Anatomy and Physiology

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Anatomy and Physiology

• Heart, Lungs, Pancreas, Liver, Kidneys and Skin

B. Paul White, MD HOD ID 2078
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(No Transcript)
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HEART
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HEART

• Hollow, muscular organ
• 300 grams (size of a fist)
• 4 chambers
• found in chest between lungs
• surrounded by membrane called Pericardium
• Pericardial space is fluid-filled to nourish and
  protect the heart.

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HEART ANATOMY

• The heart is a complex muscular pump that
  maintains blood pressure and flow through the
  lungs and the rest of the body.
• The heart pumps about 100,000 times and moves
  7200 liters (1900 gallons) of blood every day.

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HEART ANATOMY

• The heart has four chambers.
• Two atria act as collecting reservoirs.
• Two ventricles act as pumps.
• The heart has four valves for
• Pumping action of the heart.
• Maintaining unidirectional blood flow.

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Functions of the Heart

• Generates blood pressure
• Routes blood
• Heart separates pulmonary and systemic
  circulation
• Ensures one-way blood flow
• Heart valves ensure one-way flow

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Functions of the Heart

• Regulates blood supply
• Changes in contraction rate and force match blood
  delivery to changing metabolic needs
• Most healthy people can increase cardiac output
  by 300500
• Heart failure is the inability of the heart to
  provide enough blood flow to maintain normal
  metabolism

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Cardiac Cycle

• The heart is two pumps that work together, right
  (pulmonary) and left (systemic) half
• Repetitive, sequential contraction (systole) and
  relaxation (diastole) of heart chambers
• Blood moves through circulatory system from areas
  of higher to lower pressure.
• Contraction of heart produces the pressure

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Cardiac Cycle
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HEART

• Deoxygenated blood returns to the heart via the
  superior and inferior vena cava, enters the right
  atrium, passes into the right ventricle, and from
  here it is ejected to the pulmonary artery.
• Oxygenated blood returning from the lungs enters
  the left atrium via the pulmonary veins, passes
  into the left ventricle, and is then ejected to
  the aorta.

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Blood Vessels

• Blood vessels are divided into a pulmonary
  circuit and systemic circuit.
• Artery - vessel that carries blood away from the
  heart. Usually oxygenated
• Vein - vessel that carries blood towards the
  heart. Usually deoxygenated.
• Capillary - a small blood vessel that allow
  diffusion of gases, nutrients and wastes between
  plasma and interstitial fluid.

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Blood Vessels

• Systemic vessels
• Transport blood through the body part from left
  ventricle and back to right atrium
• Pulmonary vessels
• Transport blood from right ventricle through
  lungs and back to left atrium
• Blood vessels and heart are regulated to ensure
  blood pressure is high enough for blood flow to
  meet metabolic needs of tissues

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Blood Flow
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LUNGS

• Lungs comprised of
• Airways
• Alveoli

http//www.aduk.org.uk/gfx/lungs.jpg
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What do the lungs do?

• Primary function is gas exchange
• Let oxygen move in
• Let carbon dioxide move out

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How do the lungs do this?

• First, air has to move to the region where gas
  exchange occurs.
• For this, you need a normal ribcage and
  respiratory muscles that work properly (among
  other things).

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Conducting Airways

• Air travels via laminar flow through the
  conducting airways comprised of the following
  trachea, lobar bronchi, segmental bronchi,
  subsegmental bronchi, small bronchi, bronchioles,
  and terminal bronchioles.

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How do the lungs do this?

• The airways then branch further to become
  transitional/respiratory bronchioles.
• The transitional/respiratory zones are made up of
  respiratory bronchioles, alveolar ducts, and
  alveoli.

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The Airways

• Conducting zone no gas exchange occurs
• Anatomic dead space
• Transitional zone alveoli appear, but are not
  great in number
• Respiratory zone contain the alveolar sacs
• Over 8 million branches

Weibel ER Morphometry of the Human Lung. Berlin
and New York Springer-Verlag, 1963
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How does gas exchange occur?

• Numerous capillaries are wrapped around alveoli.
• Gas diffuses across this alveolar-capillary
  barrier.
• This barrier is as thin as 0.3 µm in some places
  and has a surface area of 50-100 square meters!

