Exam 2 - Key Terms Flashcards
What is absorption in the context of digestion?
Passage of digested products from the intestinal lumen through mucosal cells and into the bloodstream or lacteals
What are accessory digestive organs?
Includes teeth, tongue, salivary glands, gallbladder, liver, and pancreas
What is the accessory duct also known as?
Duct of Santorini
What is an acinus?
Cluster of glandular epithelial cells in the pancreas that secretes pancreatic juice
What is the alimentary canal?
Continuous muscular digestive tube that extends from the mouth to the anus
Define aminopeptidase.
Brush border enzyme that acts on proteins
What is the anal canal?
Final segment of the large intestine
What is an anal column?
Long fold of mucosa in the anal canal
What is the anal sinus?
Recess between anal columns
What is the appendix also known as?
Vermiform appendix
What is the ascending colon?
First region of the colon
What is bacterial flora?
Bacteria in the large intestine
What is bile?
Alkaline solution produced by the liver important for the emulsification of lipids
What is a bile canaliculus?
Small duct between hepatocytes that collects bile
What is bilirubin?
Main bile pigment responsible for the brown color of feces
Define the body in the context of the stomach.
Mid-portion of the stomach
What is a bolus?
Mass of chewed food
What is the brush border?
Fuzzy appearance of the small intestinal mucosa created by microvilli
What is the cardia in relation to the stomach?
Part of the stomach surrounding the cardiac orifice
What is the cecum?
Pouch forming the beginning of the large intestine
What is cementum?
Bone-like tissue covering the root of a tooth
What is the central vein?
Vein that receives blood from hepatic sinusoids
What is the cephalic phase?
Initial phase of gastric secretion that occurs before food enters the stomach
Define chemical digestion.
Enzymatic breakdown of food
What is a chief cell?
Gastric gland cell that secretes pepsinogen
What is a chylomicron?
Large lipid-transport compound made up of triglycerides, phospholipids, cholesterol, and proteins
What is chyme?
Soupy liquid created when food is mixed with digestive juices
What is a circular fold?
Deep fold in the mucosa and submucosa of the small intestine
What is the colon?
Part of the large intestine between the cecum and the rectum
What is the common bile duct?
Structure formed by the union of the common hepatic duct and the gallbladder’s cystic duct
What is the common hepatic duct?
Duct formed by the merger of the two hepatic ducts
What is the crown of a tooth?
Portion of tooth visible superior to the gum line
What is a cuspid?
Pointed tooth used for tearing and shredding food
What is the cystic duct?
Duct through which bile drains and enters the gallbladder
What is a deciduous tooth?
One of 20 ‘baby teeth’
What is defecation?
Elimination of undigested substances from the body in the form of feces
What is deglutition?
Three-stage process of swallowing
What is dens?
Tooth
What is dentin?
Bone-like tissue immediately deep to the enamel of the crown or cementum of the root of a tooth
What is dentition?
Set of teeth
What is deoxyribonuclease?
Pancreatic enzyme that digests DNA
What is the descending colon?
Part of the colon between the transverse colon and the sigmoid colon
What is dipeptidase?
Brush border enzyme that acts on proteins
What is the duodenal gland?
Mucous-secreting gland in the duodenal submucosa
What is the duodenum?
First part of the small intestine, which starts at the pyloric sphincter and ends at the jejunum
What is enamel?
Covering of the dentin of the crown of a tooth
What is an enteroendocrine cell?
Gastric gland cell that releases hormones
What is enterohepatic circulation?
Recycling mechanism that conserves bile salts
What is enteropeptidase?
Intestinal brush-border enzyme that activates trypsinogen to trypsin
What is an epiploic appendage?
Small sac of fat-filled visceral peritoneum attached to teniae coli
What is the esophagus?
Muscular tube that runs from the pharynx to the stomach
What is the external anal sphincter?
Voluntary skeletal muscle sphincter in the anal canal
What are fauces?
Opening between the oral cavity and the oropharynx
What are feces?
Semisolid waste product of digestion
What is flatus?
Gas in the intestine
What is the fundus of the stomach?
Dome-shaped region of the stomach above and to the left of the cardia
What is a G cell?
