Reading 1

Question 1

What is an example of engineering mimicking Nature’s Control Systems?

Answer 1

Artificial organs

Question 2

What is the benefit of equtions?

Answer 2

Condense info, and have predictive power (may predict certain phenomena not yet tested due to experimental constraints)

Question 3

An example of a system? How can this system be studied?

Answer 3

CV system comprises heart, veins, arteries, capillaries, baroreceptors, blood, and associated nervous system
- one can study properties of each component of system separately, or combine 2-3 components and study them as subsystem, or study whole CV system

Question 4

In its simplest form, what is a control system?

Answer 4

Produces a given response (OUTPUT) to a command signal (INPUT)

Question 5

Example of a control system in everyday life?

Answer 5

In a thermostatically heated room, desired (set) temp is the input, and heater and fan form system and the actual temp of room is output

Question 6

Examples control system in body?

Answer 6

• Temp is regulated about a set point by temp control system

- motor control systems controls activity of various muscles in body

Question 7

Can the output if wrong, be corrected in an open loop control system?

Answer 7

No

Question 8

Example of open loop control system?

Answer 8

Driving the car with eyes closed.
- Human operator presses on accelerator, steers the wheel, but if road uneven and car skids, operator cannot see and cannot error

Question 9

Another term for closed loop control system?

Answer 9

Feedback control system

Question 10

Example of closed loop control system?

Answer 10

Driving car with eyes open
- Human operator presses accelerator and rotates steering wheel to keep car on road. If car goes off road, output (position of car) fed back to operator’s visual system who then modifies input to steering wheel and gas pedal

Question 11

Draw a diagram of a typical feedback control system

Answer 11

Figure I-2

Question 12

What is a servomechanism/servo?

Answer 12

• type of feedback control system where output is either position or one of its derivatives (e.g. velocity)

Question 13

Example of servomechanism?

Answer 13

• Motor control system, where varying position and velocity of limbs result from descending motor commands converging on alpha motoneurons

Question 14

Describe blood pressure control systems

Answer 14

• constant signal to VMC in medulla maintains constant arterial pressure (p)
• an inc in pressure causes inc firing of baroreceptors which inhibits VMC and dec its activity
• dec in activity of VMC inc diameter of blood vessels and this produces dec in blood pressure

Question 15

Draw a diagram of the blood pressure control system

Answer 15

Figure I-3

Question 16

Describe a stretch reflex

Answer 16

Sudden stretch of muscle excites sensory endings in the spindles. This signal excites alpha motoneuron pool of stretched muscle. Activity of alpha motoneurons excite extrafusal (contractile) fibres of muscle, which contract n shorten the stretched muscle.
- stretch of muscle results in contraction via the feedback

Question 17

Describe thermaregulatory system

Answer 17

Maintains body temp near 37 degrees by maintaining balance btwn heat production and heat loss

Question 18

Describe how the thermaregulatory system maintains body temp with a fall in environmental temp

Answer 18

• e.g. sudden fall in environmental temp -> inc heat loss from body -> temp sensors in body detect fall in temp and signal the effect to the CNS -> CNS induces muscle contractions (i.e. inc muscle activity) producing shivering leading to heat production counteracting heat loss from body

Question 19

Describe how the thermaregulatory system maintains body temp with EXTRA heat production

Answer 19

• CNS induces extra heat loss by vasodilatation of peripheral blood vessels and sweating -> vasodilation causes internal body heat to be conducted to surface of body -> heat loss occurs by radiation, convection, and conduction -> sweating produces heat loss by evapouration

Question 20

Draw a diagram of the temp regulatory system

Answer 20

Figure I-5

Question 21

What is the vestibulo-ocular reflex an example of

Answer 21

Efficient OPEN LOOP control system

Question 22

Describe vestibulo-ocular reflex and how it is an open loop control system

Answer 22

Rotation of head activates semicircular canal sensors which excite or inhibit appropriate alpha motoneurons of extraocular muscle -> extraocular muscles contract (or relax) leading to rotation of eyes equal and opposite to head rotation -> no feedback of actual rotation of eye -> no correction by spindle feedback if there’s an appropriate rotation

Question 23

Diagram the vestibulo-ocular reflex

Answer 23

Figure I-6