Podcast
Questions and Answers
What is the main function of the stomach?
What is the main function of the stomach?
Initiating the enzymatic and hydrolytic breakdown of food into digestible nutrients.
Which statement is true about the region where the esophagus ends and the stomach begins?
Which statement is true about the region where the esophagus ends and the stomach begins?
- Contains cardiac glands
- Abrupt transition from simple columnar to stratified squamous epithelium (correct)
- Lacks gastric pits
- Becomes wider from the esophagus to the stomach
The tunica mucosa of the stomach has both non-glandular and glandular regions.
The tunica mucosa of the stomach has both non-glandular and glandular regions.
True (A)
The tunica mucosa of the esophagus is generally stratified squamous non-______ epithelium.
The tunica mucosa of the esophagus is generally stratified squamous non-______ epithelium.
What are the 3 major components of the digestive system discussed in the content?
What are the 3 major components of the digestive system discussed in the content?
Which type of epithelium lines the oral mucosa?
Which type of epithelium lines the oral mucosa?
Cats have rudimentary foliate papillae with taste buds.
Cats have rudimentary foliate papillae with taste buds.
Circumvallate papillae are surrounded by a deep, __________ furrow.
Circumvallate papillae are surrounded by a deep, __________ furrow.
Match the following types of papillae with their descriptions:
Match the following types of papillae with their descriptions:
What are the primary functions of the respiratory system?
What are the primary functions of the respiratory system?
Which region of the respiratory system is characterized by having pseudostratified ciliated columnar epithelium?
Which region of the respiratory system is characterized by having pseudostratified ciliated columnar epithelium?
The trachea terminates by dividing into three primary bronchi.
The trachea terminates by dividing into three primary bronchi.
The primary structural and functional unit of the respiratory system is the _ _ _ _ _ _ _ _.
The primary structural and functional unit of the respiratory system is the _ _ _ _ _ _ _ _.
Type II pneumocytes are also known as __________ cells.
Type II pneumocytes are also known as __________ cells.
Which cells in the alveoli are also referred to as Dust Cells?
Which cells in the alveoli are also referred to as Dust Cells?
What is the main function of surfactant in the alveoli?
What is the main function of surfactant in the alveoli?
Match the following endocrine organs with their correct names:
Match the following endocrine organs with their correct names:
What are the cells of the pancreas that secrete insulin?
What are the cells of the pancreas that secrete insulin?
The functional unit of the kidney is composed of the ______ and collecting tubule.
The functional unit of the kidney is composed of the ______ and collecting tubule.
Which of the following are functions of the kidney? (Select all that apply)
Which of the following are functions of the kidney? (Select all that apply)
The juxtaglomerular apparatus contains JG cells and macula densa.
The juxtaglomerular apparatus contains JG cells and macula densa.
Match the following parts of the kidney: (Match each term with its description)
Match the following parts of the kidney: (Match each term with its description)
What are some functions of Sertoli (sustentacular) cells in the male reproductive system?
What are some functions of Sertoli (sustentacular) cells in the male reproductive system?
What is the correct sequence of the phases in spermatogenesis?
What is the correct sequence of the phases in spermatogenesis?
The ductus (vas) deferens is lined by simple columnar epithelium.
The ductus (vas) deferens is lined by simple columnar epithelium.
The bulbourethral gland is also known as __________ gland.
The bulbourethral gland is also known as __________ gland.
What is the function of Brunner's gland?
What is the function of Brunner's gland?
Which of the following characteristics describe the colon?
Which of the following characteristics describe the colon?
The rectal wall in horses and cattle is thinner than the colon wall.
The rectal wall in horses and cattle is thinner than the colon wall.
The terminal segment of the digestive tract is called the ____________.
The terminal segment of the digestive tract is called the ____________.
Match the following types of salivary glands with their descriptions:
Match the following types of salivary glands with their descriptions:
What are the three layers of the sclera?
What are the three layers of the sclera?
Which layer of the eye is characterized as transparent, avascular, and highly innervated?
Which layer of the eye is characterized as transparent, avascular, and highly innervated?
