The Respiratory System
description
Transcript of The Respiratory System
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The Respiratory
System
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Respiration Includes Pulmonary ventilation
Air moves in and out of lungs Continuous replacement of gases in alveoli (air sacs)
External respiration Gas exchange between blood and air at alveoli O2 (oxygen) in air diffuses into blood CO2 (carbon dioxide) in blood diffuses into air
Transport of respiratory gases Between the lungs and the cells of the body Performed by the cardiovascular system Blood is the transporting fluid
Internal respiration Gas exchange in capillaries between blood and tissue cells O2 in blood diffuses into tissues CO2 waste in tissues diffuses into blood
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Cellular Respiration
Oxygen (O2) is used by the cells O2 needed in conversion of glucose to
cellular energy (ATP) All body cells Carbon dioxide (CO2) is produced as a
waste product The body’s cells die if either the
respiratory or cardiovascular system fails
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The Respiratory Organs
Conducting zone Respiratory passages
that carry air to the site of gas exchange
Filters, humidifies and warms air
Respiratory zone Site of gas exchange Composed of
Respiratory bronchioles Alveolar ducts Alveolar sacs
Conducting zone labeled
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Nose
Provides airway Moistens and warms air Filters air Resonating chamber
for speech Olfactory receptors
External nose
Conducting zone will be covered first
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Nasal cavity Air passes through nares (nostrils) Nasal septum divides nasal cavity in midline (to right & left halves)
Perpendicular plate of ethmoid bone, vomer and septal cartilage Connects with pharynx posteriorly through choanae (posterior nasal
apertures*) Floor is formed by palate (roof of the mouth)
Anterior hard palate and posterior soft palate
* palate
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Linings of nasal cavity Vestibule* (just above nostrils)
Lined with skin containing sebaceous and sweat glands and nose hairs
Filters large particulars (insects, lint, etc.) The remainder of nasal cavity: 2 types of mucous membrane
Small patch of olfactory mucosa near roof (cribriform plate) Respiratory mucosa: lines most of the cavity
*
Olfactory mucosa
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Respiratory Mucosa
Pseudostratified ciliated columnar epithelium Scattered goblet cells Underlying connective tissue lamina propria
Mucous cells – secrete mucous Serous cells – secrete watery fluid with
digestive enzymes, e.g. lysozyme Together all these produce a quart/day
Dead junk is swallowed
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Nasal Conchae
•Inferior to each is a meatus*•Increases turbulence of air•3 scroll-like structures•Reclaims moisture on the way out
**
*
(its own bone)
Of ethmoid
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Paranasal sinuses Frontal, sphenoid, ethmoid and maxillary bones Open into nasal cavity Lined by same mucosa as nasal cavity and
perform same functions Also lighten the skull Can get infected: sinusitis
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The Pharynx (throat) 3 parts: naso-, oro- and laryngopharynx Houses tonsils (they respond to inhaled antigens) Uvula closes off nasopharynx during swallowing so food doesn’t go into
nose Epiglottis posterior to the tongue: keeps food out of airway Oropharynx and laryngopharynx serve as common passageway for
food and air Lined with stratified squamous epithelium for protection
*
*
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The Larynx (voicebox) Extends from the level of the 4th to the 6th
cervical vertebrae Attaches to hyoid bone superiorly Inferiorly is continuous with trachea (windpipe) Three functions:
1. Produces vocalizations (speech)
2. Provides an open airway (breathing)
3. Switching mechanism to route air and food into proper channels Closed during swallowing Open during breathing
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Framework of the larynx 9 cartilages connected by membranes and ligaments Thyroid cartilage with laryngeal prominence (Adam’s apple)
anteriorly Cricoid cartilage inferior to thyroid cartilage: the only
complete ring of cartilage: signet shaped and wide posteriorly
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Behind thyroid cartilage and above cricoid: 3 pairs of small cartilages1. Arytenoid: anchor the vocal cords
2. Corniculate
3. Cuneiform
9th cartilage: epiglottis
