Intro to Homeostasis

Question 1

Homeostasis

Answer 1

refers to the body’s attempt to adjust to a fluctuating external environment

Question 2

Dynamic equilibrium

Answer 2

condition that remains stable within fluctuation limits

Question 3

Homeostasis =

Answer 3

= dynamic equilibrium

Question 4

Organisms make use of feedback systems to

Answer 4

maintain homeostasis consisting of:

Control systems

Question 5

Control systems

A monitor

Answer 5

Signals a coordinating centre

Question 6

Control systems

A coordinating centre

Answer 6

Relays the info to the appropriate regulator

Question 7

Control systems

A regulator

Answer 7

Helps restore the normal balance

Question 8

Types of feedback systems

Answer 8

Negative and positive

Question 9

Types of feedback systems

Positive

Answer 9

process by which a small effect is amplified

Less common in the body

Work to REINFORCE change
Ex. hormone oxytocin in the birthing process

Question 10

Types of feedback systems

Negative

Answer 10

process by which a mechanism is activated to restore conditions to their original state

Work to RESIST change
Ex. sweating

Question 11

Thermoregulation

Answer 11

maintenance of body temperature within a range that enables cells to function efficiently

Question 12

Hypothalamus

Answer 12

region of the vertebrate’s brain responsible for coordinating many nerve and hormone functions

Question 13

Ectotherms

Answer 13

Depend on air temperature to regulate metabolic rates

Ex. invertebrates, most fish, amphibians, and reptiles

Question 14

Endotherms

Answer 14

Able to maintain a constant body temperature regardless of their surroundings

Ex. mammals, birds
Most humans have an optimal internal temperature of 37

Question 15

The Heat Stress Response (sweating)

Answer 15

Sensors in the brain detect a rise in body temp, which signals a nerve

Nerve impulse sent to hypothalamus, which sends a signal to the sweat glands to initiate sweating
Sweat evaporates
Nerve message is also sent to the blood vessels in the skin to dilate (vasodilation)
This allows more blood flow to the skin
The cool skin cools off the blood

Question 16

The Cold Stress Response

Answer 16

Sensors on your body detect a drop in temperature, which signals a nerve

This nerve impulse is received by the hypothalamus and sends a message to the arterioles of the skin to contract
These constrictions limit blood flow which reduces heat loss from the skin
Nerve impulses are also sent to the smooth muscle that surround the hair follicles in your skin
This causes hair to “stand on end”
This erect hair traps heat and reduces heat loss

Question 17

Shivering

Answer 17

The hypothalamus also sends messages to induce shivering

Rhythmic contractions of skeletal muscles

Cycles of rapid muscle contractions of 10 - 20 times per min