Chapter 9 Flashcards
Where do single-cell eukaryotes that require oxygen to perform oxidative phosphorylation acquire it
Simple diffusion of oxygen from the surrounding medium
Ventilation
Simple movement of air in and out of the lung properly
Respiration
exchange of gases (between lungs and blood or other tissues of the body)
Conduction Zone
Parts of the respiratory system involved only in ventilation
Respiratory Zone
parts of the respiratory system involved in actual gas exchange
The respiratory system other tasks
pH regulation, thermoregulation, protection from diseases and particulate matter (mucociliary escalator, alveolar macrophages)
Pathway followed by inhaled air
nose -> nasal cavity -> pharynx -> larynx -> trachea -> primary bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar duct -> alveoli
Nose
warming, humidifying and filtering inhaled air. Nasal hairs and sticky mucus act as filters
Nasal cavity
open space within the nose
Pharynx
throat (common pathway for air and food)
Larynx
made entirely out of cartilage to keep airway open, contains epiglottis which seals the trachea during swallowing, contains vocal chords
Trachea
passageway which remains open to permit airflow. Rings of cartilage prevent its collapse
Primary bronchi
Two; each one supplies one lung, collapse is prevented by small plates of cartilage
Bronchioles
1mm wide, contain no cartilage, made out of smooth muscle which allows their diameters to be regulated to adjust airflow
Terminal Bronchioles
final and smallest branches of the conduction system. Smooth muscle walls are too thick to allow for gas exchange
Alveoli
Structures across which gas diffuses. Very thin, one cell thick
What type of cell lines the entire respiratory tract
Epithelial columnar cells; too thick to assist in gas exchange and serve as a conduit for air, but some are specialized to secret mucus (goblet cells)
Mucociliary Escalator
columnar epithelial cells of the upper respiratory tract have cilia which constantly sweep mucus towards the pharynx where they can be swallowed or coughed out
What structures are involved in gas exchange
Alveoli, alveolar ducts and the smallest bonchioles
What type of cells line gas exchange surfaces
single layer of thin delicate squamous epithelial cells
What method of protection do thin squamous epithelial cells use
Alveolar macrophages patrol the alveoli, engulfing foreign particles
Surfactant
Coats the alveoli, reduces surface tension to prevent collapse of the alveolar wall (fat cubodial epithelial cells secret surfactant)
Pulmonary Ventilation
Circulation of air into and out of the lungs to continuously replace the gasses in the alveoli with those in the atmosphere
Inspiration
active process driven by the contraction of the diaphragm
Expiration
Passive; driven by the elastic recoil of the lungs and does not require active muscle contraction
Two membranes that surround the lungs
parietal pleura and visceral pleura
Parietal Pleura
Lines the inside of the chest cavity
Visceral Pleura
Lines the surface of the lungs
Space found between the two pleura’s
Pleura membrane; negative pressured space (the two membranes are drawn together by a vacuum).
Also, a thin layer of fluid helps hold them together through surface tension
What muscles contract during inspiration?
diaphragm flattens and pulls the chest cavity downward, forcing it and the lungs to expand.
Intercostal muscles between the ribs, pulling the ribs upward and further expanding the chest cavity
Forced expiration
contraction of the abdominal muscles helps the expiration process by pressing upward on the diaphragm, shrinking the size of the lungs and forcing more air out (actively although expiration overall is passive)
Tidal volume
amount of air that moves in and out of the lungs with normal light breathing. Equal to about 10% of the total volume of the lungs
Residual Volume
amount of air that remains in the lungs after the strongest possible expiration
Vital Capacity
maximum amount of air that can be forced out of the lungs after first taking the deepest possible breath
Total Lung Capacity
vital capacity plus the residual volume
What are the principle stimuli that affect ventilation rates
Increased PCO2, decreased pH and decreased PO2
Peripheral chemoreceptors
Located in the aorta and the carotid arteries and monitor the PCO2, pH and PO2 of the blood
Central Chemoreceptors
Found in the medullary respiratory control center and monitor PCO2 and pH of the CSF
How do changes in ventilation rates affect the pH
An increase in PCO2 causes rapid effects on pH, resulting in a shift to mainting the equilibrium
What mechanical stimuli that affect ventilation rate
Physical stretching of the lungs and irritants
