Anatomy and physiology
Orientation of the human body
Anatomy: the study of the structure and shape of the body and its parts as well as their relationships to one another. Gross and microscopic anatomy.
Physiology: the study of how the body and its parts function. Neuro- and cardiac physiology.
Relationship between anatomy and physiology - inseparable as structure determines the function.
Levels of structural organisation
Atoms -> molecules -> cells -> tissue -> organs -> organ systems -> organisms
Organ systems
‣ Urinary system: removes nitrogen containing wastes from blood stream.
‣ Excretory system: Maintain water and salt balance. kidneys, bladder and ureters.
‣ Reproductive system: produce an offspring. Ovary, uterus, vagina. Penis, testis, scrotum.
‣ Integumentary system: external covering of the body. Skin, hair and nails. Waterproofs the body, protects from sunlight and helps regulate body
temperature
‣ Skeletal system: bones, cartilage and joints. Supports the body and provides a framework to cause movement. Stores minerals and create blood cells.
‣ Muscular system: manipulation of the environment, maintains posture and produces heat. Contract or shorten. Skeletal muscles.
‣ Nervous system: control system. Responds to internal and external change by activating appropriate muscles and glands. Brain, spinal cord, nerves.
‣ Cardiovascular system: blood vessels transport blood, which carries oxygen, nutrients, hormones and waste. Heart and blood vessels.
‣ Endocrine system: glands secrete hormones that regulate processes like growth, reproduction and nutrient use. Thyroid, pancreas and adrenals.
‣ Lymphatic system: lymph nodes, spleen, and tonsils. Returns leaked fluid to the bloodstream and cleanses the blood.
‣ Digestive system: oral cavity, oesophagus and stomach. Break down food and deliver nutrients to the blood.
‣ Respiratory system: keep the body supplied with oxygen and remove carbon dioxide. Larynx, pharynx and lungs.
Necessary life functions
Maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth
Survival needs
Nutrients, oxygen, water, normal body temperature and atmospheric pressure
Anatomical position: Common reference for describing surfaces, relationships and directions of movement.
◦ the body is upright
◦ feet slightly apart
◦ toes pointing forward.
◦ arms hang at sides
◦ palms face forward
Body planes (along which movement takes place)
• Sagittal plane - divides the body into left and right. Median sagittal divides the body in equal parts left and right
• Coronal or frontal - divides the body into front and back
• Horizontal or transverse - divides the body into upper and lower parts
Surfaces of the body
• Anterior / ventral: forward or in front of
• Posterior / dorsal: backward or behind
• Medial: towards the midline
• Lateral: further from the midline
• Proximal: towards the origin
• Distal: further from the origin
• Superficial: towards the surface
• Deep: further from the surface, more internal
• Superior / cranial / cephalad : higher or towards the head
• Inferior / caudal: lower or below
Homeostasis
Balance, dynamic state if equilibrium. Imbalance leads to illness. Stimulus - receptor - input - control centre - output - effector - response.
- Receptor: sensor that monitors and responds to stimuli in the environment. Afferent pathway to control centre.
- Control centre: determines the set point variables are to be maintained at. Analyses info and determines response. Efferent pathway to effector.
- Effector: results to the response and feedback to the stimulus
◦ negative feedback: reduce amount of change by shutting off the mechanism or reducing intensity
◦ positive feedback: increase the amount of change at a faster rate
, cells and tissues
Structural unit of all living things. The body has 50 to 100 trillion cells, that are 60% water. Composed of carbon, hydrogen, oxygen and nitrogen.
Cell theory:
1. Cell is the basic structural and functional unit of all living organisms
2. The activity of an organism depends on the collective activities if its cells
3. Principle of complementarity: biochemical activities if cells are dictated by the relative number if their specific sub cellular structures.
4. Continuity of life has a cellular basis.
General anatomy of a cell
• Nucleus: control centre of the cell. Contains genetic material - deoxyribonucleic acid (DNA) - which is necessary for building proteins and cell production
- nuclear envelope (membrane): consists of a double membrane that bounds the nucleus.
Contains nuclear pores that allow for exchange of material with the rest of the cell.
Encloses the nucleoplasm. Contains one or more nucleoli.
- nucleolus: site of ribosome assembly. Ribosomes migrate into the cytoplasm through nuclear pores to serve as the site of protein synthesis.
- chromatin: composed of histone protein and DNA. Present when the cell is not dividing and is scattered throughout the nucleus. Condense to form
dense, rod-like bodies called chromosomes when the cell divides.