Gastrin-secreting enteroendocrine cell
What is the gallbladder?
Accessory digestive organ that stores and concentrates bile
Define gastric emptying.
Process by which mixing waves gradually cause the release of chyme into the duodenum
What is a gastric gland?
Gland in the stomach mucosal epithelium that produces gastric juice
What is the gastric phase?
Phase of gastric secretion that begins when food enters the stomach
What is a gastric pit?
Narrow channel formed by the epithelial lining of the stomach mucosa
What is gastrin?
Peptide hormone that stimulates secretion of hydrochloric acid and gut motility
What is the gastrocolic reflex?
Propulsive movement in the colon activated by the presence of food in the stomach
What is the gastroileal reflex?
Long reflex that increases the strength of segmentation in the ileum
What is gingiva?
Gum
What is haustral contraction?
Slow segmentation in the large intestine
What is a haustrum?
Small pouch in the colon created by tonic contractions of teniae coli
What is the hepatic artery?
Artery that supplies oxygenated blood to the liver
What is a hepatic lobule?
Hexagonal-shaped structure composed of hepatocytes that radiate outward from a central vein
What is the hepatic portal vein?
Vein that supplies deoxygenated nutrient-rich blood to the liver
What are hepatic sinusoids?
Blood capillaries between rows of hepatocytes that receive blood from the hepatic portal vein and the branches of the hepatic artery
What is the hepatic vein?
Vein that drains into the inferior vena cava
What are hepatocytes?
Major functional cells of the liver
What is the hepatopancreatic ampulla?
Bulb-like point in the wall of the duodenum where the bile duct and main pancreatic duct unite
What is the hepatopancreatic sphincter?
Sphincter regulating the flow of bile and pancreatic juice into the duodenum
What is hydrochloric acid (HCl)?
Digestive acid secreted by parietal cells in the stomach
What is the ileocecal sphincter?
Sphincter located where the small intestine joins with the large intestine
What is the ileum?
End of the small intestine between the jejunum and the large intestine
What is an incisor?
Midline, chisel-shaped tooth used for cutting into food
What is ingestion?
Taking food into the GI tract through the mouth
What is the internal anal sphincter?
Involuntary smooth muscle sphincter in the anal canal
What is an intestinal gland?
Gland in the small intestinal mucosa that secretes intestinal juice
What is intestinal juice?
Mixture of water and mucus that helps absorb nutrients from chyme
What is the intestinal phase?
Phase of gastric secretion that begins when chyme enters the intestine
What is intrinsic factor?
Glycoprotein required for vitamin B12 absorption in the small intestine
What is the jejunum?
Middle part of the small intestine between the duodenum and the ileum
What is the labial frenulum?
Midline mucous membrane fold that attaches the inner surface of the lips to the gums
What is a labium?
Lip
What is lactase?
Brush border enzyme that breaks down lactose into glucose and galactose
What is a lacteal?
Lymphatic capillary in the villi
What is the large intestine?
Terminal portion of the alimentary canal
What is the laryngopharynx?
Part of the pharynx that functions in respiration and digestion
What is the left colic flexure?
Point where the transverse colon curves below the inferior end of the spleen
What is the lingual frenulum?
Mucous membrane fold that attaches the bottom of the tongue to the floor of the mouth
Define lingual lipase
Digestive enzyme from glands in the tongue that acts on triglycerides
What is the function of lipoprotein lipase?
Enzyme that breaks down triglycerides in chylomicrons into fatty acids and monoglycerides
What is the liver known for?
Largest gland in the body whose main digestive function is the production of bile
What does the lower esophageal sphincter regulate?
Food movement from the esophagus to the stomach
What is the main pancreatic duct also known as?
Duct of Wirsung
Where does the hepatopancreatic ampulla open?
Into the duodenum at the major duodenal papilla
What is maltase?
Brush border enzyme that breaks down maltose and maltotriose into glucose
Define mass movement in the digestive system
Long, slow, peristaltic wave in the large intestine
What is mastication?
Chewing
What is mechanical digestion?
Chewing, mixing, and segmentation that prepares food for chemical digestion
What does the mesoappendix refer to?
