Forces in Function

Forces in Function

Ashley Davidoff MD The Common Vein Copyright 2014


 Physiology relates to the interaction of the forces in the body.  The forces have both physical and chemical forms.

Genetic Forces

Power of the Genes

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Forces in the Central Nervous System

Chemical Forces Allowing Impulse Transmission Across a Synapse

Synaptic Cleft Requiring Chemical Transmitters eg Acetylcholine to Transmit Impulse Across Nerve Junctions

72046.800 mitochondria transmitter vesicles presynaptic terminal post synaptic terminal soma of neuron synaptic cleft acetyl choline norepinephrine dopamine serotonin forces chemical energy function principles Davidoff art Davidoff drawing Davidoff MD

Electrical Transmission Along a Nerve

Sodium Potassium Pump MEchanism in the Transmission of a Nerve Impulse

72045b04.800 nerve conduction force electricity electric force positive force negative force sodium pump Na pump Patassium pump K+ pump diffusion conduction of impulses Davidoff drawing Davidoff art Davidoff MD

Forces in the Cardiovascular System

Creating Pressure Gradients

Creating Pressure Gradients by Muscular Pump Action49483b01 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

 Mechanical and Electrical Forces

Wiggers Diagram – Pressures in th Cardiovascular System33808b.800 heart cardiac physiology pressure EKG ECG pressure curves diagram LV aorta LA left atrium left ventricle systole diastole acv waves Davidoff MD

Elastic Forces

Elastic Forces

This CTscan shows a theoretical changes of the aortic wall during diastole (a) sytolic expansion (b) and return to normal in diastole (c) In systole (b) the suprarenal artery is expanded by the pulse but is relatively decompressed by the the low resistance and high flow renal arteries. The infrarenal aorta is relatively more expanded in systole (b) since the iliac arteries offer a relative resistance. This increased resistance causes the elastic tissue in the aorta to stretch (b) so that the recoil in diastole (c) results in a sustained forward moving force assisting the blood to get to their most distal destination – the feet. When the aorta starts to lose its elasticiy the recoil of systole gradually is weakened so that the aorta does not return to its normal diameter after each systolic expansion. Over many years this lack of recoil is progressive so that the resulting wall is weaker and dilated, until an aneurysm can be formed.

Courtesy Ashley Davidoff 24877c03 code CVS artery aorta AAA infrarenal circulatory elasticity recoil

Fluid Gradients at the Capillary Level

42445b03d06 capillary interstitium arteriole arteriolar pressure capillary pressure venule venular presure interstitial pressure colloid osmotic pressure plasma colloid osmotic pressure Forces tending to move fluid out of the capillary is capillary pressure of 25mmHg, negative intertitial presure = 6mmHg and and interstitial osmotic pressure of 5 mmHg = total of 36mmHg Forces holding the holding the fluid in the capilaries include the plasma oncotic pressure of 28mmhg and thus the net outward force is about 8mmHg Davidoff art Davidoff drawing Davidoff MD

Respiratory System

Moving Forces

Keeping the Lungs attached to the Chest Wall via A Two Layered Pleura – Capillary Forces

The coronally reformatted image of the lung parenchyma has been outlined with the visceral pleura, (pink) the pleural fluid in the pleural space, (orange) and the parietal pleura. (green) Note how at end expiration the parietal pleura in the costophrenic sulcus extends beyond the lung margin so that the visceral pleura is absent in the costophrenic sulcus and there are two layers of parietal pleura facing each other. During inspiration the lung expands into this space. Courtesy Ashley Davidoff MD 32634b10 lung pleura pulmonary 


45771 chest lungs fx normal chest CT anatomy Courtesy Ashley Davidoff MD Davidoff art 45769 45770 45771 45772 45773 45774 45775 45776

Mechanical Forces Bringing Air to Alveoli

Chest Wall,  Diaphragm,  Alveolar Expansion

The five major layers that keep the air moving include the outer bony cage, the muscular layer represented in maroon, the pleural complex (orange yellow orange) the lung (blue) and surfactant within the alveolus. (pink) Courtesy Ashley Davidoff MD. 42530b05b09b01a08 Davidoff art

Gradients Createrd at the Alveolar Level

Oxygen Gradients Created by the Lungs Across the Alveolar Membrane

This diagram again shows the alveolus in teal, the arteriolar component of the capillary with red cells in blue and venular component replenished by oxygen in red. As noted above, the PO2 of the arterial blood is 40mmHg while the inspired air is 104mmHg. A pressure gradient thus exists and diffusion from the high to the low pressure occurs with a net movement of oxygen into the blood to equilibrate the pressure. Venous blood is now rich in oxygen with a PO2 of 104mmHg.

Courtesy Ashley Davidoff MD. 42445b08b Davidoff art

Chemical Forces Used to Maintain Patency of Alveoli

Chemical Force of Surfactant to Keep the Alveoli Open during Respiration

This a grape like cluster of normal alveoli. Courtesy Ashley Davidoff MD 32163 code lung alveolus terminal bronchiole respiratory bronchiole RS normal anatomy drawing Davidoff art

Gastrointestinal System

Chemical Forces – Acid Production by the Stomach for Antimicrobial Action

PH probe to Detect Gastric Acid Reflux During Surgery49462 chest esophagus PH probe intraoperative monitoring for aspiration of stomach contents CXR plain X-Ray of the chest Davidoff MD

Forces for the Processing of Food

Chewing Carbohydrates with Chemical Action of Amylase results in Glucose Availability

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Pump Action – Peristalsis Moving it On for Further Processing

39548b03 stomach antrum fx narrowing with normal mucosal folds dx antral contraction wave antral peristalsis normal UGI uper GI barium imaging radiology

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Genitourinary Tract

Pressure Gradients and Osmotic Gradients

The Initial Filter – Bowman’s Capsule –  and then

Countercurrent Mechanism in the Tubes of Henle to Generate a Gradient to Recapture

Water and Excrete and Secrete Uriniferous Waste

16100b.800 kidney renal arteriole Bowman’s capsule filter tubule proximal convoluted tubule distal convoluted tubule collecting tubule ureter countercurrent mechanisms urine production gradients membrane flter bladder urethra drawing Davidoff art Davidoff MD

Peristalsis in Ureter and Bladder – Contraction to Move Urinary Waste Out 

31843 kidney ureters bladder post void calyces pelvis post void forces physiology contraction IVP physiology Plain X-ray KUB Davidoff MD

Muscular Forces

Contracted Fetal Biceps

47757b02 24 week fetus arm hand biceps thumb index finger human opposing thumb and index grape in hand normasl anatomy MRI Davidoff MD concepts Davidoff food in the body

Coordinated Muscular Forces80753pb01.800 Dancers Arielle Davidoff art Davidoff photography Courtesy Ashley Davidoff MD

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Skeletal System

Design of the Joints Disc Material and Shape of the Spine to Accomodate the MEchanical and Gravitational Forces Created with the Evolution of the Upright Position

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Gravitational and Muscular Forces result in Moulding of Bone to Accomodate the Mechanical Forces

49464 bone femur fx healed fracture compensation total knee replacement plain X-Ray Davidoff MD 49465