See this lesson in powerpoint format:

Digestive HERE

Circulatory  HERE

Respiratory  HERE

Nutritional Requirements

Cells need:

• Water
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
• Vitamins-- Study Table 41.1 pg. 854
• Minerals - Table 41.2 pg. 855

Digestion: the breakdown of ingested food materials into molecules that can be delivered to and utilized by the individual cells.

Can be both mechanical and chemical.

"The Gut"- continuous surface with the outside of body!

I. The Digestive Tract in Vertebrates: Fig.41.13 pg. 860

Made of 4 layers

• Mucosa: (innermost) -epithelial, connective, some smooth muscle
• Submucosa: connective, nerve fibers, blood & lymph vessels
• Muscularis Externa: muscle tissue (circular & longitudinal)
• Serosa: outer covering of connective tissue

Peristalsis: coordinated contractions of circular muscles along digestive tract which move food along

Sphincters: thickened, heavy bands of muscle along tract that act as valves by contracting (closing) and relaxing (opening) to control of materials

A. The Oral Cavity: Initial Processing:

Teeth: mastication (chewing) for mechanical digestion

• incisors- cutting
• canines- tearing, stabbing
• premolars- "bicuspids" 2 cups (protuberances)
• molars- 4 or 5 cusps

Other Animals--

• rasping tongue:  ex- lamprey, frogs
• grinding organ (gizzard): ex- birds, earthworms
  

Chemical Digestion (enzymatic hydrolysis): saliva, mucous

3 pairs of salivary glands and buccal glands in jaw:  lubricates, softens food

Enzymes- slightly alkaline (sodium bicarbonate), salivary amylase (hydrolysis of starch)

B. The Pharynx & Esophagus: Swallowing

Swallowing: passage of food to the esophagus ----> stomach

• begins as voluntary action (striated muscles in upper part of esophagus) lower portion involuntary (smooth muscle)= "peristalsis"
• Esophagus opens into Stomach
• Abdominal cavity lined with peritonium / organs are suspended by mesentaries

C. The Stomach: Storage & Liquefaction

Stomach: a collapsible, muscular, j-shaped bag with many folds and ridges

• mucosal lining folds into gastric pits, lined with mucous secreting epithelial cells
• gastric glands secrete HCl and pepsinogen (precurser to pepsin)
• pH between 1.5 & 2.5 (mucous barrier between acids + stomach lining )- ulcers?

- HCl:

• kills bacteria
• loosens tissues for digestion
• converts pepsinogen to pepsin

-Pepsin: breaks down proteins into peptides

Semi-liquid mass moves to lower end of stomach => Pyloric Sphincter (takes about 4 hrs.) "Chyme"

Rate of leaving Stomach = H₂O, carbs, proteins, fat, protein/fat combo

the three phases of gastric secretion animation

D. The Small Intestine: Digestion

• folds in submucosa VILLI ( microscopic fingerlike projections) and tiny MICROVILLI on surface of epithelial cells
• about 6 meters long (adult), total surface area about 300 m²

1. Digestion:

Duodenum- 1st 25 cm- most digestion takes place here; receives several juices/ enzymes from ACCESSORY GLANDS, liver pancreas, gall bladder

Accessory Glands- neutralize stomach acids with alkaline secretions

Bile- produced by liver, stored in gall bladder; contains salts (emulsify fats),sodium bicarbonate (neutralize pH to optimum 7 or 8)

Pancreas =

1. Amylase: continue starch dig.-->disacchanides-->lactose maltase sucrase-->monosaccharide
2. Trypsin: breaks down proteins --> AA’s
3. Lipase: hydrolyzes fats

** See chart, Fig. 41-21 pg. 859**

2. Absorption of Nutrients:

food absorbed through epithelial cells of intestinal mucosa

Active Transport: Monosaccharides, Dipeptides, Amino Acids

Diffusion: fatty acids

Lipids resynthesize into triglycerides, phospholipids (blood & lymph vessels), Cholesterol

Ruminants: symbiotic w/ bacteria (anaerobic), Vitamins B & K and break down plant matter

E. The Large Intestine: Further Absorption & Elimination

The Large Intestine continues absorption of water, sodium, and other minerals (which begins in small intestine)

E. coli Bacteria: makes Vit.K, A.A. synthesis

Appendix: vestigial organ?

Waste: "fecal matter" = Water, bacteria, dead cells, indigestible matter (cellulose) - lubricated with mucus, Temp. storage in rectum

F. Accessory Glands:

Pancreas: exocrine gland--->secretes hydrolytic enzymes

endocrine gland---> secretes regulatory hormones (insulin, glucagon, somatostatin)

"Islets of Langerhans"

Liver: (~3lbs. avg.)

