Physiology Exam Review #5 Flashcards
What kind of process is digestion?
It is a multistep process and is both chemical and physical in nature
What is happening during the hydrolysis reaction within digestion?
Digestion is breaking down polymers into monomer building blocks
What are polymers?
Complex structures (whole protein - carbohydrates, fats, and proteins)
What are monomers?
The broken down simpler forms of polymers
What helps in taking monomers into the bloodstream to be used by the cells?
Absorption - which takes place in the lining of the gut
This tract is open at both ends and is continuous with the environment - considered “outside” of the body
The digestive tract
This type of transport allows for specialization of function along the digestive tract
One-way transport
Term that means movement of food through the tract
Motility
Term that means taking food into the mouth
Ingestion
Term that means chewing and mixing food with saliva
Mastication
Term that means swallowing
Deglutition
Term that means wave-like, one-way movement through tract
Peristalsis
Term that means churning and mixing while moving forward
Segmentation
This digestive tract function involves digestive enzymes, hydrochloric acid, mucus, water, and bicarbonate
Exocrine secretion
This digestive tract function involves hormones that regulate digestion
Endocrine secretion
This term means breaking down food into smaller units, both physically and chemically
Digestion
This term means passing broken-down food into blood or lymph
Absorption
These cells within the digestive tract prevent swallowed pathogens from entering the body
Simple columnar epithelium with tight junctions
This tract is about 30 feet long, from mouth to anus
Gastrointestinal tract (GI tract, alimentary canal)
What are the accessory organs of the digestive tract?
Teeth, tongue, salivary glands, liver, gallbladder, and pancreas
This layer of the alimentary tract in the inner secretory and absorptive layer; which may be folded to increase surface area - also the location of goblet cells
Mucosa
This layer of the alimentary tract is very vascular in order to pick up nutrients, and also has some glands and nerve plexuses
Submucosa
This layer of the alimentary tract is made of smooth muscle and is responsible for peristalsis and segmentation; contains the myenteric plexus for control by the ANS
Muscularis
This layer of the alimentary tract is the outer binding and protective layer where visceral peritoneum covers the organs and the parietal peritoneum lines the abdominal cavity
Serosa
What are the two extrinsic regulations of the GI tract?
Parasympathetic division and sympathetic division
This nerve that is part of the parasympathetic division stimulates the esophagus, stomach, small intestine, pancreas, gallbladder, and proximal part of the large intestine
The vagus nerve
These nerves stimulate the distal large intestine
Spinal nerves in sacral region
This division of the extrinsic regulation reduces peristalsis and secretion, and stimulates contraction of sphincters
Sympathetic division
What takes place in intrinsic regulation?
- Intrinsic sensory neurons in gut wall help in intrinsic regulation via separate enteric nervous system
- Paracrine receptors
This contains mucus - an antimicrobial agent - and salivary amylase - which is a carbohydrate digesting enzyme - to start digestion of starch
Saliva
This involves coordinated contraction of 25 pairs of muscles in the mouth, pharynx, larynx, and esophagus
Deglutition
What are the three parts of deglutition?
- Oral: voluntary; muscles of mouth and tongue mix food with saliva to form a bolus
- Pharyngeal: involuntary; initiated by receptors in the posterior oral cavity and oropharynx
- Esophageal: automatic; controlled by the swallowing center of the brain stem; bolus is moved down esophagus to stomach via peristalsis
This lifts to cover the nasopharynx and the epiglottis covers the vocal cords during the pharyngeal part of deglutition
Uvula
A condition that occurs when part of the normal stratified squamous epithelium of the esophagus is replaced by columnar epithelium
Barrett’s Esophagus
What are the functions of the stomach?
- Stores food
- Churns food to mix with gastric secretions
- Begins protein digestion
- Kills bacteria in the food
- Movies food into small intestine in the form of a pasty material called chyme
What is the upper region of the stomach called?
Fundus
What is the lower region of the stomach called?
Body
What is the distal region of the stomach called?
Pyloric region; ends at the pyloric sphincter
What are the folds in the lining of the stomach called?
Rugae
These secretory cells secrete mucus to help protect stomach lining from acid
Mucus neck cells
These secretory cells secrete HCl acid and intrinsic factor - which helps the small intestine absorb vitamin B12
Parietal cells
Theses cells secrete pepsinogen, which is the inactive form of the protein digesting enzymes
Chief (zygomatic) cells
These cells secrete the hormone gastrin
G cells
These cells secrete the hormone somatostatin
D cells
These cells secrete the hormone ghrelin that signals the brain to regulate hunger and body weight
P/D1 cells
What is the only stomach function essential for life?
The production of intrinsic factor that is needed for intestinal absorption of vitamin B12, which is necessary for RBC production
Highly acidic mixture of exocrine gland secretions and a large amount of water
Gastric juice
What are at the base of folds that lead to gastric glands - which contain several types of secretory cells
Gastric pits
What are the functions of HCl in the stomach when a drop in pH hits 2?
