Nutrient In Humans Flashcards
What is the term for the process by which organisms obtain food and energy?
Nutrition
Nutrition involves ingestion, digestion, absorption, assimilation, and egestion.
What is the first step of nutrition where food is taken into the body?
Feeding/Ingestion
This process typically occurs through the mouth.
What is the process of breaking down food molecules into simpler molecules called?
Digestion
This occurs so that the molecules can be absorbed by the alimentary canal.
Where does the absorption of digested food primarily take place?
Small intestine
The small intestine is crucial for nutrient absorption.
What term describes the conversion of absorbed nutrients into new cell components?
Assimilation
Assimilation also includes using nutrients to provide energy.
What is the process of removing undigested food as faeces called?
Egestion
Egestion is the final step of the nutrition process.
What is the main function of the digestive system?
To break down food into smaller, simpler soluble molecules
This process enables the body to absorb nutrients.
True or False: Digestion only involves physical processes.
False
Digestion involves both physical and chemical processes.
Fill in the blank: The _______ is responsible for producing bile, which aids in digestion.
Liver
The liver plays a key role in digestion through bile production.
What role do enzymes play in digestion?
They break down food molecules
Enzymes facilitate the chemical digestion of food.
What increases the surface area of the small intestine for better absorption?
Villi
Villi are small, finger-like projections that enhance nutrient absorption.
What are the two types of digestion carried out by the digestive system?
Physical digestion and chemical digestion
Define physical digestion.
The mechanical break-up of food into smaller pieces for efficient action of digestive enzymes
What actions contribute to physical digestion?
- Chewing action of the teeth and tongue
- Churning action of stomach muscles
- Emulsification of fats by bile
What is emulsification in the context of digestion?
The breaking up of fats into tiny droplets by bile to increase surface area for digestion
What is bile and what role does it play in digestion?
An alkaline, greenish-yellow liquid produced by the liver that aids in emulsification of fats
What is chemical digestion?
The breakdown of food into simpler, soluble molecules that can be absorbed by the body
What carries out chemical digestion?
Digestive enzymes
Fill in the blank: The _______ action brought about by stomach muscles mixes food with digestive juices.
churning
True or False: Bile contains enzymes for digestion.
False
List the organs involved in the human digestive system.
- Salivary glands
- Mouth
- Teeth
- Tongue
- Pharynx
- Epiglottis
- Oesophagus (gullet)
- Diaphragm
- Liver
- Gall bladder
- Bile duct
- Pancreatic duct
- Duodenum
- Stomach
- Pancreas
- Small intestine
- Colon
- Ileum
- Large intestine
- Rectum
- Anus
What is the primary function of the mouth in the digestive system?
Ingests food and breaks it into smaller pieces by chewing
Salivary glands secrete saliva, and the tongue mixes food with saliva to form boli.
What role does the pharynx play in digestion?
Joins the mouth to the oesophagus, larynx, and trachea
Prevents food from entering the trachea during swallowing using the epiglottis.
What is the function of the oesophagus?
Joins the pharynx to the stomach and pushes food towards the stomach
Achieves this through wave-like contractions of its walls.
What are the main functions of the stomach?
Breaks down food into smaller pieces and secretes gastric juice
Forms chyme, a mixture of enzymes and food.
What parts make up the small intestine?
Duodenum and ileum
Digestion is completed in these sections.
What does the small intestine secrete?
Intestinal juice containing maltase, peptidases, and lipase
Also receives pancreatic juice and bile.
What is the function of the large intestine?
Absorbs water and mineral salts from undigested food
Consists of the colon, rectum, and anus.
What is the role of the liver in digestion?
Secretes bile and stores it in the gall bladder
Bile aids in fat digestion.
What is the function of the pancreas?
Secretes pancreatic juice and the hormone insulin
Pancreatic juice contains digestive enzymes like amylase, lipase, and protease.
Fill in the blank: _______ is the physical breakdown of large fat molecules into smaller ones.
Emulsification
Emulsification is a physical process, not an enzymatic one.
True or False: Emulsification is part of chemical digestion.
False
Emulsification is a physical process.
