3.5 - The digestive system in animals Flashcards
1
Q
What is heterotroph?
A
A heterotroph is an organism that can’t synthesise the nutrients required for survival. Hence, eats other plants or animals for energy and nutrients.
2
Q
What is the definition of digestion?
A
Digestion is the process by which insoluble macromolecules (polymers) such as carbohydrates, protein, and lipids are broken down into their basic subunits (monomers) in the gastrointestinal tract.
3
Q
What is the main function of the digestive system? (Simple)
A
The digestive system breaks down food and absorbs nutrients needed for survival.
4
Q
Why is digestion necessary for nutrient absorption?
A
Large macromolecules (carbohydrates, proteins, lipids) are too big to be absorbed by cells. Digestion breaks them down into smaller, soluble subunits (monomers) that can be absorbed and transported.
5
Q
What are the 2 types of digestion?
A
Mechanical and Chemical.
6
Q
What is mechanical digestion?
A
Mechanical digestion occurs before chemical digestion. Mechanical digestion involves physically breaking food into smaller pieces to increase surface area for enzyme action, increasing the efficiency of chemical digestion.
7
Q
How does mechanical digestion occur in the stomach?
A
The smooth muscle of the stomach contracts in a process called churning, mixing food with gastric juices and breaking it into smaller pieces to increase surface area for pepsin.
8
Q
What is chemical digestion?
A
Chemical digestion occurs after mechanical digestion because increased surface area increases chemical digestion efficiency. Chemical digestion involves enzymes that chemically break down large molecules into smaller molecules by breaking the chemical bonds between subunits.
9
Q
What organs does the digestive system consist of?
A
Gastrointestinal tract and accessory organs.
10
Q
What is the gastrointestinal (GI) tract?
A
The gastrointestinal tract also known as the alimentary canal is a series of connected hollow organs through which food passes, starting from the mouth and ending at the rectum.
11
Q
Does the muscles of the organs in the gastrointestinal tract enable the walls to move?
A
Yes because of smooth muscle.
12
Q
What are the organs of the Gastrointestinal tract and their purpose?
A
- Mouth – Chews food (mechanical digestion) and mixes with saliva and salivary amylase (chemical digestion).
- Pharynx (Throat) – Passageway for food from mouth to esophagus.
- Esophagus – Moves food to the stomach using peristalsis (wave-like contractions).
- Stomach – Uses gastric juices (acid & enzymes) to break down food into chyme.
- Small Intestine – Break down food, absorb nutrients and water.
- Large Intestine (Colon) – Absorbs water & electrolytes, forms feces.
- Rectum – Stores feces before elimination.
- Anus – Releases waste from the body.
13
Q
What are accessory digestive organs?
A
Organs that assist digestion but food does not pass through them.
14
Q
What are the different accessory organs and their purpose?
A
- Pancreas – Produces digestive enzymes (amylase, lipase, proteases) & regulates blood sugar (insulin & glucagon).
- Liver – Produces bile to break down fats & detoxifies the blood.
- Gallbladder – Stores and releases bile into the small intestine.
- Salivary Glands – Produce saliva with amylase to begin carbohydrate digestion.
- Epiglottis – A flap of tissue that prevents food from entering the trachea during swallowing.
15
Q
What is peristalsis?
A
Peristalsis is the wave-like muscle contractions that move food through the oesophagus and other parts of the digestive tract mixing it with digestive juices, and helps prevent blockages.
16
Q
What is the function of pepsin in digestion?
A
Pepsin is an enzyme that breaks down proteins into smaller peptides.
17
Q
What are the phases of digestion.
A
- Ingestion
- Movement
- Mechanical and chemical digestion
- Absorption of nutrients
- Elimination of waste products
18
Q
What happens to food after it is swallowed?
A
Food passes through the pharynx into the oesophagus, where it is moved toward the stomach.
19
Q
What is the role of salivary amylase in digestion?
A
Salivary amylase begins the chemical digestion of carbohydrates into simple sugars.
20
Q
What is the function of saliva in the digestive process?
A
Saliva lubricates food to make it easier to swallow and contains enzymes (like amylase) that start breaking down carbohydrates.
21
Q
What is the role of the epiglottis during swallowing?
A
The epiglottis covers the trachea during swallowing to prevent food from entering the airway and cause blockage or choking.
22
Q
What is mastication?