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Epliglottis* (the 9th cartilage)Elastic cartilage covered by mucosaOn a stalk attached to thyroid cartilageAttaches to back of tongueDuring swallowing, larynx is pulled superiorlyEpiglottis tips inferiorly to cover and seal laryngeal inletKeeps food out of lower respiratory tract
*
*
Posterior views
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Cough reflex: keeps all but air out of airways
Low position of larynx is required for speech (although makes choking easier)
Paired vocal ligaments: elastic fibers, the core of the true vocal cords
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Pair of mucosal vocal folds (true vocal cords) over the ligaments: white because avascular
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Glottis is the space between the vocal cords Laryngeal muscles control length and size of opening by moving
arytenoid cartilages Sound is produced by the vibration of vocal cords as air is exhaled
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Innervation of larynx (makes surgery at neck risky) Recurrent laryngeal nerves of Vagus These branch off the Vagus and make a big downward loop under vessels, then up
to larynx in neck Left loops under aortic arch Right loops under right subclavian artery Damage to one: hoarseness Damage to both: can only whisper
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Trachea (the windpipe)
Descends: larynx through neck into mediastinum Divides in thorax into two main (primary) bronchi 16-20 C-shaped rings
of hyaline cartilage
joined by fibroelastic
connective tissue Flexible for bending
but stays open despite
pressure changes
during breathing
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Posterior open parts of tracheal cartilage abut esophagus Trachealis muscle can decrease diameter of trachea
Esophagus can expand when food swallowed Food can be forcibly expelled
Wall of trachea has layers common to many tubular organs – filters, warms and moistens incoming air Mucous membrane (pseudostratified epithelium with cilia and lamina
propria with sheet of elastin) Submucosa ( with seromucous glands) Adventitia - connective tissue which contains the tracheal cartilages)
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Carina* Ridge on
internal aspect of last tracheal cartilage
Point where trachea branches (when alive and standing is at T7)
Mucosa highly sensitive to irritants: cough reflex
*
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Bronchial tree bifurcation Right main bronchus (more susceptible to
aspiration) Left main bronchus
Each main or primary bronchus runs into hilus of lung posterior to pulmonary vessels
1. Oblique fissure2. Vertebral part3. Hilum of lung4. Cardiac impression5. Diaphragmatic surface
(Wikipedia)
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Main=primary bronchi divide into secondary=lobar bronchi, each suppliesone lobe 3 on the right 2 on the left
Lobar bronchi branch into tertiary = segmental bronchi
Continues dividing: about 23 times Tubes smaller than 1 mm called bronchioles Smallest, terminal bronchioles, are less the 0.5 mm
diameter Tissue changes as becomes smaller
Cartilage plates, not rings, then disappears Pseudostratified columnar to simple columnar to simple
cuboidal without mucus or cilia Smooth muscle important: sympathetic relaxation
(“bronchodilation”), parasympathetic constriction (“bronchoconstriction”)
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Respiratory Zone End-point of respiratory tree Structures that contain air-exchange chambers are called alveoli Respiratory bronchioles lead into alveolar ducts: walls consist of alveoli Ducts lead into terminal clusters called alveolar sacs – are microscopic chambers There are 3 million alveoli!
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Gas Exchange Air filled alveoli account for most of the lung volume Very great area for gas exchange (1500 sq ft) Alveolar wall
Single layer of squamous epithelial cells (type 1 cells) surrounded by basal lamina
0.5um (15 X thinner than tissue paper) External wall covered by cobweb of capillaries
Respiratory membrane: fusion of the basal laminas of Alveolar wall Capillary wall
Alveolar sac
Respiratorybronchiole
Alveolarduct
Alveoli
(air on one side; blood on the other)
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Bronchial
“tree” and
associated
Pulmonary
arteries
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This “air-blood barrier” (the respiratory membrane) is where gas exchange occurs Oxygen diffuses from air in alveolus (singular
of alveoli) to blood in capillary Carbon dioxide diffuses from the blood in
