Anatomy: Exam 1 st

Define Anatomy

Anatomy is what and where something is

Define physiology

Physiology is the function of that thing

Explain the relationship between anatomy and physiology

The anatomy of something contributes to its function and the function of something can tell you its anatomy.

Ex. Long bones structure provides a stable place for muscles to attach —> (function affecting structure)

What is the cell membrane composed off, what are its properties

phospholipid bilayer —> heads are polar, tails are non-polar

• The cell membrane is SELCTIVELY Permeable

• only allows for small non-polar materials to pass through without any help (or super small polar molecules like water)

• Large polar molecules need some assistance (they can’t bc they repel the tails)

• charged molecules and ions (K+, Cl-, etc) also CAN’T

Define the membrane proteins and their functions

Peripheral proteins —> found at the surface of the lipid bilayer

Integral proteins —> fully integrated; something can enter and exit

a) Channel protein —> allows particular ions to pass through the cell (PASSIVE like carrier)

b) Recognition Protein —> allows for the binding of a ligand to its receptor to activate a receptor (ACTIVE)

c) Glycoprotein —> protein with carbohydrate molecules found on its surface (ACTIVE)

What sort of cells CAN and CANNOT pass through the lipid bilayer

CAN —> Small, nonpolar molecule + small polar molecules (Water)

CAN’T —> Large polar, ions, charged molecules

Name the different ways to pass through the cell membrane:

1. Passive transport —> movement of things across the membrane without the use of cellular energy (ATP)

a) Diffusion —> High to low concentration

• Osmosis —> Water moves from high to low concentration (know Hyper + Hypotonic)

b) facilitated diffusion

1. Active transport —> movement of things across the membrane through using ATP

Explain the path of a protein destined for secretion OR insertion into a membrane:

Nucleus → ribosome/Rough ER → transport vesicle → Golgi → vesicle → destination

Nucleus —> where transcription occurs

• a gene within the DNA that codes for a specific protein is turned into mRNA.

• The protein

Rough ER —> Protein is synthesized on the ribosomes on the Rough ER and modified

• ER might: add carbohydrate (glycosylation), disulfide bonds check whether the protein folded correctly assemble multiple protein subunits

• After thats done the ER buds off and ships the protein (inside the vesicle, for a secreted protein, or inside the vesicle membrane, for a membrane protein)

Smooth ER (not rlly involved in protein shipping)—> synthesizes lipids (phospholipids, steroid hormones)

• controls and regulates the concentration of cellular Ca++ —> triggers neurotransmitter release

• breaks down certain toxins

Golgi Apparatus —>

• responsible for sorting, modifying (e.g. adding carbohydrates, etc), and shipping products delivered from the RER

• The cis side —> receives, medial —> modifies, trans —> sorts and ships

• The golgi also decides where the package will go a) Secretion —> leaves, Membrane —> combines with the membrane

Name all the organelles associated with a cell and their functions:

Nucleus —>

• Store DNA

• Ribosomes are synthesized here

Rough ER —>

• makes and modifies the proteins and ships them to the

Smooth ER —>

• responsible for lipid synthesis

• regulates ca++ —> for neurotransmitter release

• breaks down toxins

Golgi —>

• responsible for modifying, packaging, and shipping protein products

Peroxisomes —>

• carry out oxidation reactions to neutralize free radicals (produce H202 and convert them into water and oxygen, which are released into the body)

• loss of it causes Tay-Sachs

Lysosomes —>

• contains enzymes that break down unneeded cellular components

Mitochondria —>

• responsible for converting sugar to ATP for the cell to use as energy

Cytoskeleton —>

• group of fibrous proteins that provide structural support for cells

• Types —> Microfilaments, intermediate filaments, microtubules

Describe the structural organization of the body from molecules to organ systems, giving examples of each level of organization.

