Exam 3 Flashcards
1
Q
What are the three major physiological processes of respiration?
A
1) Ventilation: air from outside body to inside body
2) Gas from the air in the lungs to the blood
3) Transport of gas from lung and blood to cells
2
Q
How do gases move with respect to pressure?
A
Gas moves down the pressure gradient: High to low pressure
3
Q
What is bulk flow?
A
Is when a bunch of gasses move down the pressure gradient together. This is how air is moveing during ventilation
4
Q
What is Boyle’s law?
A
Pressure is inversely proportional to volume (when one increases the other decreases)
5
Q
What is Dalton’s Law? What does it allow for?
A
The total pressure of a gas mixture is equal to the sum of the partial pressures of al the gases in the mixture.
Allows us to calculate the partial pressure of a gas if the total pressure is known and the percent of the gas.
6
Q
What is the pressure and composition of air at sea level?
A
760mmHg. Mostly O2 & N + some argon, carbon dioxide, and water.
7
Q
How does temperature and humidity affect the partial pressure of oxygen and carbon dioxide?
A
Increased humidity and temperature decreases the partial pressure of O2.
Increased humidity and temperature also decreases the partial pressure of CO2 but not as drastically as O2.
CO2 is more soluble in water than O2
8
Q
What is Henry’s Law?
A
The amount of dissolved gas in a liquid is proportionate to the partial pressure of the gas in the air around the liquid.
9
Q
What are the ventilation pressures?
A
Patm: atmospheric pressure
Palv: Alveolar pressure
Pip: Intraplural pressrue
10
Q
What is Patm?
A
Atmospheric pressure, it is fixed (typically not changing) at about 760mmHg
11
Q
What is Palv?
A
Alveolar Pressure, the pressure inside the alveoli that is variable.
If it is less than 760 air moves in and we inhale
If it is greater than 760 air moves out and we exhale
12
Q
What causes the pressure change that allows for inspiration?
A
Diaphragm moves down and flattens
External intercostals (in between the ribs) lift the rib cage up and out
Volume of lungs increases decreasing the pressure causing air to go in
13
Q
What causes the pressure change that allows for expiration?
A
Diaphragm moves up and curves
External intercostals relax and ribcage drops.
Volume of lungs decreases, pressure increases, and air goes out
14
Q
What are the other muscles of ventilation?
A
Sternocleidomastoid and scalenes: forceful inspiration
Internal intercostals and abdominal muscles: forceful expiration “squeezing the thoracic cavity”
15
Q
What is Pip?
A
Intrapleural pressure: the pressure of the fluid in the pleural cavity that is always negative pressure
16
Q
What causes the negative pressure of the Pip?
A
The opposite pulling of the chest wall that wants to go out “spring” but is prevented by the muscles and the lungs that want to go in “balloon”
The negative pressure keeps the lungs moving with the chest wall “vacuume”
17
Q
What causes the pressure of the Pip to not be negative?
A
Damage to the serous membrane causing the cavity to no longer be sealed causing pneumothorax: air in the intraplaural space and the lung collapses
18
Q
What are the three factors affecting pulmonary ventilation?
A
Compliance, elastance and resistance.
19
Q
What is compliance in ventilation?
A
Ability of the lung to stretch.
Higher compliance: stretches more easily
Lower compliance: stretches more difficulty
20
Q
What is elastance in ventilation?
A
Ability of the lungs to recoil.
Higher elastance: high recoil- recoil easily
Lower elastance: low reoil- recoil harder
21
Q
What is resistance in ventilation?
A
Flow of air through lung tubes
Higher resistance is due to less space in the lung tubes
22
Q
What is Fibrosis and how does it affect ventilation?
A
Damage to lungs by particulates (physical damage) that causes scar tissue to form (CT, mostly collagen not the epithelial tissue that should be there)
Characterized by lower compliance and higher elasticity (it is hard to keep air in the lungs)
23
Q
What is emphysema and how does it affect ventilation?
