Lesson 1:
1. Describe the functions of cells
- Movement: i.e. muscle cells, contraction of muscles in walls of the bladder expel urine
- Conductivity: conduction as a response to a stimulus is manifested by a wave of
excitation, an electrical potential that passes along the surface of the cell. This is the chief
function of nerve cells
- Metabolic absorption: take in and use nutrients and other substances from their
surroundings. Like cells of the intestine and kidneys
- Secretion: certain cells like mucous glands can synthesize new substances from
substances they absorb and then secrete the new substances to serve as needed elsewhere.
Like cells of the adrenal glands and ovaries which secrete hormones
- Excretion: all cells can rid themselves of waste products resulting from the metabolic
breakdown of nutrients. Lysosomes contain enzymes that break down or digest larger
molecules turning them into waste products that are released from the cell
- Respiration: cells absorb oxygen which is used to transform nutrients into energy in
the form of ATP. This occurs in the mitochondria
- Reproduction: tissue growth occurs as cells enlarge and reproduce themselves. Tissue
maintenance requires that new cells be produced to replace cells that are lost normally
through cellular death. Not all cells are capable of continuous division
- Communication: is vital for cells to survive as a society of cells. Pancreatic cells
secrete and release insulin necessary to signal muscle cells to absorb sugar from the blood
for energy.
2. Explain the processes that occur in the nucleus, ribosomes, endoplasmic reticulum, Golgi
complex, lysosomes and mitochondria
Nucleus: the command center of the cell
- Contains hereditary components ( genes, DNA), messenger RNA for protein synthesis
- Primary functions are cell division and cellular function (manufactures proteins), cell
reproduction, regeneration
- Outer membrane connects with ER and controls apoptosis
Ribosomes: are RNA protein complexes that are synthesized in the nucleolus and secreted into
the cytoplasm through pores in the nuclear envelope called nuclear pore complexes
- Build proteins, use amino acids
- Once constructed glucose is added (glycosylation), they fold, and then go to the Golgi
apparatus for final packing and delivery
Mitochondria: responsible for cellular respiration and energy production (making ATP)
- Metabolic pathways involved in metabolism of carbs, lipids, and amino acids and
special pathways involving urea and heme synthesis are located in the mitochondrial
matrix
- Other functions: stores calcium, apoptosis (programmed cell death), cellular
metabolism, regulation of growth and reproduction, synthesis of steroids.
, - There are more mitochondria in muscle cells vs others because muscle uses more
energy (higher metabolic rate)
Endoplasmic Reticulum: specializes in the synthesis and transport of the protein and lipid
components of most of the cells organelles
- Folds proteins, transports proteins, detoxifies substances, synthesizes lipids, stores
enzymes, metabolizes carbs
Lysosomes: destruction of cellular material or the cell when it is no longer useful
- Lysis of cellular waste i.e. fat, carbs, protein returned to the cytoplasm
- Destroys the entire cell when injured (i.e. trauma patients or ischemic patients)
Golgi Complex: distribution and shipping for cells products, modifies proteins and lipids that
have been built in the ER and prepares them for export or transport
3. Discuss how fluids move across the cell/plasma membrane
- Proteins facilitate transport across membranes by serving as receptors, enzymes, or
transporters.
- Proteins act as: 1) recognition and binding units for substances moving in and out of the
cell 2) pores or transport channels for various electrically charged particles called ions or
electrolytes and specific carriers for amino acids 3) specific enzymes that drive active
pumps that promote concentration of certain ions particularly K+ within the cell while
keeping concentrations of other ions like Na+ below the extracellular environment 4)
cell surface markers such as glycoproteins that identify a cell to its neighbor
Membrane proteins are key components of energy transduction, converting chemical
energy into electrical energy, or electrical energy into mechanical or synthesis of ATP
4. Compare and contrast the types of plasma membrane receptors pg. 22,26
- Channel linked: also known as ligand-gated channels, involves rapid synaptic
signaling between electrically excitable cell. Channel opens and closes in response to
neurotransmitters, changing the ion permeability of the plasma membrane
- Catalytic: these function directly as enzymes once activated by ligands, function as
tyrosine-specific protein kinases
- G-protein linked: indirectly activates or inactivates the plasma membrane enzyme or
ion channel, mediated by G-protein, when activated it alters the concentration of cAMP
and Ca+, or signaling molecules
5. Describe the cell junctions
- Cells in direct physical contact with neighboring cells are often linked together at
specialized regions of their plasma membranes called cell junctions.
