HLSC120 – Human Anatomy
Chapter 2: Cells
Cells – structural and functional units of all living organisms; building blocks of the General Functions of the Plasma Membrane
human body; adult human body contains about 75 trillion cells; composed of - Permit the entry of oxygen, sugars, amino acids and other nutrients
characteristic parts that work together to allow each cell type in the body to - Facilitate the disposal of carbon dioxide and metabolic wastes before they
perform specific functions; common characteristics of cells: accumulate in the cell
o All cells perform the general functions necessary to sustain life. Cells perform - Regulate the movement of other molecules across the membrane
chemical reactions to sustain life processes. Each cell must obtain nutrients and - Communication – facilitate recognition and response to specific molecular
other materials essential for survival from its surrounding fluids. signals in the ECF and to interact w/ other cells
o Cells must dispose of the wastes they produce or else the waste would build up - Intercellular connection – help establish a flexible boundary that protects the
in the cell and lead to its death. cellular contents and provides structural support to the cell
o The shape and integrity of the cell is maintained by both its internal contents - Physical barrier – keeps ICF and cellular contents w/n the cell and ECF outside
and its surrounding membrane. the cell
o Most cells undergo cell division to make more cells of the same type. - Selective permeability – some materials are able to pass across the plasma
o Cells vary in both shape and size but their shapes tend to be related directly to membrane, while others are effectively blocked; regulates the entry of ions,
their functions. nutrients, and wastes and secretory products, and restricts the movement of
o Compartmentalization – specific organelles perform specific functions. other materials
Cytology – study of cells; cyte means cells Structure of a Membrane consists of the ff:
Micrometer – unit of measurement used to measure cell size (1 micrometer = 1/10,000 cm) o a phospholipid bilayer – the head is hydrophilic (water loving) while the two tails
Microscopy – use of microscope; valuable asset in anatomic investigations (i.e. are hydrophobic (water hating / repelled by water), in between the two
colored dye stains are used in light microscope while heavy-metal stain phospholipids is a fatty acid, thus insoluble in water, this is the reason why the
preparations are used in transmission electron microscope, scanning electron membrane is held together and does not disintegrate; can move around and change
microscope) positions; fats and oils are examples of lipids
3 PRINCIPAL PARTS OF A CELL o cholesterol molecules – provides rigidity and fluidity; strengthens the membrane
Plasma (cell) membrane and stabilizes it at temperature extremes
forms the thin outer border of the cell; flexible layer / limiting barrier separating the o integral proteins / glycoproteins – carbohydrate protein; embedded across the
internal contents of the cell from the external materials; vital, selective barrier that phospholipid bilayer
functions as a “gatekeeper” to regulate the passage of gases, nutrients, and wastes o peripheral proteins – not embedded in the lipid bilayer; attached loosely to both
b/w internal and external environments; encloses all the components (organelles) the external and internal surface of the membrane, often to the exposed parts of
inside a cell; semi-permeable protective barrier; composed of an approx. equal the integral proteins; can float and move about the bilayer (like a beach ball floating
mixture of lipids and proteins forming a fluid matrix on the water surface in a pool)
Plasmalemma – another term for the plasma membrane; plasma means something o glycocalyx – “sweet husk”; fuzzy coat / hairy elements (purple in the diagram) found
formed and lemma means husk on the external surface of the plasma membrane; substance that determines which
Fluid mosaic model – the arrangement of molecules w/n the membrane resembles cell can be associated to which cell; identifies cell-to-cell interactions; responsible
a sea of phospholipid bilayer containing many types of protein boats; lipids act as a for cell-to-cell recognition
barrier to certain substances while proteins act as “gatekeepers” to certain o transmembrane proteins - span from one side of a membrane through to the other
molecules and ions side of the membrane
, Functions of membrane proteins are moved from a region of higher concentration to a lower concentration; no
o act as membrane channel providing a hole in the membrane through w/c cellular energy (ATP) is needed for the process to occur
substances pass Diffusion – movement of molecules from higher to lower concentrations;
o some integral proteins are ion channels (Na+ - K+) this movement continues until the molecules are at equilibrium (spread
o carriers or transporters – assists the movement of a particular substance across out evenly into the available space on each side of the membrane);
the membrane example is the movement of oxygen from the lungs into the blood while
o intercellular attachment – secure cells to each other carbon dioxide moves in the opposite direction in order to guarantee that
o anchorage for the cytoskeleton – cell shape is maintained by the attachment of the blood will receive oxygen and eliminate carbon dioxide as part of
structural proteins inside the cell to membrane proteins normal respiration
o receptors – for cellular recognition; serve as binding sites for molecules outside Osmosis – movement of water molecules from higher to lower
of the cell concentrations until equilibrium is reached (i.e. upstream to downstream,
o ligand – a specific molecule that binds w/ the right receptor effortless movement); example is movement of water between the blood