What happens to faeces in the large intestine?
Stored in the rectum and expelled through the anus
The rectum contracts to facilitate expulsion.
What is peristalsis?
Wave-like contractions that push food through the digestive system
Occurs in the oesophagus and intestines.
What is peristalsis?
Peristalsis is a rhythmic contraction and relaxation of the muscles in the alimentary canal that occurs from the oesophagus to the rectum.
What is the primary function of peristalsis?
Peristalsis moves food along the gut and allows it to be mixed with digestive juices.
What types of muscles are involved in peristalsis?
Circular muscles and longitudinal muscles.
Where are circular muscles located in the alimentary canal?
Circular muscles are located next to the lumen.
Where are longitudinal muscles located in the alimentary canal?
Longitudinal muscles are located on the outer part of the organ.
What happens when circular muscles contract?
When circular muscles contract, the longitudinal muscles relax.
What happens when longitudinal muscles contract?
When longitudinal muscles contract, the circular muscles relax.
How does the alimentary canal facilitate the movement of food?
When a section constricts, the food bolus is squeezed through to the following section ahead of it, which dilates and allows the bolus to enter.
Fill in the blank: The section constricts and circular muscles contract, which _______ food forward.
pushes
Fill in the blank: When circular muscles relax, the section _______ and longitudinal muscles contract to allow food to enter.
dilates
What enzyme is produced by the salivary glands?
Salivary amylase
Salivary amylase breaks down starch into maltose.
What is the substrate for salivary amylase?
Starch
The end product of this reaction is maltose.
What is the required condition for salivary amylase to function?
Neutral, pH 7
This condition is found in the mouth.
What enzyme is produced by gastric glands?
Protease
Protease acts on proteins, breaking them down into polypeptides.
What is the substrate for protease in the stomach?
Protein
The end product is polypeptides.
What is the required condition for protease to function?
Acidic, pH 2
This is provided by hydrochloric acid in the stomach.
What enzyme is produced by the pancreas?
Pancreatic amylase
Pancreatic amylase continues the digestion of starch in the small intestine.
What is the substrate for pancreatic amylase?
Starch
The end product is maltose.
What enzyme is responsible for breaking down lipids?
Lipase
Lipase converts lipids into fatty acids and glycerol.
What are the end products of lipase action on lipids?
Fatty acids + glycerol
Lipase acts on lipids in the small intestine.
What enzyme converts maltose into glucose?
Maltase
Maltase acts on maltose in the small intestine.
What is the substrate for maltase?
Maltose
The end product of this reaction is glucose.
What enzyme breaks down polypeptides into amino acids?
Protease
This occurs in the small intestine.
What is the required condition for enzymes in the small intestine?
Alkaline, pH 8
This condition is provided by pancreatic juices, intestinal juices, and bile.
Fill in the blank: The end product of protein digestion by protease is _______.
Amino acids
Protease breaks down polypeptides into amino acids.
What is the function of amylase in digestion?
Amylase digests starch to maltose
Amylase is produced in the salivary glands and pancreas.
Where does the digestion of starch begin?
In the mouth
Starch digestion starts with salivary amylase.
What substance begins the digestion of proteins?
Pepsin
Pepsin is a protease activated by hydrochloric acid in the stomach.
What role does hydrochloric acid play in the stomach?
It provides optimum pH for pepsin and kills harmful microorganisms
The pH is about 2.
What is chyme?
Partially digested food in the stomach
Chyme is formed after food is churned and mixed with gastric juices.
What occurs in the small intestine during digestion?
Pancreatic juice and bile are released
These fluids neutralize acidic chyme and aid enzyme function.
What is the function of lipase in digestion?
Lipase digests fats
Lipase is secreted by the pancreas and intestinal epithelial cells.
What are the substrates and end products of protein digestion?
Proteins are digested to polypeptides
This occurs primarily in the stomach.
What is the pH level of the stomach for optimal enzyme activity?
About pH 2
This acidic environment is essential for pepsin activity.
Fill in the blank: The tongue rolls food into a _______ which is swallowed.
bolus
The bolus is then passed down the oesophagus.
