Exam 4 Flashcards
Internal respiration
• Refers to metabolic processes carried out within the mitochondria, which use O2 and produce CO2, while deriving energy from nutrient molecules
External respiration
• Refers to a sequence of events involved in the exchange of O2 and CO2 between the external environment and the cells of the body.
conducting zone
thick walled, move air from larynx to lungs, humidifies and warms air
respiratory zone
site of gas exchange, thin walled
air flow =
(atmospheric pressure - alveolar pressure)/resistance (mechanical)
partial pressure of a gas =
total gas pressure x fractional composition of the one gas in the mixture
If atmospheric pressure is 760 mmHg and N2 makes up 79% of the atmosphere and oxygen makes up 21%, then what are their partial atmospheric pressures?
600 mmHg and 160 mmHg
partial pressure of oxygen in systemic capillaries:
Partial pressure of oxygen in tissue cells:
100
40
so oxygen flows to tissues
partial pressure of CO2 in the systemic capillaries:
tissues:
40
46
Percentages
O2 dissolved in blood:
O2 bound to hemoglobin:
- 5%
98. 5%
Percentages:
CO2 dissolved in blood:
CO2 bound to hemoglobin:
CO2 as bicarbonate (HCO3-)
10
30
60
Hb + O2 =
oxyhemoglobin (HbO2)
CO2 + H20 =
what enzyme facilitates this reaction?
where does it take place?
carbonic acid
carbonic anhydrase
in the erythrocyte
after its formation, carbonic acid then dissociates into:
bicarbonate ions and hydrogen ions
• Hypoxia –
Condition of having insufficient O2 at the cell level
• Hyperoxia –
Condition of having an above-normal arterial PO2
• Hypercapnia –
Condition of having excess CO2 in arterial blood
• Hypocapnia –
Below normal arterial PCO2 levels
hyperoxia can only occur when:
breathing supplemental oxygen. cant happen from hyperventilation of atmospheric air
Hypercapnia is caused by
hypoventilation
hypocapnia is caused by
hyperventilation
main function of the kidneys:
fine tune blood
what are the main artery and vein of the kidneys?
renal artery and renal vein
where is the renal pelvis located?
at the medial inner core of each kidney
what are the ureters lined with/
smooth muscle
difference in urethra in males and females:
female: short and straight
male: long and curved
vascular pathway in the nephron:
starting with renal artery–>
afferent arteriole–>glomerulus–>efferent arteriole–>peritubular capillaries–>venules–>renal vein
the 3 basic renal processes:
glomerular filtration, tubular reabsorption, tubular secretion
tubular reabsorption-
o Things leaving the tubule and entering the blood
tubular secretion-
o Things leaving the capillaries and entering the tubules
what percentage of plasma that enters the glomerulus is filtered?
20%
fluid passes thru what 3 layers from the glomerulus to the bowmans capsule
capillary wall, basement membrane, inner layer of bowmans capsule
how is the glomerular capillary wall different from capillaries elsewhere?
it is more permeable to water and solutes
what is the basement membrane composed of?
collagen and glycoproteins
what kind of cells compose the inner layer of the bowmans capsule?
endothelial cells
what do tubular solutes get reabsorbed into?
the peritubular capillaries
how many barriers must reabsorbed substances cross? list them
five; luminal membrane of tubular cell, cytosol within the tubular cell, basolateral membrane of tubular cell, interstitial fluid, capillary wall
passive reabsorption occurs down what gradients?
electrochemical or osmotic
active reabsorption occurs against what gradient?
electrochemical
what percentage of energy used by kidneys is for Na+ transport?
80%
where is the Na+K+ ATPase pump located?
basolateral membrane
where is Na+ reabsorbed?
where is it not reabsorbed?
- proximal tubule and ascending limb of loop
- descending limb of loop of henle
Glucose and amino acids are reabsorbed by __________ transport
sodium-dependent, secondary active
At the beginning of the proximal tubule, _____ is actively pumped out, and water follows by osmosis. this concentrates the urine so that what has a concentration gradient and passively reabsorbs at the end of the proximal tubule?
