The Human Digestive System Flashcards
What is the digestive system an example of?
An organ system in which serval organs work together to digest and absorb food
What is the function of the mouth?
• The mouth is the beginning of the digestive system - digestion starts here
• The smell of food triggers the salivary glands in your mouth to secrete saliva (contains the carbohydrasé enzyme amylase) which chemically breaks down starch in food to maltose (which ultimately is broken down into glucose)
• Chemical digestiontakes place therefore with the enzyme amylase
• Mechanical digestion (mastication)also takes place: chewing breaks down the food into smaller pieces to increase surface area
What chemicals (inc.enzymes) are produced in the mouth?
Amylase
What is the function of the oesophagus?
• The oesophagus carries food to the stomach
• The oesophagus is a muscular tube
• Food is pushed through the oesophagus and into the stomach by means of a series of muscular contractions called peristalsis
• The mass of chewed food that passes from mouth of stomach (down the oesophagus is called thebolus
What is the function of the stomach?
• The stomach contains hydrochloric acid which kills any ingested bacteria
• It also produces protease enzymes which digest protein (chemical digestion)
• The muscular walls of the stomach contract to churnthe food, breaking it into smaller pieces and increasing its surface area (mechanical digestion)
• The mass of partially digested food + gastric juices that leave the stomach is called chyme
What chemicals are produced (inc.enzymes) in the stomach?
• The stomach contains hydrochloric acid which kills any ingested bacteria
• It also producesprotease enzymeswhich digest protein (chemical digestion)
What is the function of the liver?
• It processes absorbed food and detoxifies the blood
• It makes bile
• Bile is alkaline to neutralisehydrochloric acid from the stomach
• Bile emulsifies fat globules to form small droplets which increases the surface area
What chemicals are produced in the liver?
Bile - an alkaline substance
What is the function of the gall bladder?
The gallbladder stores excessbilebefore it is released into the small intestine
What is the function of the pancreas?
• It is a gland like the salivary gland and both provide digestive juices (enzymes)
• Among other functions, the pancreas producesdigestive enzymes
• Carbohydrate enzyme -carbohydrase
• Fat enzyme -lipase
• Protein enzyme -pancreatic protease
• These are secreted into the first segment of thesmall intestine
• These enzymes break downproteins, fats, and(chemical digestion)
• The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolising sugar
What chemicals are produced (inc.enzymes) in the pancreas
• Carbohydrate enzyme -carbohydrase (amylase)
• Fat enzyme -lipase
• Protein enzyme -pancreatic protease
What is the function of the small intestine?
• The small intestine produces protease, amylase and lipase that continue digestion (chemical digestion)
• Soluble products of digestion areabsorbedinto the blood through the walls which are covered in projections called villi (increases surface area)
What chemicals are produced (inc. enzymes) in the small intestine?
The small intestine producesprotease, amylase and lipase that continue digestion (chemical digestion)
What is the function of the large intestine?
• The large intestine connects the small intestine to the rectum. The large intestine is a highly specialised organ that is responsible for processing waste
• Bacteria break down anything that was not fully digested in the small intestine
• As material passes through the large intestine, water is absorbed into the blood
• It can then be referred to as faeces
• The faeces itself is mostly food debris (fibre) and bacteria
What is the function of the rectum?
• Receives faeces from the large intestine
• Lets the person know there is a stool which needs to be evacuated
• Holds the stool until evacuation happens
What is the function of the anus?
The anus is the last part of the digestive tract
What are some adaptations of the small intestine?
• 7m long - Ample time for absorption of soluble molecules as food travels along
• Very thin cell wall (one cell thick) - easy diffusion, shorter diffusion pathway
• Villi and microvilli - provide larger surface area for absorption
• Capillaries, good blood supply - Maintains a steep concentration gradient to aid diffusion
What are some adaptations of villi?
- Good blood supply, capillaries - maintains a steep concentration gradient
- Thin walls (one cell thick) - short diffusion distance
- Large surface area - finger like projections, has microvilli, larger SA for diffusion
Where in the digestive system does active transport take place?
• During digestion, the villi in the small intestine absorb the soluble nutrients. Over time, the concentration of nutrients in the villi reach an equilibrium with the concentration in the gut
• Active transport is used to continue the transport of the small amounts of remaining nutrients against the concentration gradient
What are products of digestion used for?
• Used to build new carbohydrates, lipids and proteins
• Some glucose is used in respiration
Why don’t vitamins or minerals need digesting?
Vitamins and minerals don’t need digesting as they are either fat soluble or water soluble
What do large multicellular organisms develop systems for?
