BI 331: final exam review

what is the composition of bone matrix?

1/3 collagen fibers and 2/3 calcium minerals

Would a given child achieve a greater adult height if he entered puberty at 11 or 13? Why?

11, because males have a longer and slower growth period than females. So if he started puberty earlier, he would most likely have a large growth spurt early and then slowly continue to grow until his epiphyseal plate fuses.

Why is proper cartilage formation important for bone?

Because cartilage is the foundation for bone, so if it is defective, the bone that forms will most likely also be defective

connective tissue functions (FSTS)

Fills internal spaces, Supports other tissues Transports materials Stores energy

granulation tissue

Forms the foundation for scar tissue development

What is the role of the osteocytes in maintaining bone?

Osteocytes regulate bone resorption through controlling osteoclasts activity

what is an osteon?

Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi, which transport blood. They are aligned parallel to the long axis of the bone. Each osteon consists of lamellae, which are layers of compact matrix that surround a central canal.

What happens if osteoclast activity is greater than osteoblast activity?

Osteoporosis, bone is being broken down faster than osteoblasts can build it back up.

How do sex hormones affect bone growth?

They cause ossification to be faster than cartilage replacement. But they also affect rate of body formation causing growth plate to close and bones to cease growing in length

How do bones grow in length?

Through the activity of hyaline cartilage of epiphyseal plate

hypodermis function

anchors skin to underlying organs and stores fate for insulation and cushion

How do bones get wider and reshape?

appositional growth

what tissues make up the dermis?

areolar and adipose tissue

what happens to keratinocytes as the migrate from the stratum basal to the stratum corneum?

as they migrate they make keratin, pick up melanin, dehydrate and then die and remain in the stratum corneum

Why is damaged cartilage difficult to heal?

because it is avascular

Why must cartilage die before blood vessels can invade during endochondral ossification?

because it is avascular, so when the calcification begins those layers are completely blocking nutrients from entering the cavity of the bone, so when cartilage dies nutrients can diffuse again.

Why must blood vessels arrive before bone can form inside the cartilage during endochondral ossification?

because the blood vessels bring the osteoblasts which lay down osteoid to form bone

Why are bisphosphonates not as successful as they seemed they could be? Would another drug be better for postmenopausal women?

because they have risks of causing breast cancer, blood clots, stokes and heart attacks. growth hormone, vitamin D (for calcium absorption) and vitamin C (for collagen

functions of the dermis

binds, sensory, nourishes, toughness (collagen) and elasticity

what would happen if collagen was not present in bone?

bones would become brittle and shatter easy

what would happen if calcium minerals were not present in bone?

bones would become too flexible and not be able to bear weight

how do osteocytes communicate with each other and receive nutrients?

canaliculi

how is cartilage different from bone?

cartilage is a thin, avascular, flexible and resistant to compressive forces. Bone is highly vascularized and its calcified matriculates makes it very strong

characteristics of epithelial tissue (PAARC)

cellularity, polarity, attachment, avascularity, regeneration

what are hormones

chemical signals sent out from the endocrine glands to enact changes in other cells

How are chondrocytes, osteoblasts & osteoclasts involved in endochondral ossification?

chondrocytes form the template of hyaline cartilage at the diaphysis, and when blood vessels invade the cavities, the osteoblasts and osteoclasts modify the calcified cartilage matrix into spongy bone.

vitamin C is required for proper formation of...

collagen

what are the different fibers in CT and where are they found

collagen fibers are most common and found in tendons and ligaments, reticular fibers are found in the stroma of organs, elastic fibers are found in elastic ligaments

what are the different specialized cells of connective tissue

fibroblasts/fibrocytes, blood cells, adipocytes, osteocytes, chondrocytes

severe burns can result in...

fluid loss, hypovolemic shock, increased metabolic demands, venous thrombosis, infection, increased body temperature, electrolyte imbalance, immune system depression

Why do we need epiphyseal plate cartilage?

for longitudinal growth of bones

what is a tissue made up of

groups of cells

what is an organ made up of

groups of tissues

what does endoderm give rise to?

