Download Lungs and External Exchanges of Gases (cont.)

Essentials of Biology
Sylvia S. Mader
Chapter 24
Lecture Outline
Prepared by: Dr. Stephen Ebbs
Southern Illinois University Carbondale
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
24.1 Digestive System
• There are three organ systems in the body
that facilitate the exchange of gases,
nutrients, and wastes with the cells and
fluids of the body.
– Digestive system
– Respiratory system
– Urinary system
• The activity of these systems helps the
body maintain homeostasis.
Tube-Within-a-Tube Body Plan
• The digestive systems of most animals is
a complete tube-within-a-tube, meaning
that it has a mouth and anus.
• This inner tube is separated from the body
wall by the coelom.
• The basic plan for the digestive system is
similar across animal species.
Tube-Within-a-Tube Body Plan
(cont.)
Tube-Within-a-Tube Body Plan
(cont.)
• The digestive system of animals performs
four essential functions.
– Ingests food
– Breaks down food into smaller molecules
– Absorbs nutrients in molecules
– Eliminates indigestible waste
Mouth
• For most animals, the digestive tract begins with
the mouth.
• While teeth mechanically tear and grind food,
the salivary glands release the enzyme amylase
into the mouth to degrade carbohydrates.
• The ground, partially-digested food material that
is swallowed is called a bolus.
Swallowing
• In many animals, the digestive and respiratory
systems share a common passage behind the
mouth called the pharynx.
• The flow of food through the pharynx and into
the esophagus is assisted by the epiglottis,
which covers the respiratory passage.
• The rhythmic contractions of the esophagus,
called peristalsis, move food to the stomach.
Swallowing (cont.)
Stomach
• The stomach is the organ in which proteins in
food are digested.
• The low pH of the stomach and the presence of
the enzyme pepsin accomplish the digestion of
proteins.
• Peristalsis moves food through the stomach
while a sphincter regulates the flow of digested
food into the intestine.
Stomach (cont.)
Stomach (cont.)
• Ruminant is a term used to describe
animals like cattle that have a stomach
with a compartment called the rumen.
• The rumen contains symbiotic bacteria
that help these herbivores digest plants.
• When animals chew cud, they are chewing
the partially-digested rumen product.
Stomach (cont.)
Small Intestine
• The digested food material the exits the stomach
and enters the small intestine is called chyme.
• The small intestine provides two functions.
– Additional digestion of food material
– Absorption of nutrients
• Three additional organs that assist the small
intestine.
– Liver
– Gallbladder
– Pancreas
Small Intestine (cont.)
• The liver produces bile to emulsify fats for
digestion and absorption.
• Excess bile is stored in the gallbladder.
• The pancreas produces a juice that contains
substances that enhance digestion.
– Sodium bicarbonate, to increase chymal pH
– Pancreatic enzymes
Small Intestine (cont.)
• There are several pancreatic enzymes.
– Pancreatic amylase to digest starches
– Trypsin to digest proteins
– Lipase to digest fats
– Nuclease to digest nucleic acids
• Absorption of the digested nutrients is facilitated
by hair-like villi in the intestine.
• The villi have microvilli to greatly increase their
surface area for absorption.
Small Intestine (cont.)
Small Intestine (cont.)
Large Intestine
• The large intestine absorbs water, salts,
and some vitamins.
• The appendix is a pouch of the large
intestine.
• Bacteria in the large intestine digest
remaining material prior to excretion of the
wastes (feces) through the anus.
Pancreas
• The pancreas functions as both an endocrine
and exocrine gland.
• The endocrine function of the pancreas involves
secretion of insulin and glucagon into the
bloodstream.
• The exocrine function of the pancreas involves
the secretion of pancreatic juice into the small
intestine.
Liver
• The liver has a variety of functions.
–
–
–
–
–
–
Removal of poisons and toxins from the blood
Production of plasma proteins
Destruction of old red blood cells
Production of bile
Storage of glucose as glycogen
Production of urea, a nitrogenous waste
• The liver functions are carried out as blood from
the intestines travels to the liver through the
hepatic portal system.
Liver (cont.)
Liver (cont.)
• Disorders of the liver can have a
significant effect on human health.
– Jaundice occurs when there is an excessive
concentration of bile pigments in the blood.
– Hepatitis is a viral infection of the liver.
– During cirrhosis, liver tissue changes to
become fatty and then non-functional scar
tissue.
24.2 Respiratory System
• The respiratory system allows for the exchange
of gases between the blood and the external air.
• Animal respiration involves three steps.
– The inspiration (inhalation) and expiration (exhalation)
of breathing
– External gas exchange between the air and blood
within the lungs
– Internal gas exchange between the blood and body
fluids
24.2 Respiratory System (cont.)
The Human Respiratory Tract
• The human respiratory system includes the
lungs and all structures that move air to and
from the lungs.
