BIO 201 final

Calcium levels in Mr. Gill's blood are dropping to dangerously low levels. The hormone PTH is released and soon blood calcium levels begin to rise. Shortly after, PTH release slows. Is this an example of a positive or negative feedback mechanism? What is the initial stimulus? What is the result?

Negative feedback mechanism. the initial stimulus is the drop in blood calcium levels. PTH is released promoting bones to release calcium. As levels return to normal the parathyroid is signaled to stop the release of PTH

The epidermis is a keratinized stratified squamous epithelium. Explain why that epithelium is much better suited for protecting the body's external surface than a membrane consisting of a simple columnar epithelium would be.

Multiple layers of epithelium compared to just one, increase its ability to protect the external surface of the body. Surface cells have the tough protein keratin to make it waterproof that prevents fluid loss, infection, toxins, and light. Squamous cells are flat, creating a sturdier barrier against physical impact compared to columnar cells which have more absorption abilities.

Osteocytes residing in lacunae of osteons of healthy compact bone are located quite a distance from the blood vessels in the central canals, yet they are well nourished. How can this be explained?

Canaliculi are microscopic channels which allow osteocytes to extend cytoplasmic processes to connect to eachother and the central canal for nutrients, oxygen, and waste disposal.

When a suicide victim was found, the coroner was unable to remove the drug vial clutched in his hand. Explain the reasons for this. If the victim had been discovered three days later, would the coroner have had the same difficulty? Explain.

This is caused by rigor mortis, the natural stiffenning of muscles after death. When ATP is no longer available muscles filaments are locked together. This problem would not be the same 3 days later as muscles would begin to decompose and therefore relax.

Explain the difference between an EPSP and an IPSP.

EPSP (Excitatory Postsynaptic Potential) is the depolarization of the postsynaptic membrane that pushes a neuron to fire and action potential while IPSP (Inhibitory Postsynaptic Potential) is hyper polarization that pushes a neuron away from its threshold and less likely to fire

Indicate the results of sympathetic activation of the following structures: sweat glands, eye pupils, adrenal medulla, heart, bronchioles of the lungs, liver, blood vessels of vigorously working skeletal muscles, blood vessels of digestive viscera, and salivation.

Sweat Glands: produce copious amounts of sweat to cool body

Eye Pupils: Let in more light and improve vision

Adrenal Medulla: release stress hormones (epinephrine and noepinephrine)

Heart: increased heart rate and contraction to pump more oxygen into blood

Bronchioles of lungs: dilate to improve airflow and oxygen intake

Liver: glycogen breakdown to release glucose for energy

Blood Vessels of vigorously working skeletal muscles: dilate to increase blood flow

Blood Vessels of digestive viscera: constrict to shunt blood away from unnecessary areas

Salivation: decreases

relationship between anatomy and physiology

structure determines function

Structural hierarchy of body

chemical, cellular, tissue, organ, organ system, organism

Organ Systems

System	Main Function	Example Organs
Integumentary	Protection, temperature regulation	Skin, hair, nails
Skeletal	Support, protection, mineral storage	Bones, cartilage
Muscular	Movement, heat production	Skeletal muscles
Nervous	Rapid communication	Brain, spinal cord, nerves
Endocrine	Hormone regulation	Pituitary, thyroid, pancreas
Cardiovascular	Transport blood	Heart, blood vessels
Lymphatic/Immune	Defends against disease	Lymph nodes, spleen, thymus
Respiratory	Gas exchange	Lungs, trachea
Digestive	Breaks down food	Stomach, intestines, liver
Urinary	Removes wastes	Kidneys, bladder
Reproductive	Produces offspring	Ovaries/testes, uterus, penis

anatomical position

• Standing upright

• Facing forward

• Arms at sides

• Palms forward

• Feet flat

superior vs inferior

above vs below

anterior (ventral) vs posterior (dorsal)

front vs back

medial vs lateral

closer to midline vs further

proximal vs distal

closer vs farther to attachment

superficial vs deep

closer vs farther from surface

Body planes

• Sagittal → left/right

• Midsagittal → equal halves

• Frontal (Coronal) → front/back

• Transverse → top/bottom

• Oblique → diagonal

dorsal cavities

cranial and vertebral cavities

ventral cavities

Thoracic: pleural, pericardial, mediastinum

Abdominopelvic: abdominal and pelvic

Components of feedback mechanisms

stimulus → receptor → control center → effector → response

clinical examples of loss of homeostasis

• Diabetes mellitus

• Hypertension

• Heat stroke

• Dehydration

types of gradients

concentration gradient: oxygen diffusion

electrical gradient: Na moves towards negative interior of cells

pressure gradient: blood flow

Temperature gradient: warm to cool
electrochemical gradient: neurons

cholesterol in the membrane

stabilizes and maintains fluidity

protein functions in membranes

Functions:

• Transport

• Receptors

• Enzymes

• Cell adhesion

• Recognition

carbohydrate functions in membranes

Attached to proteins or lipids.

Functions:

• Cell recognition

• Immune identification

Filtration

Movement driven by pressure.