• Cytoplasm: material outside the nucleus and inside the plasma membrane. Site of most cellular activities.
- cytosol: fluid that suspends other elements
- inclusions : chemical substances, such as stored nutrients or cell products
- organelles: metabolic machinery of the cell. Little organs that perform functions for the cells. Specialised cellular compartments that are membrane
bound. Compartmentalisation is critical for organelle’s ability to perform specialised functions.
▫ mitochondria: powerhouse if the cell. Change shape continuously. Double membrane wall with cristae. Carry out reactions where oxygen is
used to break down food and provide ATP (adenosine triphosphate) for cellular energy.
▫ ribosomes: bilobed dark bodies. Made of protein and ribosomal RNA. Site of protein synthesis. Found in the cytoplasm and part of rough
ER.
▫ endoplasmic reticulum: fluid filled cistern. Tunnel system for fat and protein synthesis within the cell..
• rough ER: studded with ribosomes. Protein synthesis. Transport vesicles that make, export and move proteins within the cell. protein
that is synthesised on the ribosome, migrates into rough ER cistern. Protein then folds into a functional shale. Short sugar chains
attach to the protein and forms glycoprotein. Protein is packaged into membranous sacs called transport vesicles. Travels to Golgi
apparatus for further processing.
• smooth ER: functions in lipid metabolism. Detoxification of drugs and pesticides
▫ Golgi apparatus: appears as a stack of flattened membranes associated with tiny vesicles. Modifies and packages proteins. Produces
different types of packages: secretory vesicle (exocytosis) , in-house proteins and lipids and lysosomes.
▫ Lysosomes: ribosomes produce enzymes that are then packaged by the Golgi into membranous sacks. Enzymes digest non usable cell
structures. Houses phagocytes that dispose of bacteria and cell debris.
▫ Peroxisomes: membranous sacs of oxidase enzymes. Detoxify harmful substances and breaks down free radicals. Free radicals are
converted to hydrogen peroxide and then to water. Replicate by pinching in half or budding from the ER.
▫ Centrioles: made up of microtubules and also generates microtubules. Direct the formation of the mitotic spindle during cell division.
▫ Cytoskeleton: network of protein structures that extend throughout the cytoplasm and provides the cell with an internal framework. Aids in
cellular support and motion.
• microfilaments: protein actin, blue bat like network. Muscle contraction and intracellular movement.
Help form the cytoskeleton.
• Intermediate filaments: fibrous subunits. Purple network surrounding the nucleus. Protein fibres .
Stable cytoskeleton element. Resist mechanical forces acting on the cell.
• microtubules: tubulin subunits. Gold network surrounding the nucleus. Form the spindle and asters during cell division. Form the base
of flagella and cilia.
cell extensions: surface extensions found in some cells
o cilia move materials across the cell surface: located in the respiratory system to move mucus
o flagella propel the cell: sperm is the only flagellated cell
o Microvilli: tiny fingerlike extensions of the plasma membrane that increase the surface area for absorption
• Plasma membrane : transparent barrier for cell contents and separates cell contents from surrounding environment. Contains cell contents.
Phospholipids are a good foundation for cell membranes, because they are polar molecules - the charged end interacts with water and the fatty acid
chains do not. Externally facing proteins act as receptors, transport proteins and cell-to-cell recognition.
- fluid mosaic model
o phospholipids: hydrophilic ( water loving) polar heads orientated on the inner and outer surfaces of the membrane. hydrophobic (water
hating) non polar tails form the interior of the membrane.
plasma membrane is impermeable to water-soluble molecules.
o cholesterol
o proteins: responsible for specialised functions. Roles of proteins: enzymes, receptors and transport as channels or carriers.
o sugars: glycoproteins are branched sugars attached to proteins that abut the extracellular space.
Glycocalyx is the fuzzy, sticky , sugar-rich area on the cell’s surface.
- membrane junctions. Cells are bound together in 3 ways:
• glycoproteins in the glycocalyx act as an adhesive or cellular glue.
• wavy contours if the membranes if adjacent cells fit together in a tongue and groove fashion.
• Special membrane junctions are formed, which vary structurally depending on their roles
▫ tight junctions: impermeable, bind cells in leakproof sheets, prevent substances from passing through extra cellular space.
▫ desmosomes: anchoring junctions that prevents tearing from mechanical stress.