• The respiratory tract is lined with cilia to filter
debris and dust.
• The air flowing through the respiratory system is
also warmed to body temperature and saturated
with water.
The Upper Respiratory Tract
• The upper respiratory tract consists of three
structures.
– Nasal cavities and the interconnected sinuses
– The pharynx
– The larynx, or voice box, and the vocal cords
• The tonsils are lymphatic tissue at the junction
between the mouth and pharynx.
• The glottis is the opening between the pharynx
and larynx.
The Upper Respiratory Tract
(cont.)
Lower Respiratory Tract
• The respiratory tract consists of the
respiratory tree.
– The trachea, or windpipe
– The primary bronchii leading to each lung
– The smaller, branching bronchioles within
each lung
– The sac-like alveoli at the end of each
bronchiole where gas exchange occurs
Breathing
• All terrestrial vertebrates except birds breathe
due to the contraction of the diaphragm.
• Contraction of the diaphragm creates a negative
pressure that causes inspiration.
• Relaxation of the diaphragm causes expiration.
• The method of breathing creates a bi-directional,
reversible flow of air.
Breathing (cont.)
Breathing (cont.)
• In birds, the
ventilation of the
lungs is a one-way
path.
Lungs and External Exchanges
of Gases
• The branching of the bronchioles and numerous
alveoli of the lungs provide a large surface area
for gas exchange.
• The alveoli are in close contact with blood
vessels, forming the respiratory membrane
which facilitates gas exchange.
• Emphysema is a lung condition that occurs
when the alveolar walls have been damaged.
Lungs and External Exchanges
of Gases (cont.)
Lungs and External Exchanges
of Gases (cont.)
Lungs and External Exchanges
of Gases (cont.)
• Aquatic animals use gills to facilitate gas
exchange.
• The gills have an extensive capillary
network that directly exchanges gases
with water flowing over the gills.
Lungs and External Exchanges
of Gases (cont.)
Transport and Internal Exchange
of Gases
• It is the heme group of the hemoglobin in red
blood cells that carries oxygen.
• Hemoglobin acquires oxygen as the blood flows
through the vessels surrounding the alveoli.
• Several factors can trigger the release of oxygen
from hemoglobin.
– A decrease in the oxygen concentration in the tissues
– Increased temperature
– Decreased pH
Transport and Internal Exchange
of Gases (cont.)
• Carbon dioxide is carried in the blood as
dissolved bicarbonate (HCO3-).
• When the blood passes through the vessels
surrounding the alveoli, the carbon dioxide
diffuses into the alveoli for expiration.
• The breathing center of the brain regulates the
rate of breathing by monitoring blood pH.
Transport and Internal Exchange
of Gases (cont.)
24.3 Urinary System and
Excretion
• The mammalian kidney serves several
important functions.
– Excretion of nitrogenous wastes
– Maintenance of water-salt balance of blood
– Maintenance of the blood pH
• The urine made by the kidneys passes
through the ureter to the urinary bladder,
where it is stored prior to excretion through
the urethra.
24.3 Urinary System and Excretion
(cont.)
Kidneys
• The kidney has three main regions.
– The renal cortex is the outer region.
– The renal medulla lies underneath the cortex.
– The renal pelvis is the innermost layer.
• The urine-producing cells that make up the
kidney are called nephrons.
Kidneys (cont.)
Nephrons
• Nephrons have several parts which
contribute to the formation of urine.
– The nephron capsule, which allows for the
diffusion of molecules from the blood
– The proximal tubule, tightly packed with
microvilli
– The nephron loop, which has a descending
and ascending limb
– The distal tubule
– The collecting duct
Urine Formation
• There are three steps in urine formation.
– During filtration, small molecules pass from
the blood into the nephron capsule.
– Nutrients and other molecules move back to
the blood during reabsorption.
– During secretion, wastes are selectively
transported into the distal tubule.
Urine Formation (cont.)
Problems with Kidney Function
• A variety of human illnesses are
associated with kidney problems.
– Renal disease and failure can be caused by
hypertension or diabetes.
– Kidney stones can form from pH imbalances,
excess Ca, or urinary tract infections.
– Edema (build up of fluid) can occur if too
many nephrons are blocked or are not
functioning.
Hemodialysis and Kidney
Replacement
• Patients with renal failure may require
hemodialysis to filter their blood.
– Artificial kidney machines
– Continuous ambulatory peritoneal dialysis
• In extreme situations, it is necessary to
replace the damaged kidney with a
transplant.
Hemodialysis and Kidney
Replacement (cont.)