1
Expert solutions
BIO 2301 Human Physiology - Exam 1 (CSCC -
SU18) Questions and Answers (100% Correct
Answers) Already Graded A+
Homeostasis
✓✓ The body's ability to maintain internal stability, even in the face of external
change
Components of a homeostatic mechanism
✓✓ - Control center: usually found in the hypothalamus of the brain, contains
the "set point" for the variable, receives info from the receptors and sends
instructions to effectors
- Receptors: detect or sense the variable and send that info to the control center
- Effectors: receive instructions from the control center and carry them out to get
the variable back to normal
Examples of homeostatic mechanisms
✓✓ - The maintenance of body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
Negative feedback
✓✓ - When a change in the variable occurs, the body responds by causing a
change in the opposite direction
- The main way that homeostatic mechanisms work
Positive feedback
✓✓ - When a change in the variable occurs, the body responds by causing more
of a change in the same direction
- Rarely used in the body
- Examples: blood clotting, oxytocin release during child birth, and milk release
Structure of the plasma membrane
,2
Expert solutions
✓✓ - Semi-permeable, phospholipid bilayer
- Regulates passage of substances into and out of the cell
- Principal components: lipids, proteins, carbohydrates
Phospholipids in the plasma membrane
✓✓ - Hydrophilic head
- Hydrophobic tail
- Arranged in a double layer (bilayer) with the heads surrounded by fluid and the
tails kept from the water
Cholesterol in the cell membrane
✓✓ - Hydrophobic so found in the tail
- Maintains the consistency of the cell membrane
- Strengthens it by preventing smell molecules from crossing
- Keeps the phospholipid tails from coming into contact and solidifying it to
ensure the hydrophobic tail stays fluid and flexible
Proteins in the cell membrane
✓✓ - Function as enzymes to speed up chemical reactions
- Act as receptors for specific molecules or transport materials across the cell
membrane
- Integral proteins are located within the lipid bilater
- Peripheral proteins are located outside the lipid bilayer
Carbohydrates in the cell membrane
✓✓ - Sometime attached to proteins or lipids on the outside of the cell membrane
- Form the glycocalyx which provides cushioning and protection for the
membrane, important for cell recognition and determining if cells should be there
or not, and acts as a glue to attach cells together
Polar substances
✓✓ - Water soluble
- Water, sodium, potassium
Nonpolar substances
✓✓ - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
, 3
Expert solutions
Solubility
✓✓ - Like dissolves like
- Polar liquids dissolve polar substances
- Nonpolar liquids dissolve nonpolar substances
What substances can easily pass through the phospholipid bilayer of cell
membranes?
✓✓ - Nonpolar substances will pass through easily
- Polar substances must go through a channel in the cell membrane
Disorder
✓✓ - Disorder increases
- Molecules want to go where there is more room for them to spread out
Diffusion
✓✓ - The movement of small molecules from an area of high concentration to an
area of low concentration
- Does not require ATP energy
- Consists of a solute (molecules being dissolved) and a solution (water)
- Nonpolar, small lipid-soluble molecules will easily pass through the lipid bilayer
Osmosis
✓✓ - The unassisted diffusion of water across a selective permeable membrane
- Water will go through an aquaporin (a pore) and will move from where there is
more water to where there is less water (high to low) OR movement of water
from an area of low solute concentration to an area of high solute concentration
- Happens when the membrane is not permeable to the solutes
Osmotic pressure
✓✓ - The pressure needed to stop osmosis
- Water follows salt concept
- The more particles there are, the greater the osmotic pressure
Osmolarity
Expert solutions
BIO 2301 Human Physiology - Exam 1 (CSCC -
SU18) Questions and Answers (100% Correct
Answers) Already Graded A+
Homeostasis
✓✓ The body's ability to maintain internal stability, even in the face of external
change
Components of a homeostatic mechanism
✓✓ - Control center: usually found in the hypothalamus of the brain, contains
the "set point" for the variable, receives info from the receptors and sends
instructions to effectors
- Receptors: detect or sense the variable and send that info to the control center
- Effectors: receive instructions from the control center and carry them out to get
the variable back to normal
Examples of homeostatic mechanisms
✓✓ - The maintenance of body temperature
- Blood glucose levels
- Blood sodium levels
- Blood pressure
Negative feedback
✓✓ - When a change in the variable occurs, the body responds by causing a
change in the opposite direction
- The main way that homeostatic mechanisms work
Positive feedback
✓✓ - When a change in the variable occurs, the body responds by causing more
of a change in the same direction
- Rarely used in the body
- Examples: blood clotting, oxytocin release during child birth, and milk release
Structure of the plasma membrane
,2
Expert solutions
✓✓ - Semi-permeable, phospholipid bilayer
- Regulates passage of substances into and out of the cell
- Principal components: lipids, proteins, carbohydrates
Phospholipids in the plasma membrane
✓✓ - Hydrophilic head
- Hydrophobic tail
- Arranged in a double layer (bilayer) with the heads surrounded by fluid and the
tails kept from the water
Cholesterol in the cell membrane
✓✓ - Hydrophobic so found in the tail
- Maintains the consistency of the cell membrane
- Strengthens it by preventing smell molecules from crossing
- Keeps the phospholipid tails from coming into contact and solidifying it to
ensure the hydrophobic tail stays fluid and flexible
Proteins in the cell membrane
✓✓ - Function as enzymes to speed up chemical reactions
- Act as receptors for specific molecules or transport materials across the cell
membrane
- Integral proteins are located within the lipid bilater
- Peripheral proteins are located outside the lipid bilayer
Carbohydrates in the cell membrane
✓✓ - Sometime attached to proteins or lipids on the outside of the cell membrane
- Form the glycocalyx which provides cushioning and protection for the
membrane, important for cell recognition and determining if cells should be there
or not, and acts as a glue to attach cells together
Polar substances
✓✓ - Water soluble
- Water, sodium, potassium
Nonpolar substances
✓✓ - Fat soluble
- Urea, carbon dioxide, oxygen, and alcohol
, 3
Expert solutions
Solubility
✓✓ - Like dissolves like
- Polar liquids dissolve polar substances
- Nonpolar liquids dissolve nonpolar substances
What substances can easily pass through the phospholipid bilayer of cell
membranes?
✓✓ - Nonpolar substances will pass through easily
- Polar substances must go through a channel in the cell membrane
Disorder
✓✓ - Disorder increases
- Molecules want to go where there is more room for them to spread out
Diffusion
✓✓ - The movement of small molecules from an area of high concentration to an
area of low concentration
- Does not require ATP energy
- Consists of a solute (molecules being dissolved) and a solution (water)
- Nonpolar, small lipid-soluble molecules will easily pass through the lipid bilayer
Osmosis
✓✓ - The unassisted diffusion of water across a selective permeable membrane
- Water will go through an aquaporin (a pore) and will move from where there is
more water to where there is less water (high to low) OR movement of water
from an area of low solute concentration to an area of high solute concentration
- Happens when the membrane is not permeable to the solutes
Osmotic pressure
✓✓ - The pressure needed to stop osmosis
- Water follows salt concept
- The more particles there are, the greater the osmotic pressure
Osmolarity