Rods are sensitive to bright light and perceive color.
Rods are sensitive to bright light and perceive color.
The organ of corti is located within the ________.
The organ of corti is located within the ________.
Match the following parts of the ear with their descriptions:
Match the following parts of the ear with their descriptions:
What is the primary follicle characterized by in the female reproductive system?
What is the primary follicle characterized by in the female reproductive system?
Which type of follicle has several layers of cells around the primary oocyte?
Which type of follicle has several layers of cells around the primary oocyte?
The corpus luteum secretes estrogen that stimulates FSH release.
The corpus luteum secretes estrogen that stimulates FSH release.
The corpus luteum will degenerate into the ________ if pregnancy does not occur.
The corpus luteum will degenerate into the ________ if pregnancy does not occur.
Match the anatomical regions of the oviduct (fallopian tube) with their descriptions:
Match the anatomical regions of the oviduct (fallopian tube) with their descriptions:
What is the female homologue of the penis?
What is the female homologue of the penis?
Study Notes
Oral Cavity
- Functions: ingestion, mastication, lubrication by saliva
- Consists of: oral cavity, alimentary canal, glandular portion
- Lined by oral mucosa: stratified squamous epithelium, irregular dense fibrous connective tissue (DWFCT)
Classification of Oral Mucosa
- Masticatory mucosa: keratinized stratified squamous epithelium, resists abrasion (e.g., tongue)
- Lining mucosa: non-keratinized stratified squamous epithelium, overlies thick submucosa with minor salivary glands (e.g., lips)
- Specialized mucosa: has intraepithelial "taste buds" to perceive taste (e.g., tongue)
Lips
- Junction of integument and digestive system
- Three regions: skin part, vermilion zone, mucous (internal) part
- Ruminants and horses: keratinized; carnivores and pigs: non-keratinized
Lingual Papillae
- Mucosal projections on the tongue
- Four types:
- Filiform papillae: slender, conical, keratinized stratified squamous epithelium
- Fungiform papillae: mushroom-shaped, non-keratinized stratified squamous epithelium with taste buds
- Foliate papillae: along the posterolateral aspect of the tongue, with glands of von Ebner
- Circumvallate papillae: largest, wall-like, with a deep moat-like furrow and glands of von Ebner
Teeth
- Highly mineralized structure in the oral cavity
- Important for food procurement, cutting, and crushing
- Anatomically divided into:
- Crown: visible part covered by enamel, the hardest substance in the body
- Neck: junction between crown and root
- Root: part embedded in the alveolus or socket of the mandible and maxilla
- Mineralized components:
- Enamel: hardest substance in the body, 96% calcium hydroxyapatite
- Dentin: forms the bulk of the tooth, 65-70% calcium hydroxyapatite
- Cementum: overlies dentin of the root, approximately 45-50% calcium hydroxyapatite
Digestive System: Alimentary Canal
- General structure:
- Tunica mucosa: epithelium, lamina propria, muscularis mucosae
- Tunica submucosa: houses esophageal glands
- Tunica muscularis: inner circular, outer longitudinal
- Tunica adventitia/serosa
- Regions:
- Esophagus: muscular tube, modified for involuntary movement of bolus to stomach
- Stomach: enlarged part of the alimentary canal, initiates enzymatic and hydrolytic breakdown of food
- Small intestine: where most nutrient absorption occurs
- Large intestine: absorbs water and electrolytes, stores and eliminates waste
Esophagus
- Modified for involuntary movement of bolus to stomach
- Histophysiology:
- No anatomical sphincter, but two physiological sphincters (pharyngoesophageal and gastroesophageal)
- Tunica mucosa: stratified squamous non-keratinized epithelium
- Tunica submucosa: houses esophageal glands proper
- Tunica muscularis: inner circular, outer longitudinal
- Tunica adventitia/serosa: houses esophageal glands in the cranial part
Stomach
-
Enlarged part of the alimentary canal
-
Initiates enzymatic and hydrolytic breakdown of food
-
Produces chyme (gastric juices + partially digested food) and intermittently empties into the duodenum
-
Regions:
- Non-glandular region of tunica mucosa
- Glandular region of tunica mucosa:
- Cardiac gland region
- Fundic gland region
- Pyloric gland region### Stomach
-
Entele stomach: primary fold/papillae separate the mucosal surface into shallow compartments, further divided by shorter secondary and tertiary folds.
