Chapter 24 Lecture Outline See PowerPoint Image Slides

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Chapter 24

Lecture Outline

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Exchanging Materials: Basic Principles

Large, multicellular organisms need a way to deliver oxygen and nutrients to the cells deep within tissues.

Several organ systems help deliver oxygen, nutrients to and remove wastes from cells.– Circulatory, lymphatic, respiratory, digestive, and

excretory systems


The Cardiovascular System

Pumps blood around the body Consists of

– Blood Fluid tissue that transports materials and heat

– The heart A muscular pump that forces fluid through the body

– Vessels “Pipes” that move blood through the body Arteries carry blood from the heart to the tissues. Capillaries are small vessels that carry blood through

tissues. Veins carry blood from the tissues to the heart.


The Nature of Blood

Consists of – Several types of cells

Called the formed elements

– Plasma Contains different kinds of dissolved molecules


Formed Elements

Red blood cells– Lack a nucleus– Contain hemoglobin– Transport oxygen and carbon dioxide– Carbonic anhydrase converts carbon dioxide to

bicarbonate that can be dissolved in the blood.– Anemia is a lack of oxygen resulting from a lack

of red blood cells.


Formed Elements

White blood cells– Also called leukocytes– Lack hemoglobin– Have a nucleus– Include basophils, eosinophils, neutrophils,

lymphocytes, and monocytes– Defend the body against microorganisms,

damaging chemicals, and cancer


Formed Elements

Platelets– Not whole cells– Fragments of white blood cells– Important in blood clotting

Collect at the site of a wound Release clotting factors

– Initiate a sequence of reactions that trap blood cells to form a clot

– Eventually the clots (scabs) are replaced by healthy, living tissue.


Plasma

Liquid part of the blood Contains

– Salts that serve to Buffer and maintain blood pH Maintain osmotic balance

– Keeps the tissue fluid between cells at the right solute concentration so that it flows into the capillaries, maintaining blood pressure


Plasma

Proteins– Antibodies and other immune proteins– Albumin to maintain osmotic balance

Transports bilirubin from degraded RBCs to the liver Accumulated bilirubin can cause jaundice

Nutrients– Amino acids– Sugars– Lipoproteins carry fats and cholesterol

Hormones


Composition of Blood


Functions of Blood

Transports molecules, cells – Oxygen, carbon dioxide– Nutrients– Waste products– Immune cells and antibodies– Hormones

Regulates temperature– If body temperature is too high, blood will be shunted to the

body surface to radiate heat.– If body temperature is too low, blood will be shunted to the

body core to conserve heat.


The Heart

Pumps the blood Generates the pressure necessary to move

blood through vessels– Blood must flow to move nutrients to

tissues and waste away from tissues.– Heart must repeatedly contract in order to

keep blood moving.


Mammalian Heart

Has four chambers with four valves– Two atria and two ventricles

Ventricles – Are larger and more muscular– Force blood through the arteries to the body– The aorta and pulmonary artery flow out of the

ventricles.Atria

– Are smaller with thinner walls– Pump blood into the ventricles


Mammalian Heart

Atria and ventricles are separated by atrioventricular valves. – Valves ensure that the blood only flows in one

direction. Semilunar valves in the aorta and pulmonary

arteries– Act as “check valves” to prevent blood from flowing

back into the ventricles when they relax Damaged valves causes inefficient pumping.

– Detected as heart murmurs because some of the blood is being pushed backward


The Anatomy of the Heart


Mammalian Heart

Two different sides have different jobs– The right atrium receives blood from the body.– The right ventricle pumps the blood to the lungs.

Called pulmonary circulation Allows for the exchange of carbon dioxide and oxygen in

the lungs

– The left atrium receives blood from the lungs.– The left ventricle pumps blood to all other parts of

the body. Called systemic circulation Allows for the delivery of oxygen, nutrient, and waste

exchange in the tissues


Pulmonary and Systemic Circulation


Blood Vessels

The tubes that transport blood from one place to another in the body

Types of blood vessels– Arteries– Veins– Capillaries


Arteries

Carry blood away from the heart Contraction of the ventricles increases the

pressure in the arteries.– Called systolic blood pressure

Relaxation of the ventricles decreases the pressure in the arteries.– Called diastolic blood pressure


Arteries

Blood pressure readings include both types of blood pressure.– Systolic/diastolic– 120/80

Have thick, muscular, and elastic walls– Can stretch when pressure increases

Branch into arterioles to take blood throughout the body


Veins

Collect blood from the capillaries and return it to the heart

Have very low pressure Walls not very muscular


Veins

Have valves to prevent backflow– Dysfunctional valves cause varicose veins.

