PHGY 215 – Midterm Latest Exam with
Guaranteed Pass Solutions 2026
Updated.
Physiology - Answer The scientific study of the functions of our body
Homeostasis - Answer The ability of a cell or organism to regulate and maintain its internal
environment regardless of the influences of the external environment
Set Point - Answer The range or point at which a variable physiological state tends to stabilize
3 components of a homeostatic control system - Answer Sensor, Integrator, Effector
Sensor - Answer The sensor is responsible for detecting an environmental change
Integrator - Answer The integrator compares the variable being detected to its set point
Effector - Answer The effector is responsible for initiating the changes to restore the variable
back to the set point
Intrinsic Control - Answer The sensor, integrator, and effector are all located in a tissue so that
the tissue can regulate its own internal environment
Extrinsic Control - Answer The regulatory mechanisms are outside of the tissue or organ
Positive Feedback - Answer When the effector causes changes that amplify the initial signal -
not homeostatic
Negative Feedback - Answer A change in an environmental parameter causing the effector to
initiate a response in the opposite direction, restoring the parameter to the set point - system
stops signalling once set point is achieved
Plasma Membrane - Answer The barrier that separates the cell's internal and external
environments that serves as protection and allows cells to maintain an internal fluid
composition different than the external fluid composition
,Roles of the Plasma Membrane - Answer - Plays an active role in regulating the internal fluid
composition as it controls which molecules flow in and out
- Allows nutrients to enter cells and waste products to leave
Permits chemical signals released from other cells in the body to influence a cell allowing cell to
cell communication
- Participates in joining cells together to form tissues and organs
Three primary functions of the plasma membrane - Answer - ensure the cell's survival
- maintain homeostasis
function cooperatively and in coordination with surrounding cells
Phospholipids in the Plasma Membrane - Answer - The lipid bilayer is comprised of
phospholipids
- A phospholipid has a polar head with a negatively charged phosphate group and two non-
polar fatty acid tails
- the head is hydrophilic and the tail is hydrophobic
Cholesterol in the Plasma membrane - Answer - Found tucked in between the phospholipids
- Prevent the fatty acid chains from packing too tightly together and forming rigid structures
- keeps the membrane fluid
Membrane Proteins - Answer - Inserted into the phospholipid membrane
- associated with inner or outer sides or pass all the way through the membrane
- Functions to maintain structure, regulate cell function, allow transport across the membrane,
and facilitate signalling
Ion Channels - Answer Specialized membrane proteins that span the entire lipid membrane
and permit the entry and exit of ions
Carbohydrate Chains in the Plasma Membrane - Answer - Short chains of carbohydrates that
can be attached to proteins or the bilayer to form glycoproteins and glycolipids
- Involved in stabilizing membrane structure, act as cell surface receptors, participate in
transportation across the cell membrane
Cystic fibrosis - Answer - Caused by a defect in a particular chloride ion channel that is
involved in controlling the amount of fluid and mucous within the lungs
- Patients experience fluid build up in the lungs
,Alzheimer's Disease - Answer - Results in oxidative stress which leads to the alteration and
degradation of phospholipids within brain cells
- Reduction in phospholipids compromises the integrity of the membrane, and thus impacts
neural function, resulting in memory loss and reduced cognitive function
Oxidative Stress - Answer The generation of reactive oxygen species that may result in damage
to cells
Extracellular Matrix - Answer - A network of fibrous proteins embedded in a gel-like mixture of
complex proteins
- The ECM surrounds all cells in tissues and keeps them in place, even if they are not physically
contacting their neighbour
- The watery gel allows for diffusion of nutrients from the blood and the removal of wastes from
the cells
- Referred to as interstitial fluid
- The ECM composition is different in every tissue to allow specialized function
- The majority of the ECM is secreted by fibroblast located within the interstitial space
Fibroblasts - Answer A type of cell that synthesizes the cellular matrix and collagen
cell adhesion molecules (CAMs) - Answer - Four main categories: cadherins, selectins, NCAMs,
and integrins
- Usually transmembrane proteins
- The intracellular side of the protein interacts with the cytoskeleton, while the extracellular side
interacts with the extracellular matrix CAMs from other cells
- CAMs are involved in protein-protein interactions, as they bind with other cells or with the
ECM
Types of cell junctions - Answer desmosomes, tight junctions, gap junctions
