A&P 2 Test 3 Flashcards
The digestive system consists of the _____ and is assisted by various _____
muscular digestive tract
accessory organs
6 digestive functions
- ingestion
- mechanical processing
- digestion
- secretion
- absorption
- excretion
What are the 8 components of the digestive tract
- oral cavity
- pharynx
- esophagus
- stomach
- small intestines
- large intestines
- rectum
- anus
What functions do the oral cavity, teeth, and tongue play in the digestive tract?
- Mechanical processing of food
- Moistening of food
- Mixing food with salivary secretions
What is the function of the liver in the digestive tract?
- Secretes bile
- Stores nutrients
What is an important lipid for digestion?
Bile
What is the function of the gallbladder in the digestive tract?
Stores and concentrates bile
What is the function of the pancreas in the digestive tract?
- Exocrine cells: secrete buffers and digestive enzymes
- Endocrine: secrete hormones
What is the function of the large intestines in the digestive tract?
- Dehydrates and compacts indigestible materials
- Prepares for elimination
What is the function of the salivary glands in the digestive tract?
-Secretes lubricating fluid which also contains enzymes which breaks down carbs
What is the function of the pharynx in the digestive tract?
-Provides muscular propulsion of food into the esophagus
What is the function of the esophagus in the digestive tract?
-Transports food from the mouth to the stomach
What is the function of the stomach in the digestive tract?
- Breaks down food chemically with acid and enzymes
- Muscles contract to mechanically process and break down food
What is the function of the small intestines in the digestive tracts?
- Digests food further using enzymes
- Absorbs water, organic substrates, vitamins, and ions
What are the four histological layers of the digestive tract?
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
Describe the mucosa histological layer of the digestive tract
- Epithelium
- Lamina propria (connective tissue)
Describe the submucosa histological layer of the digestive tract
- connective tissue
- nerves
- blood vessels
Describe the muscularis externa histological layer of the digestive tract
-loose connective tissue cover (adventitia)
Describe the serosa histological layer of the digestive tract
- in the peritoneal cavity
- continuous with mesentery
The structure of the digestive tract:
slide 6 & 7
How does food move through the digestive tract?
Involuntary control and contraction of smooth much of the muscularis externa
What are the two types of movement of food through the digestive tract?
Peristalsis
Segmentation
Describe peristalsis
Food is propelled along the digestive tract
Describe segmentation
Food is churned in the small intestines
The steps of contraction of muscles moving food along the digestive tract:
slide 9-12
What are the functions of the oral cavity?
- Sensory analysis of potential foods
- Mechanically process food using the teeth, tongue and palate
- lubricate food using mucus in saliva
- Begins enzymatic digestion with saliva
What is another name for the oral cavity?
Buccal cavity
What forms the floor of the oral cavity?
The tongue
What forms the roof of the oral cavity?
Hard and soft palate
What forms the walls of the oral cavity
Buccal mucosa
What is the epithelium of the buccal mucosa?
Stratified squamous
What are the specific functions of the tongue?
- Mechanically processes food
- Manipulates food to assist in chewing and swallowing
- Provides sensory analysis (taste and texture)
- Participates in speech
The anatomy of the oral cavity:
slides 16 & 17
What are the three pairs of salivary glands?
- Parotid
- Sublingual
- Submandibular
What are the functions of saliva?
- Lubricates and cleanses oral cavity
- Dissolves chemicals
- Suppresses bacterial growth
Location of salivary glands:
slide 19
What is the function of teeth
Mastication of food
Mastication
Chewing
What ligament anchors teeth to bone?
Periodontal ligament
What forms the basic shape of teeth?
Dentin
What covers the crown of teeth?
Enamel
What covers the root of teeth?
Cementum
How many deciduous teeth are humans born with?
20
Deciduous teeth
Baby teeth
How many secondary teeth do humans have?
32
Secondary teeth
Adult teeth
The basic structure of teeth:
Slides 21-23
What are the functions of the pharynx?
- Passageway for food, drink and air
- Food is propelled along the esophagus towards the stomach during swallowing by pharyngeal muscles
Describe the esophagu
- Muscular tube
- 25 cm long
What is the epithelial lining of the esophagus?
