A&P Module I

Nucleus

cell membrane

Proteins, Lipids, and CHO

• Regulates the environment in regards to ions, water, nutrients, waste and provides
• structural support.

cytoplasm

o   Ribsomes- site of protein synthesis

o   Endoplasmic Reticulum- metabolic functions

• o   Golgi complex- modifies substances and
• packages in vesicles

• o   Lysosomes and peroxisomes- hydrolytic,
• phagocytotic or transports materials to outside cell

• o   Mitochondria-power plant that produces power,
• has its own mitochondrial DNA and controls apoptosis

• Lipid Bilayer- a semi permeable layer composed of phospholipids- hydrophilic head (water loving) and
• hydrophobic tail (water/fluid fearing)

-Controls what enters and exits

Glycocalyx- participates with cell to cell adhesion “fuzzy coat" for recognition and support.

The glycocalyx is a type of identifier that the body uses to distinguish between its own healthy cells and transplanted tissues, diseased cells, or invading organisms. Included in the glycocalyx are cell-adhesion molecules that enable cells to adhere to each other and guide the movement of cells during embryonic development.

Integral: Spans the entire membrane bc they have a hydrophilic and hydrophobic region. Alpha helix structure

Peripheral: Bound to integral protein or lipid bilayer (outer surface) or lipid linked. Does not go through lipid bilayer.

• Tight Junctions- two plasma membranes (fused
• together or sealed) forming a impenetrable barrier preventing water and solutes
• from passing

• -      
• Adhering junctions- belt like, prevent cell separation,anchors microfilaments
•   
• Desmosomes- spot like adhesion molecules that
• hold together by thick protein filaments- seen in areas of mechanical distress. Extend through cells.
•    
• Gap junctions- allow for rapid communication-
• connected by connexon channels and decrease resistance

• Tight junctions: Digestive tract
• Gap junctions: excitable tissue like the heart
• Desmosomes: skin

• Positive feedback- the response of effectors increases stimulus
• -Body is moved away
• from homeostasis (lose normal range)
• -Used to speed up
• process
•  
• Ex: childbirth (fetus pushes on the cervix which releases oxytocin which causes the uterus to contract and push harder on the cervix = more hormone release until birth), blood clotting, urinary bladder

• -      
• Negative feedback-presence of effectors negates stimulus

• Body brought back into homeostasis (normal range)
• i.e: body temp drops, muscles start to contract, produce heat, brings body temp back up

• Electrolyte- substances that dissociate into solution to form charged particles or ions
•      
• Ions- charged particles (either positive or negative)
•    
• Non-Electrolytes- don’t dissolves in to ions such and glucose and urea

T

• ICF- fluid
• within all the cells in the body

• ·     
• Larger of the two compartments- 2/3 of the body
• water (40% body weight)

• ·     
• Contains almost no Ca2+, large
• amounts of K+

•  
• ECF- fluids outside of the cells, including in the interstitial (tissue) spaces (3/4 of
• ECF-14% body weight) and blood vessels (1/4 of ECF- 5% body weight)
•      
• Contains large amounts of Na+ and
• Cl-, small quantities of K+

• Passive transport- transport through a plasma
• membrane that requires no ATP. Transportation dependent on passive gradients

Active transport:transport through a plasma membrane requiring energy and ATP

Diffusion-electrolytes move from an area of higher concentration to an area of lower concentration

• Rate of movement depends on number of particles and the velocity of their movement, the number of openings in the cell
• membrane, temperature 

Simple Diffusion:Occurs through membrane openings or intermolecular spaces

-Rate directly proportional to concentration

• -Lipid soluble compounds (alcoholos, fatty acids,
• steroids)

-Dissolved gasses (oxygen and carbon dioxide)

• ·     
• Facilitated Diffusion (carrier mediated transport): Use of membrane protein channels- carrier
• mediated diffusion

-Very selective

• -Water soluble compounds, ions: Glucose and amino
• acids

• - Rate of
• diffusion approaches maximum and levels off

• Channel characteristics- dependent of
• characteristic of channel (Na+- neg charged = selectively
• permeable), can be opened of closed by gates (dependent on electrical or
• chemical substance)