Atoms —> Molecules —> Cells —> Tissues —> organs —> Organ system —> Organism

Ex. Hydrogen, H20, Keratinocytes, Eplitheal, Skin, Integumentary system, Human

Types of Tissues & GENERAL Function

Epithelial —>

• Densley apcket togther

• includes skin, lines cavities, passageways and certain glands.

• avascular (usually gets nutrients through lower layers like dermis)

Connective —>

• Sparsely packed together

• Binds the cells and organs of the body together and functions in the protection and support

• Includes bone, cartilage, blood, dermis, and fat

Muscular —>

• Skeletal, cardiovascular, smooth

• Striated (except smooth)

• responsive to stimuli, excitable, contracts

• 3 MAIN types: Skeletal, smooth, cardiac

• Smooth —> found in digestive tracts, blood vessels, intestine, urinary bladder

Nervous —>

• Involves neurons and neuroglia (glial cells)

• excitable, allowing for the spread of electrochemical signals in the form of nerve impulses in different bodily regions

List the body systems of the human body

Integumentary

Skeletal

Muscular

Nervous

Endocrine

Cardiovascular

Lymphatic

Respiratory

Digestive

Urinary

Female + Male reproductive

Integumentary system (examples + function)

Ex. Hair, Nails, Skin

Function → 

• Protects internal organs 

• Prevents water loss

• Has sensory receptors

Skeletal system (examples + function)

Ex. Bones, Joints, Cartilage

Function → 

• Protects organs 

Ex. Ribcage →Protects the heart

• Supports the body

• works with the muscular system to create movement through muscle contractions

• Produces Blood cells (Ex. WBC)

• Stores minerals 

Muscular system (examples + function)

Ex. Tendons, skeletal muscles

Function —>

• provides movement through contraction

• produces heat

• supports posture

Endocrine system (examples + function)

Ex. Ovaries, testes, Adrenal gland, pancreas, thyroid gland, pituitary gland

Function —>

• creates and releases hormones to regulate the body

cardiovascular system (examples + function)

Ex. Heart, blood vessels, and blood

Function —>

• pumps blood

• Transports oxygen, hormones, and nutrients,

• carries waste away from tissues

Lymphatic System (examples + function)

Ex. Lymph nodes, spleen (blood filter), lymphatic vessels, thymus (upper chest)

Function —>

• fight pathogen —> bodies immune sustem

• returns excess tissue fluid to the blood stream

Respiratory System (examples + function)

Ex. Lungs, airways, trachea, nasal passage

Function —>

• bring oxygen to the body

• Get rid of CO2

Digestive System (examples + function)

Ex. Small intestine, large intestine, gallbladder (breaks down fat), liver, mouth, esophagus

Functions —>

• Poop

• Breaks down food

• Helps absorb nutrients (small intestine has microvilli)

Urinary System (examples + function)

Ex. Urinary bladder, kidney, ureter, urethra

Functions —>

• release waste from the blood

• Control of water and ion balance

• produces and eliminates urine

Male reproductive system (examples + function)

Ex. Testicles, penis, epididymis, reproductive ducts

Function → 

• Sperm production → allows for reproduction

• Male sex hormones 

Female reproductive system (examples + function)

Ex. Ovaries, vagina, uterus, fallopian tubes, mammary gland 

Function →

• Egg production

• Female sex hormones 

• Mammary gland supports development of offspring 

Define Homeostasis:

a process in the body which regulates it to maintain at a stable state/ internal environment. Is able to do this through negative feedback loops

Negative feedback loop —> the body counteracting a change by doing the opposite to bring it back to normalcy

Define negative feedback loop and give an example

Negative feedback loop —> the body counteracting a change by doing the opposite to bring it back to normalcy

Ex. When it’s hot, your blood vessels widen to release heat, and when it’s cold your blood vessels get smaller to conserve heat.

Describe hyponatremia, its causes, symptoms, and its relationship to homeostasis.

