A&P Lecture Exam 2

Covers: - Integumantary System -Skeletal System -Joints

Skin and Accessories

Skin, Hair, Nails, Sudiferous glands, Sebaceous glands

Skin Functions

• Protection

• Body temperature regulation

• Water balance

• metabolic function

• blood reservoir

• excretion

Skin Protection

3 types of Barriers

• Physical/mechanical barrier: keratin and glycolipids

• Chemical barrier: antibacterial growth (acid mantle,defenses), Protects DNA from UV

• Biological Barrier: dendritic cells and macrophages

Skin: Body Temperature Regulation

• Insensible prespiration

• When Hot:

  • dilation of dermal vessels

  • increased sweat gland activity

Skin: Cutaneous Sensations

Touch, pain, temperature

Skin: Metabolic Functions

Vitamin D

Epidermis

Composed of keratinized, Stratified squamous epithelium.

Made up of 4-5 layers

Avascular

Thin Skin

• Stratum basale

• Stratum spinosum

• Stratum granulosum

• Stratum Corneum

Thick Skin

• Stratum Basale

• Stratum Spinosum

• Stratum Granulosum

• Stratum Lucidum

• Stratum Corneum

Keratinocytes

the cells in all the layers of the skin - except stratum basale

a cell that manufactures and stores the protein keratin

• cells are dead in the stratum corneum

Stratum Basale

• deepest layer of the epidermis

• attached the epidermis to the basal lamina (dermal layers are under basal lamina)

• cells bond to the dermis via basement membrane (intertwining collagen fiber)

• primarily made of basal cells

• contains merkel cells and melanocytes

Dermal Papilla

a finger-like projection found in the superficial portion of the dermis

• increases the strength of the connection between the epidermis and dermis

• greater folding → stronger connections

Basal Cell

a cuboidal-shaped stem cell found in the stratum basale

all keratinocytes are produced in this layer → constantly going through mitosis to produce new cells

old cells are pushed away from the stratum basale

Merkel Cell

functions as a receptor

responsible for stimulating sensory nerves that the brain perceives as touch

especially abundant on the surfaces of the hands and feet

Melanocytes

cells that produce the pigment Melanin → gives hair and skin its color, also helps protect the living cells of the epidermis from UV damage

Stratum Spinosum

has a spiny appearance due to protruding cell processes that join the cells via desmosomes → interlock with each other and strengthen the bond between the cells

composed of 8-10 layers of keratinocytes → result of cell division

Contains dendritic cells → Langerhans cell: functions as a macrophage by engulfing bacteria, foreign particles, and damaged cells that occur in this layer

keratinocytes: begin synthesis of keratin, release a water repelling glycolipid → helps prevent water loss from the body (makes skin waterproof)

Stratum Granulosum

have a grainy appearance, become flatter, cell membrane thickens

generate large amounts of keratin → fibrous

keratohyalin: accumulates as lamellar granules

3-5 layers deep

two proteins make up the bulk of keratinocyte mass, give grainy appearance

keratin, keratohyalin and cell membranes that die will from the stratum lucidum and corneum, as well as hair and nails

stratum lucidum

smooth, translucent layer

only found in the thick skin of the palms, soles, and digits

keratinocytes that form the stratum lucidum are dead and flattened

cells are densely packed with eleidin (clear protein), derived from keratohyalin, gives cells their transparent appearance.

stratum corneum

most superficial layer of the epidermis , layer exposed to outside environment

increased keratinization = cornification → gives it its name

15-30 layers

dry, dead layer

→ helps prevent the penetration of microbes

→ prevents the dehydration of underlying tissues.

→ provides a mechanical protection against abrasion for more delicate underlying layer

layers are shed periodically and are replaced by cells pushed up by stratum granulosum

Dermis

“core” of the integumentary system

contains blood and lymph vessels, nerves, and other structures (hair follicles & sweat glands)

made up of two layers of connective tissue (papillary layer and reticular layer) that compose an interconnected mesh of elastin and collagenous fibers → produced by fibroblasts

Papillary Layer

made up of loose, areolar CT

• collagen and elastin fibers form a loose mesh

• this layer projects into the stratum basale of the epidermis to form dermal papillae

• contains fibroblasts and adipocytes and abundance of small blood vessels

• contains phagocytes(defensive cells), lymphatic capillaries, nerve fibers, and touch receptors (Meissner corpuscles)

Reticular Layer

Ticker layer composed of dense, irregular connective tissue

well vascularized, has rich sensory and sympathetic nerve supply

appears net-like due to a tight meshwork of fibers

Elastin fibers: provide elasticity to the skin → enables movement

Collagen fibers provide structure and tensile strength, some fibers extend into papillary and hypodermis.