the capillary into the air inthe alveolus
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Surfactant
Type II cuboidal epithelial cells are scattered in alveolar walls
Surfactant is a detergent-like substance which is secreted in fluid coating alveolar surfaces – it decreases tension
Without it the walls would stick together during exhalation
Premature babies – problem breathing is largely because lack surfactant
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Microscopic detail of alveoli Alveoli surrounded by fine elastic fibers Alveoli interconnect via alveolar pores Alveolar macrophages – free floating “dust cells” Note type I and type II cells and joint membrane
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Lungs and Pleura
Pleural cavity – slit-like potential space filled with pleural fluid
Lungs can slide but separation from pleura is resisted (like film between 2 plates of glass)
Lungs cling to thoracic wall and are forced to expand and recoil as volume of thoracic cavity changes during breathing
Around each lung is a flattened sac of serous membrane called pleura
Parietal pleura – outer layerVisceral pleura – directly on lung
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CXR(chest x-ray)
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Chest x rays
Normal female Lateral (male)
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Pleura also divides thoracic cavity in three 2 pleural, 1 mediastinal
Pathology Pleuritis Pleural effusion
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Relationship of organs in thoracic cavity
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Paired lungs occupy all thoracic cavity lateral to the mediastinum
Mediastinum contains (mainly): heart, great blood vessels, trachea, main bronchi, esophagus
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Lungs
Each is cone-shaped with anterior, lateral and posterior surfaces contacting ribs
Superior tip is apex, just deep to clavicle Concave inferior surface resting on diaphragm is
the baseapex apex
base base
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Hilus or (hilum) Indentation on mediastinal (medial) surface Place where blood vessels, bronchi, lymph vessel, and
nerves enter and exit the lung “Root” of the lung
Above structures attaching lung to mediastinum Main ones: pulmonary artery and veins and main
bronchus
Medial view R lung Medial view of L lung
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Right lung: 3 lobes Upper lobe Middle lobe Lower lobe
Left lung: 2 lobes Upper lobe Lower lobe
Oblique fissure
Oblique fissure
Horizontal fissure
Abbreviations in medicine:e.g.” RLL pneumonia”
Each lobe is served by a lobar (secondary) bronchus
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Each lobe is made up of bronchopulmonary segments separated by dense connective tissue Each segment receives air from an individual
segmental (tertiary) bronchus Approximately 10 bronchopulmonary segments in each
lung Limit spread of infection Can be removed more easily because only small
vessels span segments Smallest subdivision seen with the naked eye is
the lobule Hexagonal on surface, size of pencil eraser Served by large bronchiole and its branches Black carbon is visible on connective tissue separating
individual lobules in smokers and city dwellers
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Pulmonary arteries bring oxygen-poor blood to the lungs for oxygenation They branch along with the bronchial tree The smallest feed into the pulmonary capillary
network around the alveoli Pulmonary veins carry oxygenated blood from
the alveoli of the lungs to the heart
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Stroma – framework of connective tissue holding the air tubes and spaces Many elastic fibers Lungs light, spongy and elastic Elasticity reduces the effort of breathing
Blood supply Lungs get their own blood supply from bronchial
arteries and veins Innervation: pulmonary plexus on lung root
contains sympathetic, parasympathetic and visceral sensory fibers to each lung From there, they lie on bronchial tubes and blood
vessels within the lungs
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Bronchopulmonary – means both bronchial tubes and lung alveoli together Bronchopulmonary segment – chunk receiving air
from a segmental (tertiary) bronchus*: tertiary means it’s the third order in size; also, the trachea has divided three times now
“Anatomical dead space” The conducting zone which doesn’t participate in gas
exchange
Primary bronchus:(Left main)
Secondary:(left lower lobar bronchus)
(supplyingleft lowerlobe)
Does this clarify a little?