Button like thickenings of adjacent plasma membranes.
▫ gap junctions: allow communication between cells. Hollow cylinders of proteins (connexons) span the width of the abutting
membranes. Molecules can travel between cells through these channels
Cell diversity
The human body has over 200 different cell types. Cells can be 1/12000 of an inch to over 1 yard (nerve cells). Cell shape reflects its specialised function
Cells have the ability to metabolise, digest food, dispose of waste, reproduce, grow, move and respond to stimulus.
, • Connects body parts
o fibroblasts: secrets cable-like fibres. Rough ER and Golgi apparatus.
o erythrocytes: carries oxygen in the blood stream. No organelles.
• Cover and line body organs
o epithelial cells: packed together in sheets. Intermediate fibres resist tearing during rubbing and pulling
• Move organs and body parts
o skeletal muscle and smooth muscle cells: contractile filaments allow cells to shorten forcefully.
• Stores nutrients
o fat cells: lipid droplets stored in cytoplasm.
• Fights disease
o macrophage (phagocytic cell): digest infectious micro-organisms. Contains lots of lysosomes
• Gather information and controls body function
o nerve cell (neuron): receive and transmit messages to other body structures. Cell has lots of rough ER.
• Reproduction
o oocyte: largest cell in the female body. Divides to become an embryo upon fertilisation.
o Sperm: built for swimming to the egg for fertilisation. Flagellum acts as a motile whip.
Membrane transport
Solution: homogenous mixture of two or more components. Solvent is the dissolving medium, and the solutes are the components in smaller quantities
within the solution.
Intracellular fluid: nucleoplasm and cytosol. Solution containing gasses, nutrients and salts dissolved in water.
Interstitial fluid: fluid on the exterior of the cell. Contains thousands of ingredients, such as nutrients, hormones, and waste products.
Plasma membrane is a selectively permeable barrier. Nutrients can pass through the cell, while undesirable substance cannot pass through the membrane.
• Passive process - no energy (ATP) is required
◦ diffusion: particles distribute evenly within a solution. Kinetic energy is the driving force that causes molecules to move about randomly. Molecule
movement is down a concentration gradient. The size of the molecule and the temperature affects the speed of diffusion.
‣ simple diffusion: unassisted process. Solutes are lipid-soluble or small enough to pass through membrane pores.
‣ osmosis: water moves down in concentration gradient. Highly polar water molecules easily cross the plasma membrane through aquaporins.
Isotonic solutions: same solute and water concentrations as cells. No visible changes in the cell.
Two solutions have the same concentration.
Hypertonic solutions: contain more solutes than cells do. Cell will begin to shrink (crenation).
High concentration of dissolved substances.
Hypotonic solutions: contain fewer solutes and more water than cells and the cells will thus plump up (hemolysis).
High concentration of water.
• molecules are small enough to pass through the membrane’s pores.
• molecules are lipid-soluble
• molecules are assisted by membrane carrier
‣ facilitated diffusion
• transport lipid-insoluble and large substances
• glucose is transported via facilitated diffusion
• Uses protein membrane channels or protein molecules that act as carriers
‣ filtration: water and solutes are forced through a membrane from a high to low pressure area by fluid or hydrostatic pressure. Pressure gradient
must exist. Is critical for the kidneys to work properly.
• Active process - cell must provide metabolic energy (ATP). Protein carriers known as solute pumps transport amino acids, sugars and ions.
◦ too large to travel through membrane channels
◦ not lipid soluble
◦ move against the concentration gradient.
‣ sodium-potassium pump: sodium is transported out of the cell and potassium is transported into the cell.
‣ Vesicular transport: substances are moved without crossing the plasma membrane
• exocytosis: moves materials out of the cell. Material is carried in a vesicle, that migrates and then combines with the plasma membrane. The
material is them emptied to the outside.
• endocytosis: extracellular substances are engulfed by being enclosed in membranous vesicle. Vesicle fuses with lysosome and the contents
are then digested by lysosomal enzymes. The vesicle is released by exocytosis on the opposite side of the cell.
◦ phagocytosis: cell engulfs large particles like bacteria and dead skin cells. Pseudopods are cytoplasmic extensions that separates
substances from external environment. Phagocytosis is a protective mechanism.
◦ pinocytosis: cell gulps droplets if extracellular fluid containing dissolved proteins or fats. Plasma membrane forms a pit, and edges fuse
around droplet of fluid. Routine activity for absorption like in the small intestine.