Bronchoconstriction
Contraction of smooth muscles sound in the walls of the bronchi and larger bronchioles
What happens when irritants enter the inner lining of the lung
Irritation stimulates irritant receptors and reflexive contraction of bronchial smooth muscles to prevent irritants from continuing to enter the passageways
Catabolic reactions
Reactions that break down molecules to supply energy
Anabolic reactions
Synthesis of macromolecules
GI lumen
Lines the inside of the gut and is continuous with the space outside the body
A compartment where the usable components of foodstuffs are extracted, while wastes are left to be excreted as feces
What kind of muscles are striated
Skeletal (voluntary) muscle and cardiac (heart) muscle
GI molitlity
Exhibits automaticity, its a functional syncytium, contains an enteric nervous system , hormonal input affects mobility, parasympathetic (relax) and sympathetic (contract) nervous system
GI motility serves two purposes
(1) mixing of food by disordered contractions of GI smooth muscles that result in a churning motion
(2) movement of food down the GItract by an orderly form of contractions called peristalsis
Types of GI secretions
Endocrine and exocrine
Exocrine
Excrete their products into ducts that drain into the GI lumen
(Liver, gallbladder and pancreas)
Endocrine
Ductles glands,secretion (hormones) are picked up by capillaries in the blood stream
Salivary amylase
Ptyalin, hydrolyzes starch and breaks it into fragments
What is found in saliva to assist in digestion
Lingual lipase (fat digestion) and lysozyme (attacks cell walls)
No digestion occurs in the mouth however
Esophagus
Muscular tube behind the trachea which conveys food and drink from the pharynx to the stomach
The stomachs three purposes
Partial digestion of food, regulated release of food into the small intestine and destruction of micro organisms
Gastric pH
2; leads to the destruction of micro organisms, acid-catalyze hydrolysis of many dietary proteins and conversion of pepsinogen to pepsin
Pepsin
Secreted in the inactive form (pepsinogen) and activated through autocleavage due to gastric pH
Sphincter
Lower esophageal sphincter prevents reflux of chyme into the esophagus.
Pyloric sphincter prevents the passage of food from the stomach into the duodenum
Gastrin
Hormones secreted by cells in the stomach wall known as G cells, it stimulates acid and pepsin secretion and gastric motility
Small intestine is divided into 3 parts
Duodenum, jejunum and ileum
Where does absorption begins and digestion ends
Absorption begins in the duodenum and continues through the small intestines. Digestion is completed in the duodenum and jejunum
What features allow the small intestine to accomplish absorption
It’s large surface area resulting from length, villi and micro villa
Intestinal villi’s important structures
Capillaries, absorb dietary monosaccharides and amino acids.
Lymphatic vessels called lacteals, which absorb dietary fats
Two ducts that empty into the duodenum
Pancreatic duct (delivers the exocrine secretions of the pancreas) and
The common bile duct (delivers bile)
Functions of bile
Vehicle for the disposal of waste products by the liver and digestion of fats
Two duodenum ducts empty into what?
Sphincter of Oddi
What is the enzyme secreted by the duodenal epithelial cells?
Enterokinase, activates the pancreatic zymogen trypsinogen to tripsin
Brush border enzymes
Are not secreted, but do their work inside or on the surface of the brush border epithelial cells.
What is the role of brush border enzymes?
To hydrolyze the smallest carbohydrates and proteins into monosaccharides and amino acids
What are the three main duodenal hormones?
Cholecystokinin (CCK), secretin and esterogastrone
CCK role
Secreted in response to fats in the duodenum. Causes the pancreas to secret digestive enzyme, stimulates gallbladder contraction and decreases gastric motility
Secretin role
Released in response to acid in the duodenum. Causes the pancreas to release large amounts of high-pH aqueous buffer (HCO3- in water)
Estrogasterone
Decreases stomach emptying
Colon (large intestine)
Role is to absorb water and minerals, and to form and store feces until the time of defication
Cecum
First part of the colon.
Entrance of chyme into the cecumis controlled by the ileocecal valve.
The appendix
Finger- like appendage of the cecum. Composed mostly of lymphatic tissue
Rectum
Last portion of the colon.
Anal sphincter
Controls defication.
Internal anal sphincter consists of smooth muscle, which is under autonomic control.
External anal sphincter consists of skeletal muscles and is under voluntary control
Type of bacteria found in the colon
Facultative or obligate anaerobes.