• keeps skin hydrated

Hypodermis (superficial fascia)

layer directly below the dermis

connects the skin to the underlying fascia of bones and muscles

well-vascularized. loose, contains areolar CT and adipose tissue → functions as a mode of fat storage and provides insulation and cushioning for the integument

Pigmentation

Pigments (melanin, carotene, and hemoglobin) influence the color of the skin

melanin → produced by melanocytes (found in straum basale)

melanin is transferred into the keratinocytes via a melanosome

Hair

• A keratinous filament growing out of the epidermis

• Primarily made of dead keratinized cells

• Strands of hair originate the hair follicle

• Hair Shaft → the part of the hair that is not anchored to the follicle

• Hair root → hair below the surface of the skin; anchored in the follicle

• Hair bulb → where the hair root is located; deep in the dermis

  • includes a layer of mitotically active basal cells: hair matrix

• Hair papilla → made of connective tissue, contains blood capillaries and nerve endings; surrounded by the hair bulb

Hair pt2

Basal cells of the hair bulb divide and push cells outwards in the hair root and shaft as the hair grows

medulla → forms the central core of the hair

cortex → surrounds the medulla; layer of compressed, keratinized cells that is covered by an outer layer of harder keratinized cells (cuticle)

Nails

Nail body is formed on the nail bed; protects the tips of our fingers and toes, experience max amount of mechanical stress

• nail bed: rich in blood vessels

• lunula: white part of the nail

• nail body forms a back-support for picking up objects w/fingers

• composed of densely packed dead keratinocytes

• forms at the nail root

• nail fold: helps to anchor the nail body; overlaps the nail on the sides

• nail cuticle → eponychium

Sweat Glands

• AKA sudoriferous gland

• sweat is produced when its hot to cool the body

• merocrine glands → secretions are excreted by exocytosis through a duct without affecting the cells of the gland

• 2 types:

  1. Eccrine Sweat Gland

  2. Apocrine Sweat Gland

Eccrine Sweat gland

Produces a hyptonic sweat for thermoregulation

• abundant on the palms of hands, soles of feet, and forehead

• coiled glands lay deep in the dermis, rises to a pore on skin surface

• sweat is released through exocytosis → hypotonic and mostly water, some salt, antibobdies, metabolic waste, etc.

• help maintain homeostasis

Apocrine Sweat Gland

• associated with hair follicles in densely hair areas

• larger than eccrine sweat glands

• lie deeper in the dermis

• duct empties into the hair follicle

• sweat contains water and salts, organic compounds that make sweat thicker and may have a scent

• under nervous and hormonal control, plays a role in human pheromone response

Sebaceous Glands

Type of oil gland found all over the body

• helps lubricate and waterproof skin & hair

• associated with hair follicles

• generate and excrete sebum onto the skin surface

• naturally lubricates the dry and dead layer of keratinized cells of the stratum corneum

• fatty acids of sebum prevent water loss

• secretion is stimulated by hormones

• inactive during childhood

Young’s Modulus

stress/strain

stress is force applied on a material/composite

• either compressive stress or tension

strain is the change observed on the material/composite when stress is applied

• measured as long as the change is reversible, the material regains its original shape/size/structure

High modulus → Older people

• older people have experienced more stress, so their bones are weaker/brittle → more prone to fractures

• High stress/low strain = high youngs modulus

Low modulus → Younger people

• they have less stress on their bones and aren’t as easily impacted

• their bones aren’t as STIFF so they strain more (are more elastic)

• low stress/high strain

collagen fibers → higher elasticity

hydroxyapatite (calcium phospate) → less accepting of strain

bone with lots of collagen, low minerals → bones will bend

collagen > calcium = bending bones (not enough minerals)

calcium > collagen = brittle bones (not enough collagen,too much minerals)

Wolff’s Law

remodeling of bone will depend on the amount of stress of work that they experience

someone who is bedridden will be more likely to lose their bones → higher resorption

rate of production vs. rate of absorption

healthy adults is equal

Meissner Corpuscle

Sensory nerve structure that responds to light touch

Pacinian Corpuscle

Sensory nerve structure that responds to vibration

Vitamin D Synthesis

Epidermal layer synthesizes vitamin D when exposed to UV radiation

• essential for normal absorption of calcium and phosphorus

• lack of vitamin D causes Rickets → a condition in children where the bones are misshapen due to a lack of calcium (causes bowleggedness)

• vitamin D deficiency → osteomalacia (softening of the bones)

Basal Cell Carcinoma

A form of cancer that affects the mitotically active stem cells in the stratum basale of the epidermis

• most common form of cancers in the US

• mainly caused by UV radiation

Burns of the Skin

causes death of skin cells, loss of fluid, dehydration, electrolyte imbalance and renal and circulatory failure

• may cause infection

• measured in terms of total surface area affected.

