Module One, Lecture Seven

Question 1

What are Excitable Cells?

Answer 1

Generate and conduct electrical signals, enabling the body to respond rapidly to stimuli

Question 2

How do Excitable Cells transmit information?

Answer 2

Use chemical and electrical gradients for rapid signalling events. Neurons are responsible for transmitting

Question 3

What are Neurons responsible for? ( 2 )

Answer 3

1. Sending and receiving signals, facilitate communication between different brain areas, the spinal cord, and the entire body
2. Crucial role in sensory input, motor commands, and relaying electrical signals which influence thoughts, feelings and behaviours

Question 4

What are Muscle Cells responsible for?

Answer 4

1. Contraction which leads to movement and other bodily functions
2. Basic building blocks of muscle tissue and come in three types; Skeletal, Smooth and Cardiac

Question 5

What is Diffusion?

Answer 5

The movement of molecules from a high to low concentration

Question 6

What is the definition of Osmosis?

Answer 6

Passive transport of water molecules across a semipermeable membrane from a region of high water concentration to a region of low water concentration

Question 7

What is a Semipermeable Membrane?

Answer 7

A barrier that allows some molecules ( like water ) to pass through

Question 8

How does Osmosis work?

Answer 8

Osmotic force pushes water across the semipermeable membrane, trying to equalise the concentration of the two sides of the membrane

Question 9

Define an Isotonic Solution…

Answer 9

A solution that has the same concentration of solutes as the cell’s cytoplasm or the extracellular fluid

Question 10

Define a Hypotonic Solution…

Answer 10

Has a lower concentration of solutes than the cell, leading to water moving into the cell and potentially causing it to swell

Question 11

Define a Hypertonic Solution…

Answer 11

Has a higher concentration of solutes than the cell, leading to water moving out of the cell and causing it to shrink

Question 12

What does Equilibrium mean?

Answer 12

It is an isotonic solution, the water concentration inside and outside the cell is equal, resulting in no net movement of water

Question 13

What is a Chemical Gradient?

Answer 13

A difference in the concentration of a substance across a membrane

Question 14

What is the importance of a Chemical Gradient?

Answer 14

Plays a crucial role in the movement of molecules across cell membranes, nutrient transport, and waste removal

Question 15

Describe the steps of a Chemical Gradient… ( 4 )

Answer 15

1. A chemical gradient exists when there are varying concentration of substance in different locations
2. Substances move from areas of high concentration to areas of low concentration
3. The chemical gradient provides the driving force for the movement of substances ( passive diffusion or active transport )
4. The movement of substances will continue until equilibrium is reached

Question 16

What is an example of a Chemical Gradient and its steps? ( 5 )

Answer 16

1. Sodium Ion Concentration
2. The concentration of sodium ions is much high outside of the cell than inside the cell
3. This difference creates a concentration gradient, which is a driving force for sodium ions to move into the cell
4. The inside of the cell is negatively charged which creates an Electrical Gradient
5. The Sodium-Potassium Pump helps maintain these concentration differences by pumping sodium ions out of the cell and potassium ions into the cell, against their concentration gradient ( active transport )

Question 17

What is Resting Membrane Potential?

Answer 17

-70 mV, meaning the inside of the cell is negatively charged relative to the outside

Question 18

When do Positive Ions enter the cell? ( 2 )

Answer 18

1. During a depolarization, which acts as a signalling event for excitable cells
2. The positive ions are then removed during repolarization to return to the resting membrane potential ( negatively charged )