Stratified squamous
Where is the esophagus in relation to the trachea?
Posterior
Where does the esophagus penetrate the diaphragm at the?
Esophageal hiatus
What two structures does the esophagus possess?
Upper and lower esophageal sphincters
A circular band of muscle that can pinch close to a muscular tube
Sphincter
What are the three steps of swallowing?
- Oral Phase
- Pharyngeal Phase
- Esophageal Phase
What happens during the oral phase of swallowing?
- Compaction of bolus
- Food enters the pharynx
What happens during the pharyngeal phase of swallowing?
- Elevation of the larynx
- Bending of the epiglottis
- Closing of the glottis
What happens during the esophageal phase of swallowing?
-Peristalsis pushes the bolus toward the stomach
Steps of swallowing:
slides 27-32
What are the functions of the stomach?
- Temporarily stores ingested food
- Mechanically breaks down food
- Breaks down chemical bonds in food using acid and enzymes
- Production of the intrinsic factor
What occurs during the mechanical breakdown of food in the stomach?
Chyme is formed and liquid suspension occurs
Why is intrinsic factor important?
Required for vitamin B12 absorption
What are the 4 regions of the stomach?
- Cardia
- Funus
- Body
- Pylorus
What region of the stomach is closest to the heart?
Cardia
What region of the stomach is the “hump” on top of the stomach?
Fundus
What region of the stomach is shaped like the letter “C”?
Body
What region of the stomach is guarded by a guarded by a sphincter at the exit of the stomach?
Pylorus
What sphincter guards the exit of the stomach?
Pyloric sphincter
The regions of the stomach:
slides 34 & 35
What glands in the stomach are involved in secretions?
Gastric Glands
What cells are in the gastric glands?
- Parietal
- Chief
- Goblet
- Endocrine
The anatomy of the stomach:
slides 37 & 38
What do parietal cells secrete?
HCl
What is HCl involved in?
Intrinsic factor
What do chief cells secrete?
Pepsinogen (an inactive enzyme)
What turns pepsinogen into pepsin?
HCl
What do goblet cells produce?
mucus
What do endocrine cells produce?
Gastrin ( a hormone)
What are the three phases of regulating gastric activity?
- Cephalic phase
- Gastric phase
- Intestinal phase
What occurs during the cephalic phase?
CNS prepares the stomach to receive food
When does gastric phase occur?
When food enters the stomach
What does the intestinal phase do?
Controls the pace of gastric emptying
Phases of gastric secretion:
slides 40-43
What is the stomach lined with?
Highly mitotic cells
What is a short summary of the stomach?
The stomach provides for the physical breakdown of food that must precede chemical digestion. Pepsin and acid begin the digestion of proteins. For a variable period of time after food arrives in the stomach, starch continues the digestion that began with salivary amylase
What are the regions of the small intestines?
- Duodenum
- Jejunum
- Ileum
What sphincter marks the junction between small and large intestines?
Ileocaecal valve
The segments of the small intestines:
slide 46
The mucosa of the intestinal wall has transverse folds called…
Plicae circulares
Small projections of pilcae
Villi
What are the functions of the plicae and villi?
Increases surface area of mucosa for absorption
Each villus has a ____ which is called ____
Lymphatic capillary
A lacteal
The small intestinal wall:
slide 50
Two forms of peristalsis in the small intestines
Small-scale and large-scale
Describe small-scale peristalsis
Periodic contractions of the muscularis extera
Describe large-scale peristalsis
Coordinated by gastroenteric or gastrocolic reflex
What are the 3 types of intestinal secretions
- Intestinal juice
- Mucus
- Hormones
What does intestinal juice do?
- Moistens chime
- Buffers stomach acid
- Dissolves digestive enzymes
- Dissolves products of digestion
What are some intestinal hormones in the small intestines?
- Gastrin
- Secretin
- Cholecystokinin
- Gastric Inhibitory Peptide
What part of digestion happens in the small intestine?
Most enzymatic digestion and absorption
What organs release enzymes and buffers for digestion in the small intestines?