-
Muscularis mucosae: only in upper part of larger primary folds, absent in small folds/papillae.
C omasum
- Large longitudinal primary papillae.
- Epithelium: keratinized stratified squamous.
- Muscularis mucosae: present and continuous, with interdigitating smooth muscle bundles in papillae.
D abomasum
- Glandular portion of the ruminant stomach.
- Similar in structure to the simple stomach.
Small Intestines
- Longest section of the digestive tract.
- Main function: digestion of gastric contents and absorption of nutrients.
- 3 parts: duodenum, jejunum, and ileum.
- Surface modifications:
- Plicae circulares (valves of Kerckring): transverse folds of submucosa and mucosa.
- Villi: finger-like or oak leaf-like protrusions in the lamina propria.
- Microvilli: modifications of the apical surface of epithelial cells.
Large Intestines
- Site for microbial action on the ingesta.
- Absorption of water, vitamins, and electrolytes.
- Secretion of mucus.
- Characteristics:
- Absence of villi.
- Increasing goblet cells and intestinal glands towards the caudal end.
- Plicae circulares absent (replaced by longitudinal folds).
- Conspicuous diffuse and dense lymphoid tissue.
Cecum
- Varies in size among different species.
- Similar in structure to the small intestine, except for the absence of villi.
Colon
- Thicker mucosa than the small intestine.
- Smooth mucosal surface.
- Increased number of goblet cells.
- Submucosa often distended by lymphatic tissue.
Rectum
- Smooth mucosa.
- Similar to the colon, but with more goblet cells.
Anal Canal
- Terminal segment of the digestive tract.
- Simple columnar epithelium of the rectum changes abruptly to non-keratinized stratified squamous.
Avian Digestive System
- Crop: sac-like diverticulum of the esophagus, storage organ, histologically similar to the esophagus.
- Proventriculus: "glandular stomach", characterized by macroscopic papillae with numerous microscopic folds, and proventricular glands.
- Ventriculus (Gizzard): "muscular stomach", lining is referred to as the cuticle or koilin membrane.
- Cloaca: 3 regions - coprodeum, urodeum, and proctodeum, all with similar structures, and villi.
Glands Associated with the Digestive System
- Salivary glands: made up of a series of secretory units, controlled by the autonomic nervous system.
- Major salivary glands:
- Parotid: paired, located anterior and inferior to the external ear, predominantly serous glands.
- Mandibular (Submandibular/Maxillary): paired, located inferior to the mandible, predominantly serous type in most animals, but predominantly mucous in carnivores.
- Sublingual: aggregates of smaller glands located inferior to the tongue, mucous cells predominate.
Liver
- Largest gland in the body.
- Capsule and stroma: each lobe covered by serosa, and stroma consists of connective tissue.
- Liver acinus: classic lobule, portal lobule, and liver acinus.
Gallbladder
- Hollow pear-shaped organ attached to the liver of most animals.
- Epithelium: tall columnar.
- Lamina propria: blends with tunica submucosa.
- Muscularis mucosae: absent.
- Tunica muscularis: circular bundles of smooth muscle fibers.
Pancreas
- Encapsulated, lobulated, compound tubuloacinar gland.
- Exocrine part: produces enzymes such as amylase, lipase, and trypsin.