• classified by the degree of their severity

First-degree burn

superficial burn that affects only the epidermis

skin may be painful and swollen

ex. mild sunburns

Second-degree burns

Deeper, affects both the epidermis and portion of the dermis

• swelling, painful blistering

• heals in several weeks

Third-degree burns

fully extends into the epidermis and the dermis

destroys the tissue and affects the nerve endings as well as sensory function

• require medical attention

Fourth degree burn

• Severe

• Affects underlying muscle and bone

• may require amputaion

• usually not as painful - nerve endings are damaged

• skin grafts required

Calculating Size of a Burn

• Head and Neck: 9%

• Upper and Limbs: 9% each

• Trunk: 36%

• Genitalia: 1%

• Lower limbs: 18% each

melanosome

intracellular vesicle that transfers melanin from melanocytes into keratinocytes of the epidermis

Bone

• AKA Osseous tissue

• hard, dense connective tissue → support structure of the body

• cartilage → provides flexability and smooth surfaces for movement

Skeletal System Functions

• Supports the body

• facilitates movement

• protects internal organs

• produces blood cells

• stores and releases minerals and fat

Support, Movement and Protection

• Provides a scaffold to support your body

• Facilitate movement by serving as points of attachment for your muscles

• covers and surrounds your internal organs

Mineral Storage, Energy Storage

Bone matrix acts as a reservoir for minerals

→ minerals can be released back into the bloodstream to maintain levels needed for physiological processes

→ serves as a site for fat storage

• yellow bone marrow contains adipose tissue, triglycerides can be used as a source of energy

→ blood cell production

Hematopoiesis

Production of blood cells

→ takes place in the red marrow of the bone

→RBC’s , WBC’s and platelets

Bone Classifications

• Long Bones

• Short Bones

• Irregular Bones

• Flat Bones

Long Bones

→ Cylindrical in shape, longer than it is wide

→ Function as levers, move when muscles contract

→ Ex. Humerus, Radius, Ulna, femus, tibia, fibula

Short Bones

→ Cube-like in shape

→only found in carpals of the wrist and tarsals of ankles

→ provide stability and support, liminted motion

Flat Bones

→ typically thin, often curved

→Serve as points of attachment for muscles and often protect internal organs

→Ex. Skull Bones, Shoulder bones, Sternum, Ribs

Irregular Bones

Complex shape

• protect internal organs

• ex. vertebrae, coccyx

Long Bone Anatomy

Contains Diaphysis and Epiphysis

• Diaphysis: Tubular Shaft that runs between proximal and distal ends of bones

  • Contains medullary cavity: hollow region in the diaphysis filled with yellow bone marrow

  • walls of diaphysis are composted of dendse and hard compact bone

• Epiphysis: Wider sections at end of each bone, filled with spongy bone

  • contains the epiphyseal line

  • covered with articular cartilage

• Endosteum: inner lining of the medullary cavity; bone growth, remodeling, and repair occur here

• Periosteum: outer membrane of the bone, contains blood vessels, nerves, lymphatic vessels

Hydroxyapatite

Calcium phosphate + Calcium carbonate

• gives bone their hardness and strength

  collagen fibers give bones their flexibility

Bone cells found in bone tissue

• Osteoblasts

• Osteocytes

• Osteogenic cells

• Osteoclasts

Osteoblasts

Bone formation; growing portions of bone. including periosteum and endosteum

• Bone cells responsible for forming new bone

• Found in growing portion of bone → periosteum & endosteum

• Does NOT divide

• Synthesize and secrete collagen matrix and calcium salts (Bone Matrix)

Osteocytes

maintain mineral concentration of matrix; entrapped in matrix

• Most common type and primary cells of mature bone

• maintain mineral concentration in matrix by secreting enzymes

• Located in lacuna, surrounded by bone tissue

• communicate via canaliculi channels

Osteogenic cells

Develop into osteoblasts; deep layers of periosteum and the marrow

• Undifferentiated cells with high mitotic activity

• found in deep layers of the periosteum and marrow

• Divide and differentiate into osteoblasts

Osteoclasts

Bone resorption; found on bone surfaces and at sires of old, injured, or unneeded bone

