Chapter 6 - General Physiology

The fluid compartment surrounding cells is considered the \_________________ environment.

extracellular

True or false: Most of the fluid in the body is located within the extracellular compartment.

False

Extracellular matrix is comprised of:
ground substance
blood plasma
collagen fibers
elastin fibers

ground substance
collagen fibers
elastin fibers

The largest percentage of total body water is found in the \______________________ fluid or compartment.

intracellular

Molecules that are \______ are lipid-soluble and can easily cross a plasma membrane, while \______ molecules cannot.

non-polar; polar

The \______ is comprised of protein fibers and a gel-like ground substance.

extracellular matrix

An increased temperature of a solution is likely \_____________________________.

to increase the rate of diffusion

In a solution, fluid water is known as the \______________ in which molecules may dissolve.

solvent

\_______________ is the specific term referring to the net movement of water across a selectively permeable membrane.

Osmosis

Identify the substances that can easily diffuse through the plasma membrane:
Steroid hormones
Lipids
Proteins
Sodium ions
Oxygen
Carbon dioxide

Steroid hormones
Lipids
Oxygen
Carbon dioxide

For osmosis to occur:
- the membrane must be relatively impermeable to the solute.
- the membrane must have numerous microvilli.
- the membrane must be selectively permeable.
- the membrane must be lacking channel proteins.
- there must be difference in the concentration of a solute on both sides of a membrane.

the membrane must be relatively impermeable to the solute.
the membrane must be selectively permeable.
there must be difference in the concentration of a solute on both sides of a membrane

The \______ of diffusion is dependent upon the surface area and permeability of the membrane, temperature and steepness of the concentration gradient.

rate

The pressure needed to stop osmosis is:

osmotic pressure

The \____________ of a solution takes into account all of the solutes in the solution.

osmolality

True or false: Tonicity describes the effect of a solution on the movement of water.

True

\______________ pressure is the pressure required to halt the process of osmosis.

Osmotic

A solution that will not induce osmosis to occur is \______.

isotonic

\_______ cannot function properly if osmolality is disrupted.

Neurons

Transport of molecules from high to low concentration across a membrane carrier is termed \____________ diffusion.

facilitated

Primary active transport is directly achieved by hydrolysis of \_______.

ATP

Which of the following substances will only cross a plasma membrane using facilitated diffusion?
Glucose
Lipids
Water

Glucose

Diffusion and osmosis occurring between the spaces of epithelial cells are termed \_______________ transport.

paracellular

Paracellular transport is the movement of substances:
across a membrane in two different directions
between adjacent cells
directly through the cytoplasm of a cell
across a cell in a vesicle

between adjacent cells

The membrane potential is \______.
the observation that cells appear negative inside relative to the outside
the observation that cells appear positive inside relative to the outside
the voltage of the fluid outside the cell

the observation that cells appear negative inside relative to the outside

The charge difference between the inside and outside of a cell that is not sending any impulses is known as its \____________ \_______________ \_____________.

resting membrane potential

In the broadest definition, cells can communicate with other tissue types via \______.
hormones
gap junctions
extracellular secretions
neurotransmitters

extracellular secretions

Under normal circumstances, which of the following plays the major role in determining membrane potential?
The membrane's permeability to potassium.
The concentration gradient of sodium.
The membrane's permeability to proteins.
The concentration gradient of phosphate ions.

The membrane's permeability to potassium.

Polar molecules that bind to receptors, but do not enter a cell, use \______________ \___________________ to change the activities of the cell.

secondary messengers

\____________________ are molecules that initially respond to polar regulatory molecules by opening/closing membrane ion channels or by activating enzymes, such as those that produce cyclic AMP.