- Endocrine part: produces mainly insulin and glucagon.### Respiratory Portion
- Completely intrapulmonary
- Caudal: transition zone; stratified cuboidal to non-ciliated pseudostratified columnar
- Special features: Vibrissae (tactile hair)
Respiratory Region
- Pseudostratified ciliated columnar (with goblet cells)
- Caudal 2/3 of nasal cavity proper, except at olfactory region
- Mucosa: More vascular than the mucosae of the cutaneous, transitional, or olfactory regions
Olfactory Region
- Ciliated pseudostratified columnar epithelium
- Dorsocaudal portion of the nasal cavity
- Including some of the surfaces of: Ethmoid conchae, dorsal nasal meatus, and nasal septum
- Difference from adjacent respiratory mucosa:
- Thicker epithelium
- Numerous tubular glands
- Many bundles of nonmyelinated nerve fibers in the lamina propria
- 3 primary cell types:
- A. Sustentacular cells
- B. Neurosensory olfactory cells (bipolar neurons)
- C. Basal cells (horizontal and globose)
- Kept moist by a watery secretion produced by serous tubuloacinar olfactory glands (Bowman’s glands)
Trachea
- The largest in diameter and length of these tubes
- Provides the air passageway between the larynx and the bronchi
- Incomplete C-shaped hyaline cartilage rings
- Bridged by elastic & smooth muscle fibers
- Ends of cartilage rings face posteriorly (adjacent to esophagus)
- The trachea terminates by bifurcating into two primary bronchi
Bronchioles
- Tubes of decreasing diameters; no cartilaginous support
- Epithelial lining:
- Larger bronchioles: ciliated pseudostratified columnar (respiratory epithelium) with few goblet cells
- Smaller bronchioles: ciliated simple columnar or cuboidal; occasional non-ciliated club cells (Clara cells) replacing the goblet cells
- Manufacture:
- Club cell secretory protein: believed to protect the epithelial lining
- Surfactant-like substance: helps prevent these flimsy conduits from collapsing by reducing surface tension
Bronchi
- Replaced by irregular hyaline cartilage plates
- As the bronchi continue to divide and decrease in size, the cartilage plates also decrease in size and number
- Extrapulmonary bronchi (Primary bronchi) → intrapulmonary bronchi (Secondary bronchi)
Respiratory Portion (continued)
- AVIAN RESPIRATORY SYSTEM
- Nasal cavity: epithelia similar to mammals
- Respiratory epithelium: groups of goblet cells form intraepithelial glands
- Infraorbital sinuses: drain into the nasal cavity; lined by respiratory epithelium
- Larynx: simple; devoid of vocal folds; produces little sound
- Syrinx: voice box; specialized region of the tracheobronchial junction
- Trachea: cartilages form complete rings encircling the airway; the cartilage rings overlap and interlock with adjacent rings
- Trachealis muscle: absent
Endocrine System
Pituitary Gland (Hypophysis Cerebri)
- Regulates metabolic activities in certain organs and tissues of the body
- Produce hormones (chemical substances)
- Glands
- Isolated groups of cells within certain organs
- Individual cells scattered among parenchymal cells of the body
Adenohypophysis (Anterior Pituitary)
- Oral ectoderm
- Rathke’s pouch
- A. Pars distalis
- Chromophils (Acidophils)
- Chromophils (Basophils)
- B. Pars intermedia
- C. Pars tuberalis
Neurohypophysis (Posterior Pituitary)
- Neural ectoderm
- As downgrowth of diencephalon
- Not a true endocrine gland
- Does not produce its own hormones
- Only stores and secretes hormones from hypothalamus
- Infundibular stalk
- Pars nervosa
Parathyroid Gland
- Regulate blood calcium levels
- Chief (principal) cells
- Oxyphil cells
Thyroid Gland
- Produces hormones: thyroxine (T4), triiodothyronine (T3), calcitonin
- Follicular Cells
- Parafollicular cells (clear cells / C cells)
Adrenal Gland
- Produces two different groups of hormones:
- Steroids
- Catecholamines
- 2 main regions:
- Adrenal Cortex
- Synthesize and secrete several steroid hormones without storing them
- 3 histological zones: A. Zona glomerulosa (arcuata) B. Zona fasciculata C. Zona reticularis
- Adrenal Medulla
- Chromaffin cells
- Medullary parenchymal cells
- Modified sympathetic postganglionic neurons
- With secretory function
- Produce catecholamines
- Adrenal Cortex
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Description
This quiz covers the functions and components of the human digestive system, with a focus on the oral cavity. Learn about ingestion, mastication, and the role of saliva and oral mucosa.