• Cells responsible for bone resorption/breakdown

• found on bone surfaces

• multinucleated

• originate from WBC’s

Compact Bone

• Dense/Stronger bone tissue

• Can be found under the periosteum and in the diaphysis of long bones

• Provide support and protection

Features of the Compact bone

• Osteon

  • microscopic standard unit of compact bone

  • composed of concentric rings of calcified matrix called Lamellae

• Central canal

  • runs down the center of each osteon

  • contains blood vessels, nerves, and lymphatic vessels

• Perforating Canal

  • vessels and nerves that branch off at right angles through these canals that extend to the periosteum and endosteumSp

Spongy Bone

• AKA cancellous bone

• Contains osteocytes in lacunae → found in lattice-like network Trabeculae

• Trabeculae: lattice-like network of matrix spikes

  • provides strength to the bone

  • spaces of the trabeculae provide balance to the dense bone

  • species of the network contain red marrow where hematopoiesis occurs

Blood and Nerve Supply

• Nutrient Foramen:

  • small openings in the diaphysis in which arteries enter and pass through compact bone

  • arteries nourish the spongy bone and medullary cavity

• osteocytes in the spongy bone are nourished by blood vessels of the periosteum

• nerves: play a role in regulating blood supplies and in bone growth

Embryonic development

• consists of fibrous membrane and hyaline cartilage

• 6-7 week of embryonic life: Ossification beings

• 2 osteogenic pathways:

  1. Intramembranous ossification

  2. Endochondral ossification

Intramembranous Ossification

Compact & Spongy Bone develops directly from sheets of mesenchymal connective tissue.

• Forms: flat bones, cranial bones, clavicles

  1. Mesenchymal cells:

  • gather together and begin to differentiate into specialized cells → capillaries, osteogenic cells, osteoblasts

  2. Osteoblasts secrete Osteoid (uncalcified matrix) which hardens as minerals are deposited into it → entraps osteoblasts → become osteocytes

     osteogenic cells that are in the surrounding CT → osteoblasts

  3. Osteoid is secreted around the capillaries → results in a trabecular matrix

     Osteoblasts on the surface of the spongy bone → periosteum

Endochondral Ossification

• Bone develops by replacing hyaline cartilage.

• It occurs in the formation of bones at the base of the skull and long bones.

• The process begins with mesenchymal cells differentiating into chondrocytes, which form a cartilage model.

• As the cartilage model grows, a perichondrium (connective tissue) appears around it.

• Blood vessels invade the perichondrium, bringing osteoblasts (bone-forming cells) to the area.

• Osteoblasts deposit bone matrix on the surface of the cartilage model, forming a primary ossification center.

• Osteoclasts (bone-resorbing cells) remove the calcified cartilage, creating a medullary cavity.

• Secondary ossification centers form in the epiphyses (ends) of the bone.

• The cartilage in the epiphyses is gradually replaced by bone, leaving only the articular cartilage at the joint surfaces.

• The process continues until the entire cartilage model is replaced by bone, resulting in the formation of a mature bone.

Longitudinal Growth

1. Proliferation Zone

   • makes new chondrocytes via mitosis to replace those that die

2. Hypertrophic zone

   • older cartillage cells enlarge

   • maturation of cells

3. Calcification Zone

   • matrix calcifies

   • most of the chondrocytes are dead

4. Ossification Zone

   • bone formation occurs

   • epiphyseal line remains

Appositional Growth

• Increase in diameter

  • Osteoblasts (bone-forming cells) deposit new bone matrix on the outer surface of the existing bone.

  • As new bone is added, osteoclasts (bone-resorbing cells) remove old bone tissue from the inner surface, maintaining bone shape and structure.

  • Appositional growth allows bones to become thicker and stronger, providing support and protection to the body.

  • continuous process that occurs throughout life, helping to maintain bone integrity and adapt to mechanical stresses.

