HS130: Anatomy & Physiology II

Unit 6 Seminar:

The Urinary System

Tonight’s Agenda

• Welcome

• Course Questions, Problems & Issues

• Unit 5 Review

• Seminar discussion

Unit 5 Issues to Review

• Absorption-Where?• Dietary fats are

converted into?• Carbs break down

into?• Where does Krebs

cycle occur?• Where is electron

transport?

The HeartThe Urinary SystemThe Urinary System

Chapter 19The Urinary System

Structures

• Kidneys

• Ureters

• Bladder

• Urethra

Function of Kidneys

– Excrete toxins and nitrogenous wastes– Regulate levels of many chemicals in blood– Maintain water balance– Help regulate blood pressure

Kidneys

• Under back muscles• Behind parietal peritoneum• Just above waistline• Right kidney usually a little lower than left

Inside the Kidneys

• Renal cortex• Renal medulla• Renal pyramids• Renal pelvis

– Major calyces – Minor calyces

Nephron• Microscopic• “Functional Unit” • Renal corpuscle

• Bowman’s capsule• Glomerulus

• Renal tubule• Proximal convoluted tubule• Loop of Henle• Distal convoluted tubule

• Collecting tubule

Ureters

• Narrow long tubes with expanded upper end (renal pelvis) inside kidney

• Lined with mucous

• Muscular layer in wall

• Drains urine from renal pelvis to bladder

Urinary Bladder

• Elastic muscular organ

• Capable of great expansion

• Stores urine before voiding

Urethra

• Narrow tube from urinary bladder to exterior

• Opening of urethra to the exterior called urinary meatus

Steps in UrineFormation

• Filtration

• Reabsorption

• Secretion

Micturition

• Passage of urine from body (also called urination or voiding)

• Regulatory sphincters– Internal urethral sphincter (involuntary)– External urethral sphincter (voluntary)

• Bladder wall permits storage of urine with little increase in pressure

Micturition

• Initiated by stretch reflex in bladder wall

• Bladder wall contracts

• Internal sphincter relaxes

• External sphincter relaxes, and urination

Seminar question

• The kidneys function as important homeostatic mechanisms for many conditions in the body. Predict what changes in urine production would occur in a patient who suffered a surgical injury to the hypothalamus