Ch 7 Physically demanding work

Question 1

How does the body generate energy?

Answer 1

Body generates energy similar to combustion engine:
- FOOD (FUEL) is combusted, need OXYGEN for this.
- COMBUSTION process gives energy which moves parts mechanically (through MUSCLES)
- BLOOD VESSELS act as fuel TRANSPORT and COOLING systems

Question 2

Three major systems playing an important role in the body?

Answer 2

Respiratory
Circulatory
Metabolic

Question 3

Describe what the respiratory system does

Answer 3

Moves air to and from lungs through pumping action of thorax.

Exchange of O2, CO2, H20 and heat with the blood takes place in 2-6 million alveoli (70 – 90 m2 exchange surface).

Mucus-covered surfaces of nose, mouth, throat adjust temperature of inspired air to body temperature, moisten or dry the air and remove (dirt) particles from the air.

Question 4

Respiratory volumes depend on what?

Answer 4

How much we breathe in and exhale depends on the requirements associated with the work performed

How do we respond to increased requirements?
- increase breathing rate
- increase volume breathed in

Question 5

Architecture of the Circulatory System: what are its 3 parts?

Answer 5

Heart – pump with 4 chambers, left and right atria and left and right ventricles (the atrium is the upper chamber)

Arteries – blood vessels coming from the heart

Veins – blood vessels going to the heart

Question 6

Which are the two sub-systems of the Circulatory System? How are they supplied?

Answer 6

Systemic system supplied by left side of heart
- Pulmonary system supplied by right side of heart

Question 7

What is the function of the Circulatory System?

Answer 7

Blood carries + dissolve materials:
- carries oxygen, carbohydrates, fat derivatives from lungs to combustion sites (muscles and other organs)
- carries hormones, enzymes, salt, vitamins and
- removes combustion by-products (lactic acid, carbon dioxide, water, heat) for dissipation (at surfaces of skin and lungs)

Question 8

Red blood cells have __________ which attracts O2 and transports it.

Answer 8

Red blood cells have hemoglobin which attracts O2 and transports it.

Question 9

What explains the toxicity of CO (carbon monoxyde)

Answer 9

Hemoglobin has better affinity for CO than O2 (hence toxicity of CO).

Question 10

Role of the Metabolic System

Answer 10

support chemical processes in the body, especially those that produce energy

Question 11

Describe the 5 Metabolic Processes

Answer 11

1 INGESTION: taking in food
2 DIGESTION: conversion of complex food into simple substances
3 ASSIMILATION: absorption of simple substances by cells used to build protoplasm
4 RESPIRATION: use of O2, production of CO2 with release of energy
5 EXCRETION, SECRETION, EGESTION: removal of waste products

Question 12

Equation for Human Metabolism and Work?

Answer 12

I = M = H + W + S

Where:
I = energy input (via nutrients)
M = metabolic energy generated
H = heat gained or lost
W = work generated
S = energy stored

If there is no change in energy storage S and no change in heat gained or lost H, then :

I = M = H + W

Question 13

Work efficiency: equation, and which values we can expect for most people?

Answer 13

Question 14

How does the body generate/use energy for MUSCULAR WORK in the FIRST 10 SECONDS ?

Answer 14

first 10 sec: use 2 locally available sources of energy

Question 15

How does the body generate/use energy for MUSCULAR WORK after MORE THAN 10 SECONDS?

Answer 15

after more than 10 sec: generate energy through anaerobic chemical reaction; lactic acid produced as by product (If lactic acid is not resynthesized within a minute or so, using oxygen, the muscle cannot continue to work)

Question 16

How does the body generate/use energy for MUSCULAR WORK after MINUTES AND LONGER?

Answer 16

after minutes and longer: generate energy through chemical reaction with the presence of sufficient supply of oxygen (aerobic) and removal of waste products

Question 17

A good indicator of amount of (physical) work produced is _____________.

Answer 17

AMOUNT OF OXYGEN USED

For activities lasting more than about a minute there must be a continuous supply of oxygen and continuous removal of waste products.

Amount of oxygen used is good indicator of amount of (physical) work produced.

Question 18

How can we measure amount of oxygen used or amount of work produced?

3 proposed methods

Answer 18

• Measure inhaled and exhaled air to determine amount of O2 consumed (and CO2 produced)
• Assess human energy capabilities through standard tests (eg. treadmill, bicycle ergometer)
• Measure number of unit produced (manually)

First two are not practical in an industrial setting. Last one doesn’t correlate well with an individual person.

Question 19

What is BASAL METABOLISM?

Answer 19

minimum amount of energy required to keep the body functioning, even when no activities are done (basal metabolism: about 1 kcal (4.2 kJ)/(kg-h) or 4.9 kJ/min for 70 kg person)

Question 20

What is RESTING METABOLISM?

Answer 20

energy required when a person is at rest; amount varies depending on posture

Question 21

What is WORK METABOLISM?

Answer 21

additional energy required when a person performs work

Question 22

STATIC vs DYNAMIC ENDURANCE?

Answer 22