Lecture 28: OVERVIEW AND GROSS STRUCTURE OF THE KIDNEY Flashcards
What portion of a male is water?
60%
What portion of a female is water?
55%
What is the reason for the differences in water content between males and females?
Males have more muscle which holds water while females have more adipose which holds less water
What is the total body water made up of?
1/3 extracellular fluid and 2/3 intracellular fluid
What is crucial?
Balance of water (and solutes) in the body
How does the urinary system maintain balance?
By filtering the blood and expelling:
- excess water
- excess salts
- wastes of metabolism
- many toxins and drugs
How much blood flows through the kidney per minute?
1200 ml
How much urine is produced by a typical person in a day?
800-2000ml
What is urine?
Waste product excreted to maintain balance within the body
What is found in normal urine?
Water, salts, urea, metabolites, hormones and small proteins
Is urine pH regulated?
No, not tightly (4.6-8) as it is influenced by what is being excreted
What is urine useful for?
A diagnostic tool for disease states
What is in abnormal urine?
Large proteins (too big to be filtered), RBC’s (too big to be filtered) and glucose (filtered but completely reabsorbed)
What does the urinary system need to be effective?
- delivery system for blood
- selective filtration system (based largely on size)
- filtrate recovery mechanism (reabsorption)
- system to return recovered, filtered fluid to the body
- system to remove filtrate from the body
- protection
- ability to communicate with relevant parts of the body
- adaptable to meet the body’s changing needs
What are the main components of the urinary system?
2 kidneys, 2 ureters, urinary bladder and urethra
What does the structure of the kidney allow?
- blood to be brought into close proximity with the nephron for filtering
- blood that has been filtered to leave the kidney
- a pathway for urine to be removed from the kidney, stored and then excreted
- protection
What vertebra are the kidneys between?
T12 and L3
What ribs are the kidneys near?
11th and 12th
Where does the convex side of the kidney face?
Laterally
What does the medial surface of the kidney have?
A concave notch called the hilum
What enters and exits the hilum of the kidneys?
renal blood vessels, lymphatics, nerves and the ureter
Are kidneys intra or retroperitoneal?
Retroperitoneal - located on the posterior abdominal wall, covered on the anterior side by peritoneum
What surrounds, supports and protects the kidneys?
Fat
What kidney is found slightly lower?
The right kidney because the liver is found on that side and pushes it down slightly
What are the three regions of the kidney?
Cortex, medulla and pelvis
What surrounds the kidney?
A fibrous capsule
What is the structure of inner medulla?
Divided into pyramids with each medullary pyramid ending in a papilla
What is the structure of the outer cortex?
Continuous layer with renal columns
What do the cortex and medulla form?
Functional lobes
How many lobes per kidney?
5-11
What does a lobe consist of?
One medullary pyramid and all the cortex that surrounds it (including the renal columns)
What is the kidney lobes largely made of?
Nephrons - tiny tubes that filter from blood and create urine (thousands of these)
Where does urine drain?
From each papilla and collects in a calyx
What do calyces do?
Join to form the renal pelvis
What does the pelvis do as it exits the hilum?
Narrows to become the ureter
What is the path of urine travel?
papilla > minor calyx > major calyx > renal pelvis > ureter
What does a pyelogram show?
Where urine is present in the body
How is urine produced?
By filtering waste from blood into the nephron
What part of the kidney does filtration occur in?
The cortex
What does the renal artery arise from?
The abdominal aorta and enters at the hilum
What do branching arteries do?
Get smaller and smaller until they reach the cortex
What area of the kidneys contains no vessels?
The medullary pyramids
What do veins do?
Return filtered blood from the cortex into the renal vein to the inferior vena cava
What is the path of blood supply into the cortex to be filtered?
Abdominal aorta > renal artery > series of arteries > afferent arteriole which delivers blood from the arteries to the glomerulus where filtration occurs > glomerular capillaries
What is the glomerulus made up of?
Glomerular capillaries
What is the path of blood supply away from the cortex after being filtered?
Glomerular capillary > efferent arteriole carries blood from the glomerulus to the > peritubular capillaries > series veins > renal vein > inferior vena cava
What is the innervation of the kidneys from?
A network of autonomic nerves and ganglia called the renal plexus
What do sympathetic nerves do?
Act to adjust the diameter of renal arterioles and therefore regulate blood flow
What is a nephron?
A microscopic functional unit of the kidneys
What is the bulk of the kidney made up of?
Nephrons
What does the nephron do?
Filters blood, selectively reabsorbs or secretes and produces urine
What are the components of the nephron?
Renal corpuscle (glomerulus capsule and glomerulus), proximal convoluted tube, nephron loop, distal convoluted tube, collecting duct