Mesentery of the appendix
What is a micelle?
Tiny lipid-transport compound composed of bile salts and phospholipids
What is a microvillus?
Small projection of the plasma membrane of the absorptive cells of the small intestinal mucosa
What is the migrating motility complex?
Form of peristalsis in the small intestine
What is a mixing wave?
Unique type of peristalsis that occurs in the stomach
What is the function of a molar tooth?
Used for crushing and grinding food
What hormone initiates migrating motility complexes?
Motilin
Define motility in the context of the GI tract
Movement of food through the GI tract
What is the mucosa?
Innermost lining of the alimentary canal
What is the mucosal barrier?
Protective barrier that prevents gastric juice from destroying the stomach itself
What is the role of a mucous neck cell?
Gastric gland cell that secretes a uniquely acidic mucus
What does the muscularis layer consist of?
Muscle (skeletal or smooth) layer of the alimentary canal wall
What is the myenteric plexus?
Major nerve supply to alimentary canal wall; controls motility
What does nucleosidase do?
Brush border enzyme that digests nucleotides
What is the oral cavity also known as?
Buccal cavity
What is the oral vestibule?
Part of the mouth bounded by the cheeks and lips, and gums and teeth
Define oropharynx
Part of the pharynx continuous with the oral cavity that functions in respiration and digestion
What is the palatoglossal arch?
Muscular fold extending from the lateral side of the soft palate to the base of the tongue
What is the palatopharyngeal arch?
Muscular fold extending from the lateral side of the soft palate to the side of the pharynx
What is the pancreas?
Accessory digestive organ that secretes pancreatic juice
What is pancreatic amylase?
Enzyme secreted by the pancreas that completes the chemical digestion of carbohydrates
What does pancreatic juice contain?
Digestive enzymes and bicarbonate
What is the role of pancreatic lipase?
Enzyme that participates in lipid digestion
What does pancreatic nuclease do?
Enzyme that participates in nucleic acid digestion
What does a parietal cell secrete?
Hydrochloric acid and intrinsic factor
Where is the parotid gland located?
Inferior and anterior to the ears
What is the pectinate line?
Horizontal line that runs like a ring, perpendicular to the inferior margins of the anal sinuses
What is pepsinogen?
Inactive form of pepsin
Define peristalsis
Muscular contractions and relaxations that propel food through the GI tract
How many permanent teeth do adults have?
32
What is the pharynx commonly referred to as?
Throat
What does a phosphatase enzyme do?
Digests nucleotides
What is the porta hepatis?
Gateway to the liver where the hepatic artery and hepatic portal vein enter
What constitutes the portal triad?
Bile duct, hepatic artery branch, and hepatic portal vein branch
What is a premolar also known as?
Bicuspid
What is the role of the pyloric sphincter?
Controls stomach emptying
What is the pylorus?
Lower, funnel-shaped part of the stomach continuous with the duodenum
What is the function of the rectal valve?
Separates feces from flatus
What is the rectum?
Part of the large intestine between the sigmoid colon and anal canal
What is a reticuloendothelial cell also known as?
Kupffer cell
What is the function of a reticuloendothelial cell?
Phagocyte in hepatic sinusoids that filters out material from venous blood
Define retroperitoneal
Located posterior to the peritoneum
What does ribonuclease digest?
RNA
What is the right colic flexure also known as?
Hepatic flexure
What is the root of a tooth?
Portion of a tooth embedded in the alveolar processes beneath the gum line
What is a ruga?
Fold of alimentary canal mucosa and submucosa in the empty stomach
Define saccharolytic fermentation
Anaerobic decomposition of carbohydrates
What is saliva?
Aqueous solution of proteins and ions secreted into the mouth by the salivary glands
What does salivary amylase do?
Acts on starch
What is the role of a salivary gland?
An exocrine gland that secretes saliva
Define salivation
Secretion of saliva
What is segmentation in the digestive system?
Alternating contractions and relaxations of non-adjacent segments of the intestine
What is the serosa?
Outermost layer of the alimentary canal wall present in regions within the abdominal cavity
Where is the sigmoid colon located?
End portion of the colon, which terminates at the rectum
What is the primary function of the small intestine?