Hyponatremia —> sodium in the blood becomes TOO low compared to the amount of water

• happens due to excess consumption of water

Context —> ADH is released to tell the kidneys to conserve water, typically during dehydration

Katie was in a marathon and she was sweating a lot and therefore losing electrolytes (like sodium). In this case the body would typically try to release the water by DECREASING ADH so the concentration can balance.

Katie was also drinking so much water, faster than the rate her body could release the water, so instead her ADH increased and the kidneys kept on reabsorbing the water. This causes her blood to become diluted and water to go into her cells

OVERALL → Hyponatremia is a condition in which blood sodium concentration becomes abnormally low because there is too much body water relative to sodium. Exercise-associated hyponatremia can occur when a person loses electrolytes through sweating but drinks excessive amounts of water faster than the kidneys can eliminate it. This dilutes the blood and causes water to enter cells, making them swell. Symptoms can include headache, vomiting, confusion, diarrhea, abnormal movements, and in severe cases coma or death. Hyponatremia represents a disruption of homeostasis because the body fails to maintain normal water and ion balance.

Symptoms:

Weight gain

Diarrhea

Headache/confusion

vomiting

difficulty staying upright

abnormal, repetitive leg movements

Types of Epithelial Tissues —> draw each

1. Simple squamous

2. Simple cuboidal

3. Stratified Squamous

4. Simple coumnar

5. stratified cuboidal

6. stratified columnar

Function of each layer of epithelial tissue:

1. Simple squamous —> very thin, good for diffusion & filtration (Ex. air sacs in lungs, lines capillaries)

2. Simple cuboidal —> Slightly thicker, good for absorption and secretion (found in ducts and ovaries)

3. Stratified squamous —> can handle abrasions (skin, Esophagus (friction))

4. Simple Columnar —> Often with microvilli or cilia; good for absorption, secretion, and protection (small intestines)

5. Stratified Cuboidal —> Protection and Secretion (glands and ducts)

6. Stratified Columnar —> Protection and secretion (glands and ducts)

Tay-sachs disease - what it is/symptoms, how its caused

Tay Sachs is a disease that’s caused by a dysfunction in the lysosome (specifically it misses an enzyme that breaks up fat) and that causes deterioration/damage of nerve cells

Symptoms include:

• Brain damage

• catarcat

• Jaundice

• Enlarged liver

• Kidney damage

epidermolysis bullosa; what is it, symptoms, what tissues does it affect

Epidermolysis bullosa is caused by a mutation in the COL7A1 gene.

• This gene codes for collagen

• Collagen gives structural tissues their functions

• Collagen holds together the epidermis and dermis (at basement membrane) —> without that it causes blistering and sores

• The skin condition also affects his nutrition as epithelial tissue also lines the mouth, esophagus, and stomach —> needs a feeding tube

Mostly effects —>

eplithealeal tuissue

• Main glandular tissue

• lines inside and outside

Connective tissue

• Dermis (connective) is connected to epidermis

Tissues in the integumentary system

All 4

• In the dermis there are muscles (arrector pilli)

• dermis is connective

• have nerve fibers in dermis

• Epidermis is epithelial

what 2 are the layers of the skin (+ layer below)

Epidermis —> (epithelial)

• keratinocytes → make keratin (structural protein)

• stratified squamous

• avascular —> gets nutrients by diffusion from the dermis

dermis —> (connective tissue)

hypodermis (adipose/fat —> connective tissue)

What are the layers of the epidermis and their functions

Bottom (New)

Stratum Basal

• Newest Layer

• attached to basement membranes

• Nursery: RAPID division

• Contains melanocytes —> responsible for creating melanin in the melanosome which gets delivered to neighboring cells

• Contains Merkel cells —> responsible for sensory

• Single layer of cells primarily made up off basal cell

• Basal cell is a cuboidal shaped stem cells that is a precursor of the keratinocytes of the epidermis

Dermal Papilla → a fold/projection in the dermis that increases the strength of connection between dermis and epidermis

Stratum Spinosum

• have tiny connections with other cells

• production of keratin is ramped up

• Under a microscope they dry up and look star-shaped.