- Pancreas
- Liver
- Gall Bladder
What is a brief summary of the small intestines?
The small intestine receives chyme from the stomach and raises its pH. It then absorbs water, ions, vitamins, and the products released from food molecules by the action of digestive enzymes produced by intestinal glands and the pancreas.
Where do the pancreatic ducts enter?
Duodenum
What do pancreatic ducts deliver?
Pancreatic juice
Pancreatic ducts branch ___
Repeatedly
Where do fine pancreatic duct branches end?
Pancreatic acini
What cells are found among the acini of the pancreas?
Endocrine cells
Anatomy of the pancreas:
slide 59
What are the two types of secretions from the pancreas?
- Endocrine (hormones)
- Exocrine (digestive)
What are some hormones are secreted by the pancreas?
- insulin
- glucagon
What are some digestive secretions which come from the pancreas?
- Water
- Ions
- Enzymes
What are some enzymes secreted by the pancreas
- Carbs
- Lipases
- Proteases
- Nucleases
What occurs to control pancreatic secretion?
-Chyme enters the duodenum which triggers hormone release, hormones then trigger the release of pancreatic juices
Secretin being secreted by the pancreas triggers…
Water and bicarbonate
CCK being secreted by the pancreas triggers…
Enzymes like Amylas, lipase, proteases
Brief summary of the pancreas
The exocrine pancreas produces a mixture of buffers and enzymes essential for normal digestion. Pancreatic secretion is stimulated by hormones (secretin and CCK) released from the duodenum.
What is the largest visceral organ?
Liver
How many known functions does the liver have?
Over 200
What are the 4 lobs of the liver?
- Right (largest)
- Left
- Caudate
- Quadrate
Anatomy of the liver
slides 65 & 66
What is a basic functional unit of the liver?
Liver lobule
Where is the blood supply of the liver coming from?
- Hepatic artery
- Hepatic portal vein
In the liver, blood flows past sheets of
Hepatocytes
What are the blood channels of the liver?
Sinusoids
Where does blood collect in the liver?
Central vein
What carries bile towards of the bile ducts in the liver?
Bile Canaliculi
Where are bile ducts located in the liver?
Each lobe has a duct
What is formed when liver bile ducts unite?
Common Hepatic duct
What ducts carry bile from the liver to the gall bladder?
Cystic duct
What duct carries bile from the liver to the duodenum?
Common bile duct
How does the liver regulate metabolism?
- Stores absorbed nutrients and vitamins
- Releases nutrients as needed
How does the liver carry out hematological regulation?
- Produces plasma proteins
- Removes old RBCs
Why does the liver produce bile?
It is required for fat breakdown
What is the function of the gallbladder?
Stores and concentrates bile for release into duodenum
How does bile enter the small intestine from the gallbladder?
The hepatopancreatic sphincter relaxes
Briefly describe the gallbladder
The liver is the body’s center for metabolic regulation. It produces bile that will be ejected by the gallbladder into the duodenum under stimulation of CCK. Bile is essential for the efficient digestion of lipids; it emulsifies fats so that individual lipid molecules can be readily attacked by digestive enzymes
Know the anatomy of the gallbladder
Slides 75 & 76
Describe the large intestines?
- Reabsorbs water and compacts feces
- Absorbs vitamins made by bacteria
- Stores feces before defecation
What are the three parts of the large intestines?
- Cecum
- Colon
- Rectum
Functions of the cecum
- Collects and stores material from ileum
- Begins process of compaction
- Attaches to vermiform appendix
Describe the anatomy of the colon
- Larger diameter, thinner wall than small intestine
- Bears haustra (pouches)
- Possesses taenia coli (longitudinal bands of smooth muscle)
Describe the rectum?
- Expandable for temporary storage of feces
- Terminates in anal canal
- Leads to anus
- Circular muscle forms internal anal sphincter
- Encircled by skeletal muscle
What forms the external anal sphincter?
The rectum
Know the anatomy of the large intestines
Slides 81 & 82
What does the large intestine absorb?
Water Ions Vitamins Organic wastes Bile salts Toxins
What triggers feces to move from the colon to the rectum?