Most digestion and absorption occurs here
What is the soft palate?
Posterior region of the bottom portion of the nasal cavity consisting of skeletal muscle
What is the stomach’s role in digestion?
Contributes to chemical and mechanical digestion of food
What is the sublingual gland?
One of a pair of major salivary glands located beneath the tongue
Where is the submandibular gland located?
In the floor of the mouth
What does the submucosa layer consist of?
Dense connective tissue that binds the overlying mucosa to the underlying muscularis
What is the submucosal plexus?
Nerve supply that regulates activity of glands and smooth muscle
What does sucrase do?
Breaks down sucrose into glucose and fructose
What is the tenia coli?
One of three smooth muscle bands in the large intestine
What is the tongue?
Accessory digestive organ of the mouth composed of skeletal muscle
What is the transverse colon?
Part of the colon between the ascending colon and the descending colon
What does the upper esophageal sphincter regulate?
Food movement from the pharynx to the esophagus
What is Valsalva’s maneuver?
Voluntary contraction of the diaphragm and abdominal muscles that increases intra-abdominal pressure
What is a villus?
Projection of the mucosa of the small intestine
What is the voluntary phase of deglutition?
Initial phase in which the bolus moves from the mouth to the oropharynx
What is α-dextrin?
Breakdown product of starch
What does α-dextrinase act on?
α-dextrins
What disorder in adults is caused by abnormally high levels of GH leading to growth of bones in the face, hands, and feet?
acromegaly
Acromegaly is characterized by excessive growth due to excess growth hormone (GH).
What is the function of adenylyl cyclase?
Converts ATP to cyclic AMP, creating cAMP
Adenylyl cyclase is activated by G-protein signaling.
What does the adrenal cortex produce?
Mineralocorticoids and glucocorticoids
It consists of multiple layers of epithelial cells.
Where are the adrenal glands located?
At the top of each kidney
They are important for regulating stress response, blood pressure, and fluid balance.
What hormones does the adrenal medulla produce?
Epinephrine and norepinephrine
These hormones are crucial for the stress response.
What is the role of adrenocorticotropic hormone (ACTH)?
Stimulates the adrenal cortex to secrete corticosteroid hormones
ACTH is also known as corticotropin.
What is the alarm reaction in the general adaptation syndrome?
The short-term stress response mediated by epinephrine and norepinephrine
This is the first stage of the general adaptation syndrome.
What is the function of aldosterone?
Stimulates sodium and fluid retention, increases blood volume and blood pressure
Aldosterone is produced by the adrenal cortex.
What do alpha cells in the pancreas produce?
Glucagon
Glucagon increases blood glucose levels.
What does angiotensin-converting enzyme do?
Converts angiotensin I to angiotensin II
This enzyme plays a role in blood pressure regulation.
What is antidiuretic hormone (ADH)?
Hormone that signals kidneys to reabsorb water
ADH is stored in the posterior pituitary.
What is the function of atrial natriuretic peptide (ANP)?
Reduces sodium and water reabsorption in kidneys, promotes vasodilation
ANP is produced in response to high blood pressure.
What is an autocrine signal?
Chemical signal that elicits a response in the same cell that secreted it
This signaling is crucial in various physiological processes.
What do beta cells in the pancreas produce?
Insulin
Insulin lowers blood glucose levels.
What is the role of calcitonin?
Decreases blood calcium levels
Calcitonin is produced by the parafollicular cells of the thyroid gland.
What are chromaffin cells?
Neuroendocrine cells of the adrenal medulla
They are involved in the production of catecholamines.
What is colloid in the context of thyroid follicles?
Viscous fluid containing thyroglobulin
Colloid is essential for the synthesis of thyroid hormones.
What is the function of cortisol?
Important in gluconeogenesis and downregulation of the immune system
Cortisol is a glucocorticoid produced by the adrenal cortex.
What is cyclic adenosine monophosphate (cAMP)?
Second messenger that triggers a phosphorylation cascade
cAMP is produced in response to adenylyl cyclase activation.
What do delta cells in the pancreas secrete?
Somatostatin
Somatostatin inhibits insulin and glucagon secretion.