A
Mastication is the process of chewing food to break it into smaller pieces, increasing the surface area for enzymes.
23
Q
What happens to food in the stomach?
A
The stomach secretes gastric juices (hydrochloric acid, pepsinogen, mucus) and churns food into chyme.
24
Q
What is the role of the mucus in the stomach?
A
Mucus lines the stomach protecting the internal epithelial cells from the hydrochloric acid.
25
What is the oesophagus?
The oesophagus is a hollow muscular tube connecting the pharynx to the stomach.
26
What is gastric acid, and how does it help digestion?
Gastric acid (mainly hydrochloric acid) helps break down food and activate pepsin, an enzyme that digests proteins.
27
What is the role of hydrochloric acid (HCl) in the stomach?
The hydrochloric acid lowers the pH of the stomach to between 1.5 and 3.5 to kill pathogens, denatures proteins, and activates pepsinogen into its active form, pepsin.
28
What is chyme and how is it formed?
Chyme is a semi-liquid substance formed in the stomach from the mechanical churning and chemical digestion of food. It consists of partially digested food mixed with gastric juices.
29
Why is it important that the stomach releases chyme slowly into the small intestine?
Releasing chyme slowly ensures the small intestine can efficiently digest and absorb nutrients. If released too quickly, nutrients may pass through without being absorbed properly.
30
What is the role of bile in digestion?
Bile is produced by the liver sectred directly into the small intestine or stored in the gallbladder. Bile breaks down fats, breaking them down into smaller droplets to aid digestion.
31
What are villi and their role in digestion?
Villi are finger-like projections in the small intestine that increase surface area for nutrient absorption. They contain capillaries (for glucose and amino acid absorption) and lacteals (for fatty acid absorption).
32
State the product of digestion for each macromolecule (polymer)
Carbohydrates - Glucose and simple sugars and transported blood.
Lipids - Fatty acids and glycerol and transported blood.
Proteins - amino acids and peptides and transported lymph.
33
What is the difference between absorption and assimilation?
Absorption is the process of nutrients being taken into the blood from the digestive tract, while assimilation is the process of these absorbed nutrients being used by cells in the body.
34
What is the function of the pancreas in digestion?
The pancreas produces digestive enzymes (amylase, lipase, proteases and bicarbonate) to neutralize stomach acid in the small intestine. It also helps regulate blood sugar with insulin and glucagon.
35
What enzymes are involved in carbohydrate digestion?
Saliva and pancrea amalyse and pepsin breaks down carbohydrates into glucose and simple sugars.
36
What enzymes are involved in protein digestion?
Pepsin (in the stomach) and trypsin (from the pancreas) break down proteins into amino acids.
37
What enzymes are involved in lipid digestion?
Lipase (produced by the pancreas) breaks down lipids into fatty acids and glycerol.
38
What is the role of the large intestine in digestion?
The large intestine absorbs water and electrolytes, and forms feces by compacting undigested food.
39
How is glucose absorbed in the small intestine?
Glucose is absorbed into the bloodstream through the villi of the small intestine by active transport into the capillaries.
40
What is the difference between microvilli and villi?
Villi - Larger finger like projections on the surface of the small intestise to increase surface area for absorption.
Microvilli - Smaller hair like projections on the surface of the villi to futher increase surface area for abosobtion.
Both absorb nutrients and increase surface area.
41
What is the product of protein digestion?
Proteins are broken down into amino acids and peptides.
42
What is the role of salivary glands in digestion?
Salivary glands produce saliva, which contains the enzyme amylase that begins the breakdown of carbohydrates into simple sugars in the mouth.
43
What is the role of the liver in digestion?
The liver produces bile, which helps emulsify fats, making them easier to digest. It also detoxifies harmful substances in the blood.
44
How does the structure of the small intestine contribute to absorption?
The small intestine has a large surface area due to villi and microvilli, which increases absorption of nutrients into the bloodstream.
45
What are the functions of the different parts of the small intestine?
Duodenum: Receives bile and digestive enzymes, and continues digestion of food.
Jejunum: Absorbs nutrients, such as carbohydrates, proteins, and fats.
Ileum: Absorbs vitamin B12 and bile salts.
46
What is the structure and function of villi in the small intestine and raw the villi?
Villi are finger-like projections in the small intestine that increase the surface area for nutrient absorption.