A
Alveoli deterioration due to genetics or toxins due to smoke inhalation.
Characterized by higher compliance and lower recoil. *high residule volume
24
Q
What is asthma and how does it affect ventilation?
A
Swelling of lower air ways, increased mucus production, and contraction of smooth muscles. Characterized by higher resistance.
25
How does the partial pressure of oxygen and carbon dioxide change with ventilation of 760 mmHg dry air?
Ventilation: PO2 = 160, PCO2 = 0.25
Alveoli: PO2 = 100, PCO2 = 40
Arterial blood: PO2 = 100, PCO2 = 40
Cells: PO2 <= 40, PCO2 >= 46
Venous Blood: PO2 <= 40, PCO2 >= 46
26
What accounts for the drastic change in partial pressures of oxygen and carbon dioxide in the air and in the alveoli?
The residual volume. There is lots of leftover carbon dioxide in the lungs plus the air in the lungs is very humid the increase in water vapor decreases the partial pressure of oxygen.
27
What is the structure and function of hemoglobin?
Hb has four heme groups each with a iron ion at the center which is the spot for oxygen transport
There are about 250 million Hb molecules per erythrocyte.
28
What are the methods by which oxygen is transported in the blood?
Plasma: ~2%
Hb: ~98%
29
How is oxygen transported in the plasma?
Oxygen dissolves in the water of the plasma. This method is not very efficient or reliable
30
How is oxygen transported by hemoglobin?
Oxygen binds reversibly to Hb forming oxyhemoglobin (HbO2). When the oxygen detaches the Hb is deoxyhemoglobin (HHb or Hb).
31
How do we know the saturation of hemoglobin? What is saturation?
We can measure how much oxygen is bound to the Hb.
Saturation is the percentage of Hbs in RBC that are filled with Oxygen.
32
What determines the saturation of hemoglobin?
The affinity--the ability of Hb and oxygen to stay stuck together (higher more sticky)--of Hb for oxygen.
33
What affects affinity?
The partial pressure of oxygen, the temperature, the pH, and the amount of carbon dioxide.
They change the shape of the Hb.
34
What is the effect of the partial pressure of oxygen on hemoglobin saturation?
Arterial blood: PO2 = 100mmHg Hb sat = ~98%
(lots of Oxygen is saturating the Hb)
Venous blood:
@ rest PO2 = 40mmHg, Hb ~75%
exercise: PO2 = ~20mmHg Hb sat = ~30%
35
How much oxygen is dropped of at the tissues at rest? Why?
Only ~23% oxygen is dropped off at the cells to preserve venous reserve so that when you begin exercising you can give more oxygen to the cells that need it.
36
What is the oxygen saturation curved used for? What shifts occur?
To observe a change in saturation in different situations.
Leftward shift increases affinity increasing the saturation
Rightward shift decreases affinity decreasing the saturation
37
What is the affect of temperature on affinity and saturation?
Higher: decreased affinity - systemic tissues
Lower: Increased affinity - pulmonary tissues
38
What is the affect of pH on affinity and saturation?
Lower: (more H+) decreased affinity - systemic tissue
Higher: (less H+) increased affinity - Pulmonary tissues
39
What are the factors affecting affinity and saturation in systemic tissues?
These tissues are metabolically active so the temperature is increased, the pH is lower (more H+), and there is more carbon dioxide.
40
What is the affect of carbon dioxide on affinity and saturation?
High partial pressure carbon dioxide decreases the affinity -systemic tissue
Low partial pressure carbon dioxide increases the affinity - pulmonary tissue
Carbaminohemoglobin
41
What are the methods by which carbon dioxide is transported in the blood?
Plasma: ~7% (CO2 is more soluble in H2O than O2)
Hb: ~23% (carbaminohemoglobin)
HCO3: ~70% (bicarbonate)
42
How is bicarbonate made?
