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• 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:

– 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– 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• 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• 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• 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 bladderof 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