Detecting & regulating change

Question 1

What is receptor ?

Answer 1

Receptor is a structure or cell that detects a stimulus

Question 2

The sensations provided by receptors are categorized as either:

Answer 2

• Somatic senses/ sensations

- Special senses/ sensations

Question 3

What is somatic senses ?

Answer 3

Originate from receptors present at more than one location in the body

Question 4

What are the examples of somatic senses ?

Answer 4

For example:
temperature, 
touch, 
vibration,
 pressure,
 pain

Question 5

What is special senses ?

Answer 5

Originate from receptors that are restricted to a particular areas of the body (dedicated organs)

Question 6

What are the example of special senses ?

Answer 6

For example:
Sight (the eyes)
Taste (the tongue)
Sound (the ears)

Question 7

Where is the thermoreceptors located ?

Answer 7

Hypothalamus and skin

Question 8

What stimulates the thermoreceptors ?

Answer 8

Changes in temperature

Question 9

How does thermoreceptor works?

Answer 9

The hypothalamus then regulates the body temperature based on the signals from these receptors

Question 10

Where is the osmoreceptors located ?

Answer 10

hypothalamus

Question 11

What stimulates the osmoreceptors ?

Answer 11

changes in osmotic pressure

Question 12

How does osmoreceptor works?

Answer 12

The hypothalamus then maintains the blood osmotic pressure within the tolerable limit based on the signals from these receptors

Question 13

Where is the chemoreceptors located ?

Answer 13

Located in the nose (detect odour ) and tongue (sense taste)

Chemoreceptors that monitor blood pH are located in the medulla oblongata, aortic and carotid bodies

Question 14

Where are touch receptors located?

Answer 14

Receptors that detect a light touch or vibration are close to the surface of the skin

Receptors that respond to stronger pressure and vibrations are in deep skin layers

Question 15

Where are pain receptors located?

Answer 15

Mainly found in the skin and mucous membranes

Question 16

What is the other name for pain receptors?

Answer 16

nociceptors

Question 17

What are the pain receptors stimulated by?

Answer 17

Stimulated by damage to tissues, such as from cut, or excessive heat or chemicals

Question 18

Why is pain receptors important?

Answer 18

The ability to perceive pain is essential for survival - warns us to avoid certain stimuli and informs us of injuries

Question 19

What is reflexes?

Answer 19

A reflex is a rapid, automatic response to a change in the external or internal environment.

Question 20

What are the four main important properties of reflex?

Answer 20

• A stimulus is required to trigger a reflex – the reflex is not spontaneous.
• A reflex is involuntary-it occurs without any conscious thought.
• A reflex response is rapid – only a small number of neurons are involved.
• A reflex response is stereotyped – it occurs in the same way each time it happens.

Question 21

What is reflex arc ?

Answer 21

Reflex arc (the neural pathway involved in accomplishing reflex activity) components

Question 22

Explain the pathway of reflex arc?

Answer 22

1. Receptor - detects stimulus and produces an action potential
2. Sensory neuron - Relays the impulse from receptor to the CNS
3. Synapse – The information is passed on to other neuron via synapse. May involve more than one synapse depending on the type of reflex
4. Motor neuron – Relays the impulse from CNS to the effector
5. Effector – Carries out response

Question 23

Explain the Flex & crossed extensor reflexes

Answer 23

• Stepping on sharp object activates pain receptors _ produce action potentials in sensory neurons travelling to the spinal cord
• Sensory neurons stimulate interneurons within the spinal cord _ interneurons transmit signals to motor neurons in the leg
• Some send signals to flex appropriate muscles to lift the foot (flex reflex), some send signals to extend muscles in the other leg (crossed extensor reflex)

Question 24

Explain the Patellar reflex

Answer 24

• A tap just below the knee stretches the thigh muscle
• The stretch is detected by sensory nerves _ sensory nerves send signals to the spinal cord
• Motor neurons are activated
• Signals flow from the spinal cord back to the leg
• Leg jerks in respons

Question 25

What is homeostasis?

Answer 25

Homeostasis = The maintenance of relatively constant internal environment

Importance:
Maintains optimum condition for cellular function
Organisms can live in wider range of habitats – independent of external environment

Question 26

What is the impotance of homeostasis ?

Answer 26

Homeostasis ensures that certain factors inside the body are kept within set point

Question 27

What is set point ?

Answer 27

Set point = The level at which a variable is to be maintained

Question 28

What is tolerance limit ?

Answer 28

Tolerance limit = Limit of factors such as temperature and fluid balance beyond which the body malfunctions

Question 29

What is feedback mechanism ?

Answer 29

How the body responses to changes or stimulus

The response alters the original stimulus, thus providing feedback

Question 30

What are the 2 types of feedback ?

Answer 30

Positive and negative

Question 31

What are the components of feedback system ?

Answer 31

1. Stimulus– the change in the internal environment
2. Receptor – detects change
3. Modulator– is a control centre responsible for processing information from the receptor & sends signals (via nerves or hormones) to an effector
4. Effector – carries out response (counteracting or enhancing the effect of stimulus)
5. Feedback – is achieved when original stimulus has been changed by the response

Question 32

What is negative feedback ?

Answer 32

A mechanism of homeostasis, whereby a change (stimulus) triggers a response that counteracts/opposes the change

Question 33

What is positive feedback ?

Answer 33

Response amplifies the stimulus (change)

NOT a mechanism for maintaining homeostasis

Question 34

What is the example of positive feedback ?

Answer 34

Example of positive feedback:

The hormone oxytocin stimulates and enhances labor contractions.