Ch 1 - Integumentary System

What are the 6 primary functions of the skin?

Protection, barrier, vitamin D synthesis, cutaneous sensation, thermoregulation, nonverbal communication

What are the 3 ways that the skin protects us?

chemical barrier, physical barrier, biological barrier

How is the skin a chemical barrier?

surface of skin has a low pH, therefore the growth of bacteria is slowed down

How is the skin a physical barrier?

thicker skin; covers majority of organs

How is the skin a biological barrier?

Dendrites and macrophages

Metabolic function for skin

synthesizes vitamin D

How is vitamin D synthesized?

1) Epidermis uses UV radiation to convert 7-dehydrocholesterl to previtamin D3

2) Over ~3 days, the skin converts this to vitamin D3

3) The liver adds a hydroxyl group converting it to calcidiol

4) The kidneys add another hydroxyl group and convert it to calcitriol (active vitamin D)

How many exteroceptors are used for sensation?

5

Merkel Receptor

how you detect light pressure/touch

Meissner's Corpuscles

how you detect light pressure and vibrations

Pacinian Corpuscles

how you detect deep pressure

Ruffin Cylinder

how you detect stretch

Free Nerve Endings

how to detect painful stimuli and temperature changes

short hand for pain

p!

how do we exchange "heat"?

conduction

Conduction

transfer of heat through direct contact

Convection

use of fluids

Evaporation

sweating

Radiation

transfer of heat w/o direct contact

How much of the bodies blood does the dermis hold?

5% but can be 33%

water + sodium chloride =

sweat

What are the 4 features of the integumentary system?

skin + subcutaneous tissue, hair, nails, glands

how many primary layers of the skin are there?

2

what are the layers of the skin

epidermis, dermis, hypodermis

epidermis

epithelial cells

dermis

dense connective tissue

hypodermis

adipose and areolar connective tissue

What are the cells of the epidermis?

keratinocytes, stem cells, melanocytes, dendritic cells. exteroreceptors

keratinocytes

makes up the majority of the epidermis

keratin

fibrous protein that makes the epidermis protective?

keratohyaline granules

support features of the epidermis

what do undifferentiated stem cells do?

give rise to keratinocytes

where are stem cells found?

deepest layer of the epidermis

melanocytes

synthesize pigment

where are melanocytes found?

deepest layer of the epidermis

melanin hues

red, yellow, brown, black

carotene

yellow/orange pigment in foods

hemoglobin

pigment of red blood cells

cyanosis

blue; hemoglobin is poorly oxygenated

erythema

red; indicates fever, infection, inflammation, embarassment

pallor (blanching)

white; lack of coloration, anemia, low BP, emotional stress

jaundice

yellow; build up of bilirubin (comes from the liver)

ecchymoses

bruise; colors are based on the type of tissue, location, and intensity

dendritic cells

star shaped; are biological barriers against toxins in case keratinocytes fall

layers of the epidermis (superficial to deep)

stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

Come Let's Get Sun Burnt

corneum, lucidum, granulosum, spinosum, basale

Where is the stratum lucidum found

only in thick skin

stratum basale

basal layer; deepest layer; single row of stem cells

stratum spinosum

prickly layer; several layers thick

stratum granulosum

granular layer; 1-5 layers

keratohyaline

help with the formation of keratin

lamellar

decrease water loss

stratum lucidum

clear layer; only found in thick skin

stratum corneum

horny layer; 20-30 layers of dead keratinocytes; glycolipids

What is the keratinization process?

1) Keratohyalin granules release filaggrin (protein) that binds keratin into groups

2) Keratinocytes produce envelope proteins below the plasma membrane (nearly indestructible sac)

3) Lamellar granules release a lipid mixture over the cell (waterproof shell)

4) Results in keratinocytes being cut off from nutrients, leaving the tough waterproof shell (cell dies)

What's in the dermis?

glands, hair follicles, and nail roots

Papillary layer of the dermis

loosely organized

Reticular layer of the dermis

thicker; tight bundles of collagen

Layers of the dermis

papillary and reticular

Papillary layer

loose areolar connective tissue; dermal papillae

Reticular layer

dense irregular connective tissue; flexure lines; 80% of blood tissue

Hypodermis

primarily adipose (loose connective tissue proper); anchors skin to the underlying structures

what does the adipose do in the hypodermis?

protects, stores, insulates

Boundary between the dermis and hypodermis

blurred

syringe subcutaneous injection

faster; injects into subcutaneous tissue

syringe intramuscular injection

faster; injects into intramuscular injection

micro-needle intradermal injection

longer absorption time; injects into the dermis

glandular epithelia

secretory tissue in glands

what are the 3 exocrine glands?

eccrine, apocrine, holocrine

What sweat glands does apocrine use?

Eccrine

location of eccrine glands?

pancreas, sweat glands, salivary glands

location of apocrine glands?

mammary glands

location of holocrine glands?

sebaceous glands of the skin

eccrine sweat glands

watery secretion; has a simple tubular gland

where are eccrine sweat glands found?

everywhere; concentrated palms, soles, face

apocrine sweat glands

secrete via exocytosis; thicker secretion

where are apocrine sweat glands found?

groin, axilla, anal region, areola

sebaceous glands

holocrine glands that secrete sebum; short ducts that open to a hair follicle; protects hair and skin from becoming dry

eccrine function

temp control, antibacterial properties

apocrine function

acts as sexual scent glands

sebaceous function

lubricates skin and hair, prevents water loss, antibacterial properties

eccrine method of secretion

merocrine (exocytosis)

apocrine method of secretion

merocrine (exocytosis)

sebaceous method of secretion

sebum

ceruminous glands

apocrine glands of the ear canal; produce ear wax that keep the canal moist

mammary glands

modified apocrine gland; develop during pregnancy; produce milk