Transcript Heart - HODS - Halachic Organ Donor Society

Anatomy and Physiology
Heart, Lungs, Pancreas,
Liver, Kidneys and Skin
B. Paul White, MD
HOD ID#: 2078
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HEART
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HEART
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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
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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 300–500%
• 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
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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
Weibel ER: Morphometry of the Human
Lung. Berlin and New York: SpringerVerlag, 1963
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• 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
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How does gas exchange
occur?
• Numerous capillaries are wrapped
around alveoli.
• Gas diffuses across this alveolarcapillary barrier.
• This barrier is as thin as 0.3 μm in some
places and has a surface area of 50100 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
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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
Anatomy of the Pancreas
• 5" long by 1" thick
• Head close to curve in Cshaped 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
Gray’s Anatomy of the Human Body
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Anatomy of the Pancreas
Exocrine glands have ducts that carry their secretions to specific locations.
Gray’s Anatomy of the Human Body
Robbins Basic Pathology
http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/default.htm
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Digestive gland that secretes digestive enzymes
into the duodenum through the pancreatic duct.
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Histology of the Pancreas
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
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)
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Trypsin
Chymotrypsin
Carboxypeptidase
Pancreatic amylase
Pancreatic lipases
Enzymes that reduce
DNA and ribonucleic
acid
Bicarbonate Ion Production
LIVER
LIVER
• Largest gland in the body (1.4 kg – 3 lbs.)
• Produces bile
– Stored in GB
– Emulsifies fats
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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
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• 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, 1,25dihydroxyvitamin 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
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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
Hemodialysis
Peritoneal
dialysis
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SKIN
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SKIN
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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
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Epidermis - epithelium
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Dermis – areolar &
dense irregular
connective tissue
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Hypodermis
– “beneath the dermis”
– the subcutaneous layer
next to:
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adipose layer or
muscle or
bone
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Functions of the Skin
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Protection
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Prevents invasion of environmental toxins and microorganisms
Immunologic
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Sebum has antibacterial properties which helps shed topical
bacteria
Thermoregulation
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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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• Papillary region outer layer - 20%
Dermis
– 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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• Reticular region80%
Dermis
– 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
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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
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Superficial
Superficial partial thickness
Deep partial thickness
Full thickness
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Partial Thickness Burn
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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
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Involves all layer of skin
Has waxy and dry appearance
Elasticity destroyed
Painless
Does not heal without intervention
– Autologous skin graft or banked skin
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