Large multicellular organisms develop systems for exchanging materials
What happens during the development of a multicellular organism?
During the development of a multicellular organism, cells differentiate, so that they can perform different functions
What are three tissues found in the digestive system?
• Muscular tissue
• Glandular tissue
• Epithelial tissue
What is the function of muscular tissue?
Can contract to bring about movement
What is the function of glandular tissue?
Produces substances such as enzymes and hormones
What is the function of epithelial tissue?
To cover the outside and inside of the stomach
What is the function of muscular tissue in the stomach?
To churn the contents
What is the function of the glandular tissue in the stomach?
To produce digestive juices
What is the function of the epithelial tissue in the stomach?
To cover the outside and inside of the stomach
What are carbohydrates made up of?
Units of sugar
What are simple sugars?
the most basic forms of sugar.
What do complex carbohydrates contain?
sugar molecules that are strung together in long, complex chains
What do lipids consist of?
Oxygen, carbon and hydrogen bond to each other to form lipids. Lipids like cholesterol are part of your cell membranes.
What are protein molecules made of?
amino acids
What is an enzyme?
proteins that act as biological catalysts, meaning they speed up reactions without being used up.
Enzyme-substrate complex:
a temporary molecule formed when the substrate binds to the enzyme
Enzyme-product complex:
formed towards the end of the reaction
Catalyst:
a substance that changes the rate of a chemical reaction but is itself unchanged at the end of the process
Substrate:
a substance or surface which an organism grows and lives on and uses as food.
Active site:
a region on an enzyme that binds to a protein or other substance during a reaction.
Product:
products are defined as end substances after a biological process has occurred
Denaturation:
the unfolding or breaking up of a protein, modifying its standard three-dimensional structure
Where are enzymes produced?
Your stomach, small intestine and pancreas
What can enzymes do to substrates?
They decrease the activation energy necessary for a chemical reaction to occur by stabilizing the transition state
What is the enzyme for digestion of food type (substrate) starch and where is it made?
Enzyme Salivary amylase
Where produced Salivary glands
Substrate Starch
Broken down into Maltose
What are the products of digestion of starch?
The end product of starch digestion is maltose.
Protein is digested into peptides and amino acids.
Fat gets digested into fatty acid and glycerols.
Where does the digestion of starch take place?
in the mouth (oral cavity) and in the small intestine
What is the enzyme for the digestion of protein and where is it made?
Protease (made in the pancreas
What are the products of digestion for protein?
smaller chains of amino acids
Where does the digestion of fat take place?
small intestine
What are the products of digestion for fat and what are their uses?
fatty acids are passed through the lymph system and then throughout the body via your bloodstream to be used or stored for energy, cell repair, and growth
What are conditions that increase the rate of fat breakdown by lipase?
increasing temperatures (up to around 40 ºC)
Explain the Lock and Key Hypothesis:
In 1894, German chemist Emil Fischer proposed the lock and key theory, which states that enzymes have a specific shape that directly correlates to the shape of the substrate. Basically, substrates fit into an enzyme the way a key fits into a lock.
What do most enzymes have a temperature coefficient of?
The temperature coefficient is the term used to describe the difference in the rate of a process at two different temperatures, usually separated by ten degrees. The rate of most enzyme dependent biological processes doubles when the temperature increases by ten degree celsius.
How does pH affect rate of reaction (digestion)?
When the pH value of the reaction medium changes, the shape and structure of the enzyme will change
What is optimum pH of pepsin (protease in stomach)
1.5 - 2.0
What is the optimum pH of salivary amylase?
68
What is the optimum pH of trypsin (protease in small intestine)?
8
What chemicals create the optimum pH for enzymes in some parts of the digestive system and how?
hydrochloric acid
Method for investigation to see how changing the concentration of the enzymes catalase affects the rate of reaction
Cells make the enzyme catalase to remove hydrogen peroxide. This investigation looks at the rate of oxygen production by the catalase in pureed potato as the concentration of hydrogen peroxide varies. The oxygen produced in 30 seconds is collected over water. Then the rate of reaction is calculated.
How does increasing enzyme concentration affect the rate of reaction?
speeds up the enzymatic reaction
How does increasing substrate concentration affect the rate of reaction?
It increases the rate of reaction to a certain point
Where is bile made?
The liver
The gallbladder
How are enzymes related to metabolism?
Enzymatic activity allows a cell to respond to changing environmental demands and regulate its metabolic pathways
What do digestive enzymes do?
Digestive enzymes play a key role in breaking down the food you eat
