Set 3 - Excretory System Lecture (Kidneys) - Bio 100

The physiological system that deals with getting rid of wastes is called the ______________ system. Included in this system are the skin, the large intestine, the liver, the lungs, and most importantly, the _______________.

Excretory

kidneys

The excretory system deals with all sorts of wastes, however, the kidneys only deal with ____________ (large/small), _____________ (hydrophilic/hydrophobic) wastes.

small, hydrophilic

The kidneys are part of the urinary system, which has many important homeostatic roles. We talked about five homeostatic roles that the kidneys play. What are they?

The kidneys:

~ Rid the body of small hydrophilic wastes and toxins

~ Regulate the amount of water in our body

~ Regulate the amount and types of solutes in our blood

~ Assist in blood pH regulation

~ Assist in blood pressure regulation

The kidneys also helps to make sure we have enough red blood cells, by secreting the hormone, ____________ when oxygen levels in the blood are too low.

erythropoietin

What organ sits right on top of each kidney?

adrenal gland

The abdominal aorta leads straight down to the kidneys, branching off into two __________ arteries that lead directly to the kidneys. And coming from the kidneys you have blood going back to the heart through two __________ (same name as above) _________.

renal arteries

renal veins

What is the functional unit of the kidney called (the filtering unit)? The ___________.

nephron

Thousands of nephrons exist in each kidney, each draining urine into the area called the ________________.

renal pelvis

Urine is sent from the renal pelvis to the ____________.

ureter

Each ureter drains urine into the ____________.

bladder

Where is urine stored until you're ready to "go"? In the ____________.

bladder

Urine leaves the bladder and enters the ____________ before leaving the body to enter the "cruel, harsh world".

urethra

In which order does urine exit the body from the point where it is made?

nephron --> renal pelvis --> ureter --> bladder --> urethra --> out

The first part of the nephron, which is the actual filter, is called _____________.

Bowman's capsule

What is the Glomerulus?

It is the capillary network that fits into Bowman's capsule at the beginning of the nephron. The filtrate of the blood (small, hydrophilic stuff) leaves this capillary network and goes into Bowman's capsule.

The filtrate that goes into Bowman's capsule next goes into the ____________ tubule.

proximal

Note: it's actually called the proximal convoluted tubule, but we just shortened it. :-)

Following the proximal tubule, the filtrate goes to the ________________.

Loop of Henle

After the Loop of Henle, where does the filtrate go?

the distal tubule

Note: it's actually called the distal convoluted tubule, but we just shortened it. :-)

The last part of the nephron, where you reclaim any additional water you may need is called the _____________.

From this part of the nephron, what leaves is considered "urine" as it collects in the renal ___________.

collecting ducts

pelvis

What is the order of filtrate movement from the point at which is leaves the glomerular capillaries to the renal pelvis?

glomerular capillaries --> Bowman's capsule --> proximal tubule --> Loop of Henle --> distal tubule --> collecting duct --> renal pelvis

The first step in kidney function is ___________ (reabsorption, filtration, secretion), in which a specific type of blood vessel leading out of the glomerular capillaries actually constricts, putting pressure on the fluid in the glomerular capillaries. This type of blood vessel is a(n) ____________.

filtration

arteriole

The types of substances that you may find in the filtrate leaving Bowman's capsule normally include: (select all that apply with an *)

A) H2O

B) large hydrophilic molecules

C) large hydrophobic molecules

D) red blood cells

E) white blood cells

F) small hydrophilic molecules

G) small hydrophobic molecules

The types of substances that you may find in the filtrate leaving Bowman's capsule normally include: (select all that apply with an *)

A) H2O *

B) large hydrophilic molecules

C) large hydrophobic molecules

D) red blood cells

E) white blood cells

F) small hydrophilic molecules *

G) small hydrophobic molecules

After filtration occurs at the glomerulus and Bowman's capsule, you will next refine the filtrate by reclaiming the "good stuff" back into the bloodstream and getting rid of substances (like excess H+, wastes and toxins) that may have not entered the filtrate.

Taking back the good stuff is called _____________, and expelling the "bad stuff" that accidently escaped the filtrate is called ___________.

reabsorption

secretion

Antidiuretic Hormone (ADH) is a hormone that is released by the _________ under what conditions?

On what organ does it act? ____________.

What does it cause this organ to do?

ADH is a hormone that is released by the brain when you don't have enough water in your blood (when you are dehydrated and/or your solute concentration in the blood is too high).

It acts on the kidneys, and causes the kidneys (the collecting ducts) to reabsorb more of the water that is in the filtrate back into the bloodstream, increasing the water levels in your blood.

Note: in the next lectures, we learn that the specific part of the brain that makes ADH is the hypothalamus, and it is stored and released from the posterior pituitary of the brain.

What do both caffeine and alcohol do to the release of ADH?

What occurs as a result of this action?

Caffeine and alcohol both inhibit the release of ADH, and therefore, the kidneys can't reabsorb as much water and your urine is more diluted (and a larger volume). This makes you need to "pee" more frequently.

Aldosterone is a steroid hormone that is released by the _____________.

adrenal cortex

Which of the following would NOT cause a release of aldosterone into the bloodstream? (select all that apply with an *)

High blood pressure

Low levels of sodium (Na+) in the blood

High blood volume

Which of the following would NOT cause a release of aldosterone into the bloodstream? (select all that apply with an *)

High blood pressure *

Low levels of sodium (Na+) in the blood

High blood volume *

Note: The trigger to release aldosterone is either low sodium levels, low blood volume or low blood pressure.

What organ does aldosterone act on, and what is the ultimate response?

Aldosterone acts on the kidneys, causing an increase in Na+ reabsorption.

Along with this reabsorption, you will get an increase in both blood pressure and blood volume.

Aldosterone acts to increase Na+ reabsorption into the bloodstream. How does this affect water levels in the blood?

Since Na+ is a solute, H2O is also reabsorbed along with it by osmosis.

This serves to increase Na+ levels in the blood, and the additional water results in an increase in blood pressure and an increase in blood volume.

Individuals with kidney failure often have to undergo treatment several times a week to remove wastes from the blood and maintain solute concentration. This treatment is called ___________.

dialysis