Homeostasis, Feedback Systems, and Thermoregulation

Question 1

Homeostasis

Answer 1

Body’s tendency to maintain a constant internal environment

Question 2

Feedback System

Answer 2

Homeostatic control system that has three components: sensor, control center, and effector

Question 3

Feedback System: Sensor

Answer 3

Detects changes in the environment and sends signals to the control center

Question 4

Feedback System: Control Center

Answer 4

Sets range of values within which the variable must be maintained, receives information from the sensors, and sends messages to effectors if needed

Question 5

Feedback System: Effector

Answer 5

Receives signals from the control center and responds, resulting in change in internal variable

Question 6

Negative Feedback System

Answer 6

Process which makes adjustments that bring the variable and the body back within an acceptable range

Question 7

Positive Feedback System

Answer 7

Process which moves controlled variable even further away from its steady state (reinforces change) –> allows a discrete physiological event to be accomplished rapidly, then stopped once it has been

Question 8

Positive Feedback System: Example

Answer 8

Birthing process: baby’s head presses into cervix which stimulates sensors in cervix that send signals to brain (control center), causing pituitary gland to release oxytocin, which causes uterus wall (effector) to contract, further pushing baby into cervix –> causes increasingly stronger contractions until baby is born

Question 9

Thermoregulation

Answer 9

The biological process that is responsible for maintaining a steady internal body temperature

Question 10

Heat Stress

Answer 10

1. Increase in body temp (stimulus)
2. Thermoreceptors in skin (sensor)
3. Hypothalamus (control center)
4. Sweat Glands (effector): sweat evaporates from skin, releasing heat (action)
   Blood Vessels (effector): dilate to bring blood closer to skin to increase heat loss through radiation & conduction (action)

Question 11

Cold Stress

Answer 11

1. Decrease in body temp (stimulus)
2. Thermoreceptors in skin (sensor)
3. Hypothalamus (control center)
4. Muscles (effector): contract to generate heat - shivering (action)
   Muscles in Hair Follicles (effector): hair stands up, creating “web” that traps heat closer to body (action)
   Blood Vessels (effector): constrict to reduce heat loss through skin and redirect blood/heat to deeper tissue (action)
   Hormones Released: increases body metabolism, which generates more heat

Question 12

Mammalian Diving Reflex

Answer 12

Reflexes that get activated when your face is submerged or you’re holding your breath:
Heartbeat slows, blood vessels narrow, blood shifted to more vital internal organs