair follicles
Sweat Glands (2 Main Types):
Eccrine Glands (Most numerous)
-Respond throughout life to elevated body temperature
-Open directly onto the skin surface
Apocrine Glands (Become active at puberty):
-Respond when a person is emotionally upset, frightened or in pain
-Usually, open into hair follicles
-Gives you your "natural scent" because of proteins and fatty acids
Nails:
Each consists of a nail plate that overlies a surface of the skin called nail bed
The lunula at the base of the nail plate covers the most actively growing region of the nail
Keratinocytes are responsible for generating the hair and nails.
Digestive System
Digestion:
The chemical and mechanical breakdown of complex biological molecules into their component parts.
Lipids -> Fatty acids
Proteins -> Individual amino acids
Carbohydrates -> Simple sugars
Nucleic acids -> Nucleotides
Chemical Digestion:
Uses chemicals to breakdown food so it is possible to absorb it
(Digestive enzymes are special proteins that help breakdown food)
Mechanical Digestion:
Happens on your mouth
Digestion through physical contact
(Chew, grind, mash and mix)
Phases Of Digestion:
Ingestion
Movement
Digestion
Absorption
Further digestion
Elimination
Functions:
Produce various chemicals to breakdown food
Filter out harmful substances
Get rid of solid wastes
Absorb nutrients
The Digestive Tract:
Definition: A long muscular tube with many sections and areas
(Begins in the mouth and ends in the anus)
Food moves through it by the movement of smooth muscle - Peristaltic movement/Peristalsis
Parts Of The Digestive Tract:
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Accessory Parts:
Teeth
Tongue
Salivary glands
Liver
Gall Bladder
Pancreas
Homeostasis
Levels of Organization