Human Anatomy Unit 9 - Urinary/Excretory System

Excretory System Includes

• Lungs

• Skin

• Liver

Urinary System Includes

• Kidneys

• Bladder

• Ureters

• Urethra

Kidneys Function

• Filters out toxins/wastes

• Reabsorbs useful nutrients

Gluconeogenesis Step 1

• Process of forming new glucose molecules

  • Occurs when dietary sources, reserves, and blood glucose levels are low

Gluconeogenesis Step 2

• Produces renin (regulates blood pressure) and erythropoietin (produces RBCs)

Gluconeogenesis Step 3

• Activating vitamin D

Kidneys Micro Anatomy

• Pathway of blood filtration to urine formation and secretion

Nephrons

• Functional unit of kidney that filters blood

Collecting Ducts Step 1

• Receives filtrate from nephrons

Collecting Ducts Step 2

• Transports filtrate through medullary pyramids

Collecting Ducts Step 3

• Delivers urine to the calyx

Calyx

• Delivers urine to ureters —> bladder —> urethra

Kidneys Support Tissues

1. Fibrous Capsule

2. Perirenal Fat Capsule

3. Renal Fascia

Fibrous Capsule

• Prevents infections spreading to kidneys

Perirenal Fat Capsule

• Attaches kidney posteriorly and provides cushioning

Renal Fascia

• Dense connective tissue, anchors kidney and adrenal gland

Renal Ptosis

• Cause: significant decrease of fatty capsule

  • Kidneys drop to inferior position —>

  • Ureter may twist —>

  • Urine can’t be transported —>

  • Urine backs up in kidneys (renal failure)

Adrenal Glands

• Part of endocrine system

• Secretes adrenaline: prepares body for emergency situations

Parts of the Nephron

• Bowman’s capsule

• Glomerulus

• Renal tubule

  • Proximal tube

  • Loop of Henle

  • Distal tube

Bowman’s Capsule

• Surrounds and hold glomerulus

Glomerulus

• Capillaries at top of tubule

• Porous so substances can pass through

Renal Tubule

• Reabsorption and filtration occurs

• Empties in collecting ducts

Steps of Urine Formation

1. Glomerular formation

2. Tubular reabsorption

3. Tubular secretion

Glomerular Formation

• Passive process (no energy)

• Small particles enter glomerulus

  • Water, glucose, amino acids, and waste)

• Large particles remain in blood vessel to maintain osmotic pressure

  • Plasma proteins

Tubular Reabsorption

• Selective process to reclaim useful materials

  • Glucose and amino acids

• Depending on material being reabsorbed, process can be passive or active

• Loop of Henle

  • Descending limb: reabsorbs water

    • Due to ADH (hormone)

  • Ascending limb: reabsorbs only solutes

Non-reabsorbed Substances

• Excess materials and nitrogenous waste products will be secreted

  • Ex. urea

Tubular Secretion

• Tubules remove unwanted substances directly from blood vessels

  • Removal of toxins and excess materials that were not filtered

  • Regulates blood pH

Renal Failure

• Requires dialysis (filter of blood)

  • 3.5-4 hours a day, 3+ days a week

  • Mortality on dialysis is 25% if diabetic

Reasons for Transplantation in US

• Majority due to hypertension and diabetes

• Cancer often causes renal failure

  • High mitotic rate of cells causes cell lysis —>

  • More work for kidneys to “clean up”

Donors and Recipients must be

• No diabetes or hypertension

• Healthy BMI

• Cancer and infection free

• No psychological illness - must understand donation

Transplant Team

• Transplant surgeon, nephrologist, transplant coordinators, dietician, and social worker

Living Donors

• No greater risk in the future for dialysis or renal failure

• If you need an organ later, you will automatically go to top of list

Cadaveric Donor: Adult Donor

• Each kidney goes to 1 recipient

Cadaveric Donor: Pediatric Donor

• Both kidneys go to same recipient due to size

Recipients

• Cadaveric donation: kidney lasts 8-14 years

• Living donation: kidney lasts 15+ years

Matching Donor and Recipient

1. Must be A, B, O compatible

2. Must match HLA alleles

3. Must match negative cross match

A, B, O Compatibility

• Must match with the correct blood type

• Separate wait list for each blood type

Checking HLA Allele Matches

• 3 HLAs for kidneys: A, B, and DR

  • 2 alleles for each antigen

    • Each child has 3 antigen matches with each parent (6 total)

  • Perfect match: has all 6 antigens

    • Can still do transplant even with 0 antigen match

Negative Cross Match

• Confirm antibodies do NOT exist in recipient

  • These would attack the new kidney

• Preformed antibodies:

  • Previous organ transplantation, blood transfusions, and pregnancy

Waitlist Categories

1. Standard criteria donors (young, healthy people)

2. Expanded criteria donors (older then 60)

3. CDC high risk (young donors with high risk behaviors)

4. Live donors

5. Live donors paired exchange

Transplantation

• Do not take out original kidney unless infected (PKD) or malignant

  • Attach new kidney to ureter, arteries, and veins

  • Position in anterior pelvic cavity

Immunosuppressants

• Allograph survival rate >90% with drugs

• Drug regiment

  • Cyclosporine or Prograf: inhibits T-cell proliferation

  • Cellcept: blocks DNA synthesis in T-cells —> lowers ability for T cells to divide

  • Steroids: use depending on institution