ANTR 350 Unit 5

Define the gastrointestinal (GI) tract.

A continuous muscular tube that runs from the mouth to the anus, responsible for digestion and absorption. Includes: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

Define accessory organs of the digestive system

Organs that aid digestion by secreting enzymes or mechanically processing food. Includes: teeth, tongue, salivary glands, liver, gallbladder, pancreas

List the functions of the digestive system

Ingestion, secretion, digestion (mechanical/chemical), absorption, elimination, propulsion, compaction

What are the boundaries of the oral cavity?

Anterior: lips
Lateral: cheeks
Superior: hard and soft palate
Inferior: tongue and floor of mouth
Posterior: oropharyngeal isthmus

What are the four types of teeth?

Incisors, canines, premolars, molars

Which tooth type is absent in deciduous teeth?

Premolars

When do the permanent molars erupt?

First molar: age 6
Second molar: age 12
Third molar: age 17-21 (variable)

Which division of the trigeminal nerve innervates maxillary teeth?

CN V2 (maxillary division)

Which division of the trigeminal nerve innervates mandibular teeth?

CN V3 (mandibular division).

Parasympathetic innervation to the parotid gland?

CN IX (glossopharyngeal)

Parasympathetic innervation to submandibular and sublingual glands?

CN VII (facial nerve)

Why can a parotid gland tumor cause Bell's palsy?

The facial nerve (CN VII) passes through the parotid gland and can be compressed

What forms the anterior 2/3 and posterior 1/3 of the tongue?

Anterior 2/3: body
Posterior 1/3: root

Nerve supply to anterior 2/3 (somatic sensory)?

Lingual nerve (CN V3).

Nerve supply to anterior 2/3 (taste)?

Chorda tympani (CN VII)

Nerve for posterior 1/3 (sensory + taste)?

CN IX (glossopharyngeal).

Motor nerve to the tongue?

CN XII (hypoglossal).

Order food travels through the GI tract.

Oral cavity → pharynx → esophagus → stomach → duodenum → jejunum → ileum → cecum → colon → rectum → anus

Describe the course of the esophagus

Runs inferiorly from the pharynx → through neck → posterior to the trachea → mediastinum → passes diaphragm at T10 → enters stomach

Name the serous membrane of the abdominopelvic cavity

Peritoneum

Compare parietal vs visceral peritoneum.

Parietal: lines body wall; somatic pain supply.
Visceral: covers organs; visceral pain supply

Define mesentery

A double layer of peritoneum that connects organs to the body wall; contains nerves, arteries, veins, lymphatics

What organs attach to the following mesenteries?

Falciform ligament: liver to anterior wall
Greater omentum: stomach to transverse colon
Lesser omentum: stomach/duodenum to liver
Mesentery proper: jejunum + ileum
Transverse mesocolon: transverse colon
Sigmoid mesocolon: sigmoid colon

What is found in the peritoneal cavity?

A thin layer of serous fluid.

What divides the peritoneal cavity into greater and lesser sacs?

The stomach and lesser omentum

What is the opening between the greater and lesser sac?

Epiploic (omental) foramen

How can infection spread in the peritoneal cavity?

Through free movement of fluid between peritoneal spaces

List intraperitoneal organs.

Stomach, liver, jejunum, ileum, appendix, transverse/sigmoid colon, spleen

List retroperitoneal organs

Primary: kidneys, adrenal glands, aorta, IVC
Secondary: pancreas, duodenum (except 1st part), ascending/descending colon, rectum (upper 2/3)

Order small intestine segments.

Duodenum → jejunum → ileum

Which parts are suspended by mesentery proper?

Jejunum and ileum

Order of large intestine segments

Cecum → ascending → transverse → descending → sigmoid → rectum → anal canal

Location of right colic flexure

Between ascending and transverse colon; near liver

Location of left colic flexure

Between transverse and descending colon; near spleen

Large intestine segments suspended by mesentery

Transverse colon and sigmoid colon

What is McBurney's point?

1/3 from ASIS to umbilicus; location of appendix base.

Appendicitis pain progression

Early: periumbilical (visceral).Late: RLQ at McBurney's point (parietal).

Muscles of anal sphincters

Internal sphincter: smooth muscle
External sphincter: skeletal muscle

Innervation of anal sphincters

Internal: autonomic (symp/parasymp)
External: pudendal nerve (somatic)

Describe bile flow.

Liver → L/R hepatic ducts → common hepatic duct → cystic duct → gallbladder (storage) → common bile duct → hepatopancreatic ampulla → duodenum

Describe pancreatic juice flow

Pancreas → main pancreatic duct → hepatopancreatic ampulla → duodenum

Foregut organs

Esophagus → stomach → duodenum (1st/2nd parts) → liver → gallbladder → pancreas

Midgut organs

Duodenum (3rd/4th), jejunum, ileum, cecum, appendix, ascending colon, proximal 2/3 transverse colon

Hindgut organs

Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum

Arterial supply by region

Foregut: celiac trunk
Midgut: SMA
Hindgut: IMA

Venous drainage by region

Foregut: splenic vein → portal vein
Midgut: SMV → portal vein
Hindgut: IMV → splenic vein → portal vein

Parasympathetic innervation

Foregut + midgut: vagus nerve
Hindgut: pelvic splanchnics (S2-S4)

Sympathetic cell body locations

Preganglionics: T5-L2 lateral horn
Postganglionics: prevertebral ganglia (celiac, SMA, IMA)

Referred pain regions.