• Carrier proteins- transport molecules too large
• to fit- molecule binds to receptor site, protein changes shape, molecules pass
• through (receptor site is specific to certain molecules)

• ·     
• Osmosis: Diffusion of water across the cell membrane
• (through aquaporins)

• Movement is dependent on the concentration of
• nondiffusible particles on either side- side of less particles and more water
• to side with more particles and less water
• ---Movement until particles on each side equally
• diluted

• Filtration- process by which fluid is forced
• through membrane due to differences in pressure,(ex.- plasma across renal glomerulus)

• Isotonic- equal amounts of dilution of particles  
• Hypotonic- lower concentration of particles outside the cell- water rushes in (swell)
• Hypertonic- higher concentration of particles outside the cell- water rushes out (shrinking)

1. antidiuretic hormone

2. aldosterone

3. Natriuretic peptides (to excrete Na+)

• Na+, K+, Ca2+,
• Mg2

SD: lipid-soluable compounds (alcohols, FA, steroids)

FD: water soluble compounds and ions. Rate of diffusion is dependent on # of carrier proteins available (like cars and parking spaces)

3 Na+ out, 2 K+ in

Maintains Na-K concentration across the membrane

• Active
• -uses atp
• -receptor mediated

pinocytosis-endosomes “drink” extracellular fluid (cell drinking), 

• Particles are engulfed into small,
• membrane-surrounded vesicles for movement into the cytoplasm
•  
• Phagocytosis- engulf large objects in phagosomes
• (cell eating)

• After engulfed in a phagosome, moves into
• cytoplasm fuses with lysosome and degraded by lysosomal enzymes

• Exocytosis- moves substances from interior of
• cell into extracellular space
•  
• Substance to be released is enclosed in a
• vesicle
•   
• Vesicle fuses to membrane and ruptures, spilling contents out of cell

• Important in removing cellular debris and
• hormones

•  
• Leakage (passive)- open even in unstimulated
• state

• o  
• Gated (active)- open and close to stimuli, at
• resting potential- most are closed

• Voltage-gated- electrically operated channels,
• open when membrane potential changes

• ·     
• Activation gates (open), inactive gates (closes)

• ·     
• Excitable membrane

• ·     
• Found in neural axons, skeletal muscle
• sarcolemma, cardiac muscle

• Ligand-gated- chemically operated channels,
• respond to specific receptor-bound ligands, ex. Acetylcholine

• ·     
• Found in neuron cell body and dendrites

•  
• Mechanically gated- open and close in response
• to mechanical stimuli-

Found in sensory receptors: vibrations, tissue stretching, pressure

Delay in repolarization after depolarization

this allows the heart muscle to contract

• Regulate body temp: most heat is produced by deep organs, then transferred
• to the skin to be released to the surrounding environment; the rate at which heat is dissipated from the body is controlled by constriction or dilation of the arterioles that supply blood to the skin and through evaporation of moisture and sweat from the skin surface

•  Protection: microorganisms find it
• almost impossible to penetrate the skin
• from the outside; water loss is limited from the inside; skin surface
• is covered with a thick lipid film contains bactericidal fatty acids that protect against the entry of harmful microorganisms

• Reception of stimuli: skin is richly innervated
• with pain, temp, and touch receptors; relay’s numerous qualities of touch, such as pressure,
• sharpness, dullness, and pleasure to the CNS for localization and fine discrimination.

• Excretion: skin excretes sweat to cool
• the body and release heat

• Synthesis of Vit D: 7-dehydrocholesterol, a
• subastance normally found in epidermal cells, is converted to cholecalciferol (inactive form of VitD)by UV rays from the sun

 Coordinates immune response to pathogens:Langerhans cells are antigen-presenting cells of the skin and protect against harmful pathogens as well as playing a rold in the development of allergic skin conditions

• Keratinocytes:produces keratin, most abundant cell (95% of epidermis)
• Langerhans Cells: located in the stratum spinosum; less numerous than keratinocytes.They have dendritic shape.They are immunologic cells responsible for recognizing foreign antigens harmful to the body.