*
Understand the concepts; you don’t need to know the names of the tertiary bronchi
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Ventilation
Breathing = “pulmonary ventilation” Pulmonary means related to the lungs
Two phases Inspiration (inhalation) – air in Expiration (exhalation) – air out
Mechanical forces cause the movement of air Gases always flow from higher pressure to lower For air to enter the thorax, the pressure of the air in it
has to be lower than atmospheric pressure Making the volume of the thorax larger means the air inside it
is under less pressure(the air has more space for as many gas particles, therefore it is under less pressure)
The diaphragm and intercostal muscles accomplish this
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Muscles of Inspiration
During inspiration, the dome shaped diaphragm flattens as it contracts This increases the height of
the thoracic cavity
The external intercostal muscles contract to raise the ribs This increases the
circumference of the thoracic cavity
Together:
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Inspiration continued
Intercostals keep the thorax stiff so sides don’t collapse in with change of diaphragm
During deep or forced inspiration, additional muscles are recruited: Scalenes Sternocleidomastoid Pectoralis minor Quadratus lumborum on 12th rib Erector spinae
(some of these “accessory muscles” of ventilation are visible to an observer; it usually tells you that there is respiratory distress – working hard to breathe)
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Expiration
Quiet expiration in healthy people is chiefly passive Inspiratory muscles relax Rib cage drops under force of gravity Relaxing diaphragm moves superiorly
(up) Elastic fibers in lung recoil Volumes of thorax and lungs decrease
simultaneously, increasing the pressure Air is forced out
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Expiration continued
Forced expiration is active Contraction of abdominal wall muscles
Oblique and transversus predominantly Increases intra-abdominal pressure forcing the
diaphragm superiorly Depressing the rib cage, decreases thoracic
volume Some help from internal intercostals and latissimus
dorsi
(try this on yourself to feel the different muscles acting)
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Pneumothorax (collapsed lung)
Think about the processes involved and then try and imagine the various scenarios
1. Trauma causing the thoracic wall to be pierced so air gets into the pleura
2. Broken rib can do (1); always do a CXR if there’s a broken rib
3. Visceral pleura breaks, letting alveolar air into pleural space
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Pneumothorax
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Neural Control of Ventilation Reticular formation in medulla
Responsible for basic rate and rhythm Can be modified by higher centers
Limbic system and hypothalamus, e.g. gasp with certain emotions
Cerebral cortex – conscious control Chemoreceptors
Central – in the medulla Peripheral: see next slide
Aortic bodies on the aortic arch Carotid bodies at the fork of the carotid artery: monitor O2 and
CO2 tension in the blood and help regulate respiratory rate and depth
The carotid sinus (dilated area near fork) helps regulate blood pressure and can affect the rate (stimulation during carotid massage can slow an abnormally fast heart rate)
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Peripheral chemoreceptors regulating respiration
Aortic bodies* On aorta Send sensory info to medulla
through X (vagus n)
Carotid bodies+ At fork of common carotid
artery Send info mainly through IX
(glossopharyngeal n)
*
+
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There are many diseases of the respiratory system, including asthma, cystic fibrosis, COPD (chronic obstructive pulmonary disease – with chronic bronchitis and/or emphysema) and epiglottitis
example:
normal emphysema
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you might want to think twice about smoking….
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general CXR site:
http://www.radiologyinfo.org/en/info.cfm?pg=chestrad&bhcp=1
CXR atlas: http://www.meddean.luc.edu/lumen/
MedEd/medicine/pulmonar/cxr/atlas/cxratlas_f.htm (penumothorax)
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Urinary System
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The Urinary System
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Function
1. Remove nitrogenous wastes2. Maintain electrolyte, acid-base,
and fluid balance of blood3. Homeostatic organ4. Acts as blood filter5. Release hormones: calcitriol &
erythropoietin
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Kidneys as Filters
• Diuretic- loose water; coffee, alcohol• Antidiuretic- retain water; ADH• Aldosterone- sodium & water reabsorption,
and K+ excretion• GFR= 180 liters (50 gal) of blood/day• 178-179 liters are reabsorbed back into
blood• Excrete a protein free filtrate
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Maintaining Chemical
Homeostasis
The Urinary System
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The Urinary System
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urine
blood
filtration
tubular reabsorption and secretion
General Functioning
of the Kidney
General Functioning
of the Kidney
“refreshed” blood
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Nitrogenous Wastes
ammonia
urea
uric acid
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Organs of the
Urinary System
Organs of the
Urinary System
kidneys
ureters
urinary bladder
urethra
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renal capsule
renal cortex
renal medulla
renal pelvis
renal pyramids
ureter
Kidney AnatomyKidney
Anatomy
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Kidney AnatomyKidney
Anatomy
renal artery
renal vein
nephronnephron
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urine
blood
filtration
tubular reabsorption and secretion
Nephron Functioning
Nephron Functioning
“refreshed” blood
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vein
artery
afferent arteriole
efferent arteriole
glomerulus
peritubular capillaries
Bowman’s capsule
proximal convoluted tubuledistal convoluted tubule
loop of Henle
collecting duct
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renal cortex
renal medulla
Each kidney contains over 1 million nephrons and thousands of collecting ducts
Collecting duct
Loop of Henle
PCT
DCTGlomerulus
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Glomerular Filtration
Glomerular Filtration
afferent arteriole
glomerulus
efferent arteriole
Bowman’s capsule
Filters blood; proteins can’t pass through
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Radiographic examinations of the urinary system are among the most common contrast media procedures performed in radiology departments. The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra
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The two kidneys and the ureters are organs that lie in the retroperitoneal space. These two bean-shaped organs lie on either side of the vertebral column in the most posterior part of the abdominal cavity. The right kidney generally is slightly lower or more inferior than the left because of the presence of the liver. Near the upper medial part of each kidney is a suprarenal (adrenal) gland. These important glands of the endocrine system are located in the fatty capsule that surrounds each kidney.
