short answer/essay or extra credit(exam 2)

layers of epidermis(which one is only shown in thick skin)

1. Stratum corneum

2. Stratum lucidum(the one only found in thick skin bc it is where there is high friction:callus)

3. stratum granulosum

4. stratum spinosum

5. stratum basel

What are sensory receptors? Which are found superficially or deep? 

sensory receptors have to do with light touch, pressure, vibration that we feel

superficial: merkel discs, free nerve endings, and meissner corpuscle

deep: pacinian corpuscle

Difference between the three types of hair 

lanugo: fine and non pigmented hair

vallus: short and barely visible hair

terminal: long and heavily pigmented hair

Be able to describe the difference between epidermal and deep wound healing 

epidermal: damage to the epidermis

deep: damage to all layers

steps of epidermal wound healing

1. inflammation: local immune cells coming in the clean up debris

2. migration: basel cells moving towards each other to seal wound

3. Proliferation: basel cells are actively dividing to replace what is lost

4. maturation: once cells come in contact with each other they stop dividing and wound is healed

steps of deep wound healing

1. hemostasis: the clot forming

2. inflammation: local immune cells coming in to clean up debris

3. migration: fibroblast making collagen and scab forms

4. proliferation: more cell division and fibroblast

5. scab falls off and collagen is remodeled

burns

• 1st degree burns: damage to the epidermis no function loss, redness and pain 

• 2nd degree burns: damage to the epidermis and dermis, blistering, redness, pain and may be some function lost 

• 3 degrees burns: damage to all layers of skin, most function lost, may have numbness/tingling

functions of the bone

1. Support: For body and soft organs

2. Protection: Protect brain, spinal cord, and vital organs

3. Movement:Levers for muscle action

4. Mineral and growth storage: Calcium and growth factors reservoir

5. Blood cell formation: Hematopoiesis occurs in red marrow cavities of certain bones

6. Fat storage: Fat, used for an energy source, is stored in bone cavities 

7. Hormones storage: Osteocalcin secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism

Difference between epiphyseal growth plate vs line and tissue present

• epiphyseal growth plate: consistently dividing and lets the long bone grow

• Epiphyseal line: When the plate becomes a line because the bone has stopped growing

• hyaline cartilage

What is bone remodeling? What two cells are responsible for this?

• Bone remodeling: where the bone is breaking down and building back up

• Osteoblast and osteoclast bc it is in there name

What is the difference between intra-membranous and endochondral ossification?

Intra-membranous	endochondral
Forms flat bones of skull, mandible and clavicle	Forms most bones(especially long bones)
has multiple ossification center	has 2 main ossification centers (Primary and Secondary)
Is more simpler	Has a cartilage model that turns into bone

steps of intra-membranous ossification

1. Formation of ossification center: messengers are bringing osteoblast into the center 

2. Calcification: osteoblast stop making the ECM and the osteocytes form in the lacuna. The ECM hardened bc of the calcium and mineral salts 

3. Formation of trabeculae: the trabeculae forms into spongy bone. The is is also where blood vessels are shown 

4. Formation of the periosteum: mesenchyme develops into the periosteum which forms on top of the compact and spongy bone

steps of endochondral ossification

1. Formation of the cartilage model: mesenchyme cells develop into chondroblast which forms the model 

2. Growth of the cartilage model: chondroblasts form into chondrocytes which grow and once they can not move anymore they reside in  the lacunae

3. Formation of the primary ossification center:where cartilage is replaced by bone in the shaft. And the bone formation is inward. Nutrient artery is formed   

4. Formation of the medullary cavity: osteoclasts are breaking down bone to create the cavity 

5. Formation of the secondary ossification center: occurs in the epiphysis of the bone. There the bone is forming onward  

6. Formation of the articular cartilage and epiphyseal pate: both are made up of hyaline cartilage that covers the epiphysis

Know factors that affect bone development, growth, and repair

•  Deficiency of Vitamin A: slows down bone development

•  Deficiency of Vitamin C : results in fragile bones 

•  Deficiency of Vitamin D: rickets, osteomalacia

•  Insufficient Growth Hormone: dwarfism

•  Excessive Growth Hormone: gigantism, acromegaly 

•  Insufficient Thyroid Hormone: delays bone growth

•  Sex Hormones: promote bone formation; stimulate ossification of epiphyseal plates

•  Physical Stress: stimulates bone growth

What vitamins are needed for normal bone metabolism? What do they contribute to?