CO2 is converted to HCO3 in erythrocytes and then transported in the plasma.
The HCO3 reaction is catalyzed by carbonic anhydrase
CO2 + H2O + carbonic anhydrase =(rev) H2CO3 (carbonic acid) what reversibly converts to HCO3- and H+
43
What is the significance of the bicarbonate reaction process being reversible?
In the systemic capillaries the reaction shifts towards the carbonic acid because there is lots of Carbon Dioxide
In the pulmonary capillaries the reaction shifts towards the carbon dioxide because there is lots of carbonic acid
44
What does it mean that bicarbonate acts as a buffer?
In the blood the bicarbonate helps to regulate pH
45
What is the process to get carbon dioxide from the Krebs cycle to the air?
1) CO2 diffuses out of cells into systemic capillaries
2) Only 7% of the CO2 remains dissolved in plasma
3) Nearly a fourth of the CO2 binds to hemoglobin, forming carbaminohemoglobin
4) 70% of the CO2 load is converted to bicarbonate and H+ Hemoglobin buffers H+
5) HCO3- enters the plasma in exchange for Cl- (the chloride shift)
6) At the lungs, dissolved CO2 diffuses out of the plasma
7) By the law of mass action, CO2 unbinds from hemoglobin and diffuses out of the RBC
8) The carbonic acid reaction reverses, pulling HCO3- back into the RBC and converting it back to CO2.
46
What is the function of the urinary system?
Maintain chemical consistency (composition) of blood: Conserve nutrients (so they X go to urine), maintain appropriate ion and pH levels
Filter fluid from the blood: maintains blood volume (EPO), and pressure (Renin)
Hormone secretion
Excrete toxins, metabolic wastes (urea & ammonia), and excess water (too much RBC swell & rupture) ions and vitamins (not all vitamins as some must be metabolically altered b4 excretion via urine)
47
What are the organs of the urinary system?
Kidney (main functional structure, urine production)
Ureter (long muscular tubes)
Urinary bladder (storage pouch)
Urethra (one tube)
48
Where are the kidneys located and what is their appearance?
Partially protected by the floating ribs (11&12) located between T11 & L3 vertebrae. Right kidney is lower than the left due to the liver.
Size: ~bar of soap
Shape: Kidney bean
49
What are the gross anatomy structures of the kidneys?
Hilum, renal sinus, renal capsule, renal cortex, renal columns, renal medulla, renal pyramid, renal papilla, calyx, renal pelvis
50
What is the hilum?
It is a region. The indented area on the medial side where the ureter attaches.
51
What is the renal sinus?
It is a region. The open space lateral to the hilum that contains blood vessels, adipose tissue, and the urine collecting structure before the ureter (Calyx)
52
What is the renal capsule and what is its function?
Outer protective layer composed largely of collagen.
Function: protection, shape, and structure
53
What is the renal cortex and what does it contain?
Tissue closer to the surface "cortex" containing renal columns that poke into the medulla but are cortex tissue
54
What is the renal medulla and what does it contain?
Tissue closer to the inside "medulla"
Renal pyramid: triangular segments of medullary tissues
Renal papilla: the tip of the pyramid containing the filtering structures (collecting duct) to drain urine into the calyx
55
What is the calyx and what does it do?
Plural: calyces, Tubular structures, one attached to each papilla
Function: collect urine from pyramids and drain it into the renal pelvis
56
What is the renal pelvis and what does it do?
Structure that drains urine from the calyces into the ureter
57
What is the nephron, what are the two types, and what are the differences between them?
The filtering subunit of the kidneys
1) cortical nephron: 85%, most in cortex, short nephron loop
2) juxtamedullary nephron: 15%, capsule, PCT, DCT barely in capsule, long nephron loop *to conserve lots of water & concentrate urine
58
What are the **structures** of the nephron?