Each kidney is connected to the single urinary bladder by its own ureter. Waste material, in the form of urine, travels from the kidneys to the bladder via these two narrow tubes, termed ureters. The saclike urinary bladder serves as a reservoir that stores urine until it can be eliminated from the body via the urethra.The Latin designation for kidney is ren, and renal is an adjective that is commonly used to refer to the kidney.
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Anterior view Posterior view
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Kidneys the posteriorly placed kidneys lie on either side of the vertebral column in the upper posterior abdomen. They lie posterior to the lower portion of the liver on the right and posterior to the lower spleen on the left . The lower ribcage thus forms a protective enclosure for the kidneys.
Ureters most of each ureter lies anterior to its respective kidney. The ureters follow the natural curve of the vertebral column. Each ureter initially curves forward, following the lumbar lordotic curvature, and then curves backward on entering the pelvis. After passing into the pelvis, each ureter follows the sacrococcygeal curve before entering the posterolateral aspect of the bladder
The urethra connects the bladder to the exterior. The urethra exits from the body inferior to the symphysis pubis.The entire urinary system is either posterior to or below the peritoneum. The kidneys and ureters are retroperitoneal structures, whereas the bladder and urethra are infraperitoneal structures.
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The usual orientation of the kidneys in the supine individual is shown below. The large muscles on either side of the vertebral column cause the longitudinal plane of the kidneys to form a vertical angle of about 20° with the midsagittal plane. These large muscles include the two psoas major muscles. These muscle masses grow larger as they progress inferiorly from the upper lumbar vertebrae. This gradual enlargement produces the 20° angle, wherein the upper pole of each kidney is closer to the midline than its lower pole
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These large posterior abdominal muscles also cause the kidneys to rotate backward within the retroperitoneal space. As a result, the medial border of each kidney is more anterior than the lateral border.
Transverse cross-sectional views through the level of L2 illustrate the usual amount of backward rotation of the kidneys.The normal kidney rotation of about 30° is due to the midline location of the vertebral column and the large psoas major muscles on either side. The quadratus lumborum muscles also are shown on each side just posterior to the kidneys. The deep muscles of the back include the group of erector spinae muscles on each side of the spine.
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When posterior oblique projections are used during radiographic studies of the urinary system, each kidney in turn is placed parallel to the plane of the image receptor. The body is rotated about 30° in each direction to place one kidney, and then the other, parallel to the IR plane. A 30° LPO positions the right kidney parallel to the IR, and a 30° RPO positions the left kidney parallel.
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Most abdominal radiographs are performed on expiration with the patient supine. The combined effect of expiration and a supine position allows the kidneys to lie fairly high in the abdominal cavity. Under these conditions, the kidneys normally lie about halfway between the xiphoid process and the iliac crest. The left kidney normally lies about 1 centimeter more superior than does the right one. The top of the left kidney is usually at the level of the T11-T12 interspace. The bottom of the right kidney most often is level with the upper part of L3
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Because the kidneys are only loosely attached within their fatty capsule, they tend to move up and down with movements of the diaphragm and position changes. When one inhales deeply, the kidneys normally drop about 1 inch (2.5 cm) or one lumbar vertebra. When one stands upright, the kidneys normally drop about one lumbar vertebrae, or 5 centimeters (2 inches). If the kidneys drop farther than this, a condition termed nephroptosis is said to exist. With some very thin and older patients in particular, the kidneys may drop dramatically and end up within the pelvis, which may create problems caused by “kinking” or twisting of the ureters.
