Chapter 10 - Adaptations to a way of life Flashcards
(42 cards)
What are the advantages of bipedalism?
- Can see over obstacles for finding food and spotting predators
- Frees up hands for carrying, throwing and fine skills e.g: tool making and tool use
- Efficient movement
What anatomical adaptations do humans have?
Bipedalism
Opposable thumbs
Skin colour
Surface area to volume ratio
What are the advantages of having opposable thumbs?
Allowed ancestors to manipulate tools to
• Hunt
• Build shelters
This allowed them to get food and be protected against animals and weather
What does melanin do?
Absorbs UV radiation, stopping it from damaging the skin
Why is dark skin better at protecting against UV?
It has more melanin
What is the disadvantages of melanin?
It interferes with vitamin D synthesis
What happened when humans migrated out of Africa?
Less sunny areas meant their ability to synthesise vitamin D was worsened because the sun was less intense and daylight hours were shorter
Those with paler skin were favoured by natural selection as they did not die from deficiencies such as rickets
Why is light skin an advantage in less sunny areas?
Less melanin allows for more vitamin D production, but still enough to protect against UV
How does surface area to volume ratio increase survival in different climates?
A hot climate will favour a tall, thin and long limbed shape as it loses heat quicker, increasing survival
A cold climate will favour a compact, short and fat shape as it retains heat, increasing survival
How does communication through facial expressions increase survival chances?
- They allow people to know what others are thinking or feeling
- This helps them cooperate when hunting, raising young, avoiding predators etc
- Makes survival and reproduction more likely
How does language increase survival chances?
- Allows young to communicate needs
- Makes teaching easier
- Provides information about where food and water sources are
- Advice and stories can be shared, helping culture formation
How does an extended childhood increase survival chances?
- Allows children to learn complex skills
- Ensures social maturity is reached before they reproduce
- Knowledge and culture can be passed on
- Makes likelihood of survival increased
What are the physiological adaptations of humans?
Breathing rate
Heart rate
Energy sources
What parts of the body control breathing rate?
Inspiratory and expiration centres in the medulla
Stretch receptors in the lungs
What is the first step of the ventilation cycle?
- Inspiratory centre in medulla sends impulses to intercostal muscles and diaphragm
- Pressure inside the lungs is lowered
- Inspiratory centre sends impulses to inhibit the expiratory centre
What is the second step of the ventilation cycle?
- Air enters the lungs due to pressure difference
- Stretch receptors are stimulated and send impulses to medulla
- Inspiratory centre is inhibited
What is the last step of the ventilation cycle?
- Expiratory centre sends impulses to the intercostal muscles and diaphragm to relax
- Lungs deflate, so stretch receptors become inactive
- Inspiratory centre is no longer inhibited, and cycle begins again
Why does breathing rate increase during exercise?
- The more muscles contract, the more energy they use
- More CO2 is produced
- CO2 decreases blood pH
- Chemoreceptors in the medulla, aortic bodies and carotid bodies detect a decrease
- They then send impulses to the medulla to send more frequent nerve impulses to the intercostal muscles and the diaphragm
- Rate of breathing increases, therefore removal of CO2 and supply of O2 increases
How is heart rate controlled?
- By the cardiovascular centre in the medulla
* Impulses are sent to the SAN to speed up or slow down heart rate
What factors affect heart rate?
Blood pH
Blood pressure
How does low blood pH affect HR?
- Increases heart rate
- Decrease in pH detected by chemoreceptors
- Chemoreceptors send impulses to the medulla
- Medulla sends impulses to SAN to increase HR
How does increased blood pressure affect HR?
- Decrease
- Pressure receptors in aorta wall and carotid sinuses detect arterial blood pressure change and inform brain
- If pressure is too high, pressure receptors and send impulses to the cardiovascular centre to send impulses to the SAN to slow HR
- If pressure is too low, pressure receptors send impulses to the cardiovascular centre to send impulses to the SAN to speed up HR
What is cardiac output and how is it calculated?
The volume of blood pumped by a ventricle in one minute
Cardiac output = HR x stroke volume
What is our immediate energy source?
ATP
