Tubes | Function

Tubes in The Body

Principles

Tubes of the Body

32368 tube colon small bowel lung bronchus bronchi esophagus stomach large bowel bile duct ureter brain liver urinary bladder heart cardiac artery arteries arterial system veins venous system tube principles Davidoff art Courtesy Ashley Davidoff MD

Structure

Basic Structure of Biological Tubes

32337 tube colon small bowel lung bronchus bronchi esophagus stomach large bowel bile duct ureter tube pinciples mucosa submucosa muscularis adventitia serosa Courtesy Ashley Davidoff MD Davidoff art mucosa submucosa muscularis adventitia serosa histology

Function

Tubes and Transport

The function of transport is the domain of the tubes of the body, which have to obey the universal principles of flow within a tube. If you understand flow in tubes,

you will be able to extend the principes to a large portion of of the way the body works in health and the consequences when the transport systems fail in disease.

Flow will only occur when a pressure difference exists between the two sides of the tubes. When we breathe in, the intercostal muscles contract and expand the chest laterally and the diaphragm moves down, increasing the volume of the chest cavity in a craniocaudad dimension. As a result the alveoli expand, causing a negative pressure in the alveolar side of the tubes. The pressure in the atmosphere is higher and thus air will flow from a high pressure system to a low pressure system – i.e. from the atmosphere to the lungs. During expiration, the elastic nature of the chest, with the relaxation of intercostal muscles and diaphragm, result in a return of the chest to its preinspiratory position. The chest therefore is in a contracted size, causing a relative increase of pressure in the alveoli when compared to the atmosphere, and air will flow from the alveoli to the atmosphere. Inspiration is therefore an active process requiring energy and muscle contraction, and expiration is a passive process of elastic recoil.

In the cardiovascular system the heart acts as a pump to increase the pressure on the arterial side so that flow will occur from the high pressure to the low pressure. In the gastrointestinal tract the peristalsis of smooth muscle creates the upstream high pressure so that products of ingestion and digestion can be brought to the factories of absorbtion and eventually for evacuation.

Velocity of flow relates to factors such as tubular diameter, resistance, friction, and pressure differences, as well as the nature of the medium being transported. Velocity of flow will also depend on whether the flow is laminar or turbulent. If it is laminar, it will be governed by Poiseuille’s law, which states that velocity of flow is directly proportional to the driving pressure.

Poiseuille’s law – for laminar flow

Volume flow rate = pressure difference

resistance

= P1-P2

= pressure difference X radius⁴

8/pi viscosity X length

As velocity increases however, flow tends to become turbulent and Poiseuille’s law does not apply. Flow tends to be laminar when the tubes are small, and turbulent when the tubes are large or when there are irregularities in the walls. Thus flow in the larger parts of the airways tends to be turbulent and in the smaller tubes it is laminar. Under resting conditions, laminar flow exists from the medium-sized bronchi onward down to the bronchioles. During exercise, the air flow is accelerated, and laminar flow may be confined only to the very small airways. Laminar flow is quiet while turbulent flow is noisy. Thus in the chest examination, the sound of wheezing or the presence of murmurs indicates turbulent flow which is abnormal. The audible “huffing and puffing” that occurs with exercise results from greater forcefulness of the muscles in an attempt to get more air in and out, and the turbulence becomes audible even without the stethoscope. Similarly audible wheezing in asthmatic patients reflects narrowing of the smaller airways.

The function of transport is the domain of the tubes of the body, which have to obey the universal principles of flow within a tube. If you understand flow in tubes,

you will be able to extend the principes to a large portion of of the way the body works in health and the consequences when the transport systems fail in disease.

Laminar Flow

Laminar flow

This diagram reflects the laminar flow showing the almost parallel lines of flow which is characteristic of flow in the smaller tubes. Under resting conditions, laminar flow exists from the medium-sized bronchi onward down to the bronchioles. During exercise, the air flow is accelerated, and laminar flow may be confined only to the very small airways.

Davidoff 42433b04.jpg

Turbulent Flow

Turbulent Flow

This drawing shows the lines and circles of noisy turbulent flow, which is characteristic of flow in the larger airways.

Davidoff 42434b07

Da Vinci and Turbulence

Thsi diagram is an exquisite representation the effect of the laminar flow of the waterfall on the receiving body of water creating waves of eddy currents and turbulence.

54863 da Vinci Studies of Water passing Obstacles and falling

Laminar Turbulent Mist

69207b01 Davidoff photography

CVS

Normal Pressures

49483b01 heart cardiac LV left ventricle aorta aortic systemic circulation capillary capillaries arterioles venules right atrium RA right ventricle RV normal physiology pressures hemodynamics Davidoff MD Davidoff art

Cardiac Ejection

34814c01.800 heart aorta systole normal physiology function contraction myocardial function ejetion fraction aortic valve mitral valve closed coapted Davidoff art Davidoff MD

Normal Abdominal Aorta

10254.800i abdomen abdominal aorta aorta kidney renal arteries artery iliac artery lumbar arteries angiogram angiography Davidoff MD

Right Angle Branch Flow and Turbulence

05402.800 aorta kidney lumbar arteries celiac axis MSA origin superior mesenteric artery renal artery common iliac artery mild atherosclerosis ostial stenosis plaque at the renal ostium renal cortex interlobar artery medulla pyramids calyces ureter Davidoff MD

Normal and AAA

11976c01 aorta abdomen abdominal aorta renal afrteries kidney fx normal AAA abdominal aortic aneurysm horseshoe kidney angogram angiography lumbar arteries Davidoff MD

