Transcript Biology

Biology
Mr. Karns
Excretory
system
Slide
1 of 36
End Show
Each kidney
Is supplied with blood by a renal artery and
drained by a renal vein
Posterior vena cava
Renal artery and vein
Kidney
Aorta
Ureter
Urinary bladder
Urethra
Figure 44.13a
(a) Excretory organs and major
associated blood vessels
Slide
2 of 36
End Show
38–3 The Excretory
System
Slide
3 of 36
End Show
38–3 The Excretory System
Functions of the Excretory System
Functions of the Excretory System
Every cell produces metabolic wastes.
The process by which these wastes are eliminated
is called excretion.
Slide
4 of 36
End Show
38–3 The Excretory System
Functions of the Excretory System
The skin excretes excess water and salts in the form
of sweat.
The lungs excrete carbon dioxide.
The kidneys also play a major role in excretion.
Slide
5 of 36
End Show
38–3 The Excretory System
Functions of the Excretory System
The Kidneys
What are the functions of the kidneys?
Slide
6 of 36
End Show
38–3 The Excretory System
Functions of the Excretory System
The kidneys:
• remove waste products from the blood.
• maintain blood pH.
• regulate the water content of the blood
and, therefore, blood volume.
Slide
7 of 36
End Show
38–3 The Excretory System
The Kidneys
The kidneys are located on either side of the
spinal column near the lower back.
A tube, called the ureter, leaves each kidney,
carrying urine to the urinary bladder.
The urinary bladder is a saclike organ where
urine is stored before being excreted.
Slide
8 of 36
End Show
38–3 The Excretory System
The Kidneys
Structure of the Kidneys
Kidney
Nephron
Slide
9 of 36
End Show
38–3 The Excretory System
The Kidneys
Blood enters the kidney through the renal artery.
The kidney removes urea, excess water, and other
waste products and passes them to the ureter.
The clean, filtered blood leaves the kidney through
the renal vein and returns to circulation.
Slide
10 of 36
End Show
38–3 The Excretory System
The Kidneys
Kidney Structure
A kidney has two distinct regions:
• The inner part is called the renal medulla.
• The outer part is called the renal cortex.
Slide
11 of 36
End Show
38–3 The Excretory System
The Kidneys
Cortex
Medulla
Renal
artery
Renal vein
Ureter
To the bladder
Slide
12 of 36
End Show
38–3 The Excretory System
The Kidneys
The functional units of the kidney are called
nephrons.
Nephrons are located in the renal cortex, except for
their loops of Henle, which descend into the renal
medulla.
Slide
13 of 36
End Show
38–3 The Excretory System
Bowman’s capsule
The Kidneys
Capillaries
Glomerulus
Vein
Artery
Loop of Henle
Collecting
duct
To the ureter
Slide
14 of 36
End Show
38–3 The Excretory System
The Kidneys
Capillaries
Each nephron has its
own blood supply:
• an arteriole
• a venule
Collecting
duct
• a network of
capillaries
connecting them
Vein
Artery
To the ureter
Slide
15 of 36
End Show
38–3 The Excretory System
The Kidneys
Capillaries
Each nephron releases
fluids to a collecting duct,
which leads to the ureter.
Collecting
duct
Vein
Artery
To the ureter
Slide
16 of 36
End Show
38–3 The Excretory System
The Kidneys
How is blood filtered and removed?
Slide
17 of 36
End Show
38–3 The Excretory System
Excretory Processes
Most excretory systems (4 basic parts)
Produce urine by refining a filtrate derived
from body fluids
Capillary
Filtrate
Excretory
tubule
1 Filtration. The excretory tubule collects a filtrate from the blood.
Water and solutes are forced by blood pressure across the
selectively permeable membranes of a cluster of capillaries and
into the excretory tubule.
2 Reabsorption. The transport epithelium reclaims valuable substances
from the filtrate and returns them to the body fluids.
3 Secretion. Other substances, such as toxins and excess ions, are
extracted from body fluids and added to the contents of the excretory
tubule.
Urine
Figure 44.9
4 Excretion. The filtrate leaves the system and the body.
Slide
18 of 36
End Show
38–3 The Excretory System
What are the 4 parts?
Say it outloud
Slide
19 of 36
End Show
38–3 The Excretory System
Key functions of most excretory systems
are
1. Filtration, pressure-filtering of body fluids
producing a filtrate
2. Reabsorption, reclaiming valuable solutes
from the filtrate
3. Secretion, addition of toxins and other
solutes from the body fluids to the filtrate Slide
20 of 36
End Show
38–3 The Excretory System
The Kidneys
As blood enters a nephron through the
arteriole, impurities are filtered out and
emptied into the collecting duct.
The purified blood exits the nephron
through the venule.
Slide
21 of 36
End Show
38–3 The Excretory System
The Kidneys
The mechanism of blood purification involves two
distinct processes: filtration and reabsorption.
Slide
22 of 36
End Show
38–3 The Excretory System
The Kidneys
Filtration
Passing a liquid or gas through a filter to remove
wastes is called filtration.
The filtration of blood mainly takes place in the
glomerulus.
The glomerulus is a small network of capillaries
encased in the top of the nephron by a hollow,
cup-shaped structure called Bowman's capsule.
Slide
23 of 36
End Show
38–3 The Excretory System
The Kidneys
Fluid from the blood flows into Bowman’s capsule.
The materials filtered from the blood include water,
urea, glucose, salts, amino acids, and some vitamins.
Plasma proteins, cells, and platelets remain in the
blood because they are too large to pass through the
capillary walls.