gut and lung epithelial lining

What are the 3 types of cartilage? where are they located?

hyaline: embryonic skeleton, surfaces of synovial joints elastic: ear, epiglottis fibro: intervertebral discs, pads in knee joint and pubic symphysis

deep wounds of the skin require 4 steps to heal:

inflammation, migration, proliferation and maturation

What is bisphosphonate and why has it been used for preventing osteoporosis?

it is a hormone that prevents osteoclasts activity, which therefore prevents bone rebuilding because if there are no osteoclasts breaking down bone, osteoblasts don't have anything to rebuild.

in what way is spongy bone stronger than compact bone?

it is more flexible so can handle more tensile forcing like twisting

what is the most important intracellular protein to epidermal cells, hair and nails?

keratin

What is migration during epidermal wound healing?

keratinocytes migrate around the wound site and close it

what are the different cell types present in the epidermis?

keratinocytes, melanocytes, merkel cells, langerhans cells

What is articular cartilage?

lines portion of epiphyses where bones come together to form joints, it is a thin layer of hyaline cartilage that reduces friction and acts as a shock absorber.

what do all connective tissues arise from?

mesenchyme

what does all connective tissue derive from

mesenchyme

what is osteoid made of?

mostly collagen fibers

what are the different ways cells communicate? which one is faster?

nervous system by neurotransmitters that are fast acting and short lived, or by the endocrine system by hormones that are slow acting but long lived

sebaceous glands

oil glands that help inhibit bacteria, keep our skin waterproof, and keep our hair and skin from drying out

which bone cells are incapable of mitosis?

osteoblasts, osteocytes and osteoclasts

What is the importance of endosteal and periosteal activity during bone elongation

osteoclasts in the endosperm breaks down bone and osteoblasts in the periosteum rebuilds the bone.

what can altered mitosis in lower layers of the epidermis lead to?

pathology or morphology such as psoriasis, melanoma, calluses

functions of integument and hypodermis

protection, excretion/absorption, thermoregulation, synthesis, sensation, storage

In the condition psoriasis, the skin replaces itself too quickly due to accelerated division of cells of the stratum basale. What do you think the symptoms of this condition look like?

rashes, itchiness, dryness, cracked skin

what is the is the extracellular matriculates of CT made of

solid portion is protein fibers and liquid portion is ground substance

does compact bone or spongy bone remodel more?

spongy bone

merkel cells function

stimulate nervous system, sensory cells

what epithelial cells make up the epidermis?

stratified squamous epithelium

in which layer are epidermal stem cells found?

stratum basale

where are keratinocytes initially formed?

stratum basale

where are melanocytes found?

stratum basale

what are the layers of the epidermis from bottom to top? (hint: better skin grows like crazy)

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

2 layers of the dermis

superficial papillary layer made of areolar CT and a deep reticular layer made of dense irregular CT

functions of bones

support, facilitate movement by serving as attachment points for muscles, they protect internal organs, and they serve as storage sites for minerals and fat

sudoriferous glands

sweat glands important for maintaining body temperature

what is the importance of melanocytes?

they proceed melanin to protect our skin the UV radiation.

what is the endosteum?

thin membrane that lines the medullary cavity, made of bone cells

how to hormones travel

through the blood

how are epithelial cells held together and how do they communicate

tight junctions (zipper) and desmosomes(buttons) hold cells together and gap junctions allow for communication between cells

trabeculae function

trabeculae form along lines of stress, giving the bone strength and flexibility

how does the epidermis get nutrients?

via diffusion from blood vessels in the dermis

what vitamin is synthesized in the skin? what is its active form? what does its active form do?

vitamin D, calcitrol, increases intestinal absorption of calcium

where are the receptors located for fat and water soluble hormones

water soluble are outside the cell and fat soluble are inside the cell

what are the difference in effect of water soluble vs fat soluble

water soluble tends to be faster acting and more effective but stays in the blood for a shorter time than fat soluble

What is the difference between lipid soluble and water soluble hormones in terms of transport through the blood and receptor location at target cells?

