The Human Digestive System Flashcards
[___] involves the taking in of food and drink substances through the mouth.
Ingestion
[___] digestion involves the physical breakdown of large food particles into smaller ones without chemically altering the food particles. E.g. cutting, chewing, grinding and churning.
❥ [___] digestion involves the chemical breakdown of food molecules into smaller, more water-soluble ones by the action of digestive enzymes.
❥ Mechanical digestion aids chemical digestion by breaking food into smaller pieces, which are more easily accessible by [___ ___].
❥ Chewing, grinding and churning of food are examples of [___ ___]
❥ [___] digestion is carried out by the [__].
❥ The breakdown of food by enzymes is [___ ___].
Mechanical ❥ Chemical ❥ digestive enzymes ❥ mechanical digestion ❥ Mechanical - teeth ❥ chemical digestion
[___] is the process during which the small, water-soluble molecules and ions produced by digestion pass into the bloodstream, which transports them to different body organs. Absorption mostly occurs in the [__ __].
Absorption - small intestine
[___] is the uptake of nutrients (e.g. glucose and amino acids) from the bloodstream by body cells where they are subsequently used.
Assimilation
[___] is the process of expelling out of the body through the anus, the food molecules that are not [___] and absorbed, in the form of feces. The undigested food consists of the [____] that cannot be digested in our bodies.
Egestion - digested - fiber/roughage
Teeth are embedded in sockets in the jawbones. These sockets are tightly sealed by a soft tissue (like a collar) called the [__].
❥ Gums can act as [__ ___]. They protect the underlying bone from damage during chewing.
❥ Gums also form a barrier against [___] of underlying tissues.
gum
❥shock absorbent
❥infection
The visible part of the tooth that projects into the oral cavity is called the [___].
crown
The crown of the tooth is covered by the [___]: the white to off-white, non-living substance that offers a surface for the processing of food by the teeth inside the mouth. The enamel is highly [___]. It is the hardest substance made by the human body, and it does not break or get chipped easily. However, it is sensitive to [__] which can cause its demineralization.
enamel - mineralized - acids
The [__] is a living part of the tooth that contains strands of cytoplasm. It is provided with oxygen and nutrients by the [__ __].
dentine - pulp cavity
The pulp cavity is located in the [__] of the tooth, within the [___].
❥ The pulp cavity contains [__ __] and [__ __].
❥ The blood capillaries provide [__ _ __] to the surrounding dentine and keep it
alive.
❥ The nerve endings help the tooth to detect [___] e.g. pain.
center - dentine
❥ blood capillaries - nerve endings
❥ O2 and nutrients
❥ stimulus
The part of the tooth that is embedded in the gum is called the [__].
root
The root is not covered by enamel, instead, a thin layer of hard mineralized tissue called
[__] surrounds the [__].
cement - root
[___] containing protein fibers extend from the cement to the jawbone to anchor the tooth in its socket. These [__] but strong [__] allow the tooth to slightly move while chewing or biting.
Ligaments - flexible - fibers
Description of incisors of humans:
❥ Incisors are [__ __]; they are found at the [__] of the mouth.
❥ They are used for [__ _ __] pieces of food.
❥ Humans have [_] incisors: 4 in the upper jaw and 4 in the lower jaw.
❥ Incisors have [__] roots.
❥ chisel-shaped - front
❥ biting and cutting
❥ 8
❥ single
Description of canines of humans:
❥ Canine teeth are found directly next to the [__], at each of their sides.
❥ They are more [__] than the incisors.
❥ Like incisors, they are used for [__] and [__] pieces of food.
❥ Humans have [_] canines in their milk teeth and permanent teeth.
❥ Canines have [__] roots.
❥ incisor ❥ pointed ❥ biting - cutting ❥ 4 ❥ single
Description of premolars of humans:
❥ Premolars have a [__] surface for processing food than incisors and canines.
❥ Premolars are located directly [__] the canine tooth.
❥ Each premolar has two or more elevated tips called [__], which are used for
[__ _ __] food.
❥ Humans have [_] premolars: 4 in the upper jaw and 4 in the lower jaw.
