Anatomy and Physiology Fall Week 7

Hairs (pili)

flexible strands produced by hair follicles that consist of dead hard keratinized cells

Function of hair

warning of parasites on skin; insulating, protecting the head from physical trauma, shielding the skin from sunlight

Shaft

part of the hair projecting from the skin

Root

part of the hair embedded in the skin

Medulla

inner core of keratinized cells in hair (not all hairs have this)

Cortex

middle layer of keratinized cells in hair

Cuticle

outer layer of keratinized cells in hair

Hair pigments

made by melanocytes at the base of the hair follicle and transferred to the cortical cells

Hair follicles

fold down from the epidermis into the dermis and occasionally into the hypodermis

Hair bulb

the deep, expanded end of a hair follicle surrounded by sensory nerve endings

Peripheral connective tissue sheath

component of the hair follicle with a thickened basement membrane from the dermis

Epithelial root sheath

inner component of the hair follicle derived from the epidermis

Hair matrix

actively dividing cells that produce the hair within the hair bulb

Arrector pili

a bundle of smooth muscle cells which causes the hair to stand upright with contraction

Hair papilla

dermal tissue containing a knot of capillaries that supplies nutrients to growing hair

Vellus hairs

pale fine hair

Terminal hairs

longer coarser hairs

Cycles

hair follicles grow in ______ and have a limited number of them

Alopecia

hair loss

Baldness

genetically determined, sex-influenced condition caused by a gene that changes the hair follicle in response to the hormone dihydrotestosterone

Alopecia areata

immune system attacks follicles

Sebum

an oily secretion that softens and lubricates the hair and skin, slows water loss, and is bactericidal

Sebaceous glands

function as holocrine glands that secrete sebum

Eccrine/merocrine glands

sweat glands that produce true sweat and are abundant on the palms, soles, and forehead

Secretion of eccrine glands

-99% water, salts, vitamin C, antibodies, dermcidin, metabolic wastes

-regulated by sympathetic nervous system and is used to prevent the body from over heating

Larger

apocrine sweat glands are _______ than eccrine sweat glands and have ducts emptying into hair follicles

Apocrine glands

-sweat glands confined to the armpit and anogenital areas

-produce fat and protein-rich sweat

-bacteria break down the sweat leading to body odour

-begin functioning during puberty

Ceruminous glands (cerumen)

modified apocrine glands found lining the ear canal that secrete earwax

Mammary glands

modified sweat glands that secrete milk

Nail

scale-like modification of the epidermis that forms a protective covering on the dorsal side of the distal finger or toe

Nails are made up of

hard keratin and have a free edge, a nail body attached to the skin, and a root embedded in the skin

Nail matrix

epithelium responsible for nail growth in proximal part of the nail bed

Free Edge of Nail

extends past the finger or toe

Proximal nail fold and lateral nail folds

where the skin covers over the edges of the nail

Lunula (little moon)

thick white part of the nail

Eponychium (cuticle)

stratum corneum of the epidermis at the proximal nail fold

Nail root

portion that isn't visible

Nail body

visible portion of the nail

Nail bed

skin below the nail body

Hyponychium

secures the nail to the fingertip

Distal phalanx

finger or toe bone under the nail

Chemical barriers of skin

skin secretions that are low in pH, inhibit bacterial growth, and melanin that protects the skin from UV damage

Physical barriers of skin

provided by the continuity of the skin and the hardness of keratinized cells

Biological barriers of skin

dendritic cells and the macrophages of the dermis

Skin's role in body temperature

manufacturing sweat to cool the body and causing constriction of dermal capillaries to prevent heat loss

Skin's role in sensation

cutaneous sensory receptors are a part of the nervous system in layers of the skin

Skin's role in metabolism

makes a vitamin D precursor when exposed to sunlight

Blood reservoir

skin may act as a _____________ by holding up to 5% of the body's blood supply which may be diverted to other areas of the body if needed

Shell

Core has higher temperature than the _____

Retained

Heat can be lost through increased flow to the skin or _______by bypassing vessels in the skin

Radiant flow of heat

heat exchange between our skin and the external environment occurs through

Conductive flow

flow of heat from warmer to cooler objects

Convective flow

flow of heat of warm air away from the body

Evaporation

heat loss due to loss of fluids from the lungs, oral mucosa, and the skin

Insensible heat loss

accompanies insensible water loss from the lungs, oral mucosa, and skin and accounts for about 10% of basal heat production

