Anatomy CH 5 The Integumentary System

What makes up the integumentary system

skin, hair, nails, sweat glands, sebaceous glands

epidermis consists of...

epithelial tissue and is avascular

the superficial region of the skin is...

the epidermis

dermis is...

mostly fibrous connective tissue, vascular

what underlies the epidermis

the dermis

the hypodermis is...

1. subcutaneous layer deep to skin

2. not part of skin but shares same functions

3. mostly adipose tissue that absorbs shock and insulates

4. anchors skin to underlying structures: mostly muscles

the superficial fascia is also known as...

the hypodermis

the epidermis is made up of...

keratinized stratified squamous epithelium

there are _____ cells found in the epidermis

4

cells found in the epidermis

keratinocytes, melanocytes, merkel cells, langerhans cells

keratinocytes

1. produce fibrous keratin

2. major cells of epidermis by desmosomes

3. tightly connected

4. millions slough off everyday

melanocytes

1. spider shaped cells located in deepest epidermis

2. produce pigment melanin, which is packaged into melanosomes

melanosomes are....

transferred to keratinocytes where they protect nucleus from UV damage

Dendritic (Langerhans)

1. star shaped macrophages that patrol deep epidermis and are key activators of immune system

tactile (Merkel)

sensory receptors that sense touch

epidermis is made up of _________ Layers

four or five

the five layers of the epidermis

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

stratum basale (basal layer)

1. deepest layer

2. consists of a single row of stem cells that actively divide, producing two daughter cells

3. 10-25% of layer also composed of melanocytes

stratum spinosum (prickly layer)

1. cells contain weblike systems of intermediate prekeratin filaments attached to desmosomes

2. keratinocytes in this layer appear spikey

stratum granulosum (granular layer)

1. keratinization begins: cells accumulate keratohyalin granules that help form keratin fibers in upper layers

Stratum lucidum (clear layer)

1. found only in thick skin

2. consists of thin, translucent band of two to three rows of clear, flat, dead keratinocytes

Stratum corneum (horny layer)

1. 20-30 rows of flat, anucleated, keratinized dead cells

2. cells still function to protect deeper cells from the environment

the dermis...

- is a strong, flexible connective tissue

- cells include fibroblasts, macrophages, and sometimes mast cells and white blood cells

- contains nerves, blood vessels, and lymphatic vessels

- contain epidermal hair follicles, oil glands, and sweat glands

what are the two layers of the dermis?

papillary and reticular

the papillary layer is...

the superficial region of dermis that sends finger like projections up into epidermis

the papillary projections contain...

capillary loops, free nerve endings, and touch receptors

tactile corpuscles are also known as..

Meissner's corpuscles

the reticular layer of the dermis...

- Makes up 80% of dermal thickness

- consists of coarse, dense fibrous connective tissue

- cutaneous plexus: network of blood vessels between reticular layer and hypodermis

- extracellular matrix contain pocket of adipose cells

Many elastic fibers provide

stretch-recoil properties

collagen fibers provide

strength and resiliency

striae "stretch marks" are caused by...

extreme stretching of skin which causes dermal tears, leaving silvery white scars

blisters are caused by

short term trauma

melanin is produced by...

melanocytes in stratum basale

what color is produced by pheomelanin

reddish

what color is produced by eumelonin

brown

Hemoglobin is a...

red pigment found in red blood cells

carotene is a...

yellow-orange pigment stored in the stratum corneum and adipose tissue

hair (pili) is...

flexible strands produced by hair follicles and consist largely of dead, keratinized cells

hair contains...

hard keratin which is tougher and more durable than soft keratin of the skin

hair shaft

area that extends above scalp, where keratinization is complete

hair root

area within scalp, where keratinization is still going on

hair matrix

actively dividing area of the hair bulb that produces the hair

- as it makes new cells, it pushes older ones upward

arrector pili

small band of smooth muscle attached to follicle

what is responsible for goose bumps

arrector pili

hair papilla

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

male pattern baldness is caused by...

follicular response to DHT (dihydrotestosterone)

baldness is...

genetically determined and sex-influenced condition

structure of a nail

- Scalelike modification of the epidermis that contain hard keratin

- acts as a protective cover for distal, dorsal surface of fingers and toes

- consist of free edge, nail plate, and root

- nail bed is epidermis underneath keratinized nail plate

- nail matrix: thickened portion of bed responsible of nail growth

there are ____ types of skin glands

four

sebaceous glands

secrete sebum (oil) into the hair follicles where the hair shafts pass through the dermis

eccrine sweat gland

most numerous function in thermoregulation

apocrine sweat gland

are located mainly in hair/skin: begin functioning at puberty

ceruminous glands

modified sweat glands, located in external ear canal, secretes cerumen (earwax)

functions of skin

Protection, Thermoregulation, Cutaneous Sensation, metabolic functions, Blood Reservoir, Excretion and Absorption.

the skin is exposed to...

microorganisms, abrasions, temperature extremes, and harmful chemicals

chemical barrier

secretes protective substances (melanin, sweat, sebum)

physical barrier

Flat, dead, keratinized cells of stratum corneum, surrounded by glycolipids, block most water and water-soluble substances

biological barrier

phagocytic cells

the skin contains different types of _________ __________ found in different layers

sensory receptors

sensory receptors

tactile, thermal, pain

tactile sensations

touch, pressure, vibration, itch, tickle

thermal sensations

warm, cold

Skin is a _____ reservoir

blood - can hold up to 5% of total blood volume

Skin vessels can be constricted to....

shunt blood to other organs, such as an exercising muscle

Skin can synthesize ________ needed for calcium absorption in intestine

vitamin D

circulating cholesterol molecules in dermal blood vessels _______ step in conversion to active vitamin D essential for absorbing Ca in small intestine

first

skin can develop ______ different conditions and ailments

over 1000

internal diseases reveal themselves on ....

the skin

as we age...

- epidermal replacement of cells slows

- subcutaneous fat layer diminishes

- decreased elasticity and loss of subcutaneous tissue wrinkles