o enzymes – catalyze chemical reactions; change the rate of a reaction w/o being and the ECF around cells
affected by the reaction itself (i.e. peripheral and integral proteins) Facilitated diffusion – requires the participation of specific transport
o signal transduction – transmission of a message from a molecule outside the proteins that help specific substances or molecules move across the
cell to the inside of a cell, the cell then responds by changing its functional plasma membrane (i.e. substances insoluble in lipids); permits the
activities transport protein and molecule to pass across the membrane; such
o others act as cell-identity makers movements assisted by channel proteins (i.e. glucose and some amino
acids move across the membrane by this process)
Factors influencing membrane permeability
Bulk filtration – involves diffusion of both solvents and solutes together
Ion charge – atom with a net negative or positive charge may either be repulsed or
across the selectively permeable membrane (i.e. hydrostatic pressure (fluid
attracted to the membrane structures; influences molecular movement across the
pressure exerted by blood pushing against the inside wall of a blood vessel)
membrane
forces both water and solutes from the blood across the plasma
Lipid solubility – easily dissolve through the phospholipid bilayer, so lipid-soluble
membrane of cells lining the blod vessel
molecules can pass through the membrane more easily than non-lipid-soluble
Solvents – liquids that have substances
molecules can
Solutes – dissolved in them
Molecular size – smaller molecules move across the plasma membrane readily,
Active transport – when you want to swim upstream, you have to put more effort in
while larger molecules need special transport systems to move them across the
swimming since it is moving against the current; movement of a substance across a
membrane
plasma membrane against a concentration gradient so materials move from an area
Transport across the Plasma Membrane
of low concentration to high concentration; this process requires cellular energy in
Intracellular fluid (ICF) – inside body cells
the form of ATP
Extracellular fluid (ECF) – outside body cells
ATP – adenosine tri phosphate; energy currency of the cell; where the cell’s
Interstitial fluid – in between the fluid
keep their energy; can break down and release energy like heat or light;
Plasma – blood fluid
when it breaks down: ATP -> ADP + P + energy (in the form of heat)
Lymph – lymphatic vessel fluid
Ion pumps – helps a cell to maintain its internal concentrations of small
Passive transport – when you want to swim downstream, you don’t have to put as
molecules or ions
much effort in swimming because the current will simply bring you to your
Sodium-potassium pump – exchange pump; moves one ion into
destination; materials are moved along a concentration gradient, meaning that they
the cell while simultaneously removing another type of ion
Chapter 2: Cells
Cells – structural and functional units of all living organisms; building blocks of the General Functions of the Plasma Membrane
human body; adult human body contains about 75 trillion cells; composed of - Permit the entry of oxygen, sugars, amino acids and other nutrients
characteristic parts that work together to allow each cell type in the body to - Facilitate the disposal of carbon dioxide and metabolic wastes before they
perform specific functions; common characteristics of cells: accumulate in the cell
o All cells perform the general functions necessary to sustain life. Cells perform - Regulate the movement of other molecules across the membrane
chemical reactions to sustain life processes. Each cell must obtain nutrients and - Communication – facilitate recognition and response to specific molecular
other materials essential for survival from its surrounding fluids. signals in the ECF and to interact w/ other cells
o Cells must dispose of the wastes they produce or else the waste would build up - Intercellular connection – help establish a flexible boundary that protects the
in the cell and lead to its death. cellular contents and provides structural support to the cell
o The shape and integrity of the cell is maintained by both its internal contents - Physical barrier – keeps ICF and cellular contents w/n the cell and ECF outside
and its surrounding membrane. the cell
o Most cells undergo cell division to make more cells of the same type. - Selective permeability – some materials are able to pass across the plasma
o Cells vary in both shape and size but their shapes tend to be related directly to membrane, while others are effectively blocked; regulates the entry of ions,
their functions. nutrients, and wastes and secretory products, and restricts the movement of
o Compartmentalization – specific organelles perform specific functions. other materials
Cytology – study of cells; cyte means cells Structure of a Membrane consists of the ff:
Micrometer – unit of measurement used to measure cell size (1 micrometer = 1/10,000 cm) o a phospholipid bilayer – the head is hydrophilic (water loving) while the two tails
Microscopy – use of microscope; valuable asset in anatomic investigations (i.e. are hydrophobic (water hating / repelled by water), in between the two
colored dye stains are used in light microscope while heavy-metal stain phospholipids is a fatty acid, thus insoluble in water, this is the reason why the
preparations are used in transmission electron microscope, scanning electron membrane is held together and does not disintegrate; can move around and change
microscope) positions; fats and oils are examples of lipids
3 PRINCIPAL PARTS OF A CELL o cholesterol molecules – provides rigidity and fluidity; strengthens the membrane
Plasma (cell) membrane and stabilizes it at temperature extremes