What condition is caused by dysfunction of beta cells leading to high blood glucose levels?
Diabetes mellitus
This can result from destruction of beta cells or insulin resistance.
What is diacylglycerol (DAG)?
Molecule that activates protein kinases
DAG works alongside cAMP in signaling cascades.
What does downregulation refer to in hormone signaling?
Decrease in the number of hormone receptors
This typically occurs in response to chronically excessive hormone levels.
What defines an endocrine gland?
Tissue or organ that secretes hormones into the blood and lymph
Endocrine glands lack ducts.
What encompasses the endocrine system?
Cells, tissues, and organs that secrete hormones
It plays a crucial role in regulating bodily processes.
What is epinephrine commonly known as?
Adrenaline
It is the primary catecholamine produced by the adrenal medulla.
What is the function of erythropoietin (EPO)?
Triggers bone marrow to produce red blood cells in response to low oxygen levels
EPO is crucial for maintaining oxygen levels in the blood.
What are estrogens?
Predominantly female sex hormones
They are important for reproductive health and pregnancy maintenance.
What is the role of the first messenger in hormone signaling?
Binds to a cell membrane hormone receptor
This triggers the activation of a second messenger system.
What does follicle-stimulating hormone (FSH) stimulate?
Production and maturation of sex cells
FSH is produced by the anterior pituitary.
What is the function of G protein in hormone signaling?
Initiates the next step in a second messenger system upon activation
G proteins are associated with hormone receptors.
What is the general adaptation syndrome (GAS)?
Three-stage response pattern to stress
It includes the alarm reaction, stage of resistance, and stage of exhaustion.
What disorder in children is caused by high levels of GH?
Gigantism
This results in excessive growth during childhood.
What is glucagon’s role in the body?
Stimulates catabolism of glycogen to glucose
This process increases blood glucose levels.
What are glucocorticoids?
Hormones that influence glucose metabolism
They are produced by the zona fasciculata of the adrenal cortex.
What is a goiter?
Enlargement of the thyroid gland
It can result from iodine deficiency or hyperthyroidism.
What are gonadotropins?
Hormones that regulate the function of the gonads
They include FSH and LH.
What is the primary role of growth hormone (GH)?
Promotes tissue building and influences nutrient metabolism
GH is also known as somatotropin.
What is hormone signaling?
Secretion of an endocrine organ that travels via the bloodstream to induce a response
Hormones act on target cells or tissues.
What is a hormone receptor?
Protein that binds a hormone, initiating a target cell response
Receptors can be located within the cell or on the cell membrane.
What is hyperglycemia?
Abnormally high blood glucose levels
This condition can lead to serious health issues.
What causes hyperparathyroidism?
Overproduction of parathyroid hormone (PTH)
This results in elevated blood calcium levels.
What is hyperthyroidism characterized by?
Elevated levels of thyroid hormone and increased metabolic rate
Symptoms include sweating, weight loss, and increased heart rate.
What does hypoparathyroidism result from?
Underproduction of parathyroid hormone (PTH)
This leads to low blood calcium levels.
What is the hypophyseal portal system?
Network of blood vessels enabling hypothalamic hormones to reach the anterior pituitary
This occurs without entering systemic circulation.
What is the hypothalamus responsible for?
Neural and endocrine signaling
It is located inferior to the thalamus.
What is hypothyroidism characterized by?
Low levels of thyroid hormone and low metabolic rate
Symptoms include weight gain and cold extremities.
What is the infundibulum?
Stalk connecting the pituitary gland to the hypothalamus
It contains vasculature and neural tissue.
What does inhibin do?
Inhibits FSH production by the anterior pituitary
It is secreted by the male and female gonads.
What is inositol triphosphate (IP3)?
Molecule that initiates the release of calcium ions
IP3 plays a role in intracellular signaling.
What is the role of insulin?
Enhances cellular uptake and utilization of glucose
Insulin decreases blood glucose levels.
What are insulin-like growth factors (IGF)?
Proteins that enhance cellular proliferation and inhibit apoptosis
They stimulate amino acid uptake for protein synthesis.
What is leptin?