G-proteins

Some cells can communicate directly with each other through \______, where signaling molecules diffuse through the cytoplasm of adjacent cells.

gap junctions

1. Active transport requires \________.
both ATP and a carrier protein
water
carrier protein
ATP

both ATP and a carrier protein

2. The binding of ATP to the carrier protein causes \________.

the channel to close
the carrier to change its shape
All of the choices are correct
any molecule to bind to the carrier

the carrier to change its shape

3. The movement of substances across the plasma membrane will continue until the ATP is used up. True or false

True

1. The directional movement of ions by facilitated diffusion through protein channels is determined by \__________________.
the availability of ATP
the formation of a secretory vesicle
the electrochemical gradient of the ion being transported

the electrochemical gradient of the ion being transported

2. Simple and facilitated diffusion differ because \_____________.


ions being transported by simple diffusion move along their electrochemical gradients, while ions being transported by facilitated diffusion move against their electrochemical gradients

ions being transported by simple diffusion move against their electrochemical gradients, while ions being transported by facilitated diffusion move along their electrochemical gradients

facilitated diffusion requires the presence of a transport protein within the plasma membrane, while simple diffusion does not

simple diffusion requires the presence of a transport protein within the plasma membrane, while facilitated diffusion does not

facilitated diffusion requires the presence of a transport protein within the plasma membrane, while simple diffusion does not

3. Changes in the membrane potential trigger the opening or closing of \____________________.


voltage-gated channels
ligand-gated channels
mechanically-gated channels

voltage-gated channels

Glucose is passively transported across the \______________ membrane through facilitated diffusion.

hepatocyte

1. The \____________________ determines if glucose moves into or out of the hepatocyte.


mount of intracellular ATP available
amount of intracellular ATP versus intracellular glucose
oxygen concentration between the intracellular and extracellular fluid
glucose concentration between the intracellular and extracellular fluid

glucose concentration between the intracellular and extracellular fluid

2. A reduction in the number of glucose carrier proteins within the plasma membrane \_____________ the rate of glucose diffusion.

decreases

Physiological saline is a solution containing 0.9% NaCl. A cell in 1.5% NaCl is in a(n) \___________________ solution.
hypotonic
hypertonic
isotonic

hypertonic

2. The movement of water by osmosis is always from a \_____________.
low to high water concentration
high to low water concentration
high to low solute concentration

high to low water concentration

1. Water you drink is absorbed into the blood from the digestive tract. An increase in water intake causes a(n) \___________________ in the plasma osmolarity.

decrease
increase

decrease

2. An IV solution of 0.45% NaCl is \________________ and induces the movement of water \________________.


hypertonic; out of cells
hypertonic; into cells
hypotonic; into cells
hypotonic; out of cells

hypotonic; into cells
0.9% NaCl is isotonic

2. The Na+/K+ ATPase moves sodium in the \_________________ direction compared with the direction it travels through sodium leakage channels.

opposite

1. The sodium-iodide symporter plays a role in the accumulation of iodide in the thyroid gland. Here, one iodide gets converted to one iodine, which is utilized for the formation of either of the two types of thyroid hormones, T3 and T4. T3 and T4 are named after the number of iodines found in each of these hormones. To produce a single molecule of T3, a total of \____________ sodium ions must move down their concentration gradients by secondary active transport. The movement of iodide ions occurs in the \_________________ direction as sodium ions.

six, same

2. Phagocyosis and pinocytosis differ in that \_____________.


- one is a type of exocytosis, and one is a type of endocytosis
- almost all cells are capable of phagocytosis, while few select cell types are capable of pinocytosis
- phagocytosis allows for the transport of larger particles than pinocytosis
- pinocytosis is more selective than phagocytosis

phagocytosis allows for the transport of larger particles than pinocytosis

1. An individual displaying a larger than normal number of LDL receptors is \_____________ likely to develop artherosclerosis.


more
less

less

The extracellular matrix includes \________.
cytoplasm
blood plasma
collagen
red blood cells.