Stratum Granulosum

• contain granules of keratin

• Keratin is a fibrous protein that makes the cell tougher and conserves water

CELL DEATH

Stratum Lucidum

• Dead keratinocytes densely packed

• looks clear (eledin)—> appears on the palms of the hands and feet (need an extra layer because they are more exposed)

• cells are less permeable + water proof

Stratum Corneum

• Dead flat keratinocytes

• covers the whole body

• stays on the surface for 2 weeks before coming off

Top (Old)

What are the layers of the dermis and their functions (+ hypodermus)

Dermis is a connective tissue

Within the dermis we have fibers like collagen and elastin + fibrocytes

• Core of integumentary system

• Contains blood vessels, nerves, hair follicles, sweat glands, etc

• Made of 2 layers of connective tissue

• These two layers compose an interconnected mesh of elastin and collagenous fibers produced by fibroblasts

Layers:

1. Papillary dermis

• loose connective tissue

• named for dermal papillae in the region

• Fibroblasts, fat cells, and lots of blood vessels

• Contains phagocytes

• Contains lymphatic capillaries, nerve fibers, touch receptors 
  
  

1. Reticular layer

• Dense irregular connective tissue

• Well vascularized and sensory and synthetic nerves

• Appears net like due to elastin fibers → for elasticity and movement 

• collagen extending into both the papillary layer and the hypodermis → collagen provide strength

Hypodermis

• composed of adipose tissue (fat) —> insulates us

• protection against mechanical stress

Function of Epithelial Tissue

1. Physical & Chemical Protection:

• serves as the body's first line of defense against physical wear and tear, chemical damage, and biological pathogens.   

2. Selective Permeability & Barrier Control:

• Cells form a selectively permeable barrier that regulates the absorption and transport of materials into and out of underlying tissues.  

•  All substances entering or exiting the body must cross an epithelial boundary.   

3. Secretion:

• Specialized cells synthesize and release mucus, enzymes, hormones, and sweat.

• Ex. Ciliated cells lining the respiratory tract secrete mucus to trap incoming pathogens and foreign particles.   

4. Sensation & Environmental Sensing:

• Specialized epithelial cells (neuroepithelia) contain sensory nerve endings to detect touch, pressure, temperature, and chemical stimuli (e.g., taste buds, olfactory epithelium).

5. Excretion & Absorption:

• Facilitates specialized chemical transport, such as nutrient absorption in the small intestine microvilli and metabolic waste filtration/excretion in renal tubules.

Functions of Connective Tissue

1. Support and Connection: 

• Connects tissues and organs together (e.g., muscle sheaths, tendons attaching muscle to bone, and the skeletal frame).

2. Protection:

• Forms fibrous capsules around delicate organs and mineralized bone structures for skeletal defense

3. Immune Defense: 

• Contains specialized phagocytic cells that engulf microorganisms, pathogens, and cellular debris.

• Ex. Blood WBC !!! → immunology

4. Transport: 

• Fluid connective tissues (blood and lymph) transport nutrients, fluid, waste, and chemical messengers throughout the body.

• RBC transport oxygen from the lungs to body tissues and carry carbon dioxide back to the lungs for exhalation

5. Energy Storage & Thermal Insulation: 

• Adipose (fat) cells store surplus energy and contribute to thermal insulation.

Where did skin color come from?

Melanin (pigment in our skin) absorbs/reflects different wavelengths of light

More melanin (darker) —> absorbs more light (UV) and reflects less light

Less melanin (lighter) —> absorbs less light (UV) and reflects more light

(genetic inheritance determines amount of melanin)

Eumelanin vs Pheomelanin

• Eumelanin is a brown to black pigment and gives stronger UV protection.

• Pheomelanin is yellow to reddish pigment and gives less UV protection.

