Anatomy and Physiology: Exam 2

Functions of the Integumentary System

-Resistance to trauma and infection

-Prevents loss or gain of water

-Vitamin D synthesis

-Sensory receptors for heat, cold, touch, texture, pressure, vibration, and tissue injury

-Thermoregulation

How does skin resist trauma and infection?

-Skin has low pH to reduce bacteria and fungi

-Cells are packed closely together with tough protein called keratin

Name 3 ways the integumentary system thermoregulates?

-Glands release sweat for evaporative cooling

- Vasoconstriction

- Vasodilation

Define: Vasoconstriction

narrowing of blood vessels, reduces heat loss

Define: Vasodilation

widening of blood vessels, increases heat loss

What are the 2 main parts of the integumentary system?

Epidermis- outer layer

Dermis- underlying connective tissue

Hypodermis not really part of the skin!

What does the epidermis primarily consist of?

keratinized stratified squamous epithelium

What are the epidermal derivatives?

glands, hair, nails

What are the 4 main cell types in the epidermis?

- Karatinocytes

- Melanocytes

- Tactile (Merkel) cells

- Dendritic (Langerhans) cells

Keratinocytes (functions)

most numerous cell type, make fibrous protein keratin

Melanocytes (functions)

synthesize pigment called melanin

Tactile cells (functions and 2nd name)

also called Merkel cells, receptors for the sense of touch, associated with a dermal nerve fiber

Dendritic cells (functions and 2nd name)

macrophages (big phagocytic cells) that kill microbes

What are the layers of the epidermis (list from bottom up)?

- Stratum basale

- Stratum spinosum

- Stratum granulosum

- Stratum lucidum

- Stratum corneum

What layer of the epidermis is only found in thick skin?

Straum lucidum

How many layers are found in the stratum basale?

1 layer

What cells are found in the stratum basale?

stem cells, keratinocytes, melanocytes, tactile (merkel) cells

What is the importance of the stem cells in the stratum basale?

makes it mitotically active, the stem cells divide and give rise to keratinocytes

How many layers are in the stratum spinosum?

8-10 layers

What is the appearance of the cells in the stratum spinosum, and why?

The cells are flattened, which happens as they are pushed upward

What is contained in the stratum spinosum?

Keratinocytes, dendridic (langerhans) cells

In which epidermis layers do keratinocytes produce waterproofing substances?

Stratum spinosum, stratum granulosum

What are the waterproofing substances produced by the keratinocytes?

keratin, lipids

How many layers are in the stratum granulosum?

3-5 layers

In what layer do the nuclei and organelles begin to degenerate in the keratinocytes?

stratum granulosum

What do the cells look like in the stratum granulosum and why?

They continue to flatten because of accumulation of keratin

How many layers are in the stratum lucidum, and what do they look like?

3-4 layers of translucent cells

Why are the cells in the stratum lucidum translucent?

the clear protein named eleidin

How many layers are in the stratum corneum?

up to 30 layers

What do the layers of the stratum corneum consist of?

dead scaly keratinized cells

What are 2 of the main purposes of the stratum corneum?

resistance to abrasion and water loss

What are the layers of the dermis (from top to bottom)?

Papillary layer

Reticular layer

What is the papillary layer made of?

areolar CT

What is the reticular layer made of?

irregular CT and adipose

What do you find in the papillary layer?

Meissner's corpuscles (touch receptors)

Dermal papillae (upward extensions)

What do you find in the reticular layer?

Pacinian corpuscles (pressure receptors)

Hair follicles

Sebaceous (oil) glands

Sudoriferous glands

What is the 2nd name for the hypodermis?

subcutaneous

Where is the hypodermis located?

beneath the dermis

What are the main functions of the hypodermis?

energy reservoir and thermal insulation

Why can drugs be injected into the hypodermis?

it is highly vascular

What is the hypodermis made of?

areolar CT and adipose tissue

What makes the color in the skin?

Color caused by pigments produced by melanocytes

What causes differences in skin color?

differences in quantities, distribution, and break down of pigments

What are 2 types of pigments and what is their color?

-eumelanin- brownish black

-pheomelanin- reddish yellow

What are 3 types of abnormal coloration?

Cyanosis, albinism, vitiligo

Cyanosis

blueness of skin due to deficiency of oxygen

Albinism

genetic lack of melanin

Vitiligo

autoimmune disorder leading to depigmentation in patches of skin

What causes tanning of the skin?

exposure to UV radiation, which causes an increased production of melanin by melanocytes and spreading of melanin to keratinocytes

Describe the evolution of skin color

Strong correlation between skin color and strength of sunlight across the globe; people in north evolved fair skin to absorb more UV light for vitamin D production, dark skin in tropics to block out sun

What are hair follicles formed from?

epidermal cells that become keratinized

Where are hair follicles located?

in the dermis

What are the parts of the hair?

