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Circulatory System
Circulatory System
Blood Summary
• Cells (called formed elements)
– Thrombocytes (platelets)
• No nucleus. Fragments of red bone marrow cells
• Function in clotting of blood
Blood Clotting
• Blood vessel wall
broken
• Platelets stick to each
other and to break.
Release clotting
factors.
Blood Clotting
• Protein called
prothrombin
converted to
thrombin, which
causes fibrinogen in
plasma to become
fibrin (protein
threads)
• These threads bind
together platelets and
blood cells to make
clot.
How Phagocytic WBCs work
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Damage to tissues
Mast cells release histamine
Causes blood vessels to dilate
Increases permeability of capillaries.
How Phagocytic WBCs work
• Neutrophils and monocytes stick to lining of
capillary
• Squeeze through wall into tissue
• Locate and digest invading cells.
Excretory System
Excretory System
• Quick review through the animal phyla:
– Platyhelminthes: Flame cells in protonephridia
– Draw in body fluids using cilia
– Tubule reabsorbs some materials as fluids flow to
excretory pores.
Excretory System
• Quick review through the animal phyla:
– Annelida: Nephridia. Body fluid forced into tubules
under pressure
– Some materials (salts) reabsorbed on way to pore.
Excretory System
• Quick review through the animal phyla:
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Insects: Malphigian tubules (extensions of gut)
Materials secreted into tubules by cells in walls
Tubules empty into hindgut
Some materials reabsorbed by hindgut on way out.
Excretory System
• Here we emphasize human. Rat seen in lab.
Excretory System Functions
• 1) Removal of wastes or other unwanted
materials from body
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water, salts
nitrogenous wastes (urea, ammonia, uric acid)
carbon dioxide
heavy metals (Pb, Cd, Hg)
• 2) Balance water and dissolved materials in
body tissues: osmoregulation.
Nitrogenous Wastes
• Generated when amino acids converted to other
molecules in body (deamination)
• Also when nitrogenous bases of nucleic acids
converted to other molecules.
Nitrogenous Wastes
• What formed?
– 1) Ammonia. Toxic, so must be kept highly diluted.
Feasible only for aquatic animals.
Nitrogenous Wastes
• What formed?
– 2) Urea. Much less toxic. Soluble in water, so must be
eliminated using water (in urine).
Nitrogenous Wastes
• What formed?
– 3) Uric acid. Low toxicity, not very soluble in water.
Little water used to eliminate it.
– BUT, formation complex and uses much energy.
Pretending to be Nitrogenous Wastes
• Uric acid: white material in bird droppings and
lizard poop
Excretion
• Human organs involved:
– 1) skin: sweat glands excrete water, salts (Na, K,
Ca), some urea.
Excretion
• Human organs involved:
– 2) lungs: excrete carbon dioxide, water (up to 1
liter per night), and.............alcohol.
Excretion
• Human organs involved:
– 3) liver: bile pigments get rid of rbc breakdown
products
– 4) large intestine: some salts and metals enter and
join feces.
Excretion
• Human organs involved:
– 5) kidneys: form urine. Regulate water balance and
remove urea (nitrogenous waste) and other waste
materials.
Urinary Tract
• Renal artery and vein: Blood to/from kidney
• Kidneys: one on each side
• Ureter: duct from kidney to bladder.
Urinary Tract
• Urinary bladder (expandable muscular bag): urine
storage
• Urethra: duct from bladder to opening
• Female: Urethral opening. Male: Urogenital
opening (both urine and semen pass through).
Kidney anatomy
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Renal capsule: connective tissue sheath
Cortex: outer region
Medulla: inner region
Renal pelvis: leads to ureter.
Kidney anatomy
• Functional unit: nephron
• About 1 million per kidney
• Found mostly in renal cortex, some extend into
medulla.
Nephron structure
• Arterioles enter/leave Bowman’s capsule
• Glomerulus: capillary bed inside capsule
Nephron structure
• Proximal convoluted tubule: close to capsule
• Loop of Henle: constricted portion
• Distal convoluted tubule: far from capsule
Nephron structure
• Peritubule capillaries: bring blood close to
tubules again
• Collecting duct: carries final product (urine) to
ureter.
Kidney function
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Step 1: Filtration
Step 2: Reabsorption
Step 3: Secretion
Step 4: Excretion.
Kidney function
• Step 1: Filtration
• High pressure blood enters afferent arteriole
• At glomerulus in renal corpuscle, plasma leaks
into Bowman’s capsule as filtrate
• Filtered blood leaves by efferent arteriole.
Kidney function
• Step 1: Filtration
• Filtrate passes to convoluted tubule
• Contains: water, urea, salts, glucose, amino acids,
etc. Everything in blood except formed elements
and plasma proteins.
Kidney function
• Step 2: Tubular
reabsorption
• What’s reabsorbed?
– water (65%), by Loop of
Henle and distal
convoluted tubule
– NaCl (65%), by Loop of
Henle
– glucose (100%): proximal
tubule
– most amino acids:
proximal tubule
– Most urea stays in tubule.
Kidney function
• Step 3: Tubular secretion
• Active transport of materials into collecting tubules.
• Some toxic molecules, some medicines (ex,
penicillin)
• H+ secreted to maintain blood pH (urine slightly
acidic).
Kidney function
• Step 4: Excretion
• Collecting duct to
renal pelvis to
ureter
Kidney function
• Step 4: Excretion
• To bladder, where stored
(up to 1 liter)
• Internal urethral sphincter
(smooth muscle)
• External urethral sphincter
(skeletal muscle: under
voluntary control in adults)
• Contraction of bladder and
relaxation of sphincters
allows urination.
Busy kidneys
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Body has about 5 liters blood
Kidneys filter 2000 liters of blood per day
180 liters of filtrate produced
1-2 liters of urine made per day
Kidney function
• Summary: Urine contains water, salts, urea, H+
• How balance body water content?
• Hormone called antidiuretic hormone (ADH).
Controls water reabsorption in convoluted
tubules and Loop of Henle.
Problems with the system
• Kidney stones: material in urine
crystallizes.
• If large, has hard time passing down ureter
and through urethra. Painful (stretching of
ureter)!
• Some women say worse than childbirth....
Problems with the system
• Can be broken up with ultrasound so
it passes more easily. Can be
removed surgically.
• Causes: heredity, infection, diet,
dehydration, etc.
Problems with the system
• Drink plenty of water!
Stone removed from bladder
of Afghan boy
Problems with the system
• Diabetes
– diabetes insipidus: not enough antidiuretic hormone
produced
– water not reabsorbed by nephrons. Lots of dilute
urine made.
Problems with the system
• Diabetes
– diabetes mellitus (sugar diabetes)
– actually is problem with pancreas function or liver
function low insulin production, or liver not
responsive to insulin, or combination
– results in high glucose level in blood
– kidneys adjust by not reabsorbing much glucose
from filtrate (lots glucose in urine)
– may result in kidney failure, blindness, heart
disease, etc.
Problems with the system
• Kidney failure
– transplants: from cadavers or live donors
– dialysis: using machine to artificially filter blood