Stores & releases carbohydrates

• regulates blood glucose
• synthesizes enzymes
• clotting factors
• plasma proteins
• filters red blood cells
• inactivates certain hormones
• breaks down foreign substances (ex: alcohol)

Regulation of Blood Glucose-- liver converts monsaccharides to glycogen (storage polysaccharide) and fats

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Chapter 42 - Circulation and Gas Exchange

CirculatorySystem

Blood: the "chemical highway" that connects the many cells of an organism

• Carries nutrients, Oxygen to each cell
• Carries wastes away from cells (Oxygen, urea) to kidneys, lungs, ski
• Carries enzymes, hormones, water, antibodies around body

I. The Blood

A. Plasma = 60% of blood; straw-colored fluid

90% water; carries most CO₂, nutrients, plasma proteins

plasma proteins

1. albumin (to maintain high osmotic potential)
2. fibrinogen (clotting)
3. globulins (immune, antibodies)

B. Red Blood Cells (erythrocytes)

• Transport oxygen; non-nucleated (cannot repair themselves)
• (25 trillion in bloodstream) short lifespan (120-130 days)
• Replaced by bone marrow stem cells

C. White Blood Cells (leukocytes)

(1 or 2 for every 1,000 RBC) larger than RBC, have nucleus, no hemoglobin, colorless

• Can migrate outside of vessels (RBC’s cannot)
• phagocytosis of bacteria/viruses/etc.
• "Pus"-dead WBC; new WBC form in spleen, bone marrow

D. Platelets

• colorless, oval/irregular shaped, smaller then RBC’s
• "little bags of chemicals" that function in clotting and plugging up breaks in vessels

Blood Clotting- a complex series of chemical reactions,involving platelets and "clotting factors

Thromboplastin

Prothrombin------------------------------>Thrombin

produced in liver

Fibrinogen---------------------------------------------> Fibrin

15 CF’s involved in this conversation (Hemophiliacs lack Factor VIII)

clotting animation

II. The Cardiovascular System

"Hearts"

simplest (in earthworms) just an enlarged, muscular portion of a blood vessel "aortic arches"

Mollusks= chambered heart with open circulation

Vertebrates= chambered heart with closed system

III. The Blood Vessels connective tissue DIAGRAM

Heart--->Arteries--->Arterioles--->Capillaries--->Venules--->Veins--->Heart (etc)

Arteries: thick, muscular walls, elastic (endothelium/muscle/connective tissue)

Veins: thinner walls (than arteries) , less elastic (less pressure); valves to prevent backflow (endothelium, muscle, connective

The Capillaries and Diffusion

• the site of all exchange with cells
• in very close contact with all cells
• one cell thick
• one layer of endothelium
• smallest diameter of all vessel, only about 5 um (RBC pass in single file)

IV. The Heart

multiple chambers serve to separate oxygenated/ deoxygenated blood

• Atrium (receiving chamber)
• Ventricle (pumping chamber)

The Human Heart

made of epithelial, connective tissues and Cardiac Muscles (infatiguable)

Pulmonary Circulation---> Pulmonary vein (from lungs)

Human Heart Diagram

• Four chambers (2 atria, 2 ventricles)
• Superior and Inferior Vena Cava lead into heart (right atrium)
• Pulmonary artery brings blood to lungs
• Aorta leads out to systemic circulation
  

• semilunar valves: prevent backflow into vessels/chambers

• atrioventricular valves: (mitral and tricuspid) between atria & ventricles; allow one-way flow between atria and ventricle

• septum- dividing wall between right and left side of heart

Total volume of blood pumped by heart per minute

Cardiac Output = Heart Rate x Stroke volume

(L/min) = (BPM) (L/beat)

[ex: 72 BPM* 0.07 L/beat = 5L/min.]

Heart also secretes hormone: "atrial natriuretic" (salt excretion)

• regulates blood volume and blood pressure

Human heart animated tour

A. Regulation of Heartbeat

Cardiac muscle able to initiate its own impulse

The heart's electrical circuitry

• Sinoatrial Node (SA)- "pacemaker" In Right Atrium; initiates beat through both Atria; stimulates another area near center of heart called AV Node
• Atrioventicular Node (AV)...then impulse is carried to the ventricles by the BH
• Bundle of His (BH) = like the transfer of an electrical current along a circuit

Heart Rate is modified by the Autonomic Nervous System (vagus nerve)

• Parasympathetic Nerves- slow down HR
• Sympathetic Nerves- increase HR

V. Vascular Circuitry

Systemic circulation

• portal circulation
• coronary arteries (supplies heart)
• carotid (leads to brain)
• hepatic (in/out of liver)
• digestive
• renal (in/out of kidneys)