❥ Most premolars have a [__] root but some have two roots.
❥ broader ❥ behind ❥ cusps - crushing and grinding ❥ 8 ❥ single
Description of molars of humans:
❥ Molars are found [______], behind the premolars.
❥ Molars are similar to premolars but are slightly [__], with [__ _ __] cusps each.
❥ Molars are also used for [__ _ __] food.
❥ Adult humans have [_] molars in total: 6 in the upper jaw and 6 in the lower jaw.
❥ Molars have [__ _ __] roots.
❥ at the back of the jaw ❥ larger - four or five ❥ crushing and grinding ❥ 12 ❥ two or three
[__] in the mouth combines with saliva and food forming a sticky layer that covers the teeth’s gums called [__].
❥ After a meal, food containing [__] is left behind in the teeth.
❥ The bacteria feed on sugar, then respire anaerobically changing the sugar into
[__ __].
❥ The lactic acid dissolves the [__] in the hard [__] and causes [__ __] which is manifested by the appearance of [__] in the tooth.
❥ Tooth decay may spread deep into the tooth if not managed properly and can grow larger as the lactic acid dissolves the softer [__].
❥ A dentist can clean and fill the cavities if they are discovered at [__ __]. If not the bacterial infection might reach advantages stages such as spreading to the [__ __] where nerve endings are present, causing a [___].
❥ The infection can cause an [__] or a collection of pus in the tissues accompanied by swelling, redness and pain at the root of the tooth.
❥ When the infection reaches the [__] of the tooth, the tooth will have to be taken out.
Bacteria - plaque ❥ sugar ❥ lactic acid ❥ calcium - enamel - tooth decay - cavities ❥ dentine ❥ early stages - pulp cavity - toothache ❥ abscess ❥ root
When bacteria combine with sugars from food stuck in the teeth, saliva, and other components, a sticky layer called [__] is formed over the gums and teeth.
❥ A collection of pus in the tissue accompanied by [__], [__], and pain at the root of the tooth is called an [__].
❥ The inflammation of gums that become swollen, tender, and may bleed during brushing is known as [___].
❥ If plaque remains stuck on the teeth it can harden and form [__].
plaque
❥ swelling - redness - abscess
❥ gingivitis
❥ tartar
The alimentary canal also called the [__ __] or gut is a long tube running through the body from the mouth to the anus.
❥ The main organs that make up the alimentary canal are the [__], [___], [__], [__ __] and [__ __].
❥ The accessory organs of the digestive system include: the [__], [__ __], [__] and [__ __].
digestive tract
❥ mouth - esophagus - stomach - small intestine - large intestine
❥ pancreas - gall bladder - liver - salivary glands
Saliva is an [__] digestive juice in the mouth produced by the [__ __].
❥ Saliva is a mixture of [__], [__], and [___].
❥ [__] in saliva provides the medium needed to dissolve food molecules, which
can then stimulate taste receptors.
❥ Saliva contains [__] which allows food particles to stick together forming a soft lubricated ball-like mixture known as a [__] that can be easily swallowed.
❥ The enzyme [__ __] starts the digestion of the starch found in the ingested food, breaking it down into a soluble disaccharide sugar called [__]. The digestion of starch is continued in the small intestine.
alkaline - salivary glands ❥ water - mucus - enzymes ❥ Water ❥ mucus - bolus ❥ salivary amylase - maltose
Digestion of carbohydrates begins in the [__], when starch is hydrolyzed into [__] by [__ __].
mouth - maltose - salivary amylase
Salivary glands in the mouth secrete an alkaline digestive juice called the [__].
saliva
❥ The [___] is a muscular tube that transports the food from the [__] to the [___].
❥ The inside space of this tube called lumen is lined with a mucous membrane made up of cells that secrete [__] for lubrication which facilitates the movement of the food down to the stomach.
❥ Food is pushed along the esophagus through a process called [___], which is triggered by the entry of the food bolus into the esophagus during swallowing.