When did darker shades of Human skins evolve?

we probably lost hair so our bodies could cool

MC1R gene

gene that codes for a receptor involved in signaling within melanocytes, this influences the TYPE of melainin produces (Eumelainin vs Pheomelanin)

• part of the regulation of pigmentation

• the melanin controls UV absorption though

• Reduced MC1R variation in African population indicates there is a strong selection against any alleles that would alter dark skin

More Melanin Vs Less Melainin (pros vs cons)

More melanated

• Melanin Absorbs More UV

• Greater UV protection —> less UV reached epidermal cells

• Folic acid does not break down —> we need it

• Because they can’t absorb UV, they get less UVB radiation for vitamin D production

• Need to take vitamin D supplements

Less Melanin

• Less UV protection —> More UV reached epidermal cells

• More folic acid breakdown —> BAD

• more UVB absorption —> producing sufficient vitamin D

*Folate (vitamin B9) helps your body make and repair DNA, divide cells, and produce healthy red blood cells.

How does Melanin protect the DNA from damage from UV

Melanin absorbs UV light before it can reach and damage living epidermal cells.

Explain why mutations in MC1R gene are more common in light-pigmented populations than dark-pigmented populations 

due to evolutionary pressure. There is more selection for the mutated MC1R as an active MC1R gene pushed towards eumelanin. In places with lighter people, evolutionary pressure to maintain high eumelanin levels is weaker. MC1R variants associated with lighter pigmentation are therefore more likely to persist and spread through the population.

High UV environment → strong selection for functional MC1R → more eumelanin → darker pigmentation

Low UV environment → weaker selection against MC1R variants → less eumelanin and relatively more pheomelanin → lighter pigmentation

Explain how the integumentary system interacts with other body systems to contribute to organism-level functions and homeostasis. 

1. Nervous system 

• Skin contains nerves, and sensory receptors that detect any touch

2. Cardiovascular system 

• Blood vessels in the skin regulate the temperature (dilations)

3. Muscular system 

• Small muscles called arrector pili attach to hair follicles. 

• When you are cold, these muscles contract and cause goosebumps.

4. Immune system 

• Skin is the first physical barrier against pathogens 

5. Endocrine system 

• Skin helps produce vitamin D when exposed to UV

• Vit D is important for calcium

6. Skeletal system

• Calcium is needed for bone mineralization

7. Excretory glands

• Skin has sweat glands that remove water, salt, and waste products through sweat

8. Respiratory and cardiovascular system

• Respiratory system brings in oxygen and cardiovascular system delivers it to the skin

Ultraviolet (UV) light exposure triggers - so we become darker?

• triggers keratinocytes to release signaling molecule

• this signals for more melanin, which goes back to the keratinocytes

Why Tans Fade: 

Melanosomes are eventually broken down by lysosomes

Folic acid and Vitamin D in relation to Melanin

1. Folic Acid Protection (Shielding): 

• UV radiation destroys circulating folic acid (folate), a crucial B vitamin

• Accumulation of melanin shields epidermal DNA from UV damage and prevents this nutrient breakdown.

Higher UV → Higher Melanin → Shields Folic Acid from Breakdown → PREVENTS Vitamin B Deficiency.

2. Vitamin D Synthesis (Absorption): 

• Vitamin D production requires UV light interaction in the skin. 

• While higher melanin levels protect against radiation, excessive pigmentation in low-sunlight environments can hinder Vitamin D synthesis 

• Vitamin D synthesis is vital for calcium absorption.

