B6.3 - Digestion Flashcards
What are the 4 types of human teeth
incisors
canines
premolars
molars
features of the incisors
they are at the front of the mouth
Chisel-shaped and flat
Used for biting off food (good with plant material)
8 incisors 4 bottom 4 top
features of canines
They are sharp and pointy
they piece and hold food, particularly meat so it can be chewed
4 canines two bottom two top
features of premolars
Helps with cutting and crushing off tough food like meats
Grinds plant material
Large grinding surface
8 pre molars 4 bottom 4 top
features of molars
at the back of the mouth
Have large grinding flat surfaces for chewing
for crushing and grinding food
12 molars 6 bottom 6 top
What is the top of a crown covered in
hard material called enamel
What is the second layer of the tooth
the dentine
The tooth is filled with
pulp which contains blood vessels and nerves
Cement covers the surface of the
tooth’s root
The two parts of a tooth are the
crown and the root
a soft tissue called
gum surrounds the teeth and jaw bone
What are the causes of dental decay
Many bacteria living in the mouth and feed on trapped food particles
the bacteria respire sugar in food and release acid called plaque
Plaque is very acidic and spreads by corroding the enamel and dentine until it reaches the pulp cavity where tooth ache occurs
What are some measures to prevent tooth decay
Brushing your teeth with toothpaste
Flossing to remove food particles from the mouth
Avoiding acidic foods and drinks
Explain why toothpaste is used to prevent tooth decay
It is alkaline and so neutralizes acid near teeth
Contains antibacterial substances such as mint to kill bacteria.
Contains fluoride which helps strengthen enamel and reduce acidic damage.
Fluoride also helps remove trapped food particles and plaque
Where is bile produced, stored and secreted
produced in the liver
stored in the gall bladder
secreted from the bile duct and used in the small intestine
What is the problem with digestion of fats without bile
Fats do not mix in aqueous mixtures and remain as insoluble large droplets.
This gives a small surface area for lipase enzymes to work on slowing the rate of digestion
What is the importance of bile
It emulsifies fats breaking them up into smaller droplets
The surface area increases and the rate of digestion becomes much faster
It also is alkaline and helps neutralize stomach acids that reach the small intestine
What are digestive enzymes
a group of enzymes produced in the cells lining parts of the digestive system and secreted into the alimentary canal to mix with food.
What is the function of digestive enzymes
catalyze the breakdown of larger insoluble food molecules into smaller soluble molecules that are small enough to be absorbed into the bloodstream
What are some digestive enzymes and what do they break down
Amylase: Break down starch
Protease: Break down protein
Lipase: Break down lipids/fats
What is carohydrase
a type of digestive enzyme that breaks down carbohydrates. An example of one is amylase
All about amylase
Action sites: Small intestine and mouth
Substrate: Starch
Produced: Salivary glands and pancreas
Amylase breaks down starch to glucose
All about protease
Action sites: Stomach and small intestine
Produced: Stomach wall and pancreas
Protease breaks down protein to amino acids
What enzyme breaks down maltose
maltase. It breaks down maltose into glucose
All about lipase
Action sites: Stomach and small intestine
Produced: Pancreas
Lipase breaks down lipids into molecules called glycerol and fatty acids
What are the types of protease
Pepsin (works in stomach) and trypsin (works in small intestine)
Enzymes that digest food work best in
acidic environments and suitable temperatures
Special cells in the lining of the stomach secrete
HCI into the stomach to create right conditions for enzymes
What is the importance of HCI in the stomach
Creates right conditions for optimum enzyme activity
Optimum pH for protease activity
Kills microorganisms and bacteria in food
In the small intestine enzymes from
the pancreas work best in slightly alkaline conditions
Gastric juices from the stomach entering the duodenum provide
a suitable pH for enzyme action
What is the importance of villi
Increases the internal surface area of the small intestine which:
increases the rate of transport and absorption of food molecules across the small intestine wall.
The surface area of cells lining the villi increased further with the help of
tiny microvilli
Explain why a thin layer helps rate of diffusion increase in villi
A thin layer of cells makes sure digested food molecules don’t need to travel far to be absorbed into the blood.
Explain why lots of blood capillaries helps rate of diffusion increase in villi
Well supplied blood capillaries can absorb more food molecules from small intestine to rest of body and supply fresh blood keeping the concentration gradient between digested food in intestine and cells in body high as possible. This leads to faster rate of diffusion
What are the adaptations of the villi to increase rate of diffusion
Covered in thin layer of cells
Lots of blood capillaries
Contain lacteal
Describe how lacteal helps increase rate of diffusion in villi
Villi contain lacteals which carry fat droplets separately from the rest of the food molecules as they don’t dissolve well in blood. This makes sure the rate of diffusion doesn’t slow down.
