Homeostasis (Unit 2 - Topic 1)

Question 1

Anabolism

Answer 1

= Metabolic process that builds molecules the body needs.

eg. amino acids becoming polypeptides (proteins).

Question 2

Catabolism

Answer 2

= Metabolic process that breaks down large molecules into smaller molecules.
eg. proteins becoming amino acids

Question 3

Homeostasis

Answer 3

= a stimulus-response model in which changes in the condition of the external or internal environment is detected and appropriate responses occur via negative feedback.
= is the tendency to resist change in order to maintain a stable, relatively constant internal environment

Question 4

Effectors

Answer 4

= Muscles - contract in response to neural stimuli.

= Glands - produce secretions

Question 5

Negative Feedback loop

Answer 5

= counteracts changes of various properties from their target values, known as set points
= the typical method of achieving homeostasis
= serves to reduce an excessive response and keep a variable within the normal range.
= eg. temperature regulation and control of blood glucose.

Question 6

Sensory receptors

Answer 6

= detects stimuli

= can be classified by the type of stimulus

Question 7

chemoreceptor

Answer 7

= a sensory receptor that responds to chemical stimuli

eg. Taste buds and food
eg. Carbon-dioxide receptors in lungs

Question 8

thermoreceptor

Answer 8

= a sensory receptor that responds to temperature stimuli.
eg. Thermoreceptors allow the hypothalamus to react to a predicted change in core body temperature in response to changing environmental conditions.

Question 9

mechanoreceptor

Answer 9

= a sensory receptor that responds to mechanical stress or strain

Question 10

photoreceptor

Answer 10

= a sensory receptor that responds to visible light

Question 11

nocireceptor

Answer 11

= a sensory receptor that responds to damaging or potentially damaging stimuli by sending “possible threat” signals = pain

Question 12

metabolism

Answer 12

= all of the chemical reactions involved in sustaining life

= is either catabolic or anabolic

Question 13

sensory neuron

Answer 13

= responsible for converting external stimuli from the environment into corresponding internal stimuli
= activated by physical stimuli (such as visible light, sound, heat, physical contact, etc.) or by chemical stimuli (such as smell and taste).
= pseudounipolar - they have an axon that branches into two extensions—one connected to dendrites that receive sensory information and another that transmits this information to the spinal cord

Question 14

motor neuron

Answer 14

= neurons located in the central nervous system, and they project their axons outside of the CNS to directly or indirectly control muscles
= multipolar, meaning each cell contains a single axon and multiple dendrites
= the most common type of neuron.

Question 15

axon

Answer 15

= a tube-like structure that carries an electrical impulse from the cell body (or from another cell’s dendrites) to the structures at opposite end of the neuron—axon terminals, which can then pass the impulse to another neuron

Question 16

dendrite

Answer 16

= branch-like structures extending away from the cell body

= their job is to receive messages from other neurons and allow those messages to travel to the cell body.

Question 17

soma

Answer 17

= Like other cells, each neuron has a cell body (or soma) that contains a nucleus, smooth and rough endoplasmic reticulum, Golgi apparatus, mitochondria, and other cellular components

Question 18

myelin sheath

Answer 18

= external coating functions as insulation to minimise dissipation of the electrical signal as it travels down the axon
= made from myelin, a fatty material that wraps around the axon

Question 19

node of Ranvier

Answer 19

= Periodic gaps in the myelin sheath where the signal is recharged as it moves along the axon

Question 20

synapse

Answer 20

= the chemical junction between the axon terminals of one neuron and the dendrites of the next
= It is this gap where specialized chemical interactions can occur

Question 21

action potential

Answer 21

= A short-term change in the electrical potential that travels along a cell, such as a nerve or muscle fiber, and allows nerves to communicate
= An action potential occurs when an electrical signal disrupts the original balance of Na+ and K+ within a cell membrane, briefly depolarizing the concentrations of each

Question 22

neural impulse

Answer 22

= The signal transmitted along a nerve fiber, either in response to a stimulus (such as touch, pain, or heat), or as an instruction from the brain (such as causing a muscle to contract)

Question 23

the stages of an action potential

Answer 23

= 1. Depolarization: A stimulus starts the depolarization of the membrane
= 2. Repolarisation: Once the electric gradient has reached the threshold of excitement, the repolarisation begins
= 3. Refractory Phase: The refractory phase takes place over a short period of time after the depolarization stage

Question 24

neurotransmitters

Answer 24

= a chemical released from a neuron ending in response to a nerve impulse that interacts specifically with receptors on a responding cell

Question 25

receptors

Answer 25

= a specialised structure that can detect a specific stimulus and initiate an action potential

Question 26

synaptic cleft

Answer 26

= the physical space between two neurons

= the space that separates a neuron and its target cell at a chemical synapse

Question 27

postsynaptic neurones

Answer 27

= a neuron to the cell body or dendrite of which an electrical impulse is transmitted across a synaptic cleft by the release of a chemical neurotransmitter from the axon terminal of a presynaptic neuron

Question 28

presynaptic neurones

Answer 28

= a neuron (nerve cell) that fires the neurotransmitter as a result of an action potential entering its axon terminal

Question 29

signal transduction

also known as cell signaling

Answer 29

= the transmission of molecular signals from a cell’s exterior to its interior. Signals received by cells must be transmitted effectively into the cell to ensure an appropriate response. This step is initiated by cell-surface receptors.