Orientation of the human body
Anatomy: the study of the structure and shape of the body and its parts as well as their relationships to one another. Gross and microscopic anatomy.
Physiology: the study of how the body and its parts function. Neuro- and cardiac physiology.
Relationship between anatomy and physiology - inseparable as structure determines the function.
Levels of structural organisation
Atoms -> molecules -> cells -> tissue -> organs -> organ systems -> organisms
Organ systems
‣ Urinary system: removes nitrogen containing wastes from blood stream.
‣ Excretory system: Maintain water and salt balance. kidneys, bladder and ureters.
‣ Reproductive system: produce an offspring. Ovary, uterus, vagina. Penis, testis, scrotum.
‣ Integumentary system: external covering of the body. Skin, hair and nails. Waterproofs the body, protects from sunlight and helps regulate body
temperature
‣ Skeletal system: bones, cartilage and joints. Supports the body and provides a framework to cause movement. Stores minerals and create blood cells.
‣ Muscular system: manipulation of the environment, maintains posture and produces heat. Contract or shorten. Skeletal muscles.
‣ Nervous system: control system. Responds to internal and external change by activating appropriate muscles and glands. Brain, spinal cord, nerves.
‣ Cardiovascular system: blood vessels transport blood, which carries oxygen, nutrients, hormones and waste. Heart and blood vessels.
‣ Endocrine system: glands secrete hormones that regulate processes like growth, reproduction and nutrient use. Thyroid, pancreas and adrenals.
‣ Lymphatic system: lymph nodes, spleen, and tonsils. Returns leaked fluid to the bloodstream and cleanses the blood.
‣ Digestive system: oral cavity, oesophagus and stomach. Break down food and deliver nutrients to the blood.
‣ Respiratory system: keep the body supplied with oxygen and remove carbon dioxide. Larynx, pharynx and lungs.
Necessary life functions
Maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth
Survival needs
Nutrients, oxygen, water, normal body temperature and atmospheric pressure
Anatomical position: Common reference for describing surfaces, relationships and directions of movement.
◦ the body is upright
◦ feet slightly apart
◦ toes pointing forward.
◦ arms hang at sides
◦ palms face forward
Body planes (along which movement takes place)
• Sagittal plane - divides the body into left and right. Median sagittal divides the body in equal parts left and right
• Coronal or frontal - divides the body into front and back
• Horizontal or transverse - divides the body into upper and lower parts
Surfaces of the body
• Anterior / ventral: forward or in front of
• Posterior / dorsal: backward or behind
• Medial: towards the midline
• Lateral: further from the midline
• Proximal: towards the origin
• Distal: further from the origin
• Superficial: towards the surface
• Deep: further from the surface, more internal
• Superior / cranial / cephalad : higher or towards the head
• Inferior / caudal: lower or below
Homeostasis
Balance, dynamic state if equilibrium. Imbalance leads to illness. Stimulus - receptor - input - control centre - output - effector - response.
- Receptor: sensor that monitors and responds to stimuli in the environment. Afferent pathway to control centre.
- Control centre: determines the set point variables are to be maintained at. Analyses info and determines response. Efferent pathway to effector.
- Effector: results to the response and feedback to the stimulus
◦ negative feedback: reduce amount of change by shutting off the mechanism or reducing intensity
◦ positive feedback: increase the amount of change at a faster rate
, cells and tissues
Structural unit of all living things. The body has 50 to 100 trillion cells, that are 60% water. Composed of carbon, hydrogen, oxygen and nitrogen.
Cell theory:
1. Cell is the basic structural and functional unit of all living organisms
2. The activity of an organism depends on the collective activities if its cells
3. Principle of complementarity: biochemical activities if cells are dictated by the relative number if their specific sub cellular structures.
4. Continuity of life has a cellular basis.
General anatomy of a cell
• Nucleus: control centre of the cell. Contains genetic material - deoxyribonucleic acid (DNA) - which is necessary for building proteins and cell production
- nuclear envelope (membrane): consists of a double membrane that bounds the nucleus.
Contains nuclear pores that allow for exchange of material with the rest of the cell.
Encloses the nucleoplasm. Contains one or more nucleoli.
- nucleolus: site of ribosome assembly. Ribosomes migrate into the cytoplasm through nuclear pores to serve as the site of protein synthesis.
- chromatin: composed of histone protein and DNA. Present when the cell is not dividing and is scattered throughout the nucleus. Condense to form
dense, rod-like bodies called chromosomes when the cell divides.