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The primary function of the urinary system is the production of urine and its elimination from the body. During urine production, the kidneys perform the following functions:
1.Remove nitrogenous wastes
2.Regulate water levels in the body
3.Regulate acid-base balance and electrolyte levels of the blood
Nitrogenous waste products such as urea and creatinine are formed during the normal metabolism of proteins. Buildup of these nitrogenous wastes in the blood results in the clinical condition termed uremia and may indicate renal dysfunction.
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The macroscopic internal structure of the kidney.The outer covering of the kidney is termed the renal (fibrous) capsule. Directly under the renal capsule surrounding each kidney is the cortex, which forms the peripheral, or outer, portion of the kidney. Under the cortex is the internal structure termed the medulla, which is composed of from 8 to 18 conical masses termed renal pyramids. The cortex periodically dips between the pyramids to form the renal columns, which extend to the renal sinus.
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The renal pyramids are primarily a collection of tubules that converge at an opening at the renal papilla (apex) and drain into the minor calyx. Calyces appear as hollowed, flattened tubes. From 4 to 13 minor calyces unite to form two to three major calyces. The major calyces unite to form the renal pelvis, which appears in the shape of a larger flattened funnel. Each expanded renal pelvis narrows to continue as the ureter. Thus urine formed in the microscopic or nephron portion of the kidney finally reaches the ureter by passing through the various collecting tubules, to a minor calyx, to a major calyx, and then to the renal pelvis.The general term renal parenchyma is used to describe the total functional portions of the kidneys, such as those visualized during an early phase of an intravenous urogram procedure.
The structural and functional unit of the kidney is the microscopic nephron. Approximately one million nephrons exist within each kidney.. Small arteries in the kidney cortex form tiny capillary tufts, termed glomeruli (glo-mer′-u-li). Blood initially is filtered through the many glomeruli.
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The ureters transport urine from the kidneys to the urinary bladder. Slow peristaltic waves and gravity force urine down the ureters into the bladder. This is an image taken 10 minutes after injection of contrast media into the bloodstream performed as part of an intravenous urogram procedure.
The renal pelvis leaves each kidney at the hilum to become the ureter. The ureters vary in length from 28 to 34 centimeters, with the right one being slightly shorter than the left.
As the ureters pass inferiorly, they lie on the anterior surface of each psoas major muscle. Continuing to follow the curvature of the vertebral column, the ureters eventually enter the posterolateral portion of each side of the urinary bladder.
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The ureters vary in diameter from 1 millimeter to almost 1 centimeter. Normally, three constricted points exist along the course of each ureter. If a kidney stone attempts to pass from kidney to bladder, it may have trouble passing through these three regions.
The first point is the ureteropelvic (u-re′-ter-o-pel′-vic) (UP) junction, where the renal pelvis funnels down into the small ureter. This section is best seen on the radiograph in.
The second is near the brim of the pelvis, where the iliac blood vessels cross over the ureters.
The third is where the ureter joins the bladder, termed the ureterovesical junction, or UV junction. Most kidney stones that pass down the ureter tend to hang up at the third site, the UV junction, and once the stone passes this point and moves into the bladder, it generally has little trouble passing from the bladder and through the urethra to the exterior.
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The urinary bladder is a musculomembranous sac that serves as a reservoir for urine. The empty bladder is somewhat flattened and assumes the more oval shape only when partially or fully distended.
The triangular portion of the bladder along the inner, posterior surface is termed the trigone . The trigone is the muscular area formed by the entrance of the two ureters from behind and the exit site of the urethra. The trigone is firmly attached to the floor of the pelvis. The mucosa of the trigone is smooth, whereas the remaining aspect of the inner mucosa of the bladder has numerous folds termed rugae. As the bladder fills, the top of the bladder expands upward and forward toward the abdominal cavity.
The bladder functions as a reservoir for urine and, aided by the urethra, expels urine from the body. Normally, some urine is in the bladder at all times, but as the amount reaches 250 ml, the desire to void arises. The act of voiding (urination) is normally under voluntary control, and the desire to void may pass if the bladder cannot be emptied right away. The total capacity of the bladder varies from 350 to 500 ml. As the bladder becomes more and more full, the desire to void becomes more and more urgent. If the internal bladder pressure rises too high, involuntary urination occurs.