Metabolize materials and give off gas as a waste product
Importance of colonic bacteria
(1) presence in large numbers of normal bacterial helps keep dangerous bacterial from proliferation
(2) supply us with vitamin K, essential for blood clotting
Enzymes in the exocrine pancreas
Pancreatic amylase, Pancreatic lipase, pancreatic pro teases and nucleases
Pancreatic amylase
Hydrolyze polysaccharides to disaccharides
Pancreatic lipase
Hydrolyze triglycerides at the surface of micelle
Nuclease
Hydrolyze dietary DNA and RNA
Pancreatic protease
Responsible for hydrolyzing polypeptides to di- and tripeptides
Exocrine pancreas is controlled by the
Parasympathetic nervous system activation which increases pancreatic secretion. Sympathetic activation reduces it
Endocrine Pancreas
Consists of small regions within the pancreas known as the “islets of Langerhans”
Three types of cells in the islets
Alpha cells,beta cells and gamma cells
Alpha cells in the islets
Secrete glucagon in response to low blood sugar
Beta cells in the islets
Secret insulin in response to elevated blood sugar
Gamma cells in the islets
Secrete somatostation which inhibits many digestive processes
Trypsin
Hydrolyzes polypeptides (proteins) not prolysaccharides
Hormones that can raise blood sugar
Glucagon, epinephrine and cortisol
Secretory activity of the liver
Secreted bile. Bile emulsified large fat particles in the duodenum.
Bile moves from the liver to
Either directly secreted into the duodenum or its stored for later use in the gallbladder
How does the gallbladder release bile?
The gallbladder itself has no secretory activity. CCK and the parasympathetic nervous system stimulate contraction of the gallbladder wall
Livers function
Extracts nutrients from the blood & monitors for what’s present and what’s missing
Ammonia (waste product of protein catabolism) is converted to urea which is excited in urine
Lipid metabolism, plasma protein creation and is the major center for drug and toxin detoxification in the body
Fat-soluable vitamins
require bile acids for solubilization and absorption.
A,D,E,K
Water soluable fats
Excreted in urine by the kidneys.
B1,B2,B3,B6,B12,C,Biotin and Floate
Excretory and homeostatic roles of the kidney
Excretion of hydrophilic wastes, maintenance of constant solute concentration and constant pH, maintenance of constant fluid volume
Homeostasis is accomplished in the kidneys by
Filtration, selective reabsoption and secretions (adds to filtrate) and concentration and dilution
Two components of a nephron (the functional unit of the kidney)
(1) rounded region surrounding the capillaries where filtration takes place (capsule)
(2) Renal tube; coiled tube which receives filtrate from the capillaries in the capsule at one end and empties into a collecting duct at the other end
What kind of substances are not filtered by the glomerular basement?
Substances which are too large to pass, they remain in the blood in the glomerular capillaries and drain in to the efferent arterial (I.e. Blood cells and plasma proteins)
Selective reabsoption
Substance that must return to the blood stream are extracted from the tubule, often via active transport and picked up by peritubular capillaries, which drain into venues tha lead to the renal vein
What part of the tubule does most reabsoption occur?
The part nearest Bowman’s capsule called the proximal convoluted tubule (PCT)
But also in the distal convoluted tubule (DCT)
Reabsoption in the PCT
Selective in that it chooses what to reabsorb but its not overly regulated since it reabsorbs “as much as possible” not a certain amount
What two hormones affect concentration and dilution of the urine and how?
ADH: prevents dieresis by increasing water reabsoption in the distal nephron (without ADH the distal nephron is impermeable to water)
Aldosterone: when blood pressure is low this hormone is released and causes increased reabsoption of Na+ by the distal nephron. (Leads to increased thirst and water retention which raises blood pressure)
Countercurrent multiplier
The loop of Helene is a countercurrent multiplier that makes the medulla very salty and that facilitates water reabsoption from the collecting duct. This is how the kidney is capable of making ruin with a much higher osmolarity than plasma
Vasa Recta
Return to the bloodstream any water that is reabsorbed from the filtrate
When there is a decrease in blood pressure…
The JG cells secrete an enzyme called renin into the bloodstream. Renin catalyze the conversion of angiotensinogen into angiotensin I –> angiotensin II which is a vasoconstrictor that immediately raises blood pressure
When plasma pH is too high
HCO3- is excreted in the urine (using carbonic anhydrase)
When plasma pH is too low
H+ is excreted (using carbonic anhydrase)
Renal adjustments to ph
Are slow and take several days to return plasma pH to normal after a disturbance
Respiratory pH adjustments
Are rapid, taking effect in just minutes
Calcitonin
C cells are located in the thyroid gland and are secreted when [Ca2+] is too high.
Removes it by deposition in bone, reduced absorption by the gut or excretion in the urine
Parathomone
PTH effect is opposite of calcitonin
EPO
Causes increased synthesis of red blood cells in the bone marrow. Release when oxygen content falls