Example:
Kidney filtration.

primary vs secondary active transport

primary: direct ATP use, Na/K pump (3 Na out and 2 K in)

secondary: stored energy from another ion gradient, glucose absorption in intestine

Bulk Transport

endocytosis (in) or exocytosis (out) of large materials

osmolarity

Total concentration of dissolved particles.

Higher osmolarity = more solutes.

tonicity

Effect of a solution on cell volume.
Hypertonic:higher solute outside cell
Hypotonic: higher solute inside cell

Isotonic: equal

Channal proteins

Allow ions through.

Carrier proteins

Move larger molecules.

Receptor proteins

Receive chemical signals.

Recognition proteins

Identify self from non-self.

Second-messenger system

• Hormone binds receptor.

• Receptor activates G protein.

• G protein activates adenylyl cyclase.

• ATP converted into cAMP.

• cAMP activates protein kinase.

• Cellular response occurs.

Amplifies signals so a small amount of hormone can produce a large response.

Microvilli

Function:
Increase surface area.

Found:

• Small intestine

• Kidney tubules

Purpose:
Increase absorption.

cilia

Function:
Move substances across cell surface.

Found:

• Respiratory tract

• Uterine tubes

Examples:

• Move mucus out of lungs.

• Move egg toward uterus.

epithelial tissue

• Tightly packed cells with little extracellular matrix

• Forms continuous sheets

• Avascular (lacks blood vessels)

• Attached to a basement membrane

• Exhibits polarity (apical and basal surfaces)

• Protection

• Absorption

• Secretion

cell shapes in epithelial tissue

• Squamous: flat cells

• Cuboidal: cube-shaped cells

• Columnar: tall cells

• Transitional: cells change shape when stretched

• Simple: one cell layer

• Stratified: multiple layers

• Pseudostratified: appears multilayered but is one layer

connective tissue

• Cells widely separated by extracellular matrix

• Matrix contains protein fibers and ground substance

• Usually vascular

• Support

• Protection

• Transport

types of connective tissue

Loose

• Areolar

• Adipose

• Reticular

Dense

• Dense regular

• Dense irregular

• Elastic

Supporting Connective Tissue

• Cartilage

  • Hyaline

  • Elastic

  • Fibrocartilage

• Bone

Fluid Connective Tissue

blood and lymph

Muscle Tissue

skeletal: striated, voluntary

cardiac: striated, involuntary, intercalated discs

smooth: non striated, walls of hollow organs

Nervous tissue

neurons, neuroglia, communication, signaling

Intercellular Junctions

tight junctions

desmosomes

hemidesmosomes

gap junction

tight junctions

seal adjacent cells

prevent leakage

intestinal lining

desmosomes

strong anchoring junctions

resist stretching

skin and cardiac muscle

hemidesmosomes

anchor epithelial cells to basement membrane

gap junctions

• Communication channels

• Allow ions and small molecules to pass directly between cells

• Important in cardiac and smooth muscle

endocrine glands

Definition:
Ductless glands that release hormones directly into the bloodstream.

Examples

• Pituitary gland

• Thyroid gland

• Adrenal glands

Function
Regulate growth, metabolism, reproduction, and homeostasis.

exocrine glands

Definition:
Glands that release secretions through ducts onto epithelial surfaces.

Examples

• Sweat glands

• Sebaceous glands

• Salivary glands

Functions

• Lubrication

• Cooling

• Digestion

• Protection

exocrine gland structure

Simple

• One unbranched duct

Compound

• Branched ducts

functions of integumentary system

• Protection

• Prevents water loss

• Temperature regulation

• Sensation

• Vitamin D synthesis

• Immune defense

• Blood reservoir

• Excretion of wastes

modes of secretion

Merocrine

• Exocytosis

• Example: eccrine sweat glands

Apocrine

• Part of the cell pinches off

• Example: apocrine sweat glands

Holocrine

• Entire cell ruptures

• Example: sebaceous glands

Layers of the Skin

epidermis

dermis

hypodermis

layers of epidermis

1. Stratum basale

• Stem cells

• Melanocytes

2. Stratum spinosum

• Dendritic cells

3. Stratum granulosum

• Keratin production

• Waterproofing

4. Stratum lucidum

• Thick skin only

5. Stratum corneum

• Dead keratinized cells

dermis

connective tissue

papillary layer: aerolar connective tissue, capillaries

reticular layer: Dense irregular connective tissue, Hair follicles, Sweat glands

hypodermis

• Adipose tissue

• Areolar tissue

structure of hair

• Shaft

• Root

• Hair follicle

• Hair bulb

• Dermal papilla

Nail

• Nail plate

• Nail bed

• Nail matrix

• Lunula

Cutaneous glands

sebaceous glands

eccrine sweat glands

apocrine sweat glands: groin region

ceruminous: earwax

mammary

Specialized Epidermal Cells

keratinocytes

melanocytes

dendritic cells

merkel cells

keratinocytes

Most abundant epidermal cell.

Function

• Produce keratin

• Waterproof barrier

• Protect against injury

melanocytes

Located in stratum basale.