Melanocytes:located at or in the basal layer.  They function to produce pigment granules called melanin, the substance that gives skin its color.There are two major forms of melanin: eumelanin (brown and black)and pheomelanin (yellow to red).  

Merkel Cells: clear cells found in the stratum basale; connected to other skin cells by desmosomes.  Each cells is connected to an afferent nerve terminal, forming a structure known as a Merkel disk.

They are the sparsest cells in the epidermis and are found over the entire body.

 They release hormones into the blood in response to neural stimuli,and function as specific, slowly adapting sensory touch receptors.(Neuroendocrine function)

serves as the primary source of nutrition to the epidermis.

• The two layers of the dermis: the papillary dermis and the reticular dermis,
• are composed of cells, fibers, ground substances, nerves, and blood
• vessels.  

Collagen is its main component, giving skin stress resistance.Collagen fibers are loosely arranged in the papillary dermis, but are tightly bundled in the reticular dermis.  Hair and glandular structures are embedded in this layer.

skin condition where there is purple/black discoloration at the back of the neck and arm pits.

Usually seen in type II DM bc the kerotinocytes  start responding to the extra insulin in the body by producing more cells.

Papillary "pruney" layer: The basal cells of the epidermis project into the papillary dermis, forming rete ridges, which are used for grip,and what gives you pruney fingers.  This layer of the dermis is richly vascularized. Lymph vessels and nerve tissue also are found in this layer.

Reticular Layer: forms the bulk of the dermal layer (80%). Dense irregular connective tissue. Where strength and elasticity of the skin comes from.

nociceptors (pain receptors) and thermoreceptors

T.

The largest is the pacinian corpuscle 

detecting steady pressure and virbrations.  They are rapidly adaptive and respond more to changes.

Meissner corpuscles

ruffini endings/ corpuscles

Subcutaneous layer

Pacinian corpuscles are also found here, even though they originate in the dermis

• Sebaceous gland: Not very active until puberty bc they are stimulated by the production of androgens. Almost always connected to hair follicles, secrete sebum (oil) for lubrication of skin/hair (keeps from drying
• out/evaporation), keeps skin soft, acts as bactericidal
• Eccrine Gland: More common in the
• body than apocrine glands. They produce sudoriferous (sweat), Originate in the
• dermis and open directly to the skin surface, numerously located over the body
• surface, produces thin watery secretions to regulate body temp.

• Apocrine Gland: Larger and
• located deep in the dermal layer. These sudoriferous gland empty into hair
• follicles and around primarily in the axillary and groin region, influenced by
• hormones, produces viscous secretions

• Nails: hard keratinized cells of
• epidermis, composed of: nail plate, free edge, nail bed, nail matrix,
• eponychium (cuticle), hyponychium, lunula

• Hair:comes in two primary ways: vessilus hair (unseeable) & terminal hair
• (seeable, coarse, head/genital/axillary)

• Vitiligo: It the absence of color causing pale/white patches to form on skin (hypopigmented). Sudden onset and can appear at any age. Possibly linked to hereditary predisposition, an autoimmune process, melanocyte destruction, or a lack of
• melanocyte production. aka.... Without melanocytes the cell cannot produce melanin and
• therefore no color. 

Albinism: a genetic disorder in which there is complete or partial congenital absence of pigment. This is caused by a lack of the enzyme tyrosinas, which is produced by melanocytes that converts tyrosine to a precursor of melanin. Persons with albinism lack pigmentation in the skin, hair, and iris of the eye. There is no cure for albinism. aka...has melanocytes but not the enzyme

Melasma: characterized by darkened macules on face (hyperpigmented). This condition is worsened by sun exposure. Can be treated with bleaching.

Ceruminous: located in external auditory canal. Secretes ear wax. 

Mammary glands: anatomically related to sweat glands but produces milk.