❥ esophagus - mouth - stomach
❥ mucus
❥ peristalsis
[___] is the repetitive contraction and relaxation of the smooth muscles in the alimentary canal. During esophageal peristalsis, [__ __] of the walls of the esophagus [___] above the descending food and [__] below it, thereby pushing the food in one direction, into the stomach.
Peristalsis - smooth muscles - contract - relax
During digestion, food from the mouth is pushed to the stomach through the [___] by peristaltic movements. The repetitive contraction and relaxation of the smooth muscles that pushes food in one direction down the alimentary canal is called [__].
esophagus - peristalsis
The [__] is a bag-like organ that has muscular, elastic walls and helps in the digestion of food.
The stomach is connected to the [___] at the upper end and to the [__ __] at the lower end.
stomach - esophagus - small intestine
The main function of the stomach is to continue the [___] of food chemically and mechanically, and to pass it on to the [__ __] for further digestion.
digestion - small intestine
❥ The [__ __] is found at the entrance of the stomach and is also called the lower esophageal sphincter.
❥ The [__ __] is found at the base of the stomach.
❥ Upon contracting the [__ __] closes the entrance of the stomach and prevents food from going back to the esophagus.
❥ The [__ __] relaxes and opens allowing food from the esophagus to the sphincter.
❥ The [__ __] regulates the emptying of stomach contents into the small intestine.
❥ cardiac sphincter ❥ pyloric sphincters ❥ cardiac sphincter ❥ cardiac sphincter ❥ pyloric sphincter
[__] and [___ __] can be harmful to the stomach wall. The stomach is protected from self-digestion by [__] that forms a layer covering the inner stomach walls and gastric pits.
Pepsin - hydrochloric acid - mucus
The gastric glands are glands found in the stomach, specifically in the gastric pits in the [__], they secrete gastric juices that contain [___ __], the enzyme [__] and mucus, among other substances.
mucosa - hydrochloric acid - pepsin
Hydrochloric acid in the stomach:
❥ Helps converting inactive [___] into active [__].
❥ Produces optimum [__] pH for pepsin to work.
❥ Kills any microorganisms e.g. [__ _ __] taken in with the food by [___] their enzymes.
❥ pepsinogen - pepsin
❥ acidic
❥ bacteria or fungi - denaturing
Pepsin is a [___] enzyme; secreted by the gastric glands of the stomach, it breaks down proteins into smaller [___].
protease - peptides/polypeptides
Pepsin is first released in an inactive form called [___] which is only converted into the active form pepsin, when [___ __] is secreted.
pepsinogen - hydrochloric acid
What is the role of the mouth?
[___] digestion of food occurs here, by the [__]. [__] digestion of starch into maltose by salivary amylase occurs here.
Mechanical - teeth - Chemical
What is the role of the esophagus?
Transports food from the mouth to the stomach.
What is the role of the stomach?
Digestion of [__] takes place here. Pepsinogen is released in the inactive form. In the presence of food [___ __] is released, which will convert pepsinogen into the active form pepsin. [__] is a protease that will break down proteins into peptides.
proteins - hydrochloric acid - Pepsin
What is the role of the pancreas?
[__] of enzymes such [___], [__], [__] that pass into the [__] via a duct.
Production - amylase - lipase - trypsin - duodenum
What is the role of the ileum?
Thrown into folds called the [__]. Site of [__] of soluble product of digestion into the blood stream. The site of intracellular digestion of [__] into glucose.
villi - absorption - maltose
What is the role of the gall bladder?
[__] bile. The bile contains the [__ __] that will emulsify the
[__]. Increasing the surface area of the lipids allows for faster digestion by lipase enzyme.
Stores - bile salts - lipids
What is the role of the liver?
[__] of bile. Detoxification of alcohol. [___] of amino acids. Production of [__ __], such as fibrinogen.
Production - Deamination - plasma proteins
What is the role of the rectum?
Temporarily stores the feces
What is the role of the colon?
This is where undigested material (fiber) is [___ __ __]. It is also where bile [__] and [__] are reabsorbed.
compacted into feces - salts - water
What is the role of the duodenum?