Tight junctions: hold cells together, forming a tight seal, prevent oozing into other cells.
They are barriers to diffusion, they prevent the movement of substances in the plasma
membrane. Blood brain barrier is a tight junction through which few medications pass
Anchoring junctions: keeps cells attached to each other via desmosomes
Gap junctions: channels that allow small molecules and ions to be shared between cells
,6. Briefly describe cellular metabolism, noting the differences between aerobic and
anaerobic metabolism, noting ATP and lactic acid
7. Compare and contrast how water and solutes move across the cell membrane via passive
transport, closely looking at diffusion, filtration, and osmosis
Diffusion: the movement of a solute molecule from an area of greater concentration to
an area of lesser solute concentration (difference in concentration is known as
concentration gradient). Particles want to distribute themselves evenly, therefore if the
concentration is greater in one part than another, they will distribute themselves equally
throughout the solution. If the concentration of particles is greater on one side of a
permeable membrane than on the other side, the particles diffuse spontaneously from the
area of higher concentration to the area of lesser concentration until equilibrium is
reached. Rate of diffusion is influenced by electrical potential and the size of a substance
- oxygen, carbon dioxide, and steroid hormones are nonpolar and will diffuse more
rapidly
- sugars diffuse slowly, ions diffuse slowly
Filtration: is the movement of water and solutes through a membrane because of a greater
pushing pressure (force) on one side of the membrane than on the other
- hydrostatic pressure is the mechanical force of water pushing against cellular
membranes (i.e. blood pressure)
Osmosis: the movement of water down a concentration gradient from a region of higher
water concentration to a region of lower water concentration. For osmosis to occur the
membrane must be more permeable to water than to solutes and the concentration of solutes
must be greater so that water moves more easily.
Osmotic effect of colloids, such as plasma proteins, is called the oncotic pressure
8. Compare and contrast how electrolytes, sugars, amino acids move across the cell
membrane via active transport, closely looking at transport proteins and the Na-K pump
- Na+ moves out of cell and K+ moves into cell, using ATP to move
- The transporter protein is an enzyme called ATPase
- For every ATP molecule, three molecules of Na are transported out of the cell and 2
molecules of K are transported into the cell, leading to an electric potential, inside of cell
is more negative than outside. Forms an electrical gradient to develop across the
membrane, nerve and muscle cells use this gradient
- The transport of sugars and amino acids across the plasma membrane depends on the
simultaneous movement (symport) of Na. Na dependent symport occurs primarily in the
plasma membrane of epithelial cells of the kidney tubules and intestines.
- The epithelial cells that line the intestines depend on Na to transport various amino
acids.
, 9. Briefly examine endocytosis and exocytosis as the process for moving large molecules
across the cell membrane
- Endocytosis is a cellular internalizing process where a section of the plasma membrane
enfolds substances from outside the cell, folds inward and separates from the plasma
membrane, forming an endocytic vesicle that moves into the inside of the cell.
- mediates the cellular uptake of receptor ligand complexes, nutrients, extracellular
components, bacteria, viruses, debris, and sometimes even other cells
- Regulates the composition of the plasma membrane in response to changes in the
extracellular environment, counterbalances exocytosis and maintains homeostasis
- Exocytosis is the discharge or secretion of material from the intracellular vesicles at the
cell surface. It has two main functions 1) replacement of portions of the plasma
membrane that have been removed by endocytosis 2) release of molecules synthesized by
the cells into the extracellular matrix ( example pg. 34 with insulin)
10. Explain the pathophysiologic response to hypoxia in the cell, including anaerobic
metabolism with depletion of ATP, failure of the sodium-potassium pump, and
mitochondrial injury.