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Venipuncture is defined as the percutaneous puncture of a vein for withdrawal of blood or injection of a solution such as contrast media for urographic procedures. In the past, venipuncture for urography was performed by physicians and laboratory or nursing personnel. However, in recent years, venipuncture has become part of the scope of practice for the diagnostic imaging professional.
Before contrast media is withdrawn from any vial or bottle, confirmation of the correct contents of the container, route of administration, amount to be administered, and expiration date is imperative.Water-soluble, iodinated contrast media is used for radiographic examinations of the urinary system. This type of contrast medium can be administered by either bolus injection or drip infusion.
A bolus injection is one in which the entire dose of contrast media is injected into the venous system at one time. This method of administration is used typically for maximum contrast enhancement.
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Ch 26: Urinary SystemCh 26: Urinary SystemObjectives
Identify and describe the components of the urinary system and their function
Describe the (histological) organization of the nephron
Identify the blood vessels that supply blood to the nephrons
Describe the blood flow through and around the nephron
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Functions of Urinary System (Kidneys):
● Regulate fluid balance (fluid volume) of the body
● Excrete organic waste products and conserve nutrients, etc
Stabilize pH
Regulate ion concentrations in the blood
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Kidney Kidney LocationLocation
Lateral to vertebral column high on body wall, under floating ribs in retro-peritoneal position
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Surface Anatomy
Size of bar of soap Bean shapedHilus – indentation
Three layers Renal fascia – fibrous tunic Adipose capsule – protects kidney Renal capsule – anchors kidney to body wall,
continuous with peritoneum
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Sectional Anatomy
Cortex: outer layer, light reddish brow, granular appearance (due to many capillaries)
Medulla: darker striped appearance (due to tubules) Subdivided into distinct renal pyramids, terminating with a papilla. Separated by renal columns from the cortex.
Fig 26-3
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Urine collection:
Ducts within each renal
papilla release urine
into minor calyx
major calyx
renal pelvis
ureter
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Renal CirculationRenal Circulation
Segmental arteries
Interlobar arteries
Arcuate arteries
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
Peritubular capillaries
Segmental veins
Interlobar veins
Arcuate veins
Interlobular veins
Venules
Renal Artery Renal Vein
Fig 26-4
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Functional unit: Nephron
Renal corpuscle: Glomerulus Bowman’s capsule
Tubular passageways with associated blood vessels: PCT LOH DCT CD
(>mio/kidney)
Fig 26-8
Fig 26-6
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Filtration: Passage across Three Barriers
Capillary endotheliumFenestrated
What gets through?
Basement membrane
Glomerular epithelium (= visceral layer of Bowman’s capsule)slit pores between pedicels of podocyte
Fig 26-8
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Two Types of Nephrons
Cortical nephrons (85%) shorter, mostly in cortex of kidney, produce "standard" urine
Juxtamedullary nephrons (15%), "juxta-next-to" the medulla - responsive to ADH, can concentrate urine
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Juxtaglomerular Apparatus
Macula densa
+Juxtaglomerular cells
(smooth muscle fibers from afferent arteriole)
= Juxtaglomerular Apparatus
= Endocrine system structure (renin and EPO)
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Urine Transport, Storage, and Urine Transport, Storage, and EliminationElimination
Trace drop of urine from kidneys to outside world
Lining of these parts?
Nephroptosis (= floating kidneys)
Nephrolithiasis
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Nephrolithiasis
Occurs when urine becomes too concentrated and substances crystalize. Symptoms arise when stones begin to move down ureter causing intense pain.
Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.
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Anatomy of Urinary Bladder
Retroperitoneal, behind pubis Internal folds - rugae - permit expansion (max. holding
capacity ~ 1L) Trigone - area at base delineated by openings of ureters and
urethra - without muscle Internal urethral sphincter - involuntary sphincter
Histology1. transitional epithelium2. detrusor muscle – smooth muscle
Fig 26.10
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Urethra
External urethral sphincters – voluntary at pelvic floor
Female - short – from base of bladder to vestibule
Male1. prostatic urethra – from base of bladder through
prostate gland2. membranous urethra – between prostate gland &
base of penis3. penile (spongy) urethra – traverses penis to orifice
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UTIs (esp. E.coli)
Male versus Female
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The End
Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!!
2-4 % of population only have 1 kidney!
Manneken PisFountainBrussels, 1619