collagen

Simple diffusion is defined as the movement of \________.
- molecules from areas of higher concentration to areas of lower concentration
- molecules from areas of lower concentration to areas of higher concentration
- water molecules across a membrane
- gas molecules across a membrane
- gas or water molecules across a membrane

molecules from areas of higher concentration to areas of lower concentration

Osmosis is best defined as the movement of \__________.
- water molecules from an area of high solute concentration to an area of lower solute concentration
- water molecules from an area of low solute concentration to an area of higher solute concentration
- solute molecules across a membrane from an area of low water to an area of higher water concentration
- solute molecules across a membrane from an area of high water concentration to an area of lower water concentration
- water molecules inside a container

water molecules from an area of low solute concentration to an area of higher solute concentration

The osmolality of a red blood cell is \__________ mOsmoles.

300 mOsmoles

Edema occurs when:

- There is excessive albumin production
- Blood osmolality is too high
- Tissue osmolality is too high
- There is decreased fibrinogen production

Tissue osmotically is too high

Which of the following would be used to reduce cerebral edema?

- Normal saline
- Ringer's lactate
- Mannitol
- 5% dextrose

Mannitol

What does the hydrolysis of ATP do in a Ca2+ pump or Na+/K+ pump?
- Returns the carrier to its initial shape
- Allows the ion to bind to the inside of the carrier
- Activates ATPase
- Temporarily blocks both exits of the carrier

Temporarily blocks both exits of the carrier

Facilitated diffusion occurs \__________.
- into the cell only
out of the cell only
- in either direction depending on the temperature
- in either direction depending on the concentration gradient of the molecule
- in either direction depending on the size of the molecule

in either direction depending on the concentration gradient of the molecule

Facilitated diffusion is used to transport \__________.

sugars

Choose the statement that correctly describes a ligand.
- A small molecule that binds to the alpha subunit of the G-protein
- A small molecule that binds to a membrane-bound receptor
- A large molecule that binds to the alpha subunit of the G-protein
- A large molecule that binds to a membrane-bound receptor
- A small molecule that binds to a G-protein

A small molecule that binds to a membrane-bound receptor

\___% of our water is within cells in the intracellular compartment.

__% is in the extracellular compartment

__% is in the blood plasm

__% makes up what is called tissue fluid, or interstitial fluid which connects the intracellular compartment with the blood plasma.

67

33

20

80

Extracellular Matrix
What are the three things it contains?

protein fibers of collagen and elastin, and a gel-like ground substance

Extracellular Matrix
Protein fibers provide \_____________ support

Ground substance is composed of \______________ and \_______________

What are integrins?

structural

glycoproteins (composed of proteins and sugars) and proteoglycans (composed of polysaccharides)

Integrins are glycoproteins that extend from the cell cytoskeleton and bind to components of the extracellular matrix

Extracellular Matrix
Functions of Integrins

Affect adhesion and \_____________
Relay \_______ between compartments
Impart a \________ to cells
Affect \_________________

motility
signals
polarity
proliferation

Plasma membrane is generally permeable to \___________ and \__________.

Some ions are transported creating \_______________________________ currents in certain cells

nutrients, waste

electrochemical

What are the two categories of membrane transport?

Carrier-mediated transport and non-carrier-mediated transport

What are the three types of carrier-mediated transport?

Facilitated diffusion, active transport, and secondary active transport

Passive transport moves molecules from \______to \______ concentration without utilizing metabolic energy.

Active transport moves molecules from \______to \______ concentration utilizing ATP and specific carrier pumps.

higher; lower

lower; higher (against concentration gradient)

- Simple diffusion of ions through \_____________ \______________ proteins

- Facilitated diffusion of glucose or other small organic molecules that bind to a specific \___________ \_____________ which undergoes a conformational change to release the molecule on the other side of the membrane

membrane channel

carrier protein

Molecules in a solution are in a \_______ state of motion.

If there is a concentration difference between two regions, \______ motion will establish equilibrium via \______________.