water soluble travels freely through the blood but needs a second messenger when reaching target cell b/c it can't diffuse through the membrane, fat soluble needs a binding protein to travel through blood but diffuses through the membrane at the target cell

does cartilage change shape? why?

yes, it changes shape as needed, it is in areas with high compression to accept stress and deform to allow cushioning

are bones alive?

yes, they are living tissue that contains blood vessels and are made of living cells to aid in their growth and repair

steps of endochondral ossification

(a) Mesenchymal cells differentiate into chondrocytes. (b) The cartilage model of the future bony skeleton and the perichondrium form. (c) Capillaries penetrate cartilage. Perichondrium transforms into periosteum. Periosteal collar develops. Primary ossification center develops. (d) Cartilage and chondrocytes continue to grow at ends of the bone. (e) Secondary ossification centers develop. (f) Cartilage remains at epiphyseal (growth) plate and at joint surface as articular cartilage

steps of intramembranous ossification

(a) Mesenchymal cells group into clusters, and ossification centers form. (b) Secreted osteoid traps osteoblasts, which then become osteocytes. (c) Trabecular matrix and periosteum form. (d) Compact bone develops superficial to the trabecular bone, and crowded blood vessels condense into red marrow.

how do osteocytes get nutrients?

Blood vessels in the periosteum and endosteum supply blood to blood vessels in the central canals. Nutrients leave the blood vessels of the central canals and diffuse to the osteocytes through the canaliculi

What happens when the periosteum around a bone deteriorates?

Bone becomes thinner and weaker.

What would happen if osteoblast activity was greater than osteoclast activity?

Bone grows because osteoblasts are building bone faster than osteoclasts are breaking it down

how does bone compare to cartilage?

Cartilage is thin, avascular, flexible and resistant to compressive forces. Bone is highly vascularised, and its calcified matrix makes it very strong.

What is the purpose of the fibrous layer of the periosteum?

It allows for attachment of muscle tissue to the bone and provides pathways for blood and lymphatic tissues.

medullary cavity function

The medullary cavity itself is hollow and functions to form RBCs and WBCs and acts as a calcium supply. Compact bone surrounds the medullary cavity, so the dense and hard characteristics of that bone protects the hollow medullary cavity and is very supportive

melanoma

The most serious form of skin cancer, very aggressive, can be fatal if not treated early

What is squamous cell carcinoma?

a cancer that grows on parts of your skin that get lots of sun, rarely spreads but does more than basal cell carcinoma, organ transplant recipients have high risk

What is basal cell carcimoma?

a cancer that grows on parts of your skin that get lots of sun, slow growing, accounts for 90% of skin cancer

What is the periosteum?

a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints, has 2 layers: one of bone cells and one of dense irregular CT fibers

Where are the osteoblasts and osteoclasts working to build and remodel bone?

a small amount of bone on the surface of trabeculae or in the interior of the cortex is removed by osteoclasts and then replaced by osteoblasts at the same site

langerhans cells function

activate the immune system

how is compact bone different than spongy bone?

compact bone is made of a concentric lamellae of matrix, a central canal that contains BVs and nerves, and osteocytes connected by canaliculi. It is strong and dense and makes up the outer cortex of bone and is in immediate contact with the periosteum. Spongy bone contains a open network of trabeculae, and irregular lamellae of matrix, osteocytes connected by canaliculi and between trabeculae contains red bone marrow for RBC formation and yellow bone marrow. It is lighter and makes up the inside of bones.

what does mesoderm give rise to?

connective tissue and muscle

are glands dermal or epidermal structures?

dermal

how are cells of the epidermis held together?

desmosomes

which sweat glands are predominately active in thermoregulation

eccrine gland

are hair and nails dermal or epidermal structures?

epidermal

what are the components of the cutaneous membrane?

epidermis and dermis

what does ectoderm give rise to?

epidermis and nervous system

which tissues are highly cellular?

epithelial and muscle

what is the migration that takes place during skin would healing?

epithelial cells migrate across the new tissue to form a barrier between the wound and the environment

what are the 2 categories of hormones

fat soluble and water soluble