Circulatory System Circulatory System Blood Summary Cells called

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 – Na. Cl (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 p. H (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 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