True or False: Digestion of all food substances ends in the stomach.
False
Digestion ends in the duodenum and ileum of the small intestine.
What protective function does mucus serve in the stomach?
It protects the stomach wall from being digested
Mucus also moistens the food.
How long does food typically stay in the stomach?
3 to 4 hours
This duration allows for thorough digestion.
What is the role of the pancreas in digestion?
It secretes pancreatic juice containing digestive enzymes
This includes amylase, protease, and lipase.
What is the primary function of bile?
To emulsify fats
Bile is released from the gall bladder into the small intestine.
List the enzymes secreted by intestinal epithelial cells.
- Maltase
- Protease
- Lipase
These enzymes further digest carbohydrates, proteins, and fats.
What is the effect of peristalsis in the stomach?
It churns the food, aiding in digestion
Peristalsis helps mix chyme with gastric juices.
What is movement ortood?
Movement ortood is in a forward direction through wave-like contractions.
What is pepsin?
Pepsin is a protease found in the stomach that digests proteins to polypeptides.
How does the stomach provide the optimum pH for pepsin to work?
The stomach maintains an acidic environment which is optimal for pepsin activity.
What is chyme?
Chyme is the partly digested food in the stomach.
Describe the activity of pepsin as chyme enters the small intestine.
Pepsin continues to digest proteins into smaller polypeptides as chyme enters the small intestine.
What is the main function of the small intestine?
The main function of the small intestine is the absorption of end-products of digestion and water.
Where in the small intestine is absorption particularly emphasized?
Absorption is particularly emphasized in the ileum.
How are glucose and amino acids absorbed in the small intestine?
Glucose and amino acids are absorbed by diffusion and active transport.
How are fatty acids and glycerol absorbed?
Fatty acids and glycerol are absorbed by diffusion into the epithelium.
What do fatty acids and glycerol combine to form before entering lacteals?
They combine into fat globules to enter the lacteals.
What is the structure of a villus?
A villus is a finger-like projection found mostly in the ileum of the small intestine.
What are microvilli?
Microvilli are tiny projections on the epithelial cells of the villi that increase surface area.
How do villi and microvilli aid in absorption?
They greatly increase the surface area of the small intestine, thereby increasing the rate of absorption.
What transports absorbed fats away from the villi?
Lacteals, or lymphatic capillaries, transport absorbed fats away.
Fill in the blank: The inner walls of the small intestine are highly _______.
[folded]
True or False: Villi are found throughout the entire length of the small intestine.
False
What is the role of blood capillaries in the villi?
Blood capillaries transport absorbed glucose and amino acids away.
What is the role of mitochondria in epithelial cells?
Provide energy for active transport of nutrients
Mitochondria are known as the powerhouses of the cell, producing ATP which is essential for active transport mechanisms.
List the adaptations of the small intestine for absorption.
- Relatively long organ
- Folded inner surface
- Presence of numerous villi
- Presence of microvilli on each villus
These adaptations increase the surface area available for nutrient absorption.
How does the small intestine increase the diffusion rate?
- One-cell thick wall of villus
- One-cell thick wall of blood capillary
- Steep concentration gradients maintained by rapid transport of nutrients
These features facilitate quick movement of nutrients from the intestine into the bloodstream.
What substances are absorbed by the large intestine?
Water, mineral salts, and vitamins
The large intestine plays a crucial role in reabsorbing these essential nutrients.
What is the process of expelling undigested matter from the body called?
Defecation
This process involves the storage of undigested and unabsorbed matter in the rectum before it is expelled.
Fill in the blank: Davidson’s disease is a disease that can be passed down from the parent to the _______.
offspring
This indicates that Davidson’s disease has a genetic component.
What is the function of the large intestine?
The large intestine absorbs water and electrolytes, forming and storing feces.
How are glucose and amino acids absorbed in the small intestine?
By diffusion and active transport into blood capillaries.
What is the role of the hepatic portal vein?
To transport blood rich in absorbed nutrients from the small intestine to the liver.
What happens to excess glucose in the liver?
It is converted to glycogen.
What is done with excess amino acids in the liver?
They are converted to urea.