Obeys the 2nd Law of Thermodynamics - diffusion increases \___________

constant

diffusion

entropy

Diffusion will occur \_________ a physical separation or across a permeable membrane

Net diffusion - due to random movement, the net direction of diffusion is from \_____ to \_____ solute concentration

Mean diffusion time - the average time it takes for a solution to \________
\_________ with the square of the distance the solute must travel

without

high; low

diffuse

increases (less distance, faster, distances beyond 100 um, diffusion time is too long to be effective)

Gas exchange: net diffusion of O2 into cells and C02 out of cells due to concentration gradients (Opposite in \_________)

lungs

Rate of Diffusion
Measured by the number of diffusing particles per unit of time

Depends on:
Magnitude of concentration difference - the \__________ \__________ for diffusion

Permeability of membrane to the molecules

Temp of the solution; higher temp increases rate

Surface area of the membrane; increased by \_________

driving force

microvilli

Osmosis Requirements
- Must be a \____ concentration difference on either side of a membrane permeable to water
- The membrane must be \___________ to the solute, or the concentration difference will not be maintained
Solutes that cannot cross and permit osmosis are called \_______________ \________

solute

impermeable

osmotically active

Osmotic \_________ is the force surrounding a cell required to stop osmosis.

Higher solute concentration has a \________ osmotic pressure

pressure

higher (Pure water has an osmotic pressure of zero)

Explain difference between Molarity (M) and Molality (m)

Which do we like to use better?

Molarity \= moles solute/liter solution

Molality \= moles solute/kg solvent

Molality since the amount of water never changes, we can compare the solute concentrations to predict the direction of osmosis

Osmolality is the \_______ molality of a solution when you combine all of the molecules within it

How can it be measured?

total

Freezing point depression - how much the freezing point is lowered depends on the number of particles present in the solution

Tonicity is the effect of a solute concentration on the \________ of water

Takes into account the \_____________ of the membranes of the solutes

osmosis

permeability

\___________________ in the hypothalamus detect increases in osmolality (due to dehydration) which triggers:

- thirst
- decreased excretion of water in urine through release of \_________ \___________ which is also known as vasopressin

Osmoreceptors

antidiuretic hormone (ADH)

Molecules that are too large or polar cannot diffuse across the membrane and instead need \________ \____________.

Characteristics
- are specific to a given molecule
- may be \_____________ for similar carriers or molecules
- \_______________ - the number of carriers is limited

carrier proteins

competition
Saturation

Facilitated Diffusion is powered by the \____ movement of molecules
Is ATP needed?

Net movement from \______ to \_____ concentration

Requires specific \_____________-\__________ proteins

Transport proteins may always exist in the plasma membrane or be \____________ when needed

random
No

high; low

carrier-mediated

inserted

Facilitated Diffusion - Glucose
What are transport carriers for glucose designated as?

GLUT1 - \_______
GLUT2 - \_______
GLUT 3 - \_______
GLUT 4 - \_______

GLUT followed by the number of the isoform

CNS
pancreatic beta cells & hepatocytes
neurons
adipose tissue & skeletal muscle

Primary active transport occurs when the hydrolysis of ATP is \______ responsible for the carrier protein function

What is the transport protein also?

Pump is activated by \_______________ using a Pi from ATP

directly

an ATPase enzyme that will hydrolyze ATP (cleave ATP)

phosphorylation

Ca2+ pump is what type of active transport?

Removes Ca2+ from the cytoplasm by pumping it into the extracellular fluid or \____________ of the ER

Primary active transport

cisternae

Na+/K+ Pump
Serves three functions:
1. Provides energy for \_________ transport of other molecule
2. Produces \____________ impulses in neuron and muscle cells
3. Maintains \_______________

coupled

electrochemical

osmolality

3Na+ out/2 K+ in

Steps of the Na+/K+ pump:
1. 3 Na+ from the cytoplasm move into the pump and \_____
2. \________ activated to hydrolyze ATP to ADP and Pi which blocks both openings
3. ADP released causing a \_______ change that allows 3 Na+ to exit pump to outside cell
4. 2 K+ enter carrier from the outside, releasing the Pi
5. Pump returns to original shape and releases 2K+ to the inside

bind

ATPase

shape

Secondary active transport is also called what?

