final review

Anatomy & Physiology 1          Final Review

 

*Week 9 – Skin - Integument” is another name for the skin.

-         2 layers that compose it

-         Epidermis – 90% of these cells are keratinocytes  ( a protein)

•         Dermis -  Composed of two layers 1) papillary, 2) reticular . This is where the
mechanical strength of the skin resides. All sensory receptors for pain, touch,
temperature, vibration, etc. are found in this layer. Also arrector pili
muscle.  Composed mainly of collagen and
elastic fibers.

•         *Beneath the dermis lies a loose “subcutaneous layer” rich in fat and is called the hypodermis.

 

- Keratinocytes- become filled with tough and fibrous protein called Keratin

*- Melanocytes- contribute to the color of our skin

*- Most of body is covered by “thin skin’. Palms, finger tips, soles of feet, covered by “thick skin”

 

*Skin Repair

•         Blisters - Result from injury to cells in the epidermis or from separation of the dermal-epidermal junction

•          Epidermis has ability for rapid repair about 35 days from Basale to Corneum layer

•         Desquamation = flaking away of skin

•         The dermis does not continually shed and replicate

•         In healing a wound, fibroblasts form an unusual dense mass of connective tissue, if this mass is not 

   replaced by normal tissue it remains a scar

 

*Functions of the Skin

-         Protection

-         Sensation – pressure, touch, temperature, pain, vibration

-         Excretion – regulating the volume and chemical content of sweat.

-         Vitamin D production – occurs when skin is exposed to ultraviolet light.

-         Homeostasis of body temperature

 

*Burn Ratings –determined  by the depth and extent of lesion

•         1st D- causes minor discomfort/ irritation and some reddening of the skin No blisters

•         2nd D- deep epidermal layer always involved.  Causes damage to upper layers
of dermis. Usually blisters, severe pain, generalized swelling scar common

•3rd D- Destruction to both Epi/Dermis. Many involve MM Fascia and Bone.  Insensitive to pain immediately after burn do to nerve damage. Scarring a problem.

 

·        *Heat Exhaustion – occurs when the body loses a large amount of fluid resulting
from the heat-loss mechanisms. Loss of water and electrolytes causes weakness,
muscle cramps,  vertigo, nausea, and
possibly unconsciousness. Treated with rest and fluid replacement.

·        *Heat Stroke – severe and sometimes fatal. Body temp. greater than 105
degrees. Causes rapid heart rate (tachycardia) headache, hot and dry skin,
confusion, convulsions, loss of consciousness. Body must be cooled and fluids
replaced immediately. A medical emergency.

·        *Hypothermia –Less than 95 degrees. Causes shallow and slow respirations and a faint and
slow pulse. Treated by slow warming of the body.

·        *Frostbite –. Damage is caused by formation of ice crystals. Tissue death (necrosis) and
gangrene (tissue decay) can result.

 

*Skin Disorders

·        Decubitis ulcer – bed sores

·        Uticaria  - hives

·        Psoriasis – inflammatory disorder

·        Eczema

 

*Skin Glands

-         Sweat Gland – 2 types 1) Eccrine – by far the most numerous. Produce a transparent watery
liquid rich

     in salts, ammonia, uric acid, urea, and other wastes.Located in the dermal layer

-      2) Apocrine Sweat Glands – located deep in the subcutaneous layer of skin in the armpit, nipple, and

      some areas of the genetalia. Activated at puberty. Much larger than eccrine glands. Connected with hair

            follicles.

-      *Sebaceous Glands –  ( Holocrine) secrete oil to lubricate both the skin and hair

 

*Compact Bone Structure

·        Basic unit is the osteon

o       Lamellae – concentric layers

o       Lacunae – small spaces in which the bone cell lies

o       Canaliculi – ultra small channels connecting lacunae to haversion canals. Blood/ lymph/nerve vessels.

o       Haversion Canal – extend through
osteon. Blood/ lymph/nerve vessels.

o       Volkman’s Canals – extend width wise to connect haversion canals. Blood/ lymph/nerve vessels.

 

*Bones Cells

·        Osteoblasts – produce bone and bone matrix

·        Osteocytes – mature, non-dividing bone cells

·        Osteoclasts – actively erode bone. Lots of lysosomes

 

*Types of Cartilage

·        Hyline – ends of bones. Connects bones. Tip of nose. Most abundant.

·        Elastic – external ear

·        Fibrocartilage – strong and rigid. Pubic symphsis and Intervertebral disks

 

*Layers of Bone:  ie: Endosteum, periosteum etc….

*Wolfs Law

 

*Metabolic Bone Disease

·        Osteoporosis – Most common of all bone disease. Excessive loss of bone matrix. Most common in women after menopause due to
decreased estrogen levels. Decreased estrogen causes increase osteoclast
activity. Best way to diagnose is Dual Energy X-ray Absorptometry (DEXA) scan.
Increased risk of bone fracture.

·        *Osteomyelitis – bacterial infection of bone. Most commonly Staphylococcus. Swollen, red, warm and painful area in bone with
no apparent cause.

·        *RA