- sodium
- urea
what are the 3 most important substances secreted into the tubules?
H+, K+, organic ions
where is H+ secreted?
proximal, distal and collecting tubules
where is K+ secreted?
distal and collecting tubules
where are organic ions secreted?
proximal tubule
tubular reabsorption in the proximal tubule serves to reclaim what substances?
sodium, water, and nutrients
Secretion, which occurs in ___________, actively moves what back into the filtrate?
- proximal and distal tubule
- H+, K+, some drugs, and organic ions
where does water passively leave the tubule?
the descending limb
• If the Na+/K+ ATPase stopped functioning, what would be the most immediate complication?
Dehydration.
what is the purpose of the loop of hence?
to concentrate your urine
the descending limb is highly permeable to what, but not to what?
water
NaCl
what is the concentration of filtrate at the bottom of the loop?
1200 mOsm
what leaves the tubule in the ascending limb? how?
NaCl, first by passive diffusion, then by active transport
Vasopressin-controlled, variable water re-absorption occurs in ____________
the distal tubule and the collecting duct
____ percent of water re-absorption is obligatory in the proximal tubule and the descending limb of the Loop of Henle. In the distal tubule and collecting duct it is variable, based on the secretion of ADH (anti-diuretic hormone/vasopressin).
65%
ADH inserts _____ in the distal tubule and collecting duct to increase water reabsorption.
aquaporins
Vasopressin is produced in the _______ and stored in the __________.
- hypothalamus
- posterior pituitary
________ is a vasopressin inhibitor
Alcohol
For every 250mLs of alcohol consumed, your body eliminates about ____ mLs of water in your urine.
1,000
urine stored in the body is eliminated by:
micturition
urine in the bladder stimulates:
stretch receptors
what is the micturition reflex?
relaxation of external urethral sphincter muscles
• The digestive system performs four functions:
o Motility
o Secretion
o Digestion
o Absorption
mixing motions serve two functions:
o Mixing food with digestive juices promotes digestion of foods
o Facilitates absorption by exposing all parts of intestinal contents to absorbing surfaces of digestive tract
2 types of motility of the digestive system:
propulsive and mixing movements
digestive secretions consist of:
water, electrolytes, and specific organic constituents
• The stomach also secretes a lot of acid
list the accessory digestive organs:
salivary glands, pancreas, liver (gall bladder)
list the 4 major tissue layers of the wall of the digestive tract:
mucosa, submucosa, muscularis externa, and serosa
describe the submucosa. what does it provide for the digestive tract?
thick layer of connective tissue
provides digestive tract with elasticity
what is the muscularis externa composed of?
smooth muscle
Muscularis externa consists of what 2 layers?
circular layer and longitudinal layer
what is the outermost layer of the digestive tract? what is its function?
Serosa.
secretes serous fluid to lubricate and prevent friction between digestive organs and surrounding viscera. It also supports digestive organs in proper place while allowing them freedom for mixing and propulsive movements
Saliva composition:
99.5% water
.5% electrolytes and protein
saliva is produced largely by:
3 major pairs of salivary glands
salivary amylase is rich in _______ buffers
bicarbonate
saliva has antibacterial action because:
lysozyme destroys bacteria and it rinses away food that bacteria could eat
what is the most complex reflex in your body?
swallowing
________ keeps entrance closed to prevent large volumes of air from entering esophagus and stomach during breathing
Pharyngoesophageal sphincter
prevents acid reflux
gastroesophageal sphincter
_________ push food through esophagus
peristaltic waves
the three sections of the stomach:
fundus, body, antrum
what are the 3 main functions of the stomach:
o Stores ingested food until it can be emptied into small intestine
o Secretes hydrochloric acid (HCl) and enzymes that begin protein digestion
o Mixing movements convert pulverized food to chime
_______ serves as barrier between stomach and upper part of small intestine
pyloric sphincter
the 4 aspects of gastric motility
filling, storage, mixing, emptying
Stomach filling involves ___________, which is triggered by the act of _______ and mediated by _______
- receptive relaxation
- eating
- vagus nerve
storage takes place in _______ of stomach
body
mixing takes place in ______ of stomach
antrum
emptying of the stomach is largely controlled by factors in the ________, as well as relaxation of ____________
- duodenum
- pyloric sphincter
during gastric emptying the major factor that influences strength of contraction is:
amount of chyme in the stomach
what prevents fatty chyme from being emptied into the duodenum?