Function

• Produce melanin

• Protect DNA from UV radiation

Dendritic Cells (Langerhans Cells)

• Immune defense

• Detect pathogens

• Present antigens to immune cells

merkel cells

• Touch receptors

• Fine tactile sensation

Basal Cell Carcinoma

• Most common

• Least dangerous

• Originates in stratum basale

• Rarely metastasizes

Squamous Cell Carcinoma

• Develops from keratinocytes

• More aggressive than basal cell carcinoma

• May metastasize if untreated

Melanoma

• Most dangerous

• Originates from melanocytes

• Highly metastatic

• Early detection is critical

Use the ABCDE rule:

• Asymmetry

• Border irregularity

• Color variation

• Diameter greater than 6 mm

• Evolving appearance

burns

first degree: epidermis

second degree: epidermis and part dermis

third: epidermis, dermis, and sometimes part of hypodermid

Priorities in Burn Treatment

• Stop the burning process.

• Maintain airway, breathing, and circulation (ABCs).

• Replace fluids to prevent shock.

• Prevent infection.

• Control pain.

• Maintain body temperature.

• Promote wound healing and nutrition.

• Skin grafting for severe burns.

tissue repair

1) inflammation

2)organization

3) regeneration and fibrosis

functions of skeletal system

protect, support, movement, mineral storage, blood cell formation (hematopoiesis), fat storage, hormone protection

classes of bone

long bones: diaphysis and epiphyses, femur, humerus, tibia

short bones: cube shaped, carpals, tarsals

flat bones: thin and flat, sternum, scapula, ribs

irregular: complex, vertebrae, pelvis

sesamoid bones: develops with tendons, patella

microscopic anatomy of bone

connective tissue of cells in mineralized extracellular matrix

Osteogenic cells

• Stem cells

• Differentiate into osteoblasts

• Found in periosteum and endosteum

osteoblasts

• Build new bone

• Secrete osteoid (organic bone matrix)

• Initiate mineralization

osteocytes

• Mature bone cells

• Maintain bone tissue

• Sense mechanical stress

• Communicate through canaliculi

osteoclasts

• Break down bone (bone resorption)

• Release calcium and phosphorus into the blood

compact vs spongey bone

dense strong outer layer vs porous, contains trabeculae, distributes mechanical stress

osteon

The osteon is the structural unit of compact bone.

Components:

• Central (Haversian) canal: contains blood vessels and nerves

• Concentric lamellae: rings of calcified matrix

• Lacunae: spaces containing osteocytes

• Canaliculi: tiny channels connecting osteocytes

• Perforating (Volkmann's) canals: connect central canals

Osteogenesis

intramembranous and endocondrial ossification

intramembranous ossification

flat bones of skull, mandible, clavical

• Mesenchymal cells cluster.

• Osteoblasts develop.

• Osteoid is secreted.

• Osteoid calcifies.

• Trabeculae form.

• Periosteum develops.

• Compact bone forms on the surface.

endocondrial ossification

most bones

• Hyaline cartilage model forms.

• Bone collar develops around diaphysis.

• Primary ossification center forms.

• Blood vessels invade.

• Medullary cavity develops.

• Secondary ossification centers form in epiphyses.

• Articular cartilage and epiphyseal plates remain.

Postnatal Bone Growth

length growth at epiphyseal plate

• Resting cartilage

• Proliferating cartilage

• Hypertrophic cartilage

• Calcified cartilage

• Ossification

width growth: Osteoblasts deposit new bone beneath the periosteum while osteoclasts enlarge the medullary cavity.

Bone Deposition

Performed by osteoblasts.

Occurs when:

• Calcium is added to bone.

• Bone strength increases.

Bone Resorption

Performed by osteoclasts.

Occurs when:

• Bone is broken down.

• Calcium enters the bloodstream.

Parathyroid Hormone (PTH)

Released when blood calcium is low.

Effects:

• Stimulates osteoclast activity indirectly.

• Increases calcium reabsorption in the kidneys.

• Increases vitamin D activation.

• Raises blood calcium levels.

Calcitonin

Released by the thyroid gland when blood calcium is high.

Effects:

• Inhibits osteoclast activity.

• Promotes calcium deposition in bone.

• Lowers blood calcium levels.

Vitamin D (Calcitriol)

• Increases calcium absorption from the intestines.

• Promotes bone mineralization.

Estrogen and testosterone:

• Promote bone growth.

• Help close epiphyseal plates.

• Maintain bone density in adults.

closed (simple) fracture

Bone does not penetrate the skin.

open (compound) fracture

• Bone breaks through the skin.

• Higher risk of infection.

complete fracture

Bone is broken all the way through.

incomplete fracture

Bone is partially broken.

greenstick fracture

• One side of the bone breaks while the other bends.

• Common in children.

communicated fracture

Bone breaks into several pieces.

Fracture Repair

1) hematoma fracture

2) fibrocartilaginous callus formation

3) bony callus formation

4) bone remodeling

osteoporosis

A disease characterized by decreased bone mass and deterioration of bone tissue, resulting in fragile bones and increased fracture risk.

risk factors: aging, females, low calcium intake

functions of muscle tissue

movement, posture, joint stabilization, heat production, control openings