Protein hormone that promotes satiety
It is secreted by adipose tissues in response to food consumption.
What is the function of luteinizing hormone (LH)?
Triggers ovulation and production of ovarian hormones
It also stimulates testosterone production in males.
What does melatonin regulate?
Sleep-wake cycle
It is secreted in response to low light.
What do mineralocorticoids influence?
Fluid and electrolyte balance
They are produced by the zona glomerulosa of the adrenal cortex.
What is neonatal hypothyroidism?
Condition characterized by cognitive deficits and short stature
It occurs in infants born to iodine-deficient mothers.
What is norepinephrine also known as?
Noradrenaline
It is a secondary catecholamine produced by the adrenal medulla.
What is the function of osmoreceptors?
Stimulated by changes in solute concentration in the blood
They are located in the hypothalamus.
What is oxytocin important for?
Stimulating uterine contractions and milk ejection
It also plays a role in feelings of attachment.
What organ has both exocrine and endocrine functions?
Pancreas
It is crucial for digestion and blood glucose regulation.
What are pancreatic islets?
Clusters of pancreatic cells with endocrine functions
They are also known as islets of Langerhans.
What is a paracrine signal?
Chemical signal that elicits a response in neighboring cells
Paracrine signaling is important for local communication.
What do parathyroid glands produce?
Parathyroid hormone (PTH)
PTH is secreted in response to low blood calcium levels.
What does phosphodiesterase (PDE) do?
Deactivates and degrades cAMP
This enzyme plays a role in regulating signaling pathways.
What is a phosphorylation cascade?
Signaling event where multiple protein kinases phosphorylate substrates
This process is crucial for cell signaling.
What does the pineal gland secrete?
Melatonin
Melatonin is important for regulating sleep.
What is pituitary dwarfism?
Disorder caused by low levels of GH resulting in growth retardation
It occurs in children.
What is the pituitary gland?
Bean-sized organ that produces and secretes hormones
It is also called the hypophysis.
What does PP cell in the pancreas secrete?
Pancreatic polypeptide
This is involved in regulating pancreatic secretions.
What is progesterone’s primary role?
Regulating the female reproductive cycle and pregnancy maintenance
It is a predominantly female sex hormone.
What does prolactin (PRL) promote?
Development of mammary glands and production of breast milk
PRL is secreted by the anterior pituitary.
What is a protein kinase?
Enzyme that initiates a phosphorylation cascade upon activation
Protein kinases are crucial for signaling pathways.
What is a second messenger?
Molecule that initiates a signaling cascade in response to hormone binding
Second messengers amplify the signal inside the cell.
What is the stage of exhaustion in the general adaptation syndrome?
The body’s long-term response to stress
This stage is mediated by adrenal cortex hormones.
What is the stage of resistance in the general adaptation syndrome?
Continued response to stress after the alarm reaction diminishes
This is the second stage of GAS.
What is testosterone important for?
Maturation of sperm cells and development of male reproductive system
It is a steroid hormone secreted by the testes.
What do thymosins play a role in?
Development and differentiation of T cells
Thymosins are produced by the thymus.
What is the thymus involved in?
Development and maturation of T-cells
It is particularly active during infancy and childhood.
What is the primary function of the thyroid gland?
Synthesis of thyroid hormones
It is a large endocrine gland.
What does thyroid-stimulating hormone (TSH) do?
Triggers secretion of thyroid hormones by the thyroid gland
TSH is also known as thyrotropin.
What is thyroxine (T4)?
Amino acid-derived thyroid hormone that is converted to T3
T4 is more abundant but less potent than T3.
What is triiodothyronine (T3)?
Amino acid-derived thyroid hormone that is more potent than T4
T3 plays a significant role in metabolism.
What does upregulation refer to?
Increase in the number of hormone receptors
This typically happens in response to reduced hormone levels.
What is the zona fasciculata of the adrenal cortex responsible for?
Producing glucocorticoids
It is the intermediate region of the adrenal cortex.
What does the zona glomerulosa produce?
Mineralocorticoids
It is the most superficial region of the adrenal cortex.
What does the zona reticularis produce?
Steroid sex hormones called androgens
It is the deepest region of the adrenal cortex.