Glomerular capsule (cup shaped) containing filtrate (fluid from removing things from blood), proximal convoluted (twisty) tubule, nephron loop: descending limb (more narrow), & ascending limb, distal convoluted tubule, collecting duct (collecting filtrate from more than one nephron) --> calyx
59
What are the **blood vessels** of the nephron?
Afferent arteriole (arrive), glomerulus (ball of capillaries), efferent arteriole (exit), Peritubular capillaries (wrap around PCT, DCT, & CD), Vasa recta (around nephron lood function differently than peritubular capillaries)
60
What is the renal corpuscle?
The region including the glomerulus and glomerular capsule
61
What are the cells of the glomerular capsul?
1) simple squamous epithelium: surround glomerulus
2) Podocytes: "feet" wrapping around capillaries with extensions for filtering that restrict the size of the filtered material
62
What are the cells of the glomerulus?
simple squamous epithelium, fenestrated capillaries "windows inbetween"
63
What are the filtration structures of the renal corpuscle?
Fenestrated endothelium of capillary
Filtration slits between the feet of the podocytes
Basement membrane
64
What do the filtration structures of the nephron prevent and allow?
Prevents: large proteins & formed elements
Allows: water, ions, small organic molecules (glucose, fatty acid, amino acids, vitamins, urea)
65
What is the kidneys form of filtration?
Take everything out (within reason) then put back only what you want to keep
66
What are the three processes of a nephron, what is the movement, and what are the structures? What do they allow the nephron to do?
1) Filtration blood to filtrate, glomerulus to glomerular capsule
2) Reabsorption: filtrate to blood, PCT and nephron loop to Peritubular capillaries and vasa recta
3) Secretion: blood to filtrate: peritubular capillaries to DCT
These processes allow materials to be exchanged between the filtrate and the blood
67
What are the Starling forces and where do they work?
Work in the glomerular filtration
1) Hydrostatic Pressure PH
2) Bowman's capsule hydrostatic pressure Pfluid
3) Colloid Osmotic Pressure (Pi)
68
What is the hydrostatic pressure?
PH- Favors filtration
-in arterioles
-really high 55 mmHg because there is only one way out of glomerulus: efferent a. (bottle neck)
-pushing pressure: pushes fluid and materials out of the glomerulus
69
What is the Bowmans Capsule Pressure?
Pfluid: oppose filtration
-Relatively high, 15mmHg
-bottle neck for filtrate, only leave through PCT leading to pressure build up
-push back to glomerulus
70
What is the Colloid Osmotic pressure?
Pi -oppose filtration
-relatively high 30mmHg
- no filtrate increases the concentration of the plasma, the fluid in the filtrate wants to go back to the glomerulus
-sucking pressure
71
What is the net filtration pressure?
If it is positive we get filtrate
NFP = PH - Pfluid - Pi
-typically positive because many things keep Ph high
72
What keeps the net filtration pressure positive?
Pressure around the glomerulus does not typically change
Intrinsic control (within and around kidney): myogenic response, tuboglomerular feedback
73
What is GFR?
Glomerular Filtration Rate, speed at which filtrate is made
74
What is the myogenic response?
Muscle is the whole thing: sensor, integration center, target
High/Low MAP: increased/decrease stretch of smooth muscle of afferent a., smooth muscle contracts/relax (dilate) increasing/decreasing blood flow resistance decreasing/increasing PH
75
What is the tuboglomerular feedback?
macula densa cells in ascending limb detects change in GFR faster/slower, secrete paracrine (act on self) to afferent a., constricts/relax, increase/decrease resistance, decrease/increase blood flow, PH decreases/increases, filtrate made slower/faster, GFR normalizes
76
What are the characteristics of the cells of the PCT?
Simple cuboidal epithelium, with large microvilli (increased surface area for absorption), lots of mitochondria (high energy demand)
Leaky tight junctions: held together but there are gaps for materials to sneak between
77
What is the tubular reabsorption of the PCT?
The PCT is the main location of reabsorption.