• Vitamin A stimulates activity of osteoblasts.

• Vitamin C is needed for synthesis of collagen.

• Vitamin D is essential to healthy bones because it promotes the absorption of calcium from foods in the gastrointestinal tract into the blood.

• Vitamins K and B₁₂ are needed for synthesis of bone proteins.

Explain the role of calcitonin, parathyroid hormone, and calcitriol in the regulation of calcium ion blood levels.

• calcitonin= uses osteoblasts 

  • High blood/ calcium levels stimulate the thyroid glands, which secretes calcitonin. Then there is a reduce in calcium uptake in kidney and intestines, which brings the calcium levels back to normal 

• Parathormone(PTH): uses osteoclasts 

  • Low calcium levels stimulate the parathyroid glands, which secretes PTH. then there is an increase in calcium uptake in kidneys and intestines, which restores calcium levels(going back to normal) 

steps of fracture repair

1.  Hematoma formation: breaking down of blood vessels,

2. Fibrocartilaginous callus formation/inflammation:phagocytes come in to clean up debris, fibroblast creating collagen and chondroblast creating cartilage 

3.  Bony callus formation:osteoblasts are laying down osteoids and then the bony callus is forming the spongy bone 

4.  Bone remodeling: spongy is replaced by compact bone the fracture line may disappear. Osteoclasts are also coming in the cleanup/ reshape the bone

What is a sarcomere?identify the structures on the sarcomere if presented with an image 

• Sarcomeres: many myofilaments that make up the myofibrils 

• A bands: the dark regions 

• H zone: the lighter region in the middle of the a band 

• M line: line of protein that is in the middle of the H zone 

• I band: lighter regions that are on either side of the a band 

• Z line: line of protein that is in the middle of I bands

What is contraction? What happens in the sliding filament model of contraction?

• Contraction: the activation of cross bridges to generate force 

• The thin filaments are moved and the thick filaments are staying in place 

• The Z lines are moving closer together and the the sarcomere is shortened 

• The I bands are also getting smaller

steps of cross bridge contraction cycle when there is low calcium and high calcium present.

• low calcium: troponin and tropomyosin block active sites on the action so not contraction occurs

• The myosin head can not attach to actin  

• High calcium: Ca2+ binds to troponin which changes its shape. It can then move tropomyosin away from the myosin binding sire 

  • Myosin head is then able to bind to actin, which forms the cross bridge

1. Cross bridge formation: high-energy myosin head attaches to actin thin filament active site

2. Power stroke: myosin head pivots and pulls thin filaments towards M line 

3. Cross bridge detachment: ATP attaches to myosin head, which causes the bridge to detach 

4. Cocking of myosin head: energy from hydrolysis of ATP cocks myosin head into a  high energy state( that energy will then be used for the power stroke next time) 

What is the difference between depolarization and repolarization? what are the steps?

• Depolarization: when the inside of plasma membrane becomes less negative(if threshold is reached, depolarization happens)

• Repolarization: returning to resting membrane potential

1. a stimulus from a sensory cell or another neuron causes the target cell to depolarize towards the threshold potential

2. if the change reaches the threshold, all Na+ channels open and the membrane depolarizes

3. at the peak action potential K+ channels open and it begins to leave cell the cell. at the same time to Na+ channels close

• where Repolarization starts to occur

4. the membrane becomes hyper polarized as K+ ions continue to leave to cell. the hyper polarized membrane is in a refractory period and cannot fire

5. the K+ channel then close and the Na+/ K+ transporter restores the resting potential

neuromuscular junction

1. Action potential(AP) travels down axon terminal= voltage gated Ca+ channels open synaptic bulb 

2. Ca+ is released through synaptic bulb, which opens vesicles containing Ach 

3. Ach travels through synaptic cleft to bind to ligand channels on motor end plate(muscle cell)

4. Na+ now enters the muscle= sarcolemma voltage(more positive coming it)

5. Voltage change travels down the t tubules → voltage gated Ca+ on the sarcoplasmic reticulum to open and release Ca+ inside the cell 

6. Ca+ binds to troponin → tropomyosin to expose myosin binding site on actin→cross bridge cycle→ contraction 

• How contraction ends

1. Ca+ returns to place of storage

2. acetocholinesterase=  breaks down Ach into acetic acid and chlorine(which gets recycled)