test 5 digestive system pt 1

Discipline: Medical Sciences (Anatomy, Physiology, Pharmacology etc.)

Type of Paper: Question-Answer

Academic Level: Undergrad. (yrs 3-4)

Paper Format: APA

Pages: 1 Words: 275

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Question

Biology/Human Anatomy & Physiology

1. Not everything we eat is used by the body. a. After nutrients are absorbed, some materials from foods remain that cannot be digested or absorbed, such as ________ ____ _____. b. These materials must be expelled from the body via a process called “_________”.

cellulose and fiber.
defecation

1. The “digestive system” includes the organs that:

a. Ingest food b. Transport food c. Digest the food into smaller usable components d. Absorb the necessary nutrients into the bloodstream e. Expel the waste products from the body

what are the two separate categories of organs that the digestive system are composed of

digestive organs and accessory digestive organs

a. The digestive organs collectively make up the “gastrointestinal (GI) tract” or “alimentary (Latin for “relating to nourishment”) canal”. 1) The GI tract organs include:

(a) Oral cavity (b) Pharynx (c) Esophagus (d) Stomach (e) Small intestine (f) Large intestine

a. The accessory digestive organs do not form the long GI tube, but often develop as outgrowths from and are connected to the GI tract. 1) The accessory digestive organs include:

(a) Teeth (b) Tongue (c) Salivary glands (d) Liver (e) Gallbladder (f) Pancreas

what are the six main functions of the digestive system?

ingestion, digestion, propulsion, secretion, absorption and elimination of wastes

1) “Ingestion”,

is the introduction of solid and liquid nutrients into the oral cavity.

1) “Digestion”

is the breakdown of large food items into smaller structures and molecules.

(a) “Mechanical digestion”

physically breaks down ingested materials into smaller pieces.

- The first part of mechanical digestion is “mastication” (Latin for “to chew”), the chewing of ingested food by the teeth in the oral cavity.

(a) “Chemical digestion”

breaks down ingested molecules into smaller molecules by using enzymes.

1) After the materials are swallowed, they move through the GI tract in a process termed “propulsion”. There are two types of movement involved in propulsion.

peristalsis and segmentation

peristalsis

(a) “Peristalsis” (Greek for “around constriction”) is the process of muscular contraction that forms ripples along part of the GI tract (much like pushing toothpaste out of a tube) and causes material to move further along the tract.

segmentation

(b) “Segmentation” is churning and mixing movements in the small intestine which help dispense the material being digested and combine it with intestinal secretions [See Fig. (b) on page 781].

1) “Secretion”

(Latin for “to separate” is the process of producing and releasing fluid products, such as acid, bile, digestive enzymes, and mucin. (a) When these fluids are secreted into the lumen of the GI tract, they facilitate chemical digestion and the passage of materials through the GI tract.

1) “Absorption”

(Latin for “to swallow”) involves either passive movement or active transport of electrolytes, digestion products, vitamins, and water across the GI tract epithelium and into GI tract blood and lymphatic vessels.

1) “Elimination” of wastes

is the final function of the digestive system. (a) Our bodies utilize most, but not all, components of what we eat.
(b) All undigestible materials as well as the waste products secreted by the accessory organs into the GI tract are compacted into “feces” (Latin for “dregs”), or fecal material, and then eliminated from the GI tract by the process of “defecation” (Latin for “to remove the dregs”).

1. The “oral cavity”,

or mouth, is the entrance to the GI tract.

a. The mouth is the initial site of _________ digestion (via mastication) and _______ digestion (via an enzyme in the saliva). 1) The mouth is lined with __________ ___________ that protects against the abrasive activities associated with digestion. 2) This lining is continually moistened by the secretion of ______.

mechanical
chemical
stratified epithelium
saliva

a. The oral cavity is bounded anteriorly by the _____ ____ ____ and posteriorly by the _________.

teeth and lips
oropharynx

a. The superior boundary of the mouth is formed by the

hard and soft palates

a. The floor, or inferior surface, of the oral cavity contains the

tongue as well as muscles covered with mucosa.

a. The oral cavity has two distinct regions:

1) The “vestibule” is the space between the cheeks or lips and the gums. (a) This is where persons who chew tobacco hold the material after chewing.
2) The “oral cavity proper” lies central to the alveolar processes of the mandible and maxillae.

a. The lateral walls of the oral cavity are formed by the “cheeks”, which are covered externally by the integument and contain the buccinators muscles.

1) The buccinators muscles compress the cheeks against the teeth to hold solid materials in place during chewing. 2) The cheeks terminate at the fleshy “lips” or “labia” that are formed primarily by the obicularis oris muscle and covered with a thin layer of keratinized stratified epithelium.

The “lips” have a reddish hue because

of their abundant supply of superficial blood vessels and the reduced amount of keratin within their outer skin.

a. The “gingivae” or “gums” are composed of

dense regular connective tissue, with an overlying stratified epithelium that covers the alveolar processes of the upper and lower jaws and surrounds the necks of the teeth.

1) The internal surfaces of the superior and inferior lips each are attached to the gingivae by a

thin mucosal fold in the midline, called the “labial frenulum” (Latin for “lip” and “bridle”).

a. The “palate” forms the roof of the oral cavity and acts as a barrier to separate it from the nasal cavity. 1) The “hard palate”, which makes up the anterior two-thirds, is formed by the

palatine processes of the maxillae and the horizontal plates of the palatine bones.
(a) It exhibits prominent “transverse palatine folds” or “friction ridges”, to assist the tongue in manipulating ingested materials prior to swallowing.

1) The arching “soft palate” is primarily composed of

skeletal muscle.

