Week 1 Physiology

Question 1

Homeostasis

Answer 1

State of body equilibrium or stable internal environment of the body, achieved through coordinated physiological activity

Question 2

Feedback loops

Answer 2

A process conducted by the body in response to a change to maintain homeostasis

Question 3

Features of a feedback loop

Answer 3

• Stimulus
• Receptors
• Control centre
• Effectors
• Response

Question 4

Stimulus

Answer 4

Disrupts homeostasis by increasing or decreasing a controlled condition

Question 5

Receptors

Answer 5

Detects the change in environment, sends nerve impulses or chemical signals to the control centre (brain)

Question 6

Control centre (brain)

Answer 6

Receives the input and provides nerve impulses or chemical signals to the effectors, giving an idea of how to respond to the change

Question 7

Effectors

Answer 7

Bring about a change or response to return to homeostasis

Question 8

Response

Answer 8

Alters the controlled condition

Question 9

Types of feedback loops

Answer 9

• Negative feedback
• Positive feedback

Question 10

Negative feedback loops

Answer 10

Feedback which reduces (or opposes) the intensity of the original stimulus
Examples:
* Blood pressure
* Glucose levels
* Respiratory rate
* Water reabsorption by kidneys
* pH level of blood
* Body temperature

Question 11

Positive feedback loops

Answer 11

Feedback which increases (or enhances) the intensity of the original stimulus
Examples:
* Stretching of the cervix during childbirth
* Production of prolactin (breast milk)
* Blood clotting (heal wounds by forming a scab)

Question 12

3 main components of cells (name)

Answer 12

• Cell membrane
• Cytoplasm
• Nucleus

Question 13

Cell membrane

Answer 13

• Outer barrier of the cell
• Regulates what crosses the membrane - enables the cell to have a stable environment
• Phospholipid bilayer
• Selectively permeable
• Generally negatively charged

Question 14

Cytoplasm

Answer 14

Intracellular fluid that contains organelles (e.g. cytosol, organelles)

Question 15

Nucleus

Answer 15

Contains our genetic material – DNA (e.g. chromosomes, genes)

Question 16

Osmosis

Answer 16

Diffusion of water molecules across membrane

Question 17

Hypertonic solution

Answer 17

High solute concentration

Question 18

Hypotonic solution

Answer 18

Low solute concentration

Question 19

Isotonic solution

Answer 19

Equally solute concentration

Question 20

Concentration gradient

Answer 20

Underlies the movement in all types of active transport, is the force of movement

Question 21

Moving down the concentration gradient

Answer 21

Moving something from an area of high concentration to an area of low concentration

Question 22

Moving against the concentration gradient

Answer 22

Moving something from an area of low concentration to an area of high concentration

Question 23

Membrane transport processes

Answer 23

Passive transport - no energy required:
* Simple diffusion
* Channel-mediated facilitated diffusion
* Carrier-mediated facilitated diffusion
Active transport - lots of energy required, force of movement is adenosine triphosphate (ATP):
* Primary active transport
* Secondary active transport

Question 24

Simple diffusion

Answer 24

Non-polar and non-charged particles pass through easily, no facilitation required (e.g. oxygen, carbon dioxide)

Question 25

Channel-mediated facilitated diffusion (definition)

Answer 25

Requires protein channel to help electrolytes cross the membrane (e.g. potassium, sodium, magnesium, calcium)

Question 26

Carrier-mediated facilitated diffusion (definition)

Answer 26

Requires protein carrier, changes shape to allow large substances to cross membrane (e.g. trans membrane proteins such as glucose)

Question 27

Primary active transport (definition)

Answer 27

• Uses sodium potassium pump (most common)
• Uses ATP directly
• Rule: pumps out 3 sodium ions against the concentration gradient and pumps in 2 potassium ions down the concentration gradient
• Allows the cell to maintain its specific negative charge

Question 28

Secondary active transport (definition)

Answer 28

• Sodium movement enables electrolytes and vitamins to cross the membrane
• Can only occur after primary active transport has occurred first as it sets up a concentration gradient of sodium by moving sodium out of the cell
• Allows sodium ions to move back down its concentration gradient passively
• Can take a second molecule across with it
• Uses ATP indirectly
• Allows glucose and amino acids to easily enter the cell
• Involves symporters and antiporters

Question 29

Symporters

Answer 29

Two molecules can cross the protein in the same direction (e.g. sodium and glucose, amino acids, electrolytes)

Question 30

Antiporters

Answer 30

Two molecules can cross the protein in the opposite direction (e.g. sodium in, calcium or hydrogen out)