• Cytoplasm: material outside the nucleus and inside the plasma membrane. Site of most cellular activities.
- cytosol: fluid that suspends other elements
- inclusions : chemical substances, such as stored nutrients or cell products
- organelles: metabolic machinery of the cell. Little organs that perform functions for the cells. Specialised cellular compartments that are membrane
bound. Compartmentalisation is critical for organelle’s ability to perform specialised functions.
▫ mitochondria: powerhouse if the cell. Change shape continuously. Double membrane wall with cristae. Carry out reactions where oxygen is
used to break down food and provide ATP (adenosine triphosphate) for cellular energy.
▫ ribosomes: bilobed dark bodies. Made of protein and ribosomal RNA. Site of protein synthesis. Found in the cytoplasm and part of rough
ER.
▫ endoplasmic reticulum: fluid filled cistern. Tunnel system for fat and protein synthesis within the cell..
• rough ER: studded with ribosomes. Protein synthesis. Transport vesicles that make, export and move proteins within the cell. protein
that is synthesised on the ribosome, migrates into rough ER cistern. Protein then folds into a functional shale. Short sugar chains
attach to the protein and forms glycoprotein. Protein is packaged into membranous sacs called transport vesicles. Travels to Golgi
apparatus for further processing.
• smooth ER: functions in lipid metabolism. Detoxification of drugs and pesticides
▫ Golgi apparatus: appears as a stack of flattened membranes associated with tiny vesicles. Modifies and packages proteins. Produces
different types of packages: secretory vesicle (exocytosis) , in-house proteins and lipids and lysosomes.
▫ Lysosomes: ribosomes produce enzymes that are then packaged by the Golgi into membranous sacks. Enzymes digest non usable cell
structures. Houses phagocytes that dispose of bacteria and cell debris.
▫ Peroxisomes: membranous sacs of oxidase enzymes. Detoxify harmful substances and breaks down free radicals. Free radicals are
converted to hydrogen peroxide and then to water. Replicate by pinching in half or budding from the ER.
▫ Centrioles: made up of microtubules and also generates microtubules. Direct the formation of the mitotic spindle during cell division.
▫ Cytoskeleton: network of protein structures that extend throughout the cytoplasm and provides the cell with an internal framework. Aids in
cellular support and motion.
• microfilaments: protein actin, blue bat like network. Muscle contraction and intracellular movement.
Help form the cytoskeleton.
• Intermediate filaments: fibrous subunits. Purple network surrounding the nucleus. Protein fibres .
Stable cytoskeleton element. Resist mechanical forces acting on the cell.
• microtubules: tubulin subunits. Gold network surrounding the nucleus. Form the spindle and asters during cell division. Form the base
of flagella and cilia.
cell extensions: surface extensions found in some cells
o cilia move materials across the cell surface: located in the respiratory system to move mucus
o flagella propel the cell: sperm is the only flagellated cell
o Microvilli: tiny fingerlike extensions of the plasma membrane that increase the surface area for absorption
• Plasma membrane : transparent barrier for cell contents and separates cell contents from surrounding environment. Contains cell contents.
Phospholipids are a good foundation for cell membranes, because they are polar molecules - the charged end interacts with water and the fatty acid
chains do not. Externally facing proteins act as receptors, transport proteins and cell-to-cell recognition.
- fluid mosaic model
o phospholipids: hydrophilic ( water loving) polar heads orientated on the inner and outer surfaces of the membrane. hydrophobic (water
hating) non polar tails form the interior of the membrane.
plasma membrane is impermeable to water-soluble molecules.
o cholesterol
o proteins: responsible for specialised functions. Roles of proteins: enzymes, receptors and transport as channels or carriers.
o sugars: glycoproteins are branched sugars attached to proteins that abut the extracellular space.
Glycocalyx is the fuzzy, sticky , sugar-rich area on the cell’s surface.
- membrane junctions. Cells are bound together in 3 ways:
• glycoproteins in the glycocalyx act as an adhesive or cellular glue.
• wavy contours if the membranes if adjacent cells fit together in a tongue and groove fashion.
• Special membrane junctions are formed, which vary structurally depending on their roles
▫ tight junctions: impermeable, bind cells in leakproof sheets, prevent substances from passing through extra cellular space.
▫ desmosomes: anchoring junctions that prevents tearing from mechanical stress.
