9.1 - Maintaining Internal Balance

Question 1

How does the big ears on a fennec fox help it adapt?

Answer 1

Ears are so large that its blood releases heat through its ears to cool itself (ears act as radiators)

Question 2

Define Homeostasis

Answer 2

The body’s attempt to adjust to a fluctuating external environment

• Lowers body temperature and regulates it, with sweating and body is sending blood to skin (acts as radiator)
• Your body can control CO2 and O2 in blood

Question 3

What is a steady state? Why is homeostasis not a steady state? Example?

Answer 3

A constant/certain point
- homeostasis fluctuates by decimal points around a set/certain point, because conditions in your body fluctuate

Examples: blood levels, sugar in blood, water

Question 4

Car tool that maintains homeostasis?

Answer 4

Radiators: monitor and control car engine temp so it does not overheat, by releasing the heat from the car

Question 5

5 conditions that must be monitored and adjusted in your body

Answer 5

Internal temp, hormone levels, and the pressure, pH, flow, and concentration of glucose and other solutes in the blood

Question 6

Define “Internal Environment”

Answer 6

The extracellular fluid, which consists of the interstitial fluid (space between cell and tissue), and the plasma of our blood.

Question 7

Does homeostasis act on internal environment?

Answer 7

No, we do not include intracellular fluid in homeostasis, instead we focus on fluid outside cells.
- extracellular fluid acts as a MEDIUM for delivering energy, transporting chemicals, and eliminating waste

Question 8

List 2 events that can drastically change the conditions in the internal environment

Answer 8

Rigorous physical activity and infection: changes balance in extracellular fluid, which affects cellular functions

Question 9

List 6 Body Systems involved in maintaining homeostasis (list several organs for each)

Answer 9

1. Nervous: brain, spinal cord, sensory organs, peripheral nerves
2. Endocrine: hormone secreting glands - pituitary, thyroid, adrenal, pancreas
3. Muscular: skeletal, cardiac, smooth muscle
4. Integumentary: skin, sweat glands, hair, nails
5. Excretory: kidneys, bladder, ureter, urethra
6. Reproductive: Females - ovaries, oviducts, uterus, vagina, mammary glands
   Males - testes, sperm ducts, accessory glands, penis

Question 10

Describe major function of each system in maintaining homeostasis

Answer 10

1. Nervous: receives sensory data from environment, which informs body of external conditions and transmits signals through body to regulate homeostasis
2. Endocrine: regulates levels of various hormones that are essential to life’s processes
3. Circulatory: carries these hormones and other chemicals throughout the body and distributes thermal energy
4. Immune: protects body from infection
5. Digestive: liver controls amino acid levels by breaking down amino acids that are not used, detoxifying harmful chemicals, and manufacturing important blood proteins
6. Integumentary: maintains constant body temp, since in constant contact w/ external environment

Question 11

Which 2 systems are the most important for homeostasis?

Answer 11

Endocrine and Nervous

Question 12

What is a Homeostatic Mechanism? Give 2 examples

Answer 12

A system that monitors internal and external conditions and changes bodily functions to maintain homeostasis

Ex 1: regulation of body temp

• when temp is too high, evaporation of sweat is endo, so body experiences a net loss of thermal energy absorbed by water
• when we are cold, we shiver; these tiny muscle contractions generate thermal energy and raise internal temp

Ex 2: sensations of hunger and thirst trigger behavioral responses to ensure adequate nutrition and hydration of an animal

Question 13

Describe concept of “Normal Homeostatic Ranges”.

What happens if conditions become higher or lower?

Answer 13

Conditions in body fluctuate around a set point
Example: our normal body temp is around 37 degrees, but internal temp always fluctuates a little, so it can be close to 37 as well