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Gas Exchange

• Diffusion Barrier crossed by O2 moving from air
  to blood and CO2 from blood to air is made up
  of
• 1. an aqueous surface film
• 2. epithelial cells of alveolus
• 3. interstitial layer
• 4. endothelial cells of capillaries
• 5. blood plasma
• 6. membrane of RBCs

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Alveoli

• Approximately 300 million alveoli
• 1/3 mm diameter
• Total surface area about 85 sq. meters (size of a
  tennis court)

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Gas Exchange
From Netter Atlas of Human Anatomy, 1989
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Control of Ventilation

• Arterial PO2
• When PO2 is VERY low, ventilation increases
• Arterial PCO2
• The most important regulator of ventilation,
  small increases in PCO2, greatly increases
  ventilation
• Arterial pH
• As hydrogen ions increase, alveolar ventilation
  increases, but hydrogen ions cannot diffuse into
  CSF as well as CO2

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PANCREAS
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Anatomy of the Pancreas

• 5" long by 1" thick
• Head close to curve in C-shaped duodenum
• Main duct joins common bile duct from liver
• Sphincter of Oddi on major duodenal papilla
• Opens 4" below pyloric sphincter

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Anatomy of the Pancreas
Grays Anatomy of the Human Body
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Anatomy of the Pancreas
Exocrine glands have ducts that carry their
secretions to specific locations.
Digestive gland that secretes digestive enzymes
into the duodenum through the pancreatic duct.
Grays Anatomy of the Human Body Robbins Basic
Pathology http//faculty.clintoncc.suny.edu/facult
y/Michael.Gregory/default.htm
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Histology of the Pancreas
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Histology of the Pancreas

• Acini- dark clusters
• 99 of gland
• produce pancreatic juice
• Islets of Langerhans
• 1 of gland
• pale staining cells
• produce hormones

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Bicarbonate Ion Production
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Functions of the Pancreas

• Anatomy
• Endocrine
• Pancreatic islets produce insulin and glucagon
• Exocrine
• Acini produce digestive enzymes
• Regions Head, body, tail

• Secretions
• Pancreatic juice (exocrine)
• Trypsin
• Chymotrypsin
• Carboxypeptidase
• Pancreatic amylase
• Pancreatic lipases
• Enzymes that reduce DNA and ribonucleic acid

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Bicarbonate Ion Production
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LIVER
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LIVER

• Largest gland in the body (1.4 kg 3 lbs.)
• Produces bile
• Stored in GB
• Emulsifies fats
• Involved in metabolism
• Diaphramatic and visceral surface
• Right and left lobes
• Porta hepatis major vessels and nerves
• Right and left hepatic ducts, common bile, common

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Histology of the Liver

• Hepatocytes arranged in lobules
• Sinusoids in between hepatocytes are blood-filled
  spaces
• Kupffer cells phagocytize microbes foreign
  matter

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Histology of the Liver
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Histology of the Liver
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Functions of the Liver

• Bile production
• Salts emulsify fats, contain pigments as
  bilirubin
• Storage
• Glycogen, fat, vitamins, copper and iron
• Nutrient interconversion
• Detoxification
• Hepatocytes remove ammonia and convert to urea
• Phagocytosis
• Kupffer cells phagocytize worn-out and dying red
  and white blood cells, some bacteria
• Synthesis
• Albumins, fibrinogen, globulins, heparin,
  clotting factors

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Bile

• About 600 ml of bile is produced daily
• Bile acid
• Phospholipids
• Cholesterol
• Bilirubin
• Waste products
• Electrolytes
• Mucin

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KIDNEYS
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KIDNEYS

• Play a major role in maintaining homeostasis
• Maintain water balance
• Regulate the quantity and concentration of ECF
  ions
• Regulate the plasma volume
• Regulate pH by controlling elimination of acid
  and base in urine
• Maintain osmolarity
• Regulate the concentration of plasma constituents
  (e.g. electrolytes and water)

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KIDNEYS

• Kidneys have excellent blood supply 0.5 total
  body weight but 20 of Cardiac Output.
• Kidneys process plasma portion of blood by
  removing substances from it, and in a few cases,
  by adding substances to it.
• Works with cardiovascular system (and others!) in
  integrated manner

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Functions of the kidneys

• Regulation of H2O and inorganic ion balance
  most important function!
• Removal of metabolic waste products from blood
  and excretion in urine.
• Removal of foreign chemicals in the blood (e.g.
  drugs) and excretion in urine.
• Gluconeogenesis
• Endocrine functions (e.g. renin, erythropoetin,
  1,25-dihydroxyvitamin D)
• In kidney disease, build-up of waste serious, but
  not a bad as ECF volume and composition
  disturbances.

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Functions of the kidneys

• Water balance
• Electrolyte balance
• Plasma volume
• Acid-base balance
• Osmolarity balance
• Excretion
• Hormone secretion

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Acid-Base Balance

• Kidneys VERY important for acid-base balance,
  along with respiratory system.
• Important because all biochemical processes must
  occur within an optimal pH window.
• Prevent ACIDOSIS or ALKALOSIS.
• Although the lungs excrete a large amount of CO2,
  a potential acid formed by metabolism, the
  kidneys are crucial for excreting non-volatile
  acids.
• To maintain acid-base balance, kidney must not
  only reabsorb virtually all filtered HCO3-, but
  must also secrete into the urine the daily
  production of non-volatile acids.