(a) Extending inferiorly from the posterior part of the soft palate is a conical projection called the

“uvula” (Latin for “small grape”).

(a) When you swallow, the ____ ______ and the _____ elevate to close off the posterior entrance to the nasopharynx and prevent ingested materials from entering the nasal region.

soft palate uvula

a. The palatine tonsils are located

toward the posterior lateral portions of the oral cavity and serve as an early line of defense as they monitor ingested food and drink for antigens.
(a) They can initiate an immune response when necessary.

a. The “tongue” is an accessory digestive organ that is formed primarily by

skeletal muscle.

a. Earlier we described the tongue as a participant in ______ ________

sound production.

a. In addition, the tongue manipulates and mixes ingested materials during chewing and helps compress the partially digested materials against the hard palate to turn these materials into a “_____” (Greek for “lump”), a globular mass of partially digested material.

bolus

a. The tongue also performs important functions in swallowing.

true

a. The inferior surface of the tongue attaches to the floor of the oral cavity by a thin vertical mucous membrane, the

“lingual frenulum” [See Fig. “a” on page 782]. 1) Not the location of the submandibular ducts which can squirt when you yawn!

a. The salivary glands collectively produce and secrete “saliva”, a fluid that assists in the

initial activities of digestion or to keep the mouth moist.

a. The volume of saliva secreted daily ranges between

1.0 and 1.5 liters.

a. Saliva has various functions.

1) Moistens ingested food and helps it become a slick semisolid bolus that is more easily swallowed. 2) It helps moisten and clean the oral cavity structures. 3) The salivary enzyme “amylase” begins chemical digestion by breaking down starch. 4) Saliva contains antibodies and an antibacterial substance called “lysozyme” that helps inhibit bacterial growth in the oral cavity. 5) It is a watery medium into which food molecules are dissolved so taste receptors can be stimulated.

Pairs of salivary glands located external to the oral cavity

1. parotid gland 2. submandibular gland 3. sublingual gland

The “parotid salivary glands”

are the largest salivary glands.
(a) Each parotid gland is located anterior and inferior to the ear, partially overlying the masseter muscle.

- This gland becomes infected and swollen with mumps.

The “parotid duct”, which carries the saliva to the oral cavity, travels parallel to the zygomatic arch and opens into the vestibule of the oral cavity near the second upper molar

The “submandibular salivary glands

as their name suggests, are inferior to the body of the mandible. (a) A “submandibular duct” opens from each gland in the floor of the mouth on the lateral sides of the lingual frenulum.

- These are the squirters used in “gleeking”!

The sublingual salivary glands

are inferior to the tongue and internal to the oral cavity mucosa. (a) Each sublingual salivary gland extends multiple tiny sublingual ducts that open onto the inferior surface of the oral cavity.

The salivary glands are primarily innervated by the

parasympathetic division of the autonomic nervous system.

1) In particular, the facial nerve (CN VII) innervates the ________ and _________ glands, while the glossopharyngeal nerve (CN IX) innervates the ______ glands.

submandibular
sublingual
parotid

1) ______________ innervation stimulates salivary gland secretion, which is why your mouth waters when you see a delicious dinner in front of you.

Parasympathetic

1) ___________ stimulation inhibits normal secretion from these glands, which is why persons who are frightened experience the sensation of a dry mouth.

Sympathetic

a. The “teeth” are collectively known as

“dentition” (Latin for “teething”).

a. Teeth are responsible for mastication, the first part of the mechanical digestion process.

mastication, the first part of the mechanical digestion process.

a. A tooth has an exposed “______”, a constricted “____”, and one or more “_____” that anchor it to the jaw. 1) The roots of the teeth fit tightly into “______ _______”, which are sockets within alveolar processes of both the maxillae and the mandible.

crown neck roots dental alveoli

a. Collectively, the roots, the dental alveoli, and the periodontal ligaments that bind the root to the alveolar process from a _______ _______ as described earlier in this class.

gomphosis joint

1) In an infant, 20 “__________ (Latin for “to fall away”) teeth”, also called “______ _____”, erupt between 6 months and 30 months after birth.

deciduous milk teeth

1) These infant teeth are eventually lost and replaced by 32 “permanent teeth”.

(a) The more anteriorly placed permanent teeth tend to appear first, followed by the posteriorly placed teeth (the major exception to this rule are the first molars, which appear at about age 6 and sometimes are referred to as the “6-year molars”).
(b) The last teeth to erupt are the third molars, often called “wisdom teeth”, in the late teens or early 20s.

- There may not be sufficient room in the jaw to accommodate these final molars and they may need to be extracted.

1) The most anteriorly placed permanent teeth are called

“incisors” (Latin for “to cut into”) and they are designed for slicing or cutting into food. (a) They are shaped like a chisel and have a single root.

1) Immediately posterolateral to the incisors are the

“canines” (Latin for “dog”), which have a pointed tip for puncturing and tearing food.
(a) They are also referred to as “eye teeth”.

ocated posterolateral to the canines and anterior to the molars. (a) They have flat crowns with prominent ridges called “cusps” that are used to crush and grind ingested materials. (b) They have one or two roots.

1) “Premolars”, also referred to as “bicuspids”

1) The “molars” (Latin for “millstone”)

are the thickest and most posteriorly placed teeth. (a) They have large, broad, flat crowns and distinctive cusps, and three or more roots.
(b) Molars are also adapted for grinding and crushing ingested materials.

1) If the mouth is divided into quadrants, each quadrant contains the following number of permanent teeth:

(a) 2 incisors (b) 1 canine (c) 2 premolars (d) 3 molars