Stretching of stomach and duodenum
What controls the movement of feces towards the anus?
Sphincters
What does the stretching of the rectum do?
Defecation of reflex
Release of feces requires….
Relaxation of external anal sphincter
Brief description of the large intestines
The large intestine stores digestive wastes and reduces their volume by reabsorbing water. Bacteria that live in the large intestine are an important source of vitamins, especially vitamin K, biotin, and vitamin B5
What are the two steps of processing nutrients?
Mechanical
Chemical
Processing to break down physical structure of foods
Mechanical processing
Processing to break the covalent bonds between food subunits
Chemical processing
What catalyzes mechanical processing?
Enzymes
Chemical processing activates….
The hydrolysis of large food molecules
How are starches/carbs broken down?
Amylases
What breaks initial disaccharides & trisaccharides into monosaccharides
Enzymes
Carb absorption is facilitated by
facilitated diffusion or co-transport
Describe what happens during the processing and absorption of fats
- Bile emulsifies fats to small droplets
- Lipase hydrolyzes triglycerides into fatty acids and monoglycerides
- Lipid products form micelles
- Lipids diffuse into epithelial cells
- Triglycerides are reformed
- Secreted as chylomicrons into lacteals
- Transported in lymph to thoracic duct
What are the three things the urinary system eliminates?
Nitrogenous wastes
Toxins
Drugs
How does the urinary system regulate to maintain homeostasis?
- Water balance
- Electrolytes
- Acid-base balance in the blood
- Blood pressure
- Red blood cell production
- Activation of vitamin D
Organs of the urinary system
- Kidneys
- Ureters
- Urinary bladder
- Urethra
Describe the location of the kidneys
- Against the dorsal body wall
- At the level of T12 to L3
- The right kidney is slightly lower than the left
- Attached to ureters, renal blood vessels, and nerves at renal hilus
- Atop each kidney is an adrenal gland
What are the coverings of the kidneys?
Renal capsule
Adipose capsule
Surrounds each kidney
Renal Capsule
Surrounds the kidney
Provides protection
Keeps the kidneys in the correct locations
Adipose Capsule
Outer region of the kidney
Renal Cortex
Inside the cortex of the kidney
Renal Medulla
Inner collecting tube of the kidney
Renal pelvis
Triangular regions of tissue in the medulla of the kidney
Medullary pyramids
Extensions of cortex-like material inward of the kidneys
Renal Columns
Cup-Shaped structures that funnel urine towards the renal pelvis in the kidneys
Calyces
The structural and functional units of the kidneys
Nephrons
What structure of the kidneys are responsible for forming urine?
Nephrons
What are the two main structures of nephrons?
Glomerulus
Renal Tubule
A specialized capillary bed in the kidney which attaches to arterioles on both sides of the kidneys
Glomerulus
What are the arterioles in the kidneys which are attached to the glomerulus
Large Afferent Arteriole
Narrow Efferent Arteriole
What are capillaries in the glomerulus covered with?
Podocytes from the renal tubule
Where does the glomerulus sit?
Within a glomerular capsule
Know anatomy of the renal tubule
Slide 178
Types of nephrons
Cortical
Juxtamedullary
Describe cortical nephrons
- Located entirely in the cortex
- Includes most nephrons
Describe Juxtamedullary nephrons
Found at the boundary of the cortex and medulla
Describe peritubular capillaries
Arise from efferent arteriole of the glomerulus
Normal, low pressure capillaries
Attached to a venule
Cling close to the renal tubule
Reabsorb (reclaim) some substances from collecting tubes
What are the three steps of the urine formation processes?
- Filtration
- Reabsorption
- Secretion
Describe filtration
Nonselective passive process
Water and solutes smaller than proteins are forced through capillary walls
Blood cells cannot pass out to the capillaries
Filtrate is collected in the glomerular capsule and leaves via the renal tubule
Describe Reabsorption
The peritubular capillaries reabsorb several materials
Some reabsorption is passive, most is active
Most reabsorption occurs in the proximal convoluted tubule
What do peritubular capillaries reabsorb?