Capillaries absorb amino acids and glucose.
Lacteals absorb fatty acids and glycerol.
47
What is the role of amylase in digestion?
Amylase is an enzyme that breaks down carbohydrates (such as starch) into simple sugars (like glucose). It is found in saliva (mouth) and pancreatic juice (small intestine).
48
What is the role of lipase in digestion?
Lipase is an enzyme that breaks down lipids (fats) into fatty acids and glycerol. It is produced by the pancreas and acts in the small intestine.
49
What is the role of trypsin in digestion?
Trypsin is an enzyme produced by the pancreas that breaks down proteins into smaller peptides and amino acids. It acts in the small intestine.
50
What happens in the mouth during digestion?
Food is chewed (mechanical digestion), and mixed with saliva making it easy to swallow while increasing the surface area for enzyme amylase to brake down the food partially.
51
What is the function of salivary glands?
They produce saliva, which lubricates food and contains amylase to begin carbohydrate digestion.
52
What role does the epiglottis play in digestion?
It prevents choking by preventing food from entering the trachea by covering it during swallowing.
53
Why does carbohydrate digestion stop in the stomach?
The acidic environment deactivates salivary amylase.
54
What is chyme?
Chyme is a semi-liquid mixture of partially digested food, gastric juices, and digestive enzymes that is formed in the stomach and slowly released into the small intestine for further digestion and absorption.
55
What is the role of the small intestine in digestion?
It completes chemical digestion and absorbs nutrients.
56
What substances aid digestion in the duodenum?
Pancreatic juice (contains amylase, trypsin, lipase) and bile aid in digestion of food and neutralise the acid from the stomach.
57
What secretes pancreatic enzymes, and where are they released?
The pancreas secretes pancreatic enzymes (amylase, trypsin, lipase) into the duodenum via the pancreatic duct.
58
Where is bile secreted, stored, utilise and it's purpose?
Bile is secreted by the liver and stored in the gall bladder until needed. It is released into the duodenum, where it emulsifies large fat droplets into smaller ones, increasing the surface area for pancreatic lipase to efficiently digest fats.
59
What is emulsification?
Emulsification is the process by which bile breaks down large fat droplets into smaller droplets, increasing the surface area for lipase to chemically digest fats more efficiently. Mechanical digestion.
60
How does bile assist in digestion?
Bile emulsifies fats into smaller droplets, increasing the surface area for lipase action.
61
What enzymes does the pancreas produce?
Amylase (carbohydrates → simple sugars), trypsin (proteins → amino acids), lipase (lipids → fatty acids & glycerol).
62
What is trypsin?
Trypsin is an enzyme produced by the pancreas that breaks down proteins into peptides and amino acids in the small intestine.
63
What is the role of the jejunum in digestion?
Absorbs nutrients from digested food through villi and microvilli, to break down food for nutrient uptake into the bloodstream.
64
What is the structure of villi, and why are they important?
Villi are finger-like projections in the small intestine that increase surface area for nutrient absorption.
65
What are lacteals, and what is their role in digestion?
Lacteals are lymphatic vessels in the villi of the small intestine that absorb fatty acids and glycerol from digested fats.
66
What is the function of lacteals in villi?
Lacteals absorb fatty acids and glycerol into the lymphatic system.
67
How are different macronutrients transported in the body?
Carbohydrates (glucose) → absorbed into blood.
Proteins (amino acids) → absorbed into blood.
Lipids (fatty acids & glycerol) → absorbed into lacteals.
68
What is the function of the large intestine (colon)?
It absorbs water and minerals and compacts waste into faeces.
69
How does dietary fiber affect digestion?
It promotes gut health by aiding movement through the intestines and feeding beneficial bacteria.
70
What is egestion?
The process of expelling waste (faeces) from the rectum through the anus.
71
Where does carbohydrate digestion begin and end?
It starts in the mouth (amylase) and ends in the small intestine (pancreatic amylase).
72
Where does protein digestion begin and end?
It starts in the stomach (pepsin) and ends in the small intestine (trypsin).
73
Where does lipid digestion occur?
It occurs entirely in the small intestine with the help of lipase and bile.
74
Which nutrient does not need digesting?
Simple sugars such as Glucose
75
What does the pancreatic juice consists of?
Pancreatic juice, secreted by the pancreas consists of pancreatic amylase, trypsin and pancreatic lipase.
