Organ Systems Flashcards
What is a fossil
Any trace of animal or plant that lived long ago
How can fossils be form
Gradual replacement by minerals - teeth shells and rocks don’t decay easily so are slowly replaced by minerals forming hard rock in the same shaped
Casts and impressions - when an organism is buried in soft material
From preservation places where no decay happens because there’s no impressions e.g. In glaciers
What do fossils tell us
What creatures and plants looked like
How long ago things lived
How creatures have evolved
Why is the fossil record incomplete
Many dead plants and animal don’t become fossils
Soft tissue can decay away easily and not form fossils
Some fossils are yet to be discovered
What does the Pentadactyl limb show us
It has five digits and can be seen in many different species
In each species there is a similar bone structure but they usually have different functions
This proves that all species with the pentadactyl limb have evolved from a common ancestor
What is growth
An increase in size or mass
How can you measure growth
Size - height length width or circumference
Wet mass- the mass including all of the water in the body it can change quickly
Dry mass- mass with no water in the body it can only be measured when dead
How do animals grow
By cell division mainly when their young then will stop for the most of their life
Cell differentiation is usually stopped at an early stage of life
How do plants grow
They grow continuously so continue to differentiate and develop new parts throughout their life the growth is usually due to cell elongation and cell division in the roots
What are percentile charts
When a baby’s growth is measured after birth we can predict how tall they will grow as an adult
The 50th percentile show the mass that 50 percent of babies will have reached by a certain age
Doctors are only worried if a baby is below the 2nd percentile or above the 98th
What is tissue
A group of similar cells that work together to carry out a particular function
What is an organ
A group of different tissues that work together to perform a particular function
What is an organ system
A group of organs that work together to perform a particular function
What is the structure of the heart
Four chambers and four major blood vessels
Right atrium revives deoxygenated blood from the body through the vena cava
It moves the the right ventricle and then to the lungs through the pulmonary artery
The left atrium receives oxygenated blood from the lungs through the pulmonary vein
Then to the left ventricle and the aorta moves blood around the body
The left side is much stronger than the right side because it has to pump the blood around the whole body
Valves between the chambers prevent back flow
What do red blood cells do
They carry oxygen around the body
They have a biconcave shape to give a large surface area for absorbing oxygen
They contain haemoglobin
Oxygen combines with haemoglobin to create oxyhemoglobin in the red blood cells
They have no nucleus for more space
What are whit blood cells
They defend agains the disease
They can change shape to attack the microorganisms
They produce antibodies to fight disease
Low white blood cells increase the risk of disease but high white blood cells show you may have disease
What are platelets
Small fragments of cells that help the blood to clot at a wound so little blood can get out and no microbes can get in
Lack of platelets can cause excessive bleeding and bruising
What is plasma
It is a pale yellow liquid that keeps the blood liquid and transports Red and white blood cells and platelets Carbon dioxide Glucose and amino acids Urea Hormones Antibodies and antitoxins
What are the three types of blood vessel
Arteries carry blood away from the heart
Capillaries are small and exchange materials between the blood and tissue
Veins Cary blood to the heart
What are arteries like
They walls are strong and elastic to cope with the high pressure
The lumen is the hold in the middle and it is small compared to the thick walls
There is a thick layer of muscle around the lumen
What are capillaries like
They’re really tiny
They carry blood close to every cell in the body to exchange substances
They have a really thin wall only one cell thick and it is partially permeable
They lumen is also very small
Substances can diffuse from the blood to the cells
What are veins like
They blood is at a lower pressure so the walls don’t need to be as thick
They have a big lumen to help the blood flow even with the low pressure
They have valves to help the blood flow in the right direction
The walls aren’t as thick as the arteries
What is the role of the digestive system
To break down molecules into smaller ones that are useful to the body
What are the digestive enzymes
Carbohydrates digest starch to sugars
Proteases digest proteins to amino acids
Lipase digests fats into fatty acids and glycerol