Desmosomes - Answer - Used to anchor together two adjacent cells that are not otherwise in
direct contact
- Composed of dense intracellular thickenings known as plaques that are connected by
glycoprotein filaments containing cadherins to attach the neighbouring plaques together
- Other cytoskeletal anchoring proteins can also attach to the plaque and are combined to allow
for a network of strong fibres extending through the tissues and cells
- This feature allows the desmosome containing cells to have stretch
, Cadherins - Answer Play important roles in cell adhesion by forming adherens functions to
bind cells within tissues together
Tight Junctions - Answer - Creates a tight seal between cells, preventing movement of
molecules from cell to cell
- Long strings of junctional proteins in the plasma membrane between the neighbouring cells
align and adhere to form a tight junction
- the area where opposing junctional proteins from neighbouring cells meet is called a kiss site
- this type of junction is found primarily in epithelial tissues
Epithelial Tissues - Answer Line the cavities and surfaces of blood vessels and organs
throughout the body
Gap Junctions - Answer - Within a plasma membrane, six connexin protein subunits form one
half of a gap junction (a connexon)
- When connexons of adjacent cells align a tunnel forms that connects their intracellular spaces
and allows them to communicate directly
- One small water soluble substance can pass through the junction and these tunnels can be
opened and closed as needed to control cell communication
- Common in cardiac and smooth muscle cells that rely on these junctions to spread the wave of
excitation
- Allow the spread of secondary messengers between connected cells which provides a
mechanism for cells to act in a cooperative manner
Permeable, Impermeable, Semi-permeable - Answer - If a substance can freely cross the
membrane, the membrane is said to be permeable
- If a substance cannot cross the membrane it is said to be impermeable
- the plasma membrane is semi-permeable, which means that some substances may pass freely
while others cannot
2 Factors that determine membrane permeability - Answer Size and Solubility
Size - Membrane Permeability - Answer - Small substances like ions can enter through the
membrane spanning ion channels
- Larger substances require a transport protein to move it across the membrane
Solubility - Membrane Permeability - Answer - A principal factor which determines membrane
permeability is how lipophilic the substance is
Guaranteed Pass Solutions 2026
Updated.
Physiology - Answer The scientific study of the functions of our body
Homeostasis - Answer The ability of a cell or organism to regulate and maintain its internal
environment regardless of the influences of the external environment
Set Point - Answer The range or point at which a variable physiological state tends to stabilize
3 components of a homeostatic control system - Answer Sensor, Integrator, Effector
Sensor - Answer The sensor is responsible for detecting an environmental change
Integrator - Answer The integrator compares the variable being detected to its set point
Effector - Answer The effector is responsible for initiating the changes to restore the variable
back to the set point
Intrinsic Control - Answer The sensor, integrator, and effector are all located in a tissue so that
the tissue can regulate its own internal environment
Extrinsic Control - Answer The regulatory mechanisms are outside of the tissue or organ
Positive Feedback - Answer When the effector causes changes that amplify the initial signal -
not homeostatic
Negative Feedback - Answer A change in an environmental parameter causing the effector to
initiate a response in the opposite direction, restoring the parameter to the set point - system
stops signalling once set point is achieved
Plasma Membrane - Answer The barrier that separates the cell's internal and external
environments that serves as protection and allows cells to maintain an internal fluid
composition different than the external fluid composition
,Roles of the Plasma Membrane - Answer - Plays an active role in regulating the internal fluid
composition as it controls which molecules flow in and out
- Allows nutrients to enter cells and waste products to leave
Permits chemical signals released from other cells in the body to influence a cell allowing cell to
cell communication
- Participates in joining cells together to form tissues and organs
Three primary functions of the plasma membrane - Answer - ensure the cell's survival
- maintain homeostasis
function cooperatively and in coordination with surrounding cells
Phospholipids in the Plasma Membrane - Answer - The lipid bilayer is comprised of
phospholipids
- A phospholipid has a polar head with a negatively charged phosphate group and two non-
polar fatty acid tails
- the head is hydrophilic and the tail is hydrophobic
Cholesterol in the Plasma membrane - Answer - Found tucked in between the phospholipids