Major things: nutrients (nearly 100% reabsorbed). Some ions, water, & urea (cannot get rid of all urea because would take water two
78
How are ions reabsorbed?
through PCT cells, Na+ is moved via active transport then anions (-) follow between and through cells
79
How is water reabsorbed?
Through and between cells, moved by osmosis (following the ions)
80
How are other solutes (ions and urea) reabsorbed?
Through in the cells, active transport via membrane transport and sometimes passively via diffusion.
81
How is glucose moved by the nephrons?
Glucose is all filtrated and all reabsorbed via cotransport with Na+
1) Na+ moves from the filtrate to the cell down concentration gradient and glucose piggy backs moving up concentration gradient
2) Glucose moves down concentration gradient from the cell to the blood (no energy)
3) Na+ must be kept low in cell (energy needed)
Na+ K ATPase using ATP move both Na+ and K+ against concentration gradient (Na out and K in), then K leak out
82
How does saturation occur?
Transport rate from filtrate to blood increases until plateau: max transport rate
83
What is the transport maximum of saturation?
Carrier proteins fill up = saturation
84
What is the renal threshold?
Concentration of glomerulus plasma at which saturation occurs
85
What is the glucose saturation?
Filtration is unlimited, reabsorption is limited by number of carrier proteins with a max at 375 mg/min. Over saturation leaves glucose in the filtrate which goes to the urine which causes water to follow.
86
What are the cells of the nephron loop?
Descending limb: cells are thin, simple squamous cells to absorb water and prevent dehydration
Ascending limb: cells are thick, simple cuboidal impermeable to water. Actively transports (ion ATPase pumps) Na+, K+, Cl-, out of filtrate. Keeps filtrate from becoming too concentrated.
87
What is osmosis?
The diffusion of water
88
What is osmolarity? What do the extremes of osmolarity mean?
Concentration of solute per Liter of water
High OsM = high solute concentration, low water concentration
Low OsM = low solute concentration, high water concentration.
*Water diffuses toward high levels of Osmolarity*
89
What are the osmolarities of the filtrate and the medulla as the filtrate descends toward the papilla and what does this accomplish?
As the filtrate exits the PCT and enters the descending limb it is 300mOsM and so is the medulla.
The medulla gets more concentrated the closer to the papilla it goes (500, 800, 1200 mOsM)
As the filtrate descends the water in it follows the High OsM in the medulla and the filtrate's mOsM decreases (500 800, 1200)
Filtrate becomes isosmotic to the medulla and becomes more concentrated
90
What happens to the filtrate in the ascending limb?
Ions are actively moved out of the filtrate into the medulla mostly K+ and Na+, filtrate becomes less concentrated (1200, 900, 500, 300) until it leaves as 100mOsM
91
What keeps the osmolarity of the medullary interstitial fluid constant?
The counter current multiplier
92
What is the counter current mutiplier?
The vasa recta flows opposite to the filtrate. First with its capillaries permeable to ions it picks up the ions removed from the filtrate increasing its OsM. Then it picks up water from the interstitial space becoming 300mOsM again.
93
What are the cells of the distal convoluted tubule?
simple cuboidal epithelium, microvilli that are much smaller than the PCT meaning that they are less specialized for and less involved in absorption. Numerous mitochondria for active transport
94
What is the tubular secretion of the DCT? What about absorption?
Blood to filtrate. active secretion of K+ and H+, nitrogenous wastes, dicarboxylates (alphaKG, metabolic wastes) excess vitamins (water soluble), ions and drugs (hence drug test)
Some reabsorption of Na+ and H2O by microvilli
95
What are the collecting ducts, what are their cells, and what do they do?
Big tube collecting filtrate from many nephrons
Cells: simple cuboidal transitioning into simple columnar epithelium
Function: Secrete or reabsorb ions and water as directed by hormone signals
96
What are organic anions and what is the method by which organic anions are secreted?