Slide
24 of 36
End Show
38–3 The Excretory System
The Kidneys
Reabsorption
Most of the material removed from the blood at
Bowman's capsule makes its way back into the
blood.
The process in which liquid is taken back into a
vessel is called reabsorption.
Slide
25 of 36
End Show
38–3 The Excretory System
The Kidneys
Almost 99% of the water that enters Bowman’s
capsule is reabsorbed into the blood.
When the filtrate drains in the collecting ducts, most
water and nutrients have been reabsorbed into the
blood.
Slide
26 of 36
End Show
38–3 The Excretory System
The Kidneys
Remaining material, called urine, is emptied into a
collecting duct.
Urine is primarily concentrated in the loop of Henle.
The loop of Henle is a section of the nephron tubule
in which water is conserved and the volume of urine
minimized.
Slide
27 of 36
End Show
38–3 The Excretory System
The Kidneys
As the kidney works, purified blood is returned to
circulation while urine is collected in the urinary
bladder.
Urine is stored here until it is released from the body
through a tube called the urethra.
Slide
28 of 36
End Show
38–3 The Excretory System
Control of Kidney Function
Control of Kidney Function “Homeostasis”
The activity of the kidneys is mostly controlled by
the composition of the blood.
In addition, regulatory hormones are released in
response to the composition of blood. This is
controlled by a hormone ADH from the Pituitary
Gland.
Slide
29 of 36
End Show
38–3 The Excretory System
Pituitary Gland feedback system
Pituitary Gland
What is the function of the pituitary gland?
Slide
30 of 36
End Show
38–3 The Excretory System
Pituitary Gland – master control
The pituitary gland secretes nine hormones that
directly regulate many body functions and
controls the actions of several other endocrine
glands.
Slide
31 of 36
End Show
38–3 The Excretory System
Pituitary Gland
The pituitary gland is a structure at the base of
the skull.
The gland is divided into two parts: the anterior
pituitary and the posterior pituitary.
Remember anterior – front side or ventral
posterior- toward the rear / dorsal side
Slide
32 of 36
End Show
38–3 The Excretory System
Pituitary Gland
The Pituitary Gland
Hypothalamus
Anterior
pituitary
Posterior
pituitary
Pituitary
gland
Slide
33 of 36
End Show
38–3 The Excretory System
Pituitary Gland
Slide
34 of 36
End Show
38–3 The Excretory System
Control of Kidney Function
When you drink a liquid, it is absorbed into the blood
through the digestive system.
As a result, the concentration of water in the blood
increases.
As the amount of water in the blood increases, the
rate of water reabsorption in the kidneys decreases.
Less water is returned to the blood, and excess water
is sent to the urinary bladder to be excreted as urine.
Slide
35 of 36
End Show
38–3 The Excretory System
Control of Kidney Function
When the kidneys detect an increase in salt, they
respond by returning less salt to the blood by
reabsorption.
The excess salt the kidneys retain is excreted in
urine, thus maintaining the composition of the blood.
Slide
36 of 36
End Show
38–3 The Excretory System
Antidiuretic hormone (ADH)
Increases water reabsorption in the distal tubules
and collecting ducts of the kidney
Osmoreceptors
in hypothalamus
Thirst
Hypothalamus
Drinking reduces
blood osmolarity
to set point
ADH
Increased
permeability
Pituitary
gland
Distal
tubule
STIMULUS:
The release of ADH is
triggered when osmoreceptor cells in the
hypothalamus detect an
increase in the osmolarity
of the blood
H2O reabsorption helps
prevent further
osmolarity
increase
Collecting duct
Homeostasis:
Blood osmolarity
Figure 44.16a
(a) Antidiuretic hormone (ADH) enhances fluid retention by making
the kidneys reclaim more water.
Slide
37 of 36
End Show
38–3 The Excretory System
Kidney Disorders
Kidney Disorders
Humans have two kidneys, but can survive with
only one.
If both kidneys are damaged by disease or injury,
there are two options:
•
•
a kidney transplant
kidney dialysis
Slide
38 of 36
End Show
38–3 The Excretory System
Kidney Disorders
Kidney dialysis works as follows:
• Blood is removed by a tube and pumped through
special tubing that acts like nephrons.
• Tiny pores in the tubing allow salts and small
molecules to pass through.
• Wastes diffuse out of the blood into the fluid-filled
chamber, allowing purified blood to be returned to
the body.
Slide
39 of 36
End Show
38–3 The Excretory System
Kidney Dialysis
Kidney Disorders
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Shunt
Used dialysis fluid
Air
detector
Dialysis
machine
Fresh
dialysis
fluid
Compressed
air
Slide
40 of 36
End Show
38–3
Click to Launch:
Continue to:
- or -
Slide
41 of 36
End Show
38–3
A dialysis machine performs the function of
which structure in the excretory system?
a. nephron
b. ureter
c. urethra
d. glomerulus
Slide
42 of 36
End Show
38–3
In the human body, the kidneys play an
important role in
a. producing digestive enzymes.
b. circulating the blood.
c. destroying old red blood cells.
d. maintaining homeostasis.
Slide
43 of 36
End Show
38–3
In the nephron, most filtration occurs in the
a. renal tubule.
b. capillaries.
c. glomerulus.
d. loop of Henle.
Slide
44 of 36
End Show
38–3
Urine leaves the body through the
a. loop of Henle.
b. glomerulus.
c. urethra.
d. bladder.
Slide
45 of 36
End Show
38–3
Materials filtered out of the blood include all of
the following EXCEPT:
a. water.
b. urea.
c. amino acids.
d. plasma proteins.
Slide
46 of 36
End Show
END OF SECTION