fat is already present in the duodenum
what prevents emptying of acidic gastric contents into the duodenum?
un-neutralized acid still in the duodenum
what kind of osmotic environment in the duodenum prevents gastric emptying?
hypertonic environment
Distention-
• Too much chime in duodenum inhibits emptying of more gastric contents
4 gastric secretions:
alkaline mucus, pepsinogen, HCl, Intrinsic factor
protects stomach lining from other secretions
alkaline mucus
begins protein digestion when activated
Pepsinogen
activates pepsinogen, breaks down connective tissue in food, kills microorganisms
HCl
facilitates re-absorption of Vitamin B12
Intrinsic factor
the 3 gastric hormones:
secretin, gastrin, cholecystokinin (CCK)
stimulated by acidic chime in the duodenum. Release stimulates the pancreas to release bicarbonate buffer.
secretin
stimulated by the presence of protein in the duodenum. Release stimulates chief and parietal cells to secrete more HCl.
gastrin
stimulated by presence of fat and protein in the duodenum. Release stimulates pancrease to release lipase, as well as proteolytic enzymes.
cholecystokinin
the 3 phases of gastric secretion
cephalic, gastric, and intestinal phase
o Refers to increased secretion of HCl and pepsinogen that occurs in response to stimuli acting in the head before food reaches stomach
cephalic phase
o Begins when food actually reaches the stomach
gastric phase
the presence of what increases gastric secretions?
protein
o Inhibitory phase
o Helps shut off flow of gastric juices as chime begins to empty into small intestine
Intestinal phase
The pancreas is a mixture of what tissues?
exocrine and endocrine
where is the pancreas?
behind and below the stomach
what cells secrete insulin and glucagon?
Islets of Langerhans
Pancreatic juice consists of:
- Pancreatic enzymes
* Aqueous sodium bicarbonate solution that is secreted by duct cells.
what is sodium bicarbonate from the pancreas needed for?
Needed to neutralize the pH of chime before it enters the small intestine
Name the pancreatic enzymes:
Proteolytic enzymes (Trypsin, Chymotrypsin, Carboxypeptidase)
pancreatic amylase
pancreatic lipase
Pancreatic lipase is the only enzyme in the digestive system that can:
completely digest fat.
what does the liver secrete?
bile and bile salts
where does bile go during a meal?
what about between meals?
- Duodenum
- gall bladder
bile salts are derivatives of what?
what do they do?
- cholesterol
- convert large fat globules into a liquid emulsion
where does most digestion take place?
small intestine
what is the primary method of motility in the small intestine?
segmentation
segmentation increases the rate of:
chemical reactions between chyme and digestive juices
what increases the surface area of the small intestine?
permanent circular folds in the inner surface, and villi
how often is the lining of the SI replaced?
about every 3 days
primary purpose of LI
drying and storage
The large intestine consists of:
colon, cecum, appendix, rectum
what is the appendix attached to?
the cecum
what vitamins are synthesized by bacteria in LI? they are feeding on unabsorbed nutrients btw
B12, thiamin, riboflavin, and vitamin K
we would be deficient in what if it wasnt for bacteria
vitamin K
the large intestine absorbs what 3 things?
vitamins, leftover water, salts
the defecation reflex is initiated when what happens?
stretch receptors in the rectal wall are stimulated by distension
the defacation reflex causes what to relax and what to contract?
- internal anal sphincter relaxes
- sigmoid colon contracts more vigorously
what must finally relax for defecation to occur?
the external anal sphincter