From the metabolic breakdown of drugs and other substances in the body
1) OA in blood, direct primary active transport by Na/K/ATPase keep intracellular levels of Na low, (pump Na+ out and K+ in)
2) Secondary active transport pulls Na+ inside (H-->L) and alphaKG piggy backs inside (L-->H)
3) Tertiary active transport alphaKG moves outside (H-->L) OA- piggys inside (L--> H)
4) We don't know how but anions exit to lumen by facilitated diffusion (H-->L)
97
What is the composition of urine?
95%: Water
5%: Dissolved metabolic anions (urea, alphaKG, urochrome {by product of Hb breakdown} OA-), ions (K+, Ca+2, H+, Na+) drugs, vitamins, certain hormones (pregnancy)
98
What are the ureters?
Long muscular tubes bringing urine from renal pelvis to urinary bladder where they enter through the posterior wall at the base of the bladder.
When pressure of the bladder increases the distal ends of the ureters close preventing the backflow of urine
99
What is the urinary bladder?
Muscular sac for temporary storage of the urine before release
100
What is the trigon region of the urinary bladder?
Smooth triangular area outlines by opening for ureters and urethra where bladder infections tend to occur
101
What happens when the bladder empties and fills?
Empty: collapse and rugae appear
Fill: expands and rises superiorly, rugae disappear
102
What is the structure of the female urethra?
It is not part of the reproductive system so it is short
base of bladder to external urethral orifice (opening to external environment)
Short= more prone to UTI
103
What is the structure of the male urethra?
Long because part of reproductive system less prone to UTI
1)Prostatic urethra: base of bladder and within prostate
2) Membranous/intermediate urethra: distal prostate through urogenital diaphragm to beginning of penis
3) Spongy urethra: through penis opening via external urethral orifice
104
What are the two urinary sphincters and where are they located M&F?
Internal urethral sphincter: ring of smooth muscle surrounding urethra forming a border between the urinary bladder and urethra F/M
External urethral sphincter in pelvic floor, male: after prostate, female: at the end of the urethra
skeletal muscle
105
What is micturition and the micturition reflex?
Urination.
Bladder full: reflex from bladder stretch receptors send signal to spinal cord (integration center) involuntarily relaxes internal urinary sphincter
Signal then goes to pons then cerebrum: aware bladder full and use cerebrum to go to the bathroom voluntarily relaxing external urinary sphincter. External will automatically relax if the bladder is too full.
106
What are the functions of the digestive system?
Ingestion: nutrients via food into the body
Motility: moving material through digestive tube
Secretion: of materials from organs to digestive system (what the material is depends on what specialized area of the digestive tract it is being secreted into)
Digestion: breaking down to smaller
Absorption: Digestive tract to blood stream
Elimination: left over from absorption (feces)
107
What are the types of digestion?
mechanical: physical breakdown of food to smaller pieces.
chemical: molecules from food broken down to smaller molecular fragments (necessary for absorption to occur)
108
What are the strucutes of the oral cavity?
Oral mucus: non-keratinized stratified squamous mucus membrane lining cavity
Hard palate: composed of bone separating the oral & nasal cavities
Soft palate: not bone, separate oral cavity & nasopharynx
Uvula: Hang off soft palate, keep food from going up
Tongue: Manipulate food, push to pharynx, & release enzymes 4 digestion
Teeth: adapted for different actions
Salivary glands
109
What are the different teeth and what are they specialized for?
Incisors: anterior, (4), cut & slice food
Canines: (2) pierce food
Premolars: (2) & pairs
Molars: (3) & pairs
- grinding (masticating) food to bolus (blob of chewed food)
110
What are the different salivary glands and where are they found?
Parotid: cheek,
Sublingual: under tongue, floor of mouth
Submandibular: medial surface of mandible.
111
What is the function of the pharynx and what are the notible structures?
(Oropharynx & laryngopharynx)
Passageway from oral cavity to esophagus.