Bone remodeling

• process in which matrix is resorbed on one surface and deposited on another

• Functions:

  • calcium homeostasis

  • adapt to stress

  • bone repair after fractures

• Controlled by

  • Hormonal Control

  • Mechanical Stress

Bone Fracture

1. Hematoma Form

   • Torn blood vessels hemorrage

   • Clot (Hematoma) forms

   • Inflamation occurs

   • death of bone cells around the fracture

2. Fibrocartilaginous matrix forms

   • fibroblasts secrete collagen fibers

   • chondroblasts secrete fibrocartilage matrix

   • phagocytic cells clear the debris

   • osteoblasts begin forming spongy bone

3. Bony Callus Formation

   • osteoclasts resorb the dead bone

   • cartilage is replaced by trabecular bone

   • new trabeculae forms a bony callus

4. Bone Remodeling

   • occurs in response to mechanical stressors

Growth Hormone

Increase length of long bones, enhances mineralization, and improves bone density

Thyroxine

Stimulates bone growth and promotes synthesizes of bone matrix

Calcitriol

• stimulates absorption of calcium and phosphate from digestive tract

  • tells small intestine to absorb more calcium

• helps bring calcium from the bone into the blood

  • activates osteoclasts that will resorb the bone which releases the calcium and phosphate into the blood

• produced by keratinocytes

PTH Hormone

• Activates kidney to produce more calcitriol

  • Reabsorb more calcium in urine

• Activates osteoclasts to resorb bone and deposit into the blood

Calcitonin

• Stops osteoclasts activity

• Stimulates calcium uptake by bones

Joints

Any place where adjacent bones or bone-cartilage come together to form a connection

Fibrous Joint

• Connection of adjacent bones united by Fibrous Connect Tissue

Cartilaginous Joint

• Bones joined by:

  • fibrocartilage

  • hyaline cartilage

Synovial Joint

• articulating surfaces are NOT directly connected

• Come into contact with each other in a fluid-filled cavity

  • allow free movement between bones

  • most common joints

Synarthrosis

• Immovable or nearly immovable joint

  • provides a strong union between the bones

  • where bones provide protection for internal organs

• Examples: Sutures of the skull

Amphiarthrosis

• A joint that has limited mobility

  • ex. Cartilaginous Joints in between vertebraes

    • thick pads of fibrocartilage

Diarthrosis

• Freely movable joint

• Includes all synovial joints → provides the mojority of body movements

Uniaxial Joint

Allows for motion on a single plane

• Example: Elbows

Biaxial Joint

Allows for motion within 2 planes

• Knuckle Joints

Multiaxial Joint

Allows for several directions of movement

Example: Shoulders and Hip Joints

Suture

• Type of Fibrous Joint

  • Strongly unites bones of the skull & protects the brain and form the face

  • Prevents movements between bones

  • Functionally classified as a synarthrosis

Syndesmosis

• Type of fibrous joint

  • two parallel bones are united together by fibrous CT

  • Example: Radius and Ulna→ the wide gap between the bones are united by an Interosseus membrane (broad sheet of CT).

    • Allows for rotation of the radius

Gomphosis

• Type of fibrous joint

  • anchors the root of a tooth into its bony socket in the upper jaw or lower jaw of the skull.

  • AKA Peg-and-socket joint

  • Periodontal ligament: short bands of dense CT spanning between the bony walls of the sucket and the root of the tooth

  • Synarthrosis

Synchondrosis

• Type of Cartilaginous Joint

  • Joined together by hyaline cartilage

  • can be temporary (epiphyseal plate) or permanent (thoracic cage)

  • joins the ilium, ischium and pubic bone

  • All are synarthrotic

Symphysis

• Type of cartilaginous joint

  • contains thick bundles of fibrocartilage

  • resists pulling and bending → allows limited movement

  • Narrow (Pubic) and Wide Symphysis (Intervertebral)

Synovial Joint: Features

• Has joint cavity → increased joint mobility ; most common type

• Articular Capsule: a fibrous CT strutcure attatched to bone → Walls of joint cavity

• Articular Cartilage: layer of hyaline cartilage → caps ends of the bones

• Joint Cavity: space containing lubricating synovial fluid; reduces friction b/w bones

• ALL diarthrotic

• rich nerve and blood vessel supply

Origin vs. Insertion

Origin (O) : site of attachment to the immovable bone → proximal to axial skeleton

Insertion (I) : site of attachment to the moveable bone

Gliding Movements

• One flat bone surface glides or slips over another similar surface

  • example: Intercarpal Joints, Between articular process of vertebrae

Angular Movements

• Movements that occur along the sagittal plane

• Movements that occur along the frontal plane

Flexion

• Angular Movements→across sagittal plane

• Decrease the angle of the joint

Extension

Angular Movement →across sagittal plane

• Movements increase the angle of the joint

Hyperextension:

Angular Movement →across sagittal plane

• excessive extension beyond normal range of motion

  bending over backwards

aBduction

Angular movement → Across frontal plane

• Away from the midline

  raising your arm from your side up to be horizontal with your shoulders