Most common cause of hypoxia is ischemia→ due to an obstruction of blood flow
This leads to decreased mitochondrial oxygenation which results in insufficient
ATP production
Lack of ATP leads to an increase in anaerobic metabolism which generates ATP
from glycogen when there is insufficient oxygen. When glycogen stores are
depleted there is increased lactate and decreased pH leading to nuclear chromatin
clumping
A reduction in ATP also causes the plasma membranes Na-K pump and sodium
calcium exchange to fail, resulting in increased intracellular sodium and calcium
causing the cell to swell and K to leave the cell
With continued hypoxia the entire cell becomes swollen and has increased
concentrations of Na, Cl and water, with decreased concentrations of K
These disruptions are reversible in O2. If not restored, the cytoplasm forms
vacuoles and the mitochondria swell resulting in damage
11. Describe how oxygen free radicals can lead to tissue injury; give examples of when this
phenomena is likely to occur and how free radical injury can be reduced with
antioxidants.
Free radicals are generated by 1) metabolic processes such as respiration 2)
absorption of extreme energy sources ( radiation, UV light) 3) metabolism of
chemicals, drugs, pesticides 4) metals (iron and copper) donating or accepting
electrons 5) nitric oxide and excessive production of OH (hydrogen peroxide)
Causes tissue injury by: 1) lipid peroxidation→ free radicals steal electrons from
lipids in the cell membrane which causes it to break or harden 2) alterations in
proteins leading to protein loss or misfolding 3) damage to mitochondrial DNA
which makes it unable to function
Antioxidants absorb the free radicals via fat soluble vitamins like A,C,E,
coenzyme Q, and selenium. Prevent free radicals from entering cell membrane
1. Describe the functions of cells
- Movement: i.e. muscle cells, contraction of muscles in walls of the bladder expel urine
- Conductivity: conduction as a response to a stimulus is manifested by a wave of
excitation, an electrical potential that passes along the surface of the cell. This is the chief
function of nerve cells
- Metabolic absorption: take in and use nutrients and other substances from their
surroundings. Like cells of the intestine and kidneys
- Secretion: certain cells like mucous glands can synthesize new substances from
substances they absorb and then secrete the new substances to serve as needed elsewhere.
Like cells of the adrenal glands and ovaries which secrete hormones
- Excretion: all cells can rid themselves of waste products resulting from the metabolic
breakdown of nutrients. Lysosomes contain enzymes that break down or digest larger
molecules turning them into waste products that are released from the cell
- Respiration: cells absorb oxygen which is used to transform nutrients into energy in
the form of ATP. This occurs in the mitochondria
- Reproduction: tissue growth occurs as cells enlarge and reproduce themselves. Tissue
maintenance requires that new cells be produced to replace cells that are lost normally
through cellular death. Not all cells are capable of continuous division
- Communication: is vital for cells to survive as a society of cells. Pancreatic cells
secrete and release insulin necessary to signal muscle cells to absorb sugar from the blood
for energy.
2. Explain the processes that occur in the nucleus, ribosomes, endoplasmic reticulum, Golgi
complex, lysosomes and mitochondria
Nucleus: the command center of the cell
- Contains hereditary components ( genes, DNA), messenger RNA for protein synthesis
- Primary functions are cell division and cellular function (manufactures proteins), cell
reproduction, regeneration
- Outer membrane connects with ER and controls apoptosis
Ribosomes: are RNA protein complexes that are synthesized in the nucleolus and secreted into
the cytoplasm through pores in the nuclear envelope called nuclear pore complexes
- Build proteins, use amino acids
- Once constructed glucose is added (glycosylation), they fold, and then go to the Golgi
apparatus for final packing and delivery
Mitochondria: responsible for cellular respiration and energy production (making ATP)
- Metabolic pathways involved in metabolism of carbs, lipids, and amino acids and
special pathways involving urea and heme synthesis are located in the mitochondrial
matrix
- Other functions: stores calcium, apoptosis (programmed cell death), cellular
metabolism, regulation of growth and reproduction, synthesis of steroids.