Higher UV → Higher Melanin → blocks vitamin D synthesis 

Vit D relation to calcium

Vit D helps absorb calcium

• need calcium for nervous system and muscle contractions

Rickets

The body takes calcium from the bones causing bone deformity

Functions of the skeletal system (Bones, Joints, Cartilage)

1. Protecting internal organs

• Skull surrounds brain; lungs protected by ribcage

2. Stores and releases fat

• Yellow marrow (bone marrow) stores fat

• Fat is released a s source of energy when body needs it

3. Produces blood cells

• Red marrow (bone marrow) is a site of production for blood cells → red, white, platelets

4. Stores and releases minerals

• Reservoir for minerals and ions → calcium, phosphorus → needed for functioning of body

• Any time you contract a muscle, that relies on a supply of calcium ions

5. Facilitates movement + Supports Body

• Framework for soft body tissues

• Site of attachment for muscle

• That muscle working together with skeletal system allows for movement

Axial Skeleton

• skull

• thoracic

• Ribcage

Appendicular skeleton

• appendages (upper and lower limbs)

• Pectoral girdle

• Pelvic girdle

Types of Bones

1. Flat Bones

2. Long Bones

3. Short Bones

4. Irregular bones

5. Sesamoid Bones

Flat Bone Function

• Flat surface (thin and curved)

• typically for muscle attachments

• typically protect soft tissue/internal organs

• Ex. Skull, Sternum, Ribs

• Function —> protection

Long Bones Function

• Longer than it is wide

• can vary in size (tiny like a finger bone)

• Ex. Upper/lower limb: femur, tibia, fibula, humerus, radius, ulna

• Function —> Supports weight, movement, function as levers (move when muscle contracts)

Short Bones

• have lengths equal to their widths

• external is compact, the internal is spongy

• Ex. Bone in wrist (carpal), foot (tarsal)

• Function —> Stability, movement

Irregular bone

• Elaborate, complex shape

• Doesn't fit in any categories

• compact bone covered in internal spongy bone

• Ex. vertebrae, hip bones (pelvis), and certain skull bones, spinal cord

• Function → Protects organs

Sesamoid Bones

• Small nones, sesame seed like; reinforce tendons (form in tendons)

• help tendons overcome compressive forces

• Ex. patella (knee cap), and have some in the foot

• Function → Reinforce Tendons

Tissues found within the bone:

1. Epithelial tissue → blood vessels (like capillaries inside the Haversian canals). The inner lining of these blood vessels consists of simple squamous epithelium

2. Connective tissues → marrow, blood, adipose (fat)

3. Nervous tissue → have nerves that run through them that respond to pain

4. Muscle → blood vessels in the bone are lined with smooth muscle 

Fibrodysplasia ossification progressiva (FOP), Symptoms, Tissues if effe ts

Whats going on with jasmine?

 Observations:

• Jasmine's bones were bulging out 

• Immobility in her shoulders

• Her spine and torso were stiffer bt her limbs had decent movement

• Issues with her Axial skeleton (skull, spine, ribs) → Even though her lungs were fine themselves and her respiratory system had no problem, THEY relies on the skeletal system so because of the ossification that shes having, she’s having trouble breathing

Jasmin's Condition → FOP (skeletal disorder)

Insert image

• Fibrodysplasia ossification progressiva (FOP)

• Ossification is happening where it shouldn't be → causes soft tissue like muscles, tendons, and ligament to turn into bones 

• If patient has trauma in certain places bone will form

• This would eventually result in death → her organs will get semented in place (ex. Can prohibit lungs from expanding and breathing)

Cells responsible for jasmin's condition:

1. The mutation lies in the Mesenchymal Stem cell → mutation in this cell

• Progenitor cells found in connective tissue

• Differentiate into variety of cell type inside bone, cartilage, muscle, and dat

• In FOP their is a mutation in the ACVR1 gene causes these stem cells to transform into osteoblasts leading to inappropriate bone formation  

Which tissue does Jasmine have a problem with?