How are fatty acids and glycerol absorbed in the small intestine?
By lacteals, which unite to form lymphatic vessels.
What do lymphatic vessels do after absorbing fats?
They eventually empty into the bloodstream.
Fill in the blank: All digested food substances, such as sugars, amino acids, fatty acids, and _______ are absorbed in the small intestine.
glycerol
True or False: The hepatic portal vein carries blood from the liver to the small intestine.
False
What substances are transported by the hepatic portal vein?
Glucose and amino acids.
What is the primary purpose of the small intestine’s adaptations?
To maximize absorption of nutrients.
What is assimilation?
The process in which absorbed nutrients are converted into new cytoplasm or used to provide energy.
How is glucose utilized in the body?
Glucose is taken into cells and broken down during respiration to release energy. Excess glucose is returned to the liver and stored as glycogen.
What happens to excess glucose?
Excess glucose returns to the liver and is stored as glycogen, which is converted back into glucose when energy is needed.
What are the uses of amino acids in the body?
Amino acids enter cells and are converted into new cytoplasm for growth and repair, used to form enzymes and hormones, and excess amino acids are deaminated in the liver.
What role do fats play in the body?
Fats are used to build protoplasm (e.g., cell membranes) when there is sufficient glucose, and broken down to provide energy when glucose is insufficient.
Where are excess fats stored in the body?
Excess fats are stored in adipose tissues under the skin or around the heart and kidneys.
True or False: Nutrients absorbed from the small intestines are directly transported to the rest of the body.
False
What is the first step after nutrients are absorbed?
Nutrients absorbed are first transported to the liver for metabolism and conversion into storage forms.
What are the roles of the liver?
The liver regulates blood glucose levels, aids in fat digestion, deaminates amino acids, breaks down hormones, and detoxifies substances.
What hormones regulate blood glucose concentration?
Insulin and glucagon.
What is the effect of insulin on blood glucose levels?
Insulin acts on liver cells to convert excess glucose to glycogen for storage and returns blood glucose to a normal level.
What is the effect of glucagon on blood glucose levels?
Glucagon acts on liver cells to convert glycogen to glucose for energy and returns blood glucose to a normal level.
How does the liver assist in fat digestion?
The liver secretes bile, which is stored temporarily in the gall bladder.
What process involves the removal of the amino group from an amino acid?
Deamination
Deamination converts the amino group to ammonia, which is then converted to urea for excretion.
What does the liver convert the remains of deaminated amino acids into?
Glucose and subsequently glycogen
This conversion allows for storage of energy.
What happens to hormones after they exert their effects in the body?
They are broken down by the liver
Hormones are largely protein in nature.
What is the role of the liver in detoxification?
Converts harmful substances to harmless ones
This is an essential function of liver cells.
Which enzyme in the liver breaks down alcohol?
Alcohol dehydrogenase
This enzyme converts alcohol to acetaldehyde.
What is acetaldehyde broken down into?
Compounds used in respiration for energy
This process is crucial for energy production.
What is one effect of excessive alcohol consumption on the digestive system?
Increases acidic secretions, raising the risk of stomach ulcers
This can lead to serious digestive issues.
What are the effects of prolonged alcohol abuse on the liver?
Causes liver cirrhosis
Liver cirrhosis leads to destruction of liver cells and replacement by fibrous tissue.
What are potential outcomes of liver cirrhosis?
Bleeding in the liver, liver failure, and death
These are severe consequences of liver damage.
How does alcohol affect brain function?
Slows down functions and decreases reaction time
This effect reduces a person’s responsiveness.
What are some social implications of alcohol consumption?
Reduces self-control and inhibition
This may lead to unwarranted personal and social liberties.
What are some other effects of intoxication?
Slurred speech, blurred vision, poor muscle coordination
These effects impair physical abilities.
What long-term effect can heavy alcohol consumption have on the brain?
‘Wet brain’ and shrinkage of brain volume
‘Wet brain’ refers to dementia caused by brain damage.
How can heavy alcohol consumption during pregnancy affect the fetus?
Interferes with the development of the fetus’ brain
This can lead to lifelong developmental issues.