- Ingested proteins are denatured (allows enzymes access)
- Pepsinogen is converted to active pepsin (digests proteins)
- Serves as the optimal pH for pepsin activity
What is the function of pepsin in the stomach?
Catalyzes the hydrolysis of peptide bonds in the ingested proteins
Acid and pepsin could damage the stomach lining - what are the defenses to help prevent this?
- Adherent layer of mucus with alkaline bicarbonate
- Tight junctions between epithelial cells
- Rapid epithelial mitosis that replaces epithelium every three days
What begins digestion in the stomach?
Proteins
What begins digestion in the mouth but since salivary amylase is not active at pH 2, this activity stops in the stomach
Starches
What are the only common substances to be absorbed in the stomach?
Alcohol and NSAIDs (aspirin)
What organ starts at the pyloric sphincter and ends at the ileocecal valve and is about 12 ft long?
The small intestine
What are the three sections of the small intestine?
Duodenum, Jejunum, and Ileum
Which organ completes the digestion of carbohydrates, proteins, and fats?
The small intestine
Which part of the small intestine absorbs sugars, lipids, amino acids, calcium, and iron?
Duodenum and Jejunum
Which part of the small intestine absorbs bile salts, vitamin B12, water and electrolytes
Ileum
What is required for the activation of the protein-digesting enzyme trypsin, which comes from the pancreas and activates other pancreatic enzymes
Enterokinase (enteropeptidase)
Which enzymes are needed for disaccharidase?
Sucrase, Maltase, and Lactase
Which enzymes are needed for peptidase?
Aminopeptidase and enterokinase
Which enzymes are needed for phosphatase?
Ca2+, Mg2+ - ATPase and Alkaline phosphatase
What are the functions of the large intestine?
- Absorption of water, electrolytes, vitamin K, and some B vitamins
- Production of vitamin K and B vitamins via microbial organisms
- Storage of feces
What are the several thousand different species of bacteria living in the large intestine called?
Microflora or intestinal microbiota
What is it called when the bacteria in the large intestine benefit and contain enzymes that digest dietary fiber that we can’t hydrolyze into monosaccharides
Commensal
What is it called when the bacteria in the large intestine is benefitted along with us
Mutualistic
What is the reddish brown gland located immediately inferior to the diaphragm - on the right side of the body
Liver
What is the function of the liver?
Secretes bile which contributes to digestion
A pear-shaped sac on the underside of the liver
Gallbladder
What is the function of the gallbladder?
Serves to store and concentrate bile by absorbing water and electrolytes
Yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids
Bile
Principal pigment derived from the decomposition of hemoglobin
Bilirubin
What is responsible for the brown color of feces
Bacteria in large intestine metabolizing bilirubin to urobilinogen
Steroids synthesized from cholesterol that aid in fat digestion and absorption
Bile acids (bile salts)
How much bile does the liver secrete daily?
500 to 1,000 mL
80% of bile acids are reabsorbed where?
In the ileum and then returned to the liver
What cells absorb and re-secrete bile acids?
Hepatocytes
Route of secretion, reabsorption, and re-secretion of bile acids two or more times during digestion of an average meal
Enterohepatic circulation
20% of the bile acids are excreted in ______
the feces - which is aided by soluble fiber
What organ synthesizes new bile acids from cholesterol to replace those lost in feces
The liver
What are gallstones composed of?
Cholesterol, calcium carbonate, and bilirubin
Spongy retroperitoneal gland posterior to greater curvature of stomach
Pancreas
What is the endocrine portion of the pancreas responsible for?
Pancreatic islets that secrete insulin and glucagon - concentrated in the tail of the gland
What is the majority of the pancreas?
The exocrine portion - secretes pancreatic juice
Alkaline mixture of water, enzymes, zymogens/proenzymes, sodium bicarbonate, and other electrolytes
Pancreatic juice
What is the function of bicarbonate in the pancreas?
Buffers HCl arriving from the stomach
This stimulates pancreatic acinar cells to secrete enzymes during cephalic phase of gastric control even before food is swallowed
Acetylcholine (ACh)
Secreted by mucosa of duodenum in response to arrival of fats in the small intestine
Cholecystokinin (CKK)
Released from duodenum in response to acidic chyme arriving from the stomach - also raises pH to the level required for activity of the pancreatic and intestinal digestive enzymes
Secretin
Oxygen consumed by a relaxed, awake person, in comfortable temperature, 12 to 14 hours after eating (this can be affected by age, sex, body surface area, and thyroid activity)
Basal metabolic rate
What are the water-soluble vitamins and cannot be stored in the body?
Vitamins B and C
What are the fat-soluble vitamins and can be stored in the body?
Vitamins A, D, E, and K
What are molecules with unpaired electrons?