- Prevent the fatty acid chains from packing too tightly together and forming rigid structures
- keeps the membrane fluid
Membrane Proteins - Answer - Inserted into the phospholipid membrane
- associated with inner or outer sides or pass all the way through the membrane
- Functions to maintain structure, regulate cell function, allow transport across the membrane,
and facilitate signalling
Ion Channels - Answer Specialized membrane proteins that span the entire lipid membrane
and permit the entry and exit of ions
Carbohydrate Chains in the Plasma Membrane - Answer - Short chains of carbohydrates that
can be attached to proteins or the bilayer to form glycoproteins and glycolipids
- Involved in stabilizing membrane structure, act as cell surface receptors, participate in
transportation across the cell membrane
Cystic fibrosis - Answer - Caused by a defect in a particular chloride ion channel that is
involved in controlling the amount of fluid and mucous within the lungs
- Patients experience fluid build up in the lungs
,Alzheimer's Disease - Answer - Results in oxidative stress which leads to the alteration and
degradation of phospholipids within brain cells
- Reduction in phospholipids compromises the integrity of the membrane, and thus impacts
neural function, resulting in memory loss and reduced cognitive function
Oxidative Stress - Answer The generation of reactive oxygen species that may result in damage
to cells
Extracellular Matrix - Answer - A network of fibrous proteins embedded in a gel-like mixture of
complex proteins
- The ECM surrounds all cells in tissues and keeps them in place, even if they are not physically
contacting their neighbour
- The watery gel allows for diffusion of nutrients from the blood and the removal of wastes from
the cells
- Referred to as interstitial fluid
- The ECM composition is different in every tissue to allow specialized function
- The majority of the ECM is secreted by fibroblast located within the interstitial space
Fibroblasts - Answer A type of cell that synthesizes the cellular matrix and collagen
cell adhesion molecules (CAMs) - Answer - Four main categories: cadherins, selectins, NCAMs,
and integrins
- Usually transmembrane proteins
- The intracellular side of the protein interacts with the cytoskeleton, while the extracellular side
interacts with the extracellular matrix CAMs from other cells
- CAMs are involved in protein-protein interactions, as they bind with other cells or with the
ECM
Types of cell junctions - Answer desmosomes, tight junctions, gap junctions
Desmosomes - Answer - Used to anchor together two adjacent cells that are not otherwise in
direct contact
- Composed of dense intracellular thickenings known as plaques that are connected by
glycoprotein filaments containing cadherins to attach the neighbouring plaques together
- Other cytoskeletal anchoring proteins can also attach to the plaque and are combined to allow
for a network of strong fibres extending through the tissues and cells
- This feature allows the desmosome containing cells to have stretch
, Cadherins - Answer Play important roles in cell adhesion by forming adherens functions to
bind cells within tissues together
Tight Junctions - Answer - Creates a tight seal between cells, preventing movement of
molecules from cell to cell
- Long strings of junctional proteins in the plasma membrane between the neighbouring cells
align and adhere to form a tight junction
- the area where opposing junctional proteins from neighbouring cells meet is called a kiss site
- this type of junction is found primarily in epithelial tissues
Epithelial Tissues - Answer Line the cavities and surfaces of blood vessels and organs
throughout the body
Gap Junctions - Answer - Within a plasma membrane, six connexin protein subunits form one
half of a gap junction (a connexon)
- When connexons of adjacent cells align a tunnel forms that connects their intracellular spaces
and allows them to communicate directly
- One small water soluble substance can pass through the junction and these tunnels can be
opened and closed as needed to control cell communication
- Common in cardiac and smooth muscle cells that rely on these junctions to spread the wave of
excitation
- Allow the spread of secondary messengers between connected cells which provides a
mechanism for cells to act in a cooperative manner
Permeable, Impermeable, Semi-permeable - Answer - If a substance can freely cross the
membrane, the membrane is said to be permeable
- If a substance cannot cross the membrane it is said to be impermeable
- the plasma membrane is semi-permeable, which means that some substances may pass freely
while others cannot
2 Factors that determine membrane permeability - Answer Size and Solubility
Size - Membrane Permeability - Answer - Small substances like ions can enter through the
membrane spanning ion channels
- Larger substances require a transport protein to move it across the membrane
Solubility - Membrane Permeability - Answer - A principal factor which determines membrane
permeability is how lipophilic the substance is