76
What is the function of the duodenum in digestion?
The duodenum is the first and shortest section of the small intestine. It receives pancreatic juice and bile, which help chemically digest macronutrients and neutralise stomach acid.
77
Why is it important that bile and pancreatic juice are alkaline?
They neutralise the acidic chyme from the stomach, raising the pH to around 7.8, which creates an optimal environment for pancreatic enzymes to function.
78
What does pancreatic juice contain and what are the functions of these enzymes?
Pancreatic juice contains pancreatic amylase (digests carbohydrates), trypsin (digests proteins), and pancreatic lipase (digests lipids (fats)).
79
What is the function of bile in digestion?
Bile emulsifies large fat droplets into smaller ones (mechanical digestion), increasing surface area so pancreatic lipase can digest fats more efficiently.
80
Where is bile produced and stored?
Bile is produced by the liver and either secreted directly into the duodenum or stored in the gall bladder for later use.
81
What kind of digestion occurs in the duodenum and by what enzymes?
Most chemical digestion occurs in the duodenum by pancreatic enzymes: amylase (carbohydrates), trypsin (proteins), and lipase (fats).
82
Does any absorption occur in the duodenum?
Yes, a small amount of nutrient absorption occurs in the duodenum, although most absorption takes place in the later sections of the small intestine.
83
What are the three sections of the small intestine?
The duodenum, jejunum, and ileum.
84
What is the role of peristalsis in the small intestine?
Smooth muscle contractions (peristaltic waves) move food along the small intestine.
85
What are villi and what is their function in the small intestine?
Villi are finger-like projections lining the small intestine that increase surface area for more efficient absorption of nutrients.
86
Where does most absorption of nutrients occur in the small intestine?
Most absorption occurs in the jejunum, the second section of the small intestine.
87
How does the structure of villi aid absorption?
Villi have a moist, thin epithelial lining that reduces the distance nutrients must travel and increases permeability for faster absorption.
88
How are simple sugars and amino acids absorbed in the small intestine?
They are absorbed across the epithelial lining into the blood capillaries of the villi.
89
How are fatty acids and glycerol absorbed in the small intestine?
They are absorbed into the lacteal, a lymph capillary that is part of the lymphatic system.
90
What happens to nutrients after they are absorbed in the small intestine?
They are processed by the liver and then distributed throughout the body for various functions.
91
What is another name for the large intestine?
The colon.
92
What materials enter the large intestine from the small intestine?
Undigested food and nutrients such as dietary fibre, water and electrolytes.
93
What is the main function of the large intestine?
The main function of the large intestine is to absorb water and electrolytes from undigested food, and forms form feces for elimination.
94
What role do bacteria play in the large intestine?
Help ferment undigested food, produce vitamins (K and B), break down fibers, and protect against harmful microbes.
95
Why can’t humans digest dietary fibre?
Humans lack the enzymes needed to break down dietary fibre.
96
How is dietary fibre partially broken down in the large intestine?
Beneficial bacteria in the microbiome have enzymes that can break down some types of dietary fibre.
97
What happens to indigestible fibre that cannot be broken down?
It becomes part of the faeces and is stored in the rectum before being expelled.
98
What is the process of removing faeces from the body called?
Egestion — it occurs via the anus.
99
Label the digestive system.
Mouth – Opening at the top of the digestive system; where food enters.
Pharynx – Short passage behind the mouth; leads to oesophagus.
Oesophagus – Long muscular tube behind the trachea; connects throat to stomach.
Stomach – J-shaped sac under the ribs on the left side.
Duodenum – First short section of small intestine, just after the stomach.
Jejunum – Middle section of small intestine; central in the abdomen.
Ileum – Last part of the small intestine; ends near the large intestine.
Large Intestine (Colon) – Thick tube framing the small intestine; goes up, across, and down the abdomen.
Rectum – Straight section at the end of large intestine; stores faeces.
Anus – Opening at the end of the digestive tract; for egestion.
100
What cell makes up the inner lining of the intestine?
Smooth muscle cell.
101
Explain 2 ways the stomach structure enables it to perform its function.
Smooth muscle: Allows to perform peristalis and churn food with gastric juices.
Gastric Glands: The stomach lining secretes hydrochloric acid (HCl) and digestive enzymes like pepsin, which aid in protein breakdown and kill harmful bacteria.