Arteries

Artery

46493b02 artery carotid brain blood supply tubes Davidoff MD

Veins

Veins and Valves

26032d.800 vein tube valve flow normal anatomy Davidoff MD

Respiratory System

Tracheostomy

72333 airway tracheostomy tubes treatment airways trachea ventilation Davidoff MD

GIT

Junction of Bile Duct with Duodenum at the Papilla

71731.800 bile duct duodenum papilla valvulae conniventes small bowel common bile duct CBD CHD common hepatic duct links connections tubes cystic duct remnant normal biology anatomy intraoperative cholangiogram following cholecystectomy Davidoff MD

Esophageal Stricture – Schatzki’s Ring – Hiatus Hernia

72343c01 esophagus fx stricture Schatzki’s ring barium pill tube size inflammation 13mm focal stricture stenosis hiatus hernia barium swallow upper GI Davidoff MD

GUT

Ureteral Jets at The UVJ – Delivery of Urine to the Bladder

74911c01 distal ureter uretero vesical junction UVJ normal ureters ureteric jets bladder anatomy CTscan Courtesy Ahley Davidoff MD

Disease

Principles

Basic Strcture of Tubular Systems

32347 tube colon small bowel lung bronchus bronchi esophagus stomach large bowel bile duct ureter tube principles Courtesy Ashley DAvidoff MD Davidoff art mucosa submucosa muscularis adventitia serosa histology

Mucosal Lesion

32347d01 mucosa submucosa muscularis adventitia serosa mucosal mass polyp neoplasm carcinoma acute angles with the lumen histopathology imaging diagnosis Davidoff art Davidoff MD

Submucosal Lesion

32347d02 mucosa submucosa muscularis adventitia serosa submucosal mass edema hemorrhage obtuse angles or right angle 90 degree ninety degree angle with the lumen histopathology imaging diagnosis Davidoff art Davidoff MD

Submucosal Lesion

32347d03 mucosa submucosa muscularis adventitia serosa submucosal mass edema hemorrhage obtuse angles or right with the lumen histopathology imaging diagnosis Davidoff art Davidoff MD

Extrinsic Lesion

32347d04 mucosa submucosa muscularis adventitia serosa submucosal mass edema hemorrhage neoplasm malignancy benign obtuse angles with the lumen histopathology imaging diagnosis Davidoff art Davidoff MD

Circumferential Lesion

32347d06 mucosa submucosa muscularis adventitia serosa submucosal mass edema hemorrhage neoplasm malignancy benign obtuse angles with the lumen circumferential narrowing constriction obstruction histopathology imaging diagnosis Davidoff art Davidoff MD

CVS

Normal and Tracheal Stenosis

49838d01 50 year old female with respiratory difficulty trachea bronchi rectus abdominis muscle compression fractures kyphosis dwarf dwarfism right aortic arch tracheomalacia tracheal stenosis rectus abdominis muscle hypertrophy Davidoff MD Courtesy Ashley Davidoff MD CTscan 49838 49838c01 49838c02 49838c03 49838c04 49838c05 shape size position character growth

GUT

Ureteric Stricture with Hydronephrosis

70371c01 kidney ureter fx ureteric stricture fx blunting of the calyces calyceal blunting loss of the forniceal angle fornix hydronephrosis retrgrade contrast injection Davidoff MD

Bicornuate Uterus

47673 uterus congenital infertility fx failure of fusion dx bicornuate uterus patent Fallopian tubes free spillage hysterosalpingogram Courtesy Scott Tsai MD 47673 uterus congenital infertility fx failure of fusion dx bicornuate uterus patent Fallopian tubes free spillage hysterosalpingogram Courtesy Scott Tsai MD 47671

Endometrial Carcinoma with Ureteric Involvement and Secondary Hydronephrosis

The CTscan of a 58 year female with expanded endometrial cavity is shown. (a,b) The cavity is filled with heterogenous material (green) representing a combination of tumor, fluid necrotic material and blood. Pathology showed adenocarcinoma, endometriod type, grade I/III with tumor necrosis. Tumor involvement of the right ureter (arrow in c) and secondary hydronephrosis of the right kidney is present. (d)

Cervical Stenosis

Expanded Cervical Canal

The transvaginal ultrasound is from a 50 year old peri-menopausal female with metrorrhagia. The uterine cavity and cervical cavity are filled with fluid, and soft tissue elements are identified in the expanded cervical canal. The findings are consistent with cervical stenosis, but the cause for the metrorrhagia is not obvious. The stenosis was relieved and follow up ultrasound showed resolution. No cervical mass was identified.

Diseases

Carotid Artery – small region of stenosis

This color flow doppler US of the neck shows a carotid artery with bifurcation into internal and external carotid vessels. The small area of turbulence is noted by a blue area at the bifurcation.

Courtesy Philips Medical Systems 33288

Aortic Stenosis

This series of coronal MRI images of the aortic valve (a-f) show phases from diastole (a) through systole (b,c,d,e) with a narrow (b,c) and then turbulent jet, (d,e) back to diastole (f) The diagnosis is calcific aortic valve stenosis.

Courtesy Scott TSai MD 38871c

Obstructed Left Tube

Hydrosalpinx

33 old female with left adnexal discomfort and prior history of pelvic inflammatory disease Findings on hysterosalpingogram show a dilated fallopian tube consistent with hydrosalpinx uterus fallopian tube distended hydrosalpinx

Obstructed Uterus with Pyometria

46 year old female with obstructed uterus and fluid filled endometrial cavity with pockets of air caused by cervical carcinoma complicated by pyometria.