, - There are more mitochondria in muscle cells vs others because muscle uses more
energy (higher metabolic rate)
Endoplasmic Reticulum: specializes in the synthesis and transport of the protein and lipid
components of most of the cells organelles
- Folds proteins, transports proteins, detoxifies substances, synthesizes lipids, stores
enzymes, metabolizes carbs
Lysosomes: destruction of cellular material or the cell when it is no longer useful
- Lysis of cellular waste i.e. fat, carbs, protein returned to the cytoplasm
- Destroys the entire cell when injured (i.e. trauma patients or ischemic patients)
Golgi Complex: distribution and shipping for cells products, modifies proteins and lipids that
have been built in the ER and prepares them for export or transport
3. Discuss how fluids move across the cell/plasma membrane
- Proteins facilitate transport across membranes by serving as receptors, enzymes, or
transporters.
- Proteins act as: 1) recognition and binding units for substances moving in and out of the
cell 2) pores or transport channels for various electrically charged particles called ions or
electrolytes and specific carriers for amino acids 3) specific enzymes that drive active
pumps that promote concentration of certain ions particularly K+ within the cell while
keeping concentrations of other ions like Na+ below the extracellular environment 4)
cell surface markers such as glycoproteins that identify a cell to its neighbor
Membrane proteins are key components of energy transduction, converting chemical
energy into electrical energy, or electrical energy into mechanical or synthesis of ATP
4. Compare and contrast the types of plasma membrane receptors pg. 22,26
- Channel linked: also known as ligand-gated channels, involves rapid synaptic
signaling between electrically excitable cell. Channel opens and closes in response to
neurotransmitters, changing the ion permeability of the plasma membrane
- Catalytic: these function directly as enzymes once activated by ligands, function as
tyrosine-specific protein kinases
- G-protein linked: indirectly activates or inactivates the plasma membrane enzyme or
ion channel, mediated by G-protein, when activated it alters the concentration of cAMP
and Ca+, or signaling molecules
5. Describe the cell junctions
- Cells in direct physical contact with neighboring cells are often linked together at
specialized regions of their plasma membranes called cell junctions.
Tight junctions: hold cells together, forming a tight seal, prevent oozing into other cells.
They are barriers to diffusion, they prevent the movement of substances in the plasma
membrane. Blood brain barrier is a tight junction through which few medications pass
Anchoring junctions: keeps cells attached to each other via desmosomes
Gap junctions: channels that allow small molecules and ions to be shared between cells
,6. Briefly describe cellular metabolism, noting the differences between aerobic and
anaerobic metabolism, noting ATP and lactic acid
7. Compare and contrast how water and solutes move across the cell membrane via passive
transport, closely looking at diffusion, filtration, and osmosis
Diffusion: the movement of a solute molecule from an area of greater concentration to
an area of lesser solute concentration (difference in concentration is known as
concentration gradient). Particles want to distribute themselves evenly, therefore if the
concentration is greater in one part than another, they will distribute themselves equally
throughout the solution. If the concentration of particles is greater on one side of a
permeable membrane than on the other side, the particles diffuse spontaneously from the
area of higher concentration to the area of lesser concentration until equilibrium is
reached. Rate of diffusion is influenced by electrical potential and the size of a substance
- oxygen, carbon dioxide, and steroid hormones are nonpolar and will diffuse more
rapidly
- sugars diffuse slowly, ions diffuse slowly
Filtration: is the movement of water and solutes through a membrane because of a greater
pushing pressure (force) on one side of the membrane than on the other
- hydrostatic pressure is the mechanical force of water pushing against cellular
membranes (i.e. blood pressure)
Osmosis: the movement of water down a concentration gradient from a region of higher
water concentration to a region of lower water concentration. For osmosis to occur the
membrane must be more permeable to water than to solutes and the concentration of solutes
must be greater so that water moves more easily.