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KIDNEY
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Internal Anatomy of Kidneys

• Cortex Outer area
• Renal columns
• Medulla Inner area
• Renal pyramids
• Calyces
• Major Converge to form pelvis
• Minor Papillae extend
• Nephron Functional unit of kidney
• Juxtamedullary
• Cortical

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Kidney Failure

• at age 49 years, the expected duration of life of
  a patient with end-stage renal disease on
  hemodialysis is 7 additional years compared with
  approximately 30 additional years for a person of
  the same age from the general population.

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Dialysis and Transplant
Hemo-dialysis
Peritoneal dialysis
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SKIN
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SKIN

• Largest organ of the body.
• Surface area 1.5 - 2 m2.
• Average adult weight 9 kg.
• Functions - protection, defence, sensation,
  thermoregulation, vit D synthesis, excretion,
  storage.

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SKIN

• 2 Principal portions
• Epidermis - epithelium
• Dermis areolar dense irregular connective
  tissue
• Hypodermis
• beneath the dermis
• the subcutaneous layer next to
• adipose layer or
• muscle or
• bone

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Functions of the Skin

• Protection
• Prevents invasion of environmental toxins and
  microorganisms
• Immunologic
• Sebum has antibacterial properties which helps
  shed topical bacteria
• Thermoregulation
• Insulates from heat loss and controls loss of
  heat through evaporation

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Functions of the Skin

• Fluid and Electrolyte Balance
• Controls sodium excretion
• Sebum retards fluid loss from skin
• Metabolism
• Produces Vitamin D
• Prevents excessive fluid loss
• Neurosensory
• Nerve endings and receptors process environmental
  stimuli for pain, touch, heat and cold
• Social and Interactive
• Provides body image and personal identity

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Epidermis

• Provides barrier function.
• Multilayered structure, continually regenerating.
• Thickness dependent on exposure to friction.
• Stratified squamous epithelium, organised in five
  layers.
• Stratum basale Stratum spinosum, Stratum
  granulosum, Stratum lucidum, Stratum corneum.

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Epidermis

• First layer of defense
• Composed of dead, keratinized cells and
  surrounded by a lipid monolayer
• There are no blood vessels. It is fed by
  capillaries in the dermis.
• If the epidermis is destroyed but the appendages
  of the dermis remain, a new epidermis is formed
  when the epithelial grow out of the hair
  follicles.

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• EPIDERMIS
• 4 cell types
• Keratinocytes - 90
• filled with keratin (protein)
• waterproof barrier
• Melanocytes - 8
• produce melanin (pigment)
• pass melanin to keratinocytes
• Langerhans cells
• phagocytes (from immune system)
• easily damaged by UV light
• Merkel cells
• in deepest layer of hairless skin
• sensory transduction - touch

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Epidermis
SC
SG
SS
B
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Dermis

• Varies in thickness across body.
• 1 mm on face , 4 mm on back.
• Responsible for most major functions of the skin.
• Two distinct layers
• Papillary dermis,
• Reticular dermis.

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Dermis

• Few cells present - fibroblasts, macrophages,
  adipocytes
• Intracellular matrix thick with many protein
  fibers collagen, elastin, reticular
• The location for blood vessels, nerves and
  sensory receptors, glands, hair follicles

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Dermis

• Collagen and fibrous connective tissue
• Contains capillaries and arterioles
• Has special sensory nerve fibers and lymph system
• Meissner Corpuscle light touch, just beneath
  epidermis
• Vater Pacini Corpuscles pressure sensors, deep
  in subq
• Ruffini Corpuscles heat sensors, deep in subq
  tissue
• Krause Corpuscles cold sensors, deep in
  subcutaneous tissue

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Dermis

• Papillary region - outer layer - 20
• areolar connective tissue, elastic fibers
• dermal papillae mound-like projections to
  increase the surface area for nutrition from
  capillaries
• some papillae contain Meissner's corpuscles (for
  light touch)

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Dermis

• Reticular region-80
• dense, irregular connective tissue
• collagen, elastic fibers in a network surrounding
  the various cells
• fibers give strength, elasticity, extensibility
• tears in reticular region - "stretch marks -
  long straight red or white streaks

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Layers of the Dermis.
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Subcutaneous Tissue

• Connective tissue
• Fat cells in most areas
• Blood vessels
• Nerves
• Base of hair follicles
• Function
• Insulation
• Storage of nutrients

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Skin Blood Vessels
Superficial dermal plexus.
Cutaneous plexus
Subcutaneous plexus.
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Types of Burns

• Superficial
• Superficial partial thickness
• Deep partial thickness
• Full thickness

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Partial Thickness Burn

• Can be superficial or deep
• Involves epidermis and dermis
• Has blister formation
• Moist appearance
• Tactile and pain sensors intact
• Will usually heal on own but will scar

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Full Thickness Burn

• Involves all layer of skin
• Has waxy and dry appearance
• Elasticity destroyed
• Painless
• Does not heal without intervention
• Autologous skin graft or banked skin