Button like thickenings of adjacent plasma membranes.
▫ gap junctions: allow communication between cells. Hollow cylinders of proteins (connexons) span the width of the abutting
membranes. Molecules can travel between cells through these channels
Cell diversity
The human body has over 200 different cell types. Cells can be 1/12000 of an inch to over 1 yard (nerve cells). Cell shape reflects its specialised function
Cells have the ability to metabolise, digest food, dispose of waste, reproduce, grow, move and respond to stimulus.
, • Connects body parts
o fibroblasts: secrets cable-like fibres. Rough ER and Golgi apparatus.
o erythrocytes: carries oxygen in the blood stream. No organelles.
• Cover and line body organs
o epithelial cells: packed together in sheets. Intermediate fibres resist tearing during rubbing and pulling
• Move organs and body parts
o skeletal muscle and smooth muscle cells: contractile filaments allow cells to shorten forcefully.
• Stores nutrients
o fat cells: lipid droplets stored in cytoplasm.
• Fights disease
o macrophage (phagocytic cell): digest infectious micro-organisms. Contains lots of lysosomes
• Gather information and controls body function
o nerve cell (neuron): receive and transmit messages to other body structures. Cell has lots of rough ER.
• Reproduction
o oocyte: largest cell in the female body. Divides to become an embryo upon fertilisation.
o Sperm: built for swimming to the egg for fertilisation. Flagellum acts as a motile whip.
Membrane transport
Solution: homogenous mixture of two or more components. Solvent is the dissolving medium, and the solutes are the components in smaller quantities
within the solution.
Intracellular fluid: nucleoplasm and cytosol. Solution containing gasses, nutrients and salts dissolved in water.
Interstitial fluid: fluid on the exterior of the cell. Contains thousands of ingredients, such as nutrients, hormones, and waste products.
Plasma membrane is a selectively permeable barrier. Nutrients can pass through the cell, while undesirable substance cannot pass through the membrane.
• Passive process - no energy (ATP) is required
◦ diffusion: particles distribute evenly within a solution. Kinetic energy is the driving force that causes molecules to move about randomly. Molecule
movement is down a concentration gradient. The size of the molecule and the temperature affects the speed of diffusion.
‣ simple diffusion: unassisted process. Solutes are lipid-soluble or small enough to pass through membrane pores.
‣ osmosis: water moves down in concentration gradient. Highly polar water molecules easily cross the plasma membrane through aquaporins.
Isotonic solutions: same solute and water concentrations as cells. No visible changes in the cell.
Two solutions have the same concentration.
Hypertonic solutions: contain more solutes than cells do. Cell will begin to shrink (crenation).
High concentration of dissolved substances.
Hypotonic solutions: contain fewer solutes and more water than cells and the cells will thus plump up (hemolysis).
High concentration of water.
• molecules are small enough to pass through the membrane’s pores.
• molecules are lipid-soluble
• molecules are assisted by membrane carrier
‣ facilitated diffusion
• transport lipid-insoluble and large substances
• glucose is transported via facilitated diffusion
• Uses protein membrane channels or protein molecules that act as carriers
‣ filtration: water and solutes are forced through a membrane from a high to low pressure area by fluid or hydrostatic pressure. Pressure gradient
must exist. Is critical for the kidneys to work properly.
• Active process - cell must provide metabolic energy (ATP). Protein carriers known as solute pumps transport amino acids, sugars and ions.
◦ too large to travel through membrane channels
◦ not lipid soluble
◦ move against the concentration gradient.
‣ sodium-potassium pump: sodium is transported out of the cell and potassium is transported into the cell.
‣ Vesicular transport: substances are moved without crossing the plasma membrane
• exocytosis: moves materials out of the cell. Material is carried in a vesicle, that migrates and then combines with the plasma membrane. The
material is them emptied to the outside.
• endocytosis: extracellular substances are engulfed by being enclosed in membranous vesicle. Vesicle fuses with lysosome and the contents
are then digested by lysosomal enzymes. The vesicle is released by exocytosis on the opposite side of the cell.
◦ phagocytosis: cell engulfs large particles like bacteria and dead skin cells. Pseudopods are cytoplasmic extensions that separates
substances from external environment. Phagocytosis is a protective mechanism.
◦ pinocytosis: cell gulps droplets if extracellular fluid containing dissolved proteins or fats. Plasma membrane forms a pit, and edges fuse
around droplet of fluid. Routine activity for absorption like in the small intestine.