Hair root (in the hair follicle)

Hair shaft (part that continues past the skin)

What makes the hair stand on end?

Arrector pili

What causes different hair textures?

differences in cross-sectional shape

What causes differences in hair color? What makes some hair gray/white?

Melanin

Gray/white hair lacks pigment, and contains air bubbles in the shaft

What causes male pattern baldness?

Genetically dominant trait expressed in the presence of high level of testosterone

What is the purpose of the nails?

protect the digits

What are nails formed from?

specialized epithelial cells that become keratinized as they move away from the root

Glands

specialized cells that produce and secrete substances into ducts

Sebaceous glands

associated with a hair follicle, secrete an oily substance called sebum

Sebum

oily substance secreted by the sebaceous glands

What is the function of sebum

- lubricates and waterproofs hair and skin

- weakens or kills bacteria on skin surface

What causes whiteheads and blackheads?

a buildup of sebum

What are the 2 sweat glands?

Apocrine glands

Eccrine sweat glands

Apocrine glands

open into hair follicles in anal region, groin, and armpits

Which sweat gland begins to secrete at puberty?

Apocrine glands

What is a main purpose of the eccrine sweat glands

Opens onto surface of the skin

When body heats up, lowers body temperature with sweat

What makes up sweat (perspiration)?

mostly water, but also excretes wastes

Skin cancer

mutation of the skin cell DNA

What are the 2 broad categories of skin cancer, and what is the main difference between them?

Nonmelanoma cancer- less likely to metastasize (spread)

Melanoma cancer- more likely to spread

What are the 2 main types of nonmelanoma cancer, and where do they arise from?

Basal cell carcinoma- arises from stratum basale

Squamous cell carcinoma- arises from stratum spinosum

What is the most common type of skin cancer?

Basal cell carcinoma

What is the ABCDE Rule?

characteristics of a mole that are warning signs of melanoma

What does ABCDE stand for in the ABCDE Rule?

A ssymetrical

B orders are irregular

C olor is uneven and several colors may be present OR color changes in a mole

D iameter is greater than 6mm (larger than a pencil eraser)

E levation (elevated above the skin)

What problems can come with burns?

fluid loss and infection

What part of the skin if affected by a first degree burn?

epidermis

What part of the skin if affected by a second degree burn?

the entire epidermis and part of the dermis

What part of the skin if affected by a third degree burn?

the entire thickness of the skin

How can you tell the difference between a first and second degree burn?

second degree burn has blisters while a first degree burn does not

Which tissue usually repairs well?

epithelial tissues- they regenerate

Fibrosis

when connective tissue is replaced by fibrous connective tissue (when it repairs itself), causes scarring

List the events of tissue repair in order

-Bleeding/inflammation

- Scab formation

- Formation of granulation tissue (soft mass of perfused tissue)

- Regeneration/fibrosis

What does the skeleton consist of?

Bone and cartilages

What are the 3 types of cartilage?

Hyaline cartilage

Elastic cartilage

Fibrocartilage

Hyaline cartilage (describe it and say where it is found)

Clear, glassy matrix

Found: articular cartilage at ends of long bones, in trachea

Elastic cartilage (describe it and say where it is found)

very flexible

Found: external ear

Fibrocartilage

fibers give it strength

Found: interverbral discs

How many named bones are there on average in the human skeleton?

206

Axial Skeleton

Forms the long axis of the body (skull, vertebral column, rib cage)

What are the functions of the axial skeleton?

protects, supports, and carries other body parts

Appendicular skeleton

appendages (bones of the upper and lower limbs and shoulder, hip bones)

What are the functions of the Appendicular skeleton?

locomotion and manipulation of environment

What are the functions of the skeleton (define those functions)?

Support- hold up body, supports muscles

Protection- enclose and protect brain, spinal cord, heart, and lungs

Movement- connect with muscles for movement

Mineral storage- stores calcium and phosphate; also involved in acid-base balance

Hematopoiesis- blood formation in red bone marrow

Describe the change in bone marrow as bones age?

Red bone marrow becomes yellow bone marrow that can't produce blood cells

What are 2 types of bone?

Compact bone and Spongy bone

Compact bone

dense outer layer that looks smooth and solid

Spongy bone

arrangement of spicules and trabeculae (looks like a sponge)

Spicule

small needle-like pieces in the spongy bone

Trabelculae

spaces filled with bone marrow in the spongy bone