Bolus moved toward oro by tongue & uvula keeps it moving down. Epiglottis keeps bolus moving toward laryngopharynx
112
What is the pathway of the esophagus and what is notable about it?
Mediastinum to diaphragm to stomach.
Superior esophageal sphincter: wrap around and contract to close, skeletal muscle
Inferior esophageal sphincter: meet stomach, smooth muscle
- keep stomach contents from getting out easily
Expandible
Surrounded by muscle: food goes to stomach via rhythmic contractions of smooth muscle
113
What are the two smooth muscle contractions?
Peristalsis: move bolus in one direction, contract 1 spot, move, contract, move
Segmentation: Contract ++ sports at same time X move food mixes. Mix to allow all food to come in contact with intestine mucosa
114
What are the structures of the stomach? What happens to the bolus?
The bolus becomes chyme
Rugae: folds
Gastroesophageal junction
Fundus: superior to GE jct
Cardia: w/i 3cm of GE jct, (not stick up like fundus)
Body: largest region b/w fundus & pylorus
Pylorus: leads to exit to the duodenum
-pyloric sphincter that regulates the passage to the duodenum so as not to dump out acids
115
What are the regions of the small intestine and what makes them different?
Duodenum: 10 in, receive food from stomach "chyme" and enzymes from pancreas, bile from gall bladder
Jejunum: 8 ft, & illium 12 ft: actively involved in chemical digestion with pancreatic enzymes, bile, and enzymes from the intestine. Also where absorption occurs.
116
What increases the surface area of the small intestine?
The length and twistiness of the small intestine, the plica- circular ridge-like folds, villi- finger-like folds off plica, microvilli: simple cuboidal
117
What are the accessory organs of the small intestine?
Liver, gallbladder, and pancreas
118
Where is the liver located, what is its special vein and what is the use for this vein?
Right hypochondriac region & epigastric region, with hepatic portal vein that takes blood from nutrient-rich mesentery and stomach capillaries for protection-liver cells are good at detoxing poisons- and to modify nutrients before they are given to the vena cava (ie glucose to glycogen)
119
What does the liver produce and what is it used for?
Produces bile from hemoglobin breakdown and stores it in the gallbladder. It will be released via the hepatopancreatic.
Function: digest fats via emulsifying them- breaking them down into smaller bits to increase surface area.
120
What does the pancreas make for digestion and how is it released?
Produce pancreatic juice in acini
Acini: clusters of secretory cells that produce enzymes0 protease, nuclease, amylase, lipase, (that do not function in a pH of 1)
Ducts produce water and bicarbonate (that buffers turning pH to 8)
Both released to duodenum by the relaxation of the hepatopancreatic sphincter.
121
How is the hepatopancreatic sphincter normally and how is it controlled?
Normal: closed and contracted
Hormonal control (primary)
Cholecystokinin (CCK)
Secretin
Other chemical control: large amounts of bile salts recovered from ilium to liver stimulates gallbladder release bile
Neural control: vagus nerve stimulates contraction of gallbladder to release bile
122
Why are cholecystokinin and secretin released and what do they do?
CCK: released by intestinal cells exposed to fats and proteins in chyme. Stim GB release bile, stim relaxation of hepatopancreatic sphincter, pancreatic juices & bile enter duodenum
Secretin: released by intestinal cells exposed to gastric acid, stimulate gallbladder release bile
123
What are the structures and sections of the large intestine?
Haustra: poches store digested materials & allow for expansion
Taenia coli: Smooth muscle contract to propel food through large intestine
Cecum: Square-shaped dead end where ilium contact large intestine. Location of appendix: small, tail-like extends off of cecum for helpful bacterial reserve
Ascending colon - transverse c. - descending c. - sigmoid flexure/c. - rectum (store food until excreted)
124
What are the structures of the anus?
Anus: internal sphincter (smooth muscle), external sphincter (skeletal muscle)