- Some water
- Glucose
- Amino Acids
- Ions
What materials are not reabsorbed
- Urea
- Uric Acid
- Creatinine
- Excess water
Reabsorption in reverse
secretion
During secretion, some materials move from the peritubular capillaries to
renal tubules
What is secreted?
Hydrogen and potassium ions
Creatinine
Materials left in the renal tubule move…
toward the ureter
What are the characteristics of urine used during medical diagnosis?
Colored somewhat yellow due to the pigment urochrome (from the destruction of hemoglobin) and solutes Sterile Slightly aromatic Normal pH of around 6 Specific gravity of 1.001 to 1.035
Describe ureters
Slender tubes attaching the kidney to the bladder
Runs behind the peritoneum
Peristalsis aids gravity in urine transport
The ureters are continuous with the
renal pelvis
Where do ureters enter the bladder?
Posterior aspect
Describe the urinary bladder wall
Three layers of smooth muscle (detrusor muscle)
Mucosa made of transitional epithelium
Walls are thick and folded in an empty bladder
Bladder can expand significantly without increasing internal pressure
Describe the Urethra
Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis
Release of urine is controlled by two sphincters
What are the two sphincters in the urethra
Internal Urethral sphincter
External Urethral Sphincter
Involuntary urethra sphincter?
Internal
Voluntary urethral sphincter
External
Female urethra length and location
3-4cm (1 in)
Along the wall of the vagina
Male urethra length and location
20 cm (8 in) Through the prostate and penis
Females function of the urethra
Only carries urine
Males function of the urethra
Carries urine and is passageway for sperm cells
Normal amount of water in a young adult female
50%
Normal amount of water in a young adult male
60%
Normal amount of water in babies
75%
Normal amount of water in elderly
45%
Micturition
Voiding
What must happen to allow voiding
both sphincter muscles must relax
Describe voiding
The internal urethral sphincter is relaxed after stretching of the bladder
Activation is from an impulse sent to the spinal cord and then back via the pelvic splanchnic nerves
The external urethral sphincter must be voluntarily relaxed
Where is intracellular fluid
inside cells
Where is extracellular fluid
Outside cells
What are examples of extracellular fluid
interstitial fluid
Blood plasma
Describe the link between water and salt
Changes in electrolyte balance causes water to move from one compartment to another
Describe maintenance of water balance
-water intake must equal water output
Sources for water instake
- ingested foods and fluids
- water produces from metabolic processes
Sources of water output
- Vaporization out of the lungs
- lost in perspiration
- leaves the body in the feces
- urine production
If water intake is excessive…
Dilute urine is produced
If large amounts of water are lost….
Less urine (concentrated) is produced
Proper concentrations of various electrolytes….
must be present in urine
Regulation of water and electrolyte is primarily due to
Antidiuretic hormone (ADH) prevents excessive water loss in urine Aldosterone regulates sodium ion content of extracellular fluid
Cells in the kidneys and hypothalamus are active monitors
water and electrolyte reabsorption
Blood pH must remain between….
7.35-7.45
pH too high
Alkalosis
pH too low
Acidosis
Most ions originate as….
Byproducts of cellular metabolism
Most acid-base balance is maintained by…
the kidneys
Blood buffers and respiration are
acid-base controlling systems
Describe blood buffers
Molecules react to prevent dramatic changes in hydrogen ion (H+) concentrations
Bind to H+ when pH drops
Release H+ when pH rises
Three major chemical blood buffer systems
Bicarbonate buffer system
Phosphate buffer system
Protein Buffer System
Describe renal mechanisms of Acid-base balance
Excrete bicarbonate ions if needed
Conserve or generate new bicarbonate ions if needed
Urine pH varies from 4.5 to 8.0
Functional kidneys are developed by…
month three
Urinary system of a newborn
bladder is small
Urine cannot be concentrated
When does the control of the voluntary urethral sphincter start?
18 mos.
What are the only common issue with the urinary bladder before old age
UTI
Describe aging and the urinary sytem
There is a progressive decline in urinary function
The bladder shrinks with aging
Urinary retention is common in males