Free radicals
Regulatory molecules secreted by adipocytes that affect hunger, metabolism, and insulin sensitivity
Adipokines
This is secreted by the stomach when it is empty - when the stomach is full, this is reduced
Ghrelin
These levels rise during and right after a meal, suppresses hunger, and is the antagonist to ghrelin
Cholecystokinin (CKK)
These reduce appetite and stimulates release of MSH from arcuate nucleus
Polypeptide YY (PYY)
This reduces hunger and controls hunger for long term - the more adipose tissue you have, the more of this you secrete
Leptin
This reduces hunger indirectly by increasing the storage of fat (which results in leptin production)
Insulin
Energy expended to adapt in ambient temperature and digestion/absorption of food
Adaptive thermogenesis
Where do germ cells or gametes (sperm and ova) form?
In the gonads - testes and ovaries
What is the process that an individual progresses?
Zygote –> embryo –> fetus
What are the copulatory organs for males and females?
Penis and vagina
What are the primary sex organs for males and females?
Gonads - which produce gametes (testes and ovaries)
Organs other than gonads that are necessary for reproduction
Secondary sex organs
What are the male secondary sex organs?
System of ducts, glands, and penis
What are the female secondary sex organs?
Uterine tubes, uterus, and vagina
What is the term for 23 chromosomes?
Haploid
What is the term for 23 pairs of chromosomes?
Diploid
The sex of a child is determined by the contributing _____
sperm
Which sex has two X chromosomes
Female
Which sex has an X and a Y chromosome
Male
What is the signal that determines embryonic gonads to become either testes or ovaries
Testis-determining factor (TDF)
Which cells begin making large amounts of androgen (for testosterone) about 8 weeks after fertilization
Leydig cells
Puberty begins with a release of what?
LH hormone
This is secreted by adipose cells and is required for the onset of puberty
Leptin
This is where spermatogenesis occurs
Seminiferous tubules
This hormone receptor is found on Sertoli cells
FSH
Which hormone influences spermatogenesis
FSH
This is where Leydig cells make testosterone and is also filled with blood and lymphatic capillaries
Interstitial tissue
Which hormone receptor is found on Leydig cells
LH
What is secreted in response to LH
Testosterone
What is the maturation of spermatids into functioning spermatozoa called
Spermatogenesis
The site of sperm maturation and storage - where sperm becomes motile
The epididymis
Fluid that contains fructose - energy for sperm
Seminal fluid
Fluid that contains citric acid, calcium, and vesiculase
Prostate fluid
An enzyme that causes semen to coagulate after ejaculation
Vesiculase
Causes the semen to become liquid, freeing the sperm
Fibrinolysis
The movement of semen into the urethra
Emission
The site of oocyte and sex steroid production
Ovaries
These have fimbriae that partially wrap around the ovaries and “catch” the oocyte ovulation
Fallopian tubes
The site of embryonic development
Uterus
The inner layer of the uterus - where the embryo implants and develops
Endometrium
The middle muscular layer of the uterus
Myometrium
The outer connective tissue layer of the uterus
Perimetrium
The narrow bottom region of the uterus
Cervix
This hormone stimulates monthly cohorts of about 24 oocytes to complete meiosis I
FSH
Large daughter cell that is the product of meiosis I
Secondary oocyte
This is the smaller cell that ultimately disintegrates - a means of discarding the extra set of haploid chromosomes
First polar body
Where are primary oocytes contained
Within primary follicles that have one layer of cells
Continued growth results in fused vesicles to form a single antrum called
Mature Graafian follicle
In the Graafian follicle, what are the cell layers called that form around the oocyte
Corona radiata and zona pellucida
Continued development of one Graafian follicle occurs because of stimulation of which hormones
FSH and Estradiol
Which follicle is protected from atresis and forms a bulge on the surface of the ovary
A mature Graafian follicle
After ovulation, the remaining follicle becomes this
Corpus Luteum (yellow body)
Which hormones does the corpus luteum secrete?
Estradiol and progesterone - play a role in the menstrual cycle and maintaining a pregnancy
Toward the end of a non-fertile cycle, the corpus luteum regresses to become what
A nonfunctional corpus albicans
This ovarian phase is characterized by increasing levels of estradiol production from granulosa cells
Follicular phase
During this ovarian phase, FSH causes the Graafian follicle to bulge out of the ovary wall
Ovulation
During the ovarian luteal phase, high levels of estradiol and progesterone feedback on the pituitary gland and inhibit these hormones
FSH and LH
During this phase, follicle development is shut down to prevent further ovulation long enough to give the secondary oocyte a chance to be fertilized
Ovarian luteal phase
A decrease in the levels of these hormones stimulate the sloughing of the endometrium and menstruation
Estradiol and progesterone
How are capacitated sperm guided to the oocyte
By chemotaxis and thermotaxis
Where does fertilization occur
In the fallopian tubes
What does the sperm contribute during fertilization
1/2 chromosomes, centrosome, and mitochondria
What does the egg contribute during fertilization
1/2 chromosomes, cytoplasm, and all other organelles
Which hormone is secreted by the blastocyst and is needed for the maintenance of the endometrium
Human Chorionic Gonadotropin (hCG)
This hormone has the same effect as LH and maintains the Corpus Luteum, maintains production of estrogen and progesterone
Human Chorionic Gonadotropin (hCG)
