The Reflex Arc

Question 1

What is a reflex?

Answer 1

-a fixed response to a stimulus
-a stimulus is a detachable change in the physical or chemical nvironment of an organism

Question 2

How do organelles detect stimuli?

Answer 2

-receptors with sense organs
-tongue,eye,skin,ear, nose (senses)
-reflexes are either voluntary or involuntary

Question 3

Voluntary reflexes

Answer 3

Involves the brain

Question 4

Involuntary reflexes

Answer 4

Do not involve the brain

Question 5

What is a reflex arc ?

Answer 5

-A neutral pathway that controls a reflex.
-This allows for faster reflex actions to occur by activating spinal motor neurones without the delay of routing signals through the brain
-reflex arcs control involuntary reflexes
-they have a quicker response rare that enable us to protect ourselves from harmful stimuli

Question 6

Reflex response examples

Answer 6

-sneezing
-reactions to pain or functioning to prevent pain
-blinking

Question 7

Denature - neurone cell

Answer 7

Receives communications from other neural cells through their tree-like projections

Question 8

Cell body/Stoma- neuron cell

Answer 8

Encapsulates the nucleus

Question 9

Nucleus - neuron cell

Answer 9

Contains the genetic material/ info that controls the neuron

Question 10

Myelin sheath- neuron cell

Answer 10

Outer coating of axon, protect and maintains health of the axon
Acts as an electrical insulator

Question 11

Node of ranvier- neuron cell

Answer 11

Allows impulses to jump by a process called ‘saltatory conduction’ this means that impulses can jump through gaps in the axon to speed up responses

Question 12

Schwann cell - neuron cell

Answer 12

Helps to form the myelin sheath and speeds up transmission of nerve impulses

Question 13

Axon terminals - neuron cell

Answer 13

Connects the neuron to target cells such as effector cells and nerve cells

Question 14

Synapses

Answer 14

A junction between two neurons

Question 15

Synaptic cleft

Answer 15

The space between two neurons where substances can be transferred

Question 16

Synaptic fatigue

Answer 16

-caused by the pre-synaptic neurone being overstimulated which causes damage to neural pathways
-eventually impulses are not passed through the synapses due to lack of neurotransmitters
-can cause neurological disorders such as canine epilepsy

Question 17

Canine epilepsy

Answer 17

-certain dog breeds are predisposed to reflex epilepsy whereby certain stimuli and triggers can bring on seizures
-triggers: overexcitement, vet trips, groomers, boarding facilities, car journeys, other animals, lack of sleep, stress and lack of medication
-mainly affects dogs over 5
-use anti-epileptic drugs to treat eg phenobarbital (does not prevent stimuli-specific seizures)