forms the thin outer border of the cell; flexible layer / limiting barrier separating the o integral proteins / glycoproteins – carbohydrate protein; embedded across the
internal contents of the cell from the external materials; vital, selective barrier that phospholipid bilayer
functions as a “gatekeeper” to regulate the passage of gases, nutrients, and wastes o peripheral proteins – not embedded in the lipid bilayer; attached loosely to both
b/w internal and external environments; encloses all the components (organelles) the external and internal surface of the membrane, often to the exposed parts of
inside a cell; semi-permeable protective barrier; composed of an approx. equal the integral proteins; can float and move about the bilayer (like a beach ball floating
mixture of lipids and proteins forming a fluid matrix on the water surface in a pool)
Plasmalemma – another term for the plasma membrane; plasma means something o glycocalyx – “sweet husk”; fuzzy coat / hairy elements (purple in the diagram) found
formed and lemma means husk on the external surface of the plasma membrane; substance that determines which
Fluid mosaic model – the arrangement of molecules w/n the membrane resembles cell can be associated to which cell; identifies cell-to-cell interactions; responsible
a sea of phospholipid bilayer containing many types of protein boats; lipids act as a for cell-to-cell recognition
barrier to certain substances while proteins act as “gatekeepers” to certain o transmembrane proteins - span from one side of a membrane through to the other
molecules and ions side of the membrane
, Functions of membrane proteins are moved from a region of higher concentration to a lower concentration; no
o act as membrane channel providing a hole in the membrane through w/c cellular energy (ATP) is needed for the process to occur
substances pass Diffusion – movement of molecules from higher to lower concentrations;
o some integral proteins are ion channels (Na+ - K+) this movement continues until the molecules are at equilibrium (spread
o carriers or transporters – assists the movement of a particular substance across out evenly into the available space on each side of the membrane);
the membrane example is the movement of oxygen from the lungs into the blood while
o intercellular attachment – secure cells to each other carbon dioxide moves in the opposite direction in order to guarantee that
o anchorage for the cytoskeleton – cell shape is maintained by the attachment of the blood will receive oxygen and eliminate carbon dioxide as part of
structural proteins inside the cell to membrane proteins normal respiration
o receptors – for cellular recognition; serve as binding sites for molecules outside Osmosis – movement of water molecules from higher to lower
of the cell concentrations until equilibrium is reached (i.e. upstream to downstream,
o ligand – a specific molecule that binds w/ the right receptor effortless movement); example is movement of water between the blood
o enzymes – catalyze chemical reactions; change the rate of a reaction w/o being and the ECF around cells
affected by the reaction itself (i.e. peripheral and integral proteins) Facilitated diffusion – requires the participation of specific transport
o signal transduction – transmission of a message from a molecule outside the proteins that help specific substances or molecules move across the
cell to the inside of a cell, the cell then responds by changing its functional plasma membrane (i.e. substances insoluble in lipids); permits the
activities transport protein and molecule to pass across the membrane; such
o others act as cell-identity makers movements assisted by channel proteins (i.e. glucose and some amino
acids move across the membrane by this process)
Factors influencing membrane permeability
Bulk filtration – involves diffusion of both solvents and solutes together
Ion charge – atom with a net negative or positive charge may either be repulsed or
across the selectively permeable membrane (i.e. hydrostatic pressure (fluid
attracted to the membrane structures; influences molecular movement across the
pressure exerted by blood pushing against the inside wall of a blood vessel)
membrane
forces both water and solutes from the blood across the plasma
Lipid solubility – easily dissolve through the phospholipid bilayer, so lipid-soluble
membrane of cells lining the blod vessel
molecules can pass through the membrane more easily than non-lipid-soluble
Solvents – liquids that have substances
molecules can
Solutes – dissolved in them
Molecular size – smaller molecules move across the plasma membrane readily,
Active transport – when you want to swim upstream, you have to put more effort in
while larger molecules need special transport systems to move them across the
swimming since it is moving against the current; movement of a substance across a
membrane
plasma membrane against a concentration gradient so materials move from an area
Transport across the Plasma Membrane
of low concentration to high concentration; this process requires cellular energy in
Intracellular fluid (ICF) – inside body cells
the form of ATP
Extracellular fluid (ECF) – outside body cells
ATP – adenosine tri phosphate; energy currency of the cell; where the cell’s
Interstitial fluid – in between the fluid
keep their energy; can break down and release energy like heat or light;
Plasma – blood fluid
when it breaks down: ATP -> ADP + P + energy (in the form of heat)
Lymph – lymphatic vessel fluid
Ion pumps – helps a cell to maintain its internal concentrations of small
Passive transport – when you want to swim downstream, you don’t have to put as
molecules or ions
much effort in swimming because the current will simply bring you to your
Sodium-potassium pump – exchange pump; moves one ion into
destination; materials are moved along a concentration gradient, meaning that they
the cell while simultaneously removing another type of ion