VI. Blood Pressure

120 = systole; ventricles contract (empty);arteriole diameter enlarged

80 =diastole; ventricles relax (fill)

arterial BP----->venous BP

Cardiovascular Regulating Center (in medulla)

• controls activity of the nerves regulating the smooth (circular) muscle contraction of the blood vessel
• also controls strength of heartbeat, HR
• receives and interprets and responds to sensors through the cardiovascular system (esp. in the walls of the vessels) baroreceptors, CO₂ receptors

VII. The Lymphatic System

"Osmotic potential" of blood= concentration of plasma proteins in blood which keeps water from osmosing out of blood vessels into tissues (interstitial fluid)

Under arterial pressure, the BP exceeds the osmotic potential, thus forcing some plasma and WBC out into tissues. This is collected by Lymph vessels which clean the tissue/ cellular debris (such as bacteria) out of the body cells.

Lymph flows thru Lymph Nodes to be cleaned

These also make Lymphocytes (WBC’s)

Lymph re-enters the circulatory vessels via the Subclavian Veins in the neck (back into bloodstream)

The Respiratory System

Respiration: exchange of O₂

• Cellular Respiration: mitochondria --> ATP...

• Organismal Respiration: exchange of gases between cells and environment

I. Diffusion & Air Pressure:

Atmospheric pressure: mm Hg

O₂

(higher altitude, lower pressure)

enters blood via Diffusion

II. Evolution of the Respiratory System:

Diffusion-->Direct Respiration-->Indirect Respiration-->Resp. Organs

ex. Insects = Tracheae (cuticle-lined tubules in abdomen) good for small animals only

A. GILLS- arose as a feeding device

Increase respiratory surface; bring blood in contact w/ O₂

Thin, one cell thick membranes, folded, layered (high surface area)

"Counter Current Exchange"

circulatory vessels are arranged so blood is pumped through in opposite direction of water (O₂)

(Regulated by movement of fish’s mouth and operculum)

B. LUNGS- internal cavities

• More efficient than gills (21% O2/Air, 0.5% O2 in Water)

• Fish must process more H2O to get the same amount of O2 as in Air (Energy-Consuming)

• Snails- primitive lungs

• Lungfish

• Amphibians, Reptiles- simple lungs

C. RESPIRATION IN LARGE ANIMALS-

1. "Bulk-flow" of air into lungs (thin, close to blood vessels)

2. Diffusion of O2 across membrane into blood  animation
   

3. Bulk-flow of O2 in blood to tissues

4. Diffusion of O₂ into individual cells

III. The Human Respiratory System:

Nasal passages (mucus,cilia)-->pharynx-->larynx-->trachea-->R&L bronchi-->bronchioles-->alveoli

• Smooth Muscles can dilate/constrict the bronchi, bronchioles

• Alveoli (alveolus) thin walls surrounded by capillaries; gas exchange through capillary/alveolar walls via diffusion

• thin Pleural Membrane encases lungs-- secretes lubricants

IV. Mechanics of Respiration:

Breathing- due to pressure changes w/in thoracic cavity

breathing animation

muscles:

• diaphragm = relaxes--> rises / contracts--> lowers

• Inspiration -vs- Expiration

• Abdominals/ Intercostals

V. Transport and Exchange of Gases:

A. HEMOGLOBIN - respiratory pigment; oxygen-carrying protein molecule w/ central iron (Fe) atom

Mollusks & Arthropods: hemocyanin, blue w/ O₂

heme carried on RBC, can carry 4 Oxygen molecules each (O not very soluble in plasma)

Most CO₂ is carried in the plasma as carbon anhydrase (in RBC), carbonic acid, bicarbonate ion (HCO₃^-)

Gas Exchange depends upon pressure and concentration differences between atmosphere and bloodstream

"Diving Reflex" in marine mammals

B. MYOGLOBIN- respiratory pigment found is skeletal muscle

• has higher O₂ affinity than hemoglobin

• O₂ reserve for muscles under stress

VI. Control of Respiration:

• Respiratory under control of brainstem (medulla)
• Involuntary, but can be brought under voluntary control temporarily
• Many "sensors" located throughout body that give feed back to brain resp. centers: sensors sensitive to CO₂, O₂, H⁺ levels stretch sensors in lungs & chest
• Chemoreceptors in Carotid Arteries detect [O₂]

ex: [H⁺] up, (= high [CO₂] in blood), breathing becomes faster/deeper

changes in the partial pressures of oxygen and carbon dioxide  animation