Site of [__] of starch into maltose by pancreatic amylase, lipids into fatty acids and [__] by pancreatic lipase and
protein into amino acids by pancreatic [__].
digestion - glycerol - trypsin
The pancreas secretes digestive juice into the duodenum via a pancreatic duct. This digestive juice includes the following enzymes: pancreatic [__], pancreatic [__], and trypsin. The pancreatic juices also contain [__ __ __].
lipase - amylase - sodium hydrogen carbonate
❥ The sodium hydrogen carbonate or sodium [___] protects the duodenum from the action from the [__ __] and pepsin coming from the stomach.
❥ Sodium hydrogen carbonate in the pancreatic juice is a [__] base that helps neutralize the acidic [__] coming from the stomach.
❥ bicarbonate - hydrochloric acid
❥ weak - chyme
[__] is produced by the liver, stored in the [__ __], and released into the [__ __] to emulsify [__].
Bile - gall bladder - small intestine - fats
Bile contains [__ __] that help in the physical breakdown of large lipid globules into smaller droplets by a process known as [____]. This helps increase the [__ __] of the lipids which allows [__] to act more rapidly. Bile helps to neutralize [__ __].
bile salts - emulsification - surface area - lipase - acidic chyme
What is the function of the villous?
The absorption of digested food and water from the small intestine into the blood.
What is the function of the goblet cell?
Responsible for the production of mucus
What is the function of the lacteal?
Responsible for the transport of fatty acids/fats.
What is the function of the blood capillaries?
Thin walled blood vessels for the absorption of products of digestion including amino acids, glucose and minerals.
What is the function of the microvilli?
Provide a large surface area for the maximum absorption of
products of digestion.
❥ In order to allow plenty of time for digested food to be absorbed the ileum has to
be very [__].
❥ The ileum has numerous finger like projections called [__] which provide its
inner surface with a large [__ __].
❥ Each villus is made up of cells that has numerous small projections on its surface known as the [___]. This further increases the [__ __] for absorption.
❥ Each villus contains a [__] for absorption of [__].
❥ Each villous is highly vascularized. Each villous contains a network of [__ __] for the absorption of amino acids, glycerol and some fat.
❥ In order for the digested food to pass readily, the lining of the epithelium (one cell thick) is [__].
❥ long ❥ villi - surface area ❥ microvilli - surface area ❥ lacteal - fat ❥ blood capillaries ❥ thin
❥ Absorption can occur through [__] or [__] transport.
❥ Absorption of food takes place across the [__] in the ileum.
❥ Inside each villus there is a dense network of [__ __] and a single lymph vessel.
❥ Glucose, mineral salts, and amino acids are absorbed into the [__] capillaries.
❥ Some of the fatty acids and glycerol pass into the capillaries of the [__].
❥ Most lipids move from the [__] cells into the lacteals which are [__] capillaries. These lacteals carry a fluid called [__] that will rejoin the blood circulation.
❥ Most water is absorbed in the [__] intestine. A certain amount is reabsorbed in the large intestine/[__] as well.
❥ active - passive ❥ villi ❥ blood capillaries ❥ blood ❥ villi ❥ intestinal - lymphatic - lymph ❥ small - colon
❥ ORT involves the administration of a dilute solution of [__] and salts dissolved in [__].
❥ It prevents and treats [___] that results from severe water and salt loss from the body.
❥ It is used to treat [__] infection.
❥ sugars - water
❥ dehydration
❥ cholera
❥ Cholera is an infection of the [__ __] that causes a large amount of watery diarrhea.
❥ Cholera bacterium produces a toxin that causes secretion of [__ __] from the cells of the small intestine into the [__].
❥ The water potential in the lumen becomes [__] than the water potential of the blood capillaries in the wall of the intestine.
❥ Water moves out of the [__] into the [__] of the small intestine by osmosis.
❥ Large amounts of water and [__] are lost in diarrhea.
❥ The infected person becomes [___].
❥ small intestine ❥ chloride ions - lumen ❥ lower ❥ capillaries - lumen ❥ salts ❥ dehydrated