1. primarily Connective Tissue → bones 

1. There is bone where there shouldn't be 

2. Muscle tissue  → 

1. turns into connective tissue and into bone

Basic Unit of a bone

Esteon

Cells within the Osteon

Osteoprogenitor, Osteoblasts, Osteocytes, Osteoclasts (not from progenitor)

ACVR1 gene Mutation

causes mesenchymal stem cells to transform into osteoblasts, leading to inappropriate bone formation (muscle tissue turns into bone)

Osteoprogenitor (Osteogenic) Cells → Stem cells

• Bone STEM cells

• can undergo mitosis

• Living in the membrane that lines the bone (periosteum and endosteum)

• Differentiate and become osteoblasts

Ostoblasts

• Build bone 

• Laying down a collagen matrix (unmineralized matrix)

• This gets impregnated with minerals

• Essentially get buried/embredded in the hardened tissue 

• After entrapment, becomes osteocyte

Osteocytes

• Bone cells

• Inside hardened matrix

• Survives through the Canaliculi

• Canaliculi → allows cell to connect to neighboring cells AND blood supply 

Osteoclast

• Large, multinuclear, phagocytic cells

• Consuming cells

• Function in the bone matrix too remove the bone matrix

• Consume bone cells

• Osteoblasts and osteoclasts come together to remodel bones

Cleidocranial Dysplasia

Some mesenchyme cells are prevented from turning into osteoblasts —> less bone

Anatomy of the long bone:

Anatomy of bone cross section including osteon:

Epiphysis Function

• knobby region at the end of the bone

• strengthens the join

• serves to connect tendon and ligament

• padded with articular cartilage

• has spongy bone —> contains red marrow (makes RBC)

Diaphysis Function

• shaft/long portion

• contains a medullary cavity with yellow marrow (fat/adipose)

Articular cartilage Function

• cartilage at the ends of long bones

• To reduce friction and absorb shocl

Periosteum Function

• tough sheath that covers the outer layer of bone

• covers every area except articular cartilage

• contains blood vessels and nerves —> plays a role in bone growth and repair

Medulla Function

• hollow, cylindrical space within the diaphysis

• stores adipose —> yellow marrow

Proximal vs Distal Epiphysis

• Relative to body center

• Proximal means closest to the center of the body

Endosteum Function

• lines medullary cavity

• thin membrane of cells that covers ALL internal surfaces of bone including medullary cavity

• In the endosteum, bone growth, repair and remodling occur

Red Marrow Relevant Info?

• Found in spongy bone

• contains stem cells that form blood cells and platelets

• for children its located in spongy bone and medullary cavity

• In adults, most red marrow becomes yellow marrow

• only in some parts of the AXIAL skeleton

Yellow Marrow

Fat storage

Types of bone tissues in bones and theur properties:

1. Compact Bone

• very solid/dense

• present in the external walls of bones

1. Spongy Bone

• more porous

• located internally, mostly in epiphysis

Haversian (Central) Canal characteristics

• the haversion canal is in the center of the osteon.

• Within it are blood vessels, nerves, and connective tissue that supplies the bone with nutrient and oxygen

Concentric lamellae

• rings of calcified bone that surround the central canal

• Contains collagen fibers and mineral deposits

• gives bone strength and resistance

Osteocytes

• Bone cells found in the lacunae within the osteon

• They are connected together via canaliculi, which allow the ostocytes to exgnge waste, nutrient, and chemical signals.

• maintaining bone matrix, bone health, and communicating with neighboring cells

Canaliculi Function

• Tiny microscopic channels that Connect lacunae together and to the haversian channel

• allow the ostocytes to exgnge waste, nutrient, and chemical signals throughout the bone.

Lacunae Function

• tiny spaces where the osteocytes sit

• These spaces protect the bone cells and allow them to maintain the tissue

Whats Ossfication, what are types, Name them:

Ossification —> process of bone formation

2 Types:

Endochondral ossification —>

• Bone is produced from a cartilage model

• typically forms the long bones

Intramembranous ossification —>

• Bone forms from via embryonic tissue

• produces flat bones (skull, facial bones, jaw, etc)

metaphysis

Metaphysis is the narrow area that contains the epiphyseal (growth) plate, a layer of cartilage growing in the bone

• When the bone stops growing (reaches adulthood) that cartilage is replaced by osseous tissue AND the epiphyseal plate become epiphyseal line

What does collagen fiber do for the bone

make it flexible so its not brittle

Spongy bone functional unit

trabeculae!!