Contraction of leg muscles aids in pushing blood through veins.– Sitting or standing for a long time can cause

pooling of blood in the feet.Causes swellingCan cause fainting because the brain doesn’t

get enough blood


The Structure of Arteries, Veins, and Capillaries


Capillaries

Tiny vessels, one-cell thick– RBC go through capillaries single file

Have thin walls– Only one-cell thick– Allows materials to diffuse into and out of the blood– Allows liquid to be exchanged between the blood and tissue

fluid

Are numerous– All cells in the body have a capillary nearby.

Flow of blood through capillaries is slow– Allows time for diffusion and fluid exchange


Capillaries


The Lymphatic System

A second circulatory system A collection of thin-walled vessels

– Called lymph vessels– Branch throughout body and lymph organs

Functions– Moves fat from digestive system to blood stream– Transports excess fluid back to cardiovascular

system– Carries immune cells





Lymph– Fluid tissue that is moved through the lymph

organs via lymph vessels– Emptied into large veins near the heart– Moved through lymph vessels by muscle

contraction

Edema– Accumulation of fluid in tissues


Lymph Organs

Lymph nodes– Filter lymph– Contain large numbers of white blood cells– Remove microorganisms and foreign particles from the

lymph– When an infection is active, the lymph nodes enlarge

Tonsils– Near the throat– Contain the tonsils and the adenoids– Filter pathogens that enter through the mouth and nose


Lymph Organs

Spleen– Contains a large number of white blood cells– Filters the blood

Cleans out pathogens and dying RBCs

– Located just below the diaphragm

Thymus– Produces WBCs called T-lymphocytes– Most active in children– Shrinks as one ages


Lymph Organs

Red bone marrow– Found in children’s bones– Reduced in adult bones– Produces RBCs, WBCs, and platelets


The Respiratory System

Moves air into and out of the body Lungs

– Allow gas exchange between air and blood Trachea

– A tube that carries air into and out of the lung– Branches into bronchi then into bronchioles– Bronchioles end in alveoli– Alveoli are small sacs where gas exchange takes place

Air-transport pathway– Includes the nose, mouth, and throat– Pulls air into the trachea


Respiratory Anatomy


Breathing System Regulation

Breathing is the process of moving air into and out of the lungs.

Involves the diaphragm– A large muscle that separates the chest cavity (containing

lungs) from the abdominal cavity– When contracted, the diaphragm moves down

Creates negative pressure in the chest cavity Pulls air into the lungs

– When relaxed, the diaphragm resumes its normal position Generates positive pressure in the chest cavity Pushes air out of the lungs


Breathing Movements


Breathing During Exercise

Exercise increases the body’s demand for oxygen.– Requires faster gas exchange in lungs– Accomplished by

Increased breathing rate– Can involve greater diaphragm contraction

to pull in more air


Breathing During Exercise

Can also involve contraction of abdominal muscles to fully empty the lungs– This happens when carbon dioxide concentration

increases in the blood and blood pH. Sensed by brain, then brain causes increased

contraction of the diaphragm and intercostal muscles

– Increased air exchange volume in each breath


The Control of Breathing Rate


Lung Function

Lungs are specialized so that blood and air can come very close together.– This facilitates gas exchange between them.– Blood flows through capillaries in the lungs that

come very close to the air in the alveoli.– Oxygen and carbon dioxide cross the alveoli and

capillary walls.– Therefore, the surface area of the alveoli must be

very large (collectively). This is why there are so many alveoli.


The Association of Capillaries with Alveoli


Lung Function

Gas exchange is facilitated by blood and air movement.– Blood enters the lungs high in carbon dioxide and

low in oxygen.– Air enters the lungs high in oxygen and low in

carbon dioxide.– Therefore, carbon dioxide diffuses from the blood

to the air and oxygen diffuses from the air to the blood.