Foregut: epigastric (T5-T9)
Midgut: umbilical (T10-T12)
Hindgut: hypogastric (L1-L2)

What are the main functions of the urinary system?

Excretion of metabolic wastes, regulation of blood volume/pressure, electrolyte balance, acid-base balance, and hormone production (EPO & renin).

What are the functional units of the kidneys?

Nephrons

What are the two main parts of a nephron?

Renal corpuscle and renal tubule.

What structures make up the renal corpuscle?

Glomerulus + Bowman's (glomerular) capsule.

What drives filtration in the glomerulus?

Glomerular hydrostatic pressure

What is NOT normally filtered into Bowman's capsule?

Large proteins and blood cells

What are the three layers of the filtration membrane?

Fenestrated endothelium, basement membrane, podocyte slit diaphragms.

What is the primary site of reabsorption in the nephron?

Proximal convoluted tubule (PCT)

What is reabsorbed in the PCT?

65% of Na⁺, water, glucose, amino acids, bicarbonate

What is the function of the descending limb of the loop of Henle?

Water reabsorption

What is the function of the ascending limb of the loop of Henle?

Reabsorbs ions (Na⁺, Cl⁻), impermeable to water.

Where does aldosterone act?

Distal convoluted tubule (DCT) and collecting duct.

What is the effect of aldosterone?

Increases Na⁺ reabsorption and K⁺ secretion → increases blood volume and pressure

Where does ADH act?

Collecting duct

What is the effect of ADH?

Inserts aquaporins → increases water reabsorption → concentrates urine.

What is the juxtaglomerular apparatus (JGA)?

Structure that regulates blood pressure and GFR; includes macula densa + JG cells.

What stimulates renin release?

Low blood pressure, sympathetic stimulation, or low NaCl at macula densa.

What does the renin-angiotensin-aldosterone system (RAAS) do?

Raises blood pressure by vasoconstriction and increasing blood volume.

What is GFR?

Glomerular Filtration Rate = amount of filtrate formed per minute.

What happens if GFR is too high?

Insufficient reabsorption → dehydration, electrolyte loss

What happens if GFR is too low?

Excessive reabsorption → waste retention (↓ kidney clearance).

What is obligatory water reabsorption?

Water follows solutes (especially Na⁺) automatically in PCT and descending limb.

What is facultative water reabsorption?

Water reabsorption in collecting duct under control of ADH.

What is tubular secretion?

Movement of substances from blood → nephron (H⁺, K⁺, drugs, toxins).

What is the normal pH of urine?

6 (range 4.5-8).

What gives urine its yellow color?

Urochrome (bilirubin breakdown product).

What prevents urine backflow from bladder to ureters?

Oblique entry of ureters + one-way valve.

What muscle contracts to empty the bladder?

Detrusor muscle.

What allows voluntary urination control?

External urethral sphincter (skeletal muscle).

What is the micturition reflex?

Stretch receptors → spinal reflex → detrusor contracts + internal sphincter relaxes.

What are homologous structures in male vs female reproductive systems?

Structures that arise from the same embryologic tissue and share similar functions (e.g., glans penis ↔ glans clitoris, scrotum ↔ labia majora).

What is the common function of male and female erectile tissues?

To fill with blood and aid in sexual arousal.

What forms the anterior border of the perineum?

Pubic symphysis

Posterior border of the perineum?

Coccyx

Lateral borders of the perineum?

Ischial tuberosities

What are the two triangles of the perineum?

Urogenital triangle and anal triangle.

Contents of the urogenital triangle (female)?

External genitalia, urethra, vaginal orifice

Contents of the anal triangle?

Anal canal, anus, external anal sphincter.

Name the organs of the male reproductive system.

Testes, epididymis, ductus deferens, seminal vesicles, prostate, bulbourethral glands, penis.

What does the scrotum contain?

Testes and epididymis

What structures run in the spermatic cord?

Ductus deferens, testicular artery, pampiniform plexus, lymphatics, nerves.

Blood supply of testes?

Testicular arteries.

Venous drainage of testes?

Pampiniform plexus → testicular vein.

What structure is cut in a vasectomy?

Ductus deferens

Layers covering testes from superficial → deep?

Parietal tunica vaginalis → cavity → visceral tunica vaginalis → tunica albuginea.

What is a hydrocele?

Fluid accumulation in the cavity of the tunica vaginalis.

What is a hematocele?

Blood accumulation in the tunica vaginalis

What two structures form the ejaculatory duct?

Seminal vesicle duct + ampulla of ductus deferens.

Order sperm travels from testes to outside the body?

Testis → epididymis → ductus deferens → ejaculatory duct → prostatic urethra → membranous urethra → spongy urethra → external urethral orifice

Function of the prostate?

Produces ~30% of semen volume; secretes alkaline fluid.

What is BPH?

Enlargement of prostate compressing the urethra → weak stream, difficulty starting urination.