The energy needed to move molecules across their concentration gradient is acquired by moving \________ back into the cell

Since the sodium was originally pumped out of the cell using ATP, this is considered active transport.

Coupled transport

sodium

Transport Across Epithelial Membranes
- Involves \______________ transport: movement of molecules through the cytoplasm of the epithelial cells
- May also involve \____________ transport: movement across the tiny gaps between cells

transcellular

paracellular

What is paracellular transport limited by?
1. Zonula occludens: tight junctions
2. Zonula adherens: \_______ desmosomes
3. Macula adherens: \________________

Junctional complexes

belt
desmosomes

Does bulk transport require ATP?

Which large molecules use exocytosis and endocytosis?

Yes since need moto proteins to make sure reaches membranes

Exo: proteins, hormones, and neurotransmitters

Endo: cholesterol (large molecules)

What makes the inside of the cell more negative compared to the outside?

Potential difference: difference in charge on each side of the plasma membrane

Since the membrane is so permeable to \____, this potential difference is usually maintained by \___ concentration gradient

The inside has a voltage of \________ lower than the outside

K+, K+

-90mV

What equation is used to calculate equilibrium potentials and is based on ion concentrations?

Nerst equation

In most cells, the resting potential is between \________ and \_________

Neurons are usually at \________

-65, -85 mV

-70 mV

Cell signaling
What are gap junctions?

Paracrine signaling?

Allow adjacent cells to pass ions and regulatory molecules through a channel between the cells (no extracellular space)

Cells within an organ secrete molecules that diffuse across the extracellular space to nearby target cells - also called local signaling (extracellular space)

Polar or large signal molecules bind to receptors on the cell surface. What are the intermediates called and examples?

Second messengers

May be ions (Ca2+) or molecules

cAMP is a common second messenger

Steps to activate:
1. A signaling molecules binds to a \___________.
2. This activates an enzyme that produces cAMP from \____.
3. cAMP activates other enzymes in the cytoplasm.
4. Cell activities change in response.

receptor
ATP

G-proteins are there to shuttle the receptor protein and enzyme proteins and are made up of 3 subunits which are?

alpha, beta, and gamma

Which of the following is NOT a function of integrins?
- Glue components of the matrix
- Allow diffusion to occur through the plasma membrane
- Establish cell polarity
- Communicate between the intracellular and extracellular compartments

Allow diffusion to occur through the plasma membrane

Where is the receptor for a nonpolar, lipid-soluble regulatory molecule?
- Embedded in the outer surface of the plasma membrane
- Embedded in the inner surface of the plasma membrane
- In the cytoplasm or nucleus of the cell
- All of the choices are correct.

In the cytoplasm or nucleus of the cell

Regardless of solubility, a cell signaling molecule could not affect a target cell without \________.

- being attached to another cell
- a second messenger in the plasma membrane
- specific receptor proteins within the cell or in the plasma membrane
- All of the choices are correct.

specific receptor proteins within the cell or in the plasma membrane

Which of the following is NOT true of cyclic AMP?
- It is found on the outside of a plasma membrane
- It is a second messenger for polar regulatory molecules.
- It is made from ATP.I
- t activates enzymes inside a cell to produce the desired effect.

It is found on the outside of a plasma membrane.

Clinical Application
What family of enzymes can break down extracellular matrix proteins?

What disease has a CFTR protein and had salty sweat, and in the pancreas and lungs can result in dense, vicious mucus that promotes pancreatic and pulmonary disorders?

Matrix metalloproteinases (MMPs) because of their need for a zinc ion cofactor

Cystic fibrosis