Disrupting Lung Function

Interfering with blood flow or gas exchange will reduce the efficiency of the organism.– A poorly pumping heart reduces the amount of

blood that is sent to the lungs.– Constriction of bronchioles (asthma) reduces the

amount of air that can enter the alveoli.– Reducing the number of alveoli (emphysema)

reduces the surface area for gas exchange.


The Digestive System

Responsible for processing and distributing nutrients– Mechanical processing– Chemical processing– Nutrient uptake– Chemical alteration

Consists of – A muscular tube– Glands that secrete digestive juices


The Digestive System


Mechanical and Chemical Processing

The process of taking large pieces of food and breaking them down into individual molecules that can be absorbed

Mechanical processing– Chewing in the oral cavity generates a food bolus.

Increases surface area of foodAllows digestive enzymes greater access to

the food



Salivary glands produce saliva containing some digestive enzymes.– Chewing mixes the food with the saliva.

Salivary amylase begins to break down starch.

– Tongue Tastes food Pushes food back toward throat



Food bolus passes through the esophagus to the stomach

– Moves from mouth to the pharynx into the esophagus– Contractions of the pharynx move the food toward the

stomach.

In the stomach, food is churned.– Mixes food with digestive juices

Pepsin breaks down proteins.

– Low pH denatures proteins– The food then moves to the small intestine where chemical

breakdown is completed.



Chemical processing in the small intestine– Also known as the duodenum– Receives digestive enzymes and bicarbonate ions

from the pancreas Digestive enzymes complete the chemical processing of

food. Bicarbonate neutralizes the low pH of the food coming

from the stomach.

– Receives bile from the liver by way of the gall bladder

Emulsifies fat into smaller fat globules Allows digestive enzymes greater access to the fats



Finally, the remainder of the undigested food passes from the small intestine to the large intestine (colon).– 1.5 meters long– Water is reabsorbed.– Contains bacteria that utilize the undigested food

These bacteria produce vitamins that we need.


Digestive Enzymes


Nutrient Uptake

Once food is broken down into individual macromolecules, they can be absorbed into the bloodstream.– Absorption occurs through the lining of the small

intestine.– Requires a large surface area

The small intestine is very long (6 to 8 meters).The lining of the small intestine has fingerlike

projections called villi.


Nutrient Uptake

Each villus contains – Several capillaries– A lymphatic vessel called a lacteal

Involves diffusion – Water and small ions move into blood via simple

diffusion.– Sugars and amino acids move into blood via

carrier proteins.– Fatty acids and glycerol enter intestinal cells

where they are built into fats and transported into the lacteals.


Chemical Alterations: The Role of the Liver

The nutrient-rich blood leaves the intestine and goes straight to the liver.– Moves through the hepatic portal vein

In the liver– Enzymes modify the nutrient molecules.– Foreign organisms are filtered out.


Chemical Alterations: The Role of the Liver

Toxic substances are detoxified– Ethyl alcohol– Plant toxins

Excess glucose is collected and stored as glycogen.

Excess amino acids are converted to – Other types of amino acids– Glucose and stored– Urea and sent to the kidneys


The Excretory System (The Urinary System)

Responsible for the processing and elimination of metabolic waste– Urea– Toxic substances– Hydrogen ions– Water– Salts

Consists of– Kidneys– Ureters– Urinary bladder– Urethra


The Urinary System


Kidney Structure


Kidney Function

In order to filter out waste, kidney must have a close association with bloodstream– Exchange of waste occurs across a surface– Requires large surface area

Glomerulus represents a large surface area


Kidney Function

Major activities in kidney– Filtration

Blood enters glomerulus under pressure as the heart contracts.

Glomerular capillaries are porous.– Glucose, amino acids, ions, and water are pushed through

the pores into the nephron tubules.


Kidney Function

Reabsorption– Not everything that is filtered into the nephron needs

to be excreted.– Some molecules are reabsorbed into capillaries

around the nephron. Amino acids, glucose, sodium

– Occurs mostly in the proximal convoluted tubule– Water is reabsorbed in the Loop of Henle.

Occurs because of osmotic gradients that exist in the kidney

Concentrates the urine and conserves water


Kidney Function

Secretion– Additional waste is moved from the capillaries

around the nephron into the distal convoluted tubule.


Specific Functions of the Nephron

Chapter 24 Lecture Outline See PowerPoint Image Slides

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muscularforce blood

lack of red blood cells

thinner wallspump blood

cells oxygen

lack of oxygen

body core

body surface