10b. Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of stable conditions in the internal environment

Question 2

What are some external environmental challenges?

Answer 2

• Microparticles
• traffic fumes
• Industrial fumes
• Microorganisms
• External temperature

Question 3

What are some internal environmental challenges?

Answer 3

• Exercise
• metabolic reactions and heat production
• quality of foods and liquids ingested, levels of nutrients, effects on BP urinary output etc

Question 4

What does the regulatory system consist of?

Answer 4

Nervous and endocrine system

Question 5

What is the set point?

Answer 5

A point chosen by the system as the most stable point for maintaining homeostasis

Question 6

What is negative feedback?

Answer 6

Tells the regulatory system to reduce or reverse a process

Question 7

What is positive feedback?

Answer 7

Tells the regulatory system to amplify or increase a response beyond the set point

Question 8

What are endotherms?

Answer 8

They regulate body temperature by producing heat or active mechanisms of heat loss (mouse, human , horse)

Question 9

What are ectotherms

Answer 9

Animals whose body temperatures are determined mainly by external sources of heat

Question 10

How is heat generated in the body?

Answer 10

Metabolism

Question 11

How is head released from the body?

Answer 11

Evaporation

Question 12

How does blood flow reduce body heat?

Answer 12

Blood flow to skin is another way to reduce body heat. Heat from the body bia blood to skin is lost to the environment

Question 13

How is body heat generated?

Answer 13

All energy reactions in the body are inefficient and produce heat as a by product

Question 14

What is the basal metabolic rate?

Answer 14

BMR of an endotherm is the lowest metabolic rate necessary for biochemical and physiological processes f a resting animal

Question 15

What is hypothesis

Answer 15

Heating or cooling the hypothalamus will result in predictable changes to body temperature

Question 16

What does the hypothalamus do when body temperature is below normal?

Answer 16

• Heat produciton
• Blood vessels constrict
• Skeletal muscles contract
• Shivering

Question 17

What does the hypothalamus do when body temperature is above normal?

Answer 17

• Heat loss
• Blood vessels dilate
• Skeletal muscles relax
• Panting, sweating

Question 18

What does heat stress equate to?

Answer 18

The sum of heat generated in the body (metabolic heat) plus heat gained from the environment (environmental heat) minus heat lost from the body to the environment.

Question 19

What are the 4 climatic factors that determine the body’s heat balance?

Answer 19

• Air temperature
• Radiant temperature
• Humidity
• Air movement

Question 20

What are the 2 non climatic factors that determine the body’s heat balance?

Answer 20

Clothing and the metabolic heat produced at rest or during physical activities

Question 21

How does heat dissipation occur?

Answer 21

through dry heat loss (radiation and convection) and evaporative heat loss (sweating)

Question 22

What are the 3 progressively worse steps in heat stress?

Answer 22

Heat cramps, heat exhaustion, heat stroke

Question 23

What happens in heat cramps?

Answer 23

• Exercise associated cramps
• Due to dehydration and loss of sodium via sweating
• Painful muscle spasms

Question 24

What happens in heat exhaustion?

Answer 24

• Symptoms are nausea, vomiting, weakness, headache, fainting, sweating and cold skin
• If left untreated, heat exhaustion can lead to heatstroke

Question 25

What happens in heat stroke?

Answer 25

Life threatening condition requiring immediate medical attention
Symptoms include confusion, irritability, headache, dizziness, fainting, nausea, vomiting, visual problems, fatigue and seizures and failure of major organs or even death in 20% of cases

Question 26

Why does heat stress cause failure of organs or death?

Answer 26

Hyperthermia leads to improper function of proteins and cell membranes and can ultimately lead to cell death (enzymes cannot bind to substrate causing denaturation)

Question 27

What is hypothermia?

Answer 27

A below normal body temperature due to starvation, exposure to extreme cold, serious illness, anaesthesia
-Drop in temperature is unregulated

Question 28

What is hibernation

Answer 28

Regulated hypothermia - adaptation in animals to scare food or periods of cold
-regulated drop in body temperature

Question 29

What is a heterotherm?

Answer 29

An animal that regulates its body temperature at a constant level sometimes but not others, such as a hibernator.