Chapter 10 - Adaptations to a way of life Flashcards
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
How is ATP produced?
The respiration of glucose, glycogen and triglycerides
What is the first energy source to be used?
Glucose
What is the next source used?
Glycogen
Can be easily hydrolysed into glucose or used directly
What is the last energy source?
Triglycerides
Hydrolysed to glycerol and fatty acids
Good long-term energy store as they have lots of energy per gram
Describe the differences between the 2 types of respiration:
Aerobic:
• Uses oxygen and produces CO2
• Releases more energy from each glucose molecule
Anaerobic:
• Does not use oxygen
• Produces lactate which lowers blood pH
• Less efficient than aerobic
When does the body anaerobically respire?
When the body needs more oxygen than is available
Why is lactate produced?
- It is toxic
- Oxygen is needed to get rid of the lactate - this is the oxygen debt
- Lactate is broken down or carried to the liver where it is converted to glucose/ stored as glycogen
How are humans adapted to adjust to high altitude?
- Air pressure decreases as altitude increases
- There are fewer air molecules, so people have more RBC’s
- More RBC’s = more haemoglobin
- Blood can carry more oxygen and supply it to muscles
Explain the use of haemoglobin
- A protein in RBC’s which carry oxygen
* Hb + 4O2 < > HbO8
What is a parasite?
An organism that lives in/ on a host, feeding on it and causing it damage
What adaptations do parasites have to survive inside a host?
Adaptations against digestion:
• Thick cuticle
• Anti-enzymes - inhibit host enzymes
Adaptations against immune system:
• Antigenic variation - immune system never catches up
• Living in host cells - antibodies can’t reach them
Adaptations to remain in the host and get food:
• Anatomical adaptations - e.g.: hooks to hang on gut wall, piercing mouthparts to suck blood
What adaptations do parasites have to increase infection of a new host?
Produce lots of offspring
Using secondary hosts for transmission
Why have some parasites adapted to reduce organ systems?
They are not needed so energy isn’t wasted on organs and their processes
Name some examples of reduced organ systems
No locomotion organs - they do not need to move
No digestive system - food is already digested
No nervous system or sensory organs - don’t need eyes, little information to process
What is Toxocara canis?
A parasite that lives in dogs and can infect humans
How can humans become infected with Toxocara?
- Dog faeces can contain the eggs
- They can remain in the soil for a long time
- If people touch soil or dogs and put their hands in mouth or eyes, they can get infected
- Children are vulnerable as they crawl, eat soil and organisms and put hands in their mouths
When is risk of infection increased?
Dogs excreting in public places such as parks
What adaptations does Toxocara have?
- Large numbers of eggs
- Cuticle
- Larvae secrete thick mucus
- Strong shell
- Can remain dormant
- Sticky eggs