Sensible heat loss

occurs when body temperature rises and sweating increases water vaporization

Heat cramps

when sweating is heavy and prolonged, losses of water and NaCl can cause painful muscle spasms

Hypothalamus

part of the brain that controls body temperature

Heat promoting mechanisms

maintain or increase core body temperature and include constriction of cutaneous blood vessels, shivering, increase in metabolic rate, and increased release of thyroxine (in infants)

Heat loss mechanisms

protect the body from excessively high temperatures and include dilation of cutaneous blood vessels, sweating and behaviours that promote heat loss or reduce heat gain

Frostbite

occurs when blood flow to the skin is restricted due to extreme cold, causing skin cells to be deprived of oxygen and nutrients

Hypothermia

-low core body temperature from cold exposure, leading to a decrease in vital signs

-shivering stops at core temp 30-32C and can progress to coma and death at 21C

Hyperthermia

elevated body temperature that overwhelms the body's ability to cool down

Heat stroke

a positive-feedback loop begins at 41C core temperature which further increases body temperature and can be fatal

Heat exhaustion

heat associated collapse after vigorous exercise due to dehydration and low blood pressure

Fever

-controlled increase in body temperature that results when macrophages and other cells release cytokines that act as pyrogens

-causes the hypothalamus to reset to a higher than normal temperature

-cryogens reset the thermostat to normal

Cancer

occurs when the DNA of a cell is damaged or mutated and the cell begins to grow uncontrollably

Carcinoma

cancer that develops from the epithelial tissue

Adenocarcinoma

cancer from glandular epithelium

Sarcoma

cancer of the connective tissues other than blood

Leukemia and Lymphoma

cancers from blood-forming cells

Benign tumor

mass of cells that are not cancerous (malignant) because they lack the ability to invade neighboring tissues or spread throughout the body (metastasize)

Basal cell carcinoma

-the least malignant and the most common skin cancer

-stratum basal cells proliferate and slowly invade dermis and hypodermis

-cured by surgical excision usually

Squamous cell carcinoma

-the second most common type of skin cancer and can metastasize

-derives from keratinocytes of the stratum spinosum

-present as scaly reddened papule; grow rapidly

Melanoma

-cancer of melanocytes, most dangerous because it's highly metastatic and resistant to chemo

-treated by excision and immunotherapy

ABCDE of Melanoma

Asymmetry, Border Irregularity, Multiple Colors, Large Diameter, Evolution

Burn

tissue damage resulting from intense heat, electricity, radiation, or certain chemicals which denature cell proteins and cause cell death

Risks to a burn patient

dehydration, electrolyte imbalance, infection

Rule of Nines

-used to evaluate burns

-the body is broken to 11 sections with each section representing 9% except the genitals which account for 1%

First-degree burns

-epidermal damage only

-localized redness, swelling, and pain

Second-degree burns

epidermal and upper dermal damage, blisters appear

Partial thickness burns

First- and second-degree burns are referred to as ______________ because only the epidermis and upper dermis are involved

Third-degree burns

-involve the entire thickness of the skin

-skin turns grey-white, cherry red, or blackened

-typically not painful because nerve endings are destroyed

Critical burns

->25% of the body had 2nd-degree burns

->10% of the body has 3rd-degree burns

-face, hands or feet have 3rd-degree burns

Fourth degree burns

destroy all layers of skin and also burn into fat tissue

Fifth degree burns

burning into muscle

Sixth degree burns

burning into bone

Organs

bones are ______ because they contain different types of tissues; nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells

Osseous

bone connective tissue

Compact bone

smooth and solid dense outer layer of bone

Spongy bone

inside compact bone which consists of honeycomb, needle-like, or flat pieces called trabeculae

Red bone marrow

full of red blood cells

Yellow bone marrow

full of adipose cells

Diaphysis

long tubular shaft of bone made of outer layer of compact bone around a central medullary cavity filled with yellow bone marrow in adults

Epiphysis

ends of long bones that consist of compact bone around spongy bone filled with red marrow

Metaphysis

transition between the diaphysis and epiphysis

Epiphyseal line

-found in the metaphysis

-the remnant of the childhood epiphyseal plate where bone growth occurs

Articular cartilage

hyaline cartilage that covers ends of bones in synovial joints

Osteogenic layer

inner layer in contact with bone that contains osteogenic stem cells that gives rise to most all bone cells

6 Functions of Bones

support, protection, movement, mineral and growth factor storage, blood cell formation, fat storage,