Osmotic effect of colloids, such as plasma proteins, is called the oncotic pressure
8. Compare and contrast how electrolytes, sugars, amino acids move across the cell
membrane via active transport, closely looking at transport proteins and the Na-K pump
- Na+ moves out of cell and K+ moves into cell, using ATP to move
- The transporter protein is an enzyme called ATPase
- For every ATP molecule, three molecules of Na are transported out of the cell and 2
molecules of K are transported into the cell, leading to an electric potential, inside of cell
is more negative than outside. Forms an electrical gradient to develop across the
membrane, nerve and muscle cells use this gradient
- The transport of sugars and amino acids across the plasma membrane depends on the
simultaneous movement (symport) of Na. Na dependent symport occurs primarily in the
plasma membrane of epithelial cells of the kidney tubules and intestines.
- The epithelial cells that line the intestines depend on Na to transport various amino
acids.
, 9. Briefly examine endocytosis and exocytosis as the process for moving large molecules
across the cell membrane
- Endocytosis is a cellular internalizing process where a section of the plasma membrane
enfolds substances from outside the cell, folds inward and separates from the plasma
membrane, forming an endocytic vesicle that moves into the inside of the cell.
- mediates the cellular uptake of receptor ligand complexes, nutrients, extracellular
components, bacteria, viruses, debris, and sometimes even other cells
- Regulates the composition of the plasma membrane in response to changes in the
extracellular environment, counterbalances exocytosis and maintains homeostasis
- Exocytosis is the discharge or secretion of material from the intracellular vesicles at the
cell surface. It has two main functions 1) replacement of portions of the plasma
membrane that have been removed by endocytosis 2) release of molecules synthesized by
the cells into the extracellular matrix ( example pg. 34 with insulin)
10. Explain the pathophysiologic response to hypoxia in the cell, including anaerobic
metabolism with depletion of ATP, failure of the sodium-potassium pump, and
mitochondrial injury.
Most common cause of hypoxia is ischemia→ due to an obstruction of blood flow
This leads to decreased mitochondrial oxygenation which results in insufficient
ATP production
Lack of ATP leads to an increase in anaerobic metabolism which generates ATP
from glycogen when there is insufficient oxygen. When glycogen stores are
depleted there is increased lactate and decreased pH leading to nuclear chromatin
clumping
A reduction in ATP also causes the plasma membranes Na-K pump and sodium
calcium exchange to fail, resulting in increased intracellular sodium and calcium
causing the cell to swell and K to leave the cell
With continued hypoxia the entire cell becomes swollen and has increased
concentrations of Na, Cl and water, with decreased concentrations of K
These disruptions are reversible in O2. If not restored, the cytoplasm forms
vacuoles and the mitochondria swell resulting in damage
11. Describe how oxygen free radicals can lead to tissue injury; give examples of when this
phenomena is likely to occur and how free radical injury can be reduced with
antioxidants.
Free radicals are generated by 1) metabolic processes such as respiration 2)
absorption of extreme energy sources ( radiation, UV light) 3) metabolism of
chemicals, drugs, pesticides 4) metals (iron and copper) donating or accepting
electrons 5) nitric oxide and excessive production of OH (hydrogen peroxide)
Causes tissue injury by: 1) lipid peroxidation→ free radicals steal electrons from
lipids in the cell membrane which causes it to break or harden 2) alterations in
proteins leading to protein loss or misfolding 3) damage to mitochondrial DNA
which makes it unable to function
Antioxidants absorb the free radicals via fat soluble vitamins like A,C,E,
coenzyme Q, and selenium. Prevent free radicals from entering cell membrane
