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Excretory System. The Kidneys. regulate the volume and chemical make-up of the blood metabolize vitamin D . Kidney Structure. Pelvis: expansion of upper ureter (lies within kidney) Calyces: divisions of the renal pelvis Cortex: Outer Layer Medulla: Inner Portion
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The Kidneys • regulate the volume and chemical make-up of the blood metabolize vitamin D
Kidney Structure • Pelvis: expansion of upper ureter(lies within kidney) • Calyces: divisions of the renal pelvis • Cortex: Outer Layer • Medulla: Inner Portion • Pyramids: triangular divisions of the medulla
Nephron: the structural unit of the kidney • Bowman’s Capsule: cup-shaped top of nephron • Glomerulus: network of capillaries surrounded by Bowman’s capsule • Renal Tubule: • Proximal Convoluted Tubule • Loop of Henle: extension of proximal tubule • Collecting Tubule • Distal Convoluted Tubule:
Filtration: in the glomerulus • Blood flows into kidneys and more specifically into the glomerulus • The blood exerts pressure high enough to push water and dissolved substances out of the glomerulus and into the Bowman’s Capsule.
Tubular Reabsorption: in the Loop of Henle • Substances move out of the renal tubules into the capillaries • Those substances reabsorbed include: • Water • Glucose • Sodium
Ureters: slender tubes that convey urine from the kidneys to the bladder • Bladder: collapsible muscular sac that, in males, is just anterior to the rectum, and in females, is anterior to the vagina and uterus. • Urethra: is a thin-walled muscular tube that drains urine from the bladder and conveys it out of the body.
Mechanisms for Urine Volume Control • Adrenal Cortex: produces aldosternone • Stimulates tubules to absorb salt at a faster rate • Increases tubular reabsporption rates • Posterior Pituitary Gland: produces antidiuretic hormone (ADH) • Makes distal and collecting tubules permeable to water • Decrease amount of urine excreted
Micturition:he act of emptying the bladder • As urine accumulates, the bladder stretches and stretch receptors are activated. • Occurs when about 200 mL of urine has accumulated • impulses are sent to the brain and one begins to feel the urge to urinate • Activation of the micturition center in the pons signals the need to urinate
Characteristics of Urine • clear and pale to deep yellow • slightly acidic • around 6. 95% of urine volume is water • largest solute component is urea, a product of protein breakdown • other nitrogenous wastes include creatine and uric acid • In certain diseases, urine composition will change dramatically.
Abnormal urinary constituents can include: • Glucose - due to diabetes mellitus • Proteins - due to hypertension or glomerulunephritis • Ketone bodies - due to starvation or diabetes mellitus • Leukocytes - due to urinary tract infection • Erythrocytes - due to a bleeding urinary tract.
Thursday March 17 Excretory Exam