• 1st Degree Burn: superficial burn, only involves outer layers of the epidermis, they are red, pink, dry and painful (think sun burn). Usually no blister formation, heal in
• ~3-10 days

• 2nd Degree full thickness Burn: involve both the entire epidermis and the dermis. Blisters and edema form. They appear mottled pink, red, or waxy white areas. These burns
• heal in ~1 month, scar formation is normal, very painful (most pain sensors
• remain intact), need supportive medical care.

• 3rd Degree Burn: extends into subcutaneous tissue (can even involve muscle and bone), extensive edema, no pain because nerve sensors have been destroyed, usually surrounded by 2nd degree burns (which are surrounded by areas of 1st degree burns),  scar formation. Burns wider than 1.5 inches require skin grafts bc all regenerative elements have
• been destroyed. 

1) pressure (shocking!) 2) shearing force 3) friction 4)moisture

stage II. 

Stage one is the beginning, mostly just erythematous. 

• full-thickness loss involving
• damage/necrosis of subcutaneous tissue extending down to, but not through,
• underlying fascia. Manifests as deep crater

• Conduction: The direct transfer of heat from one molecule to another. Normally only a small amount of body heat is
• lost through conduction to a cooler surface

• Blood carries, or conducts heat from the inner
• core of the body to the skin surface

Radiation:Transfer of heat through air or a vacuum

• Heat loss with radiation varies with the
• temperature of the environment
• Environmental temperature must be less than that of the body for heat loss to occur

 

Convection: Heat transfer through the circulation of air currents. Think of a fan or wind chill.


Evaporation:Involves the use of body heat to convert water on the skin to water vapor

Sweating occurs through the sweat glands and is controlled by the sympathetic nervous system

• -      
• Sweating is mediated by Acetylcholine 

• o   Anticholinergic
• drugs can interfere with heat loss by interrupting sweating

• -      
• When the temperature of the surrounding
• environment is greater than skin temperature, evaporation is the only way the
• body can rid itself of heat

Temperature Increasing Mechanisms

• -      
• Thermoreceptors stimulate afferent nerve impulses trigger the heat promoting area of the hypotahalmus (heat loss area inhibited) ---->The Autonomic Nervous System and efferent fibers then triggers one or more of these:

o   Vasoconstriction

• o   Increase
• in metabolic rate

• o   Enhanced
• thyroxine release

o   Shivering

Temperature Decreasing Mechanisms

• -      
• Afferent nerve impulses trigger the heat loss
• area of hypothalamus (heat promoting area is inhibited) ---->The Autonomic Nervous System then triggers one  or more of these:

Vasodilation of blood vessels

 Sweating (sympathetic outflow tract to skin)

Decrease in heat production

• Intracranial
• Intra-thoracic 
• Intra-abdominal

• bacterial/viral illness
• brain tumor in the hypothalamus
• CNS injury
• Allergic rxn
• Environmental conditions such as heat stroke

• bacteria or breakdown products of bacteria
• are engulfed by phagocytic cells

• phagocytic cells release pyrogenic cytokines, (principally interleukin-1, interleukin-6 and
• tumor necrosis factor a)

These pyrogens get released into the bloodstream for transport to the hypothalamus where they exert their action (aka formation of prostaglandins)

• -      
• Prostaglandin E2 (PGE2) binds to receptors in the hypothalamus to raise its set point the hypothalamus initiates shivering and vasoconstriction that raise
• the body’s core temperature to the new set point and fever is established 

they block prostaglandin production, therefore the hypothalamus wont raise it's set point = no fever, chills, shakes ect..

examples: Ibuprofen, aspirin, acetaminophen

• Fever: represents an increase in body temperature that results from a cytokine induced increase in the set point of the
• thermostatic center in the hypothalamus by the production of prostaglandins by macrophages after they engulf bacteria/exogenous pyrogens.

Hyperthermia:The thermoregulatory center is overwhelmed by either excess heat production (hyperthyroidism), impaired heat loss (spinal cord injury), or excessive environmental heat (heat stoke). ***This is an increase in body temp without a change to the set point in the hypothalamus!***

Malignant Hyperthermia: Abnormal release of intracellular calcium from the sarcoplasmic reticulum causes sustained hypermetabolic rate and increased muscle contraction = fever and rigidity