1. the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae

• trabeculae is NOT a random network → each trabecula forms along lines of stress to provide strength to the bone.

• spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter

Nutrient foramen 

Spongy bone and medullary cavity receive nourishment from arteries that pass through compact bone through the Nutrient foramen.

Cartilage —> What is it, it’s relation to bone:

• Bone is a replacement tissue —> it replaces cartilage (template) as we become older

• cartilage provides a template of where bones would be

• Cartilage is avascular —> has no blood vessels

• Cartilage gets its nutrients by diffusion through the matrix

• therefore cannot repair itself as readily

Intramembranous ossification

Overview —> Made directly from connective tissues. Mesenchymal cells turn directly into bone-building cells called osteoblasts, making woven bone that later remodels into compact and spongy bone.

Flat bones (ranial, skull, faaial)

• Mesenchymal cells (STEM cells) turn into other cells —> osteoblasts

• gather to form an ossification center

• secret osteoid —> uncalcified extracellular matrix

• after it calcifies the cells turn into osteocytes.

In Addition

• Mesenchymal connective tissue on the outer surface condenses to form the periosteum. Entrapped blood vessels within the trabecular network condense to form red bone marrow

Endochondral Ossification

Overview —> Made from a cartilage templaye which blood vessels invade and is broken down so bone can take its place

Bone types —> long bones

• Mesenchemal cells dufferentiate into chondrocytes (cartilage cells)

• These cells lay down in a cartilage model

• connective tissue membrane called the perichondrium forms around the outside of the hyaline cartilage model.

• Chondrocytes in the central area enlarge (hypertrophy) and matrix begins to calcify —> blocks diffusion —> they die leaving empty cavities

• Blood vessels invade these empty spaces, bringing along osteogenic cells

• The expanding and merging cavities form the central medullary cavity

• Capillaries penetrating the outer cartilage membrane trigger the perichondrium to convert into the bone-forming periosteum

• Osteoblasts in the periosteum build a periosteal collar of compact bone around the diaphysis shaft. 

• As bone replaces cartilage in the diaphysis, cartilage continues growing at the ends (future epiphyses) to lengthen the bone.

• After birth, the exact same sequence (calcification chondrocyte death blood vessel invasion osteoblast activity) repeats in the epiphyses. 

• These regions are known as secondary ossification centers.

How Bones Grow in Length

• The epiphyseal plate is the area of growth in a long bone (found in kids that are growing)

1. layer of hyaline cartilage where ossification occurs in immature bones.

• On the epiphyseal side of the epiphyseal plate → cartilage is formed. 

• On the diaphyseal side → cartilage is ossified, and the diaphysis grows in length. (Process of cartilage replaced by bone→ Endochondral Ossification!!)

Explain how the skeletal system interacts with other body systems to contribute to organism-level functions and homeostasis. 

1. Muscular System 

• Muscles contract and they pull in bones producing movement

2. Nervous System

• We have nerves within our bones in the periosteum and bone marrow that sense pain signals and control healing

• Nervous system controls skeletal muscle contractions

• Skull protects the brain, vertebral column protects the spinal cord

3. Cardiovascular System

• RBC are produced inside the red marrow 

• Cardiovascular system transports blood cells throughout body

4. Immune System

• WBC develop in bone marrow → fights pathogens

5. Endocrine System

• Hormones help regulate bone growth and calcium levels

6. Digestive System

• Digestive system absorbs calcium and phosphate from food which are used to build bone

• Vitamin D helps the intestine absorb calcium

7. Integumentary System

• Skin helps produce vitamin D after exposure to sun 

• Vitamin D helps the digestive system absorb calcium which creates stronger bones

8. Urinary System

• The kidney help regulate calcium and phosphate levels 

• They also activate vitamin D into its active form 

• Helps maintain calcium balance

9. Respiratory System

• Rib cafe protects the lungs; protects respiratory organ