Digestion
Food enters the mouth where it is mechanically broken down by the teeth and tongue. Salivary amylase is release by the salivary glands, this saliva is an enzyme which breaks down the starch in the food. The food is formed into a bolus autonomic muscles contract the bolus into the esophagus, by the epiglottis which is a flap in the pharynx. The esophagus sends the food into the stomach which mechanically churns the food and also releases gastric juices that begins the digestion of proteins. The stomach is lined with chief cells which release pepsinogen, perietal cells which secrete hydrochloric acid, keeping the pH of the gastric juice at about 2.5. it also kills any unwanted bacteria or substances that are in the stomach. The third cell produces mucous which protects the lining of the stomach from being burned by the gastric juice. Food leaves the stomach through the pyloric sphincter and into the small intestine. By the time the food reaches the duodenum, it is completly digested. The enzymes inside the intestine, along with pancreatic amylase break down starch and glycogen into maltose. The liver produces bile, and that bile is sent to the gallbladder wher it is stored. That bile is released into the small intestine when it is needed to break down fats. This creates a greater surface area for digestive enzymes inside the small intestine. Peptidases, such as trypsin and chyromtrypsin continue to break down proteins. Nucleic acids are broken down by nuclease. once all of the nutrients the molecules are digested, the bottom of the small intestine absorbs all of the nutrients. Villi, which are small hair like structures, line the small intestine and these are what do the absorbing. Each villi contains capillaries which allows the nutrients to be moved throughout the body faster. The large intestine sends the food to the colon, then to the rectum where it is excreted from the body.
Liver and Pancreas
Pancreas- Enzymes, or digestive juices, produced by the pancreas are secreted into the small intestine to further break down food after it has left the stomach. The gland also produces the hormone insulin and secretes it into the bloodstream in order to regulate the body's glucose or sugar level. Insulin also causes the liver to convert glucose to glycogen and store it for when it is needed.
Liver- The liver has many jobs
Liver- The liver has many jobs
- produces bile- The liver's main function is to produce substances that help the body break down fat. The liver manufactures bile that assists in the breakdown and digestion of food.
- Glucose and Blood- The liver converts glucose to glycogen (sugar), the body's main source of energy. It also detoxifies the blood making it clean and pure for use in the body.
- Storage- The liver stores many vitamins and minerals such as vitamins A, D, K and B12. It also produces certain amino acids that are the building blocks of necessary proteins.
- Produce Urea- The liver manufactures urea, which is the main component of urine. It helps the body secrete excess waste, ammonia, nitrogen and protein.
Blood Flow Through Heart
![Picture](/uploads/2/5/9/4/25948740/7917030.jpg?477)
Right atrium > Tricuspid valve > Right ventricle> Pulmonary valve > Pulmonary arteries to lungs > pulmonary veins from lungs > Left atrium > Left AV valve > Left venticle > Semi lunar valve > Aorta > (renal, subclavian, carotid arteries) to rest of body > arterioles > capilleries > venules > veins > Superior vena cava (upper) and inferior vena cava (lower) > Right atrium
Circulatory System
- 5 types of blood vessels
- Arteries-
- carry blood away from heart.
- Thick walls
- Highest blood pressure
- the smooth muscle can regulate size
- connects arteries to arterioles
- smaller than arteries
- can get bigger or small depending on blood pressure
- Blood back to heart
- thin walls
- has valves so there is no backflow
- Lowest blood pressure
- Connect veins to cappileries
- really thin walls
- narrow tubes, blood cells will pass through single file
- nutrient/ waste exchange
- than wall allow for diffusion
- Largest surface area (allows for gas exchange)
Pulmonary Vs. Systematic
- Pulmonary- The pulmonary circuit takes blood from the heart, to the lungs and then back to the heart.
- Returns deoxygenated blood too capilleries in lungs (CO2 out, O2 in)
- Return Oxygen rich blood to heart
- External Gas exhcange between alveoli and blood (HbCO2 > Hb + CO2, HHb > H + Hb, Hb + O2 > HbO2, H + HCO3 > (carbonic amylase) H2CO3 > H20 + CO2)
2. Systematic- The systematic takes blood from every cell in the body and returns it to the heart
- Oxygenated blood delivered to cells (O2 out of blood, CO2 into blood)
- Deoxygenated blood returns to heart
- Internal Gas exchange between blood and tissue (HbO2 > Hb + O2, Hb + CO2 > HbCO2, Hb + H > HHb, CO2 + H2O > (carbonic amylase) H2CO3 > H + HCO3)
Fetal Circulation
The placenta is the organ responsible for delivery of nutrients, removal of waste products and
delivery of oxygenated blood to the fetus through diffusion and active transport mechanisms. The placenta is crucial to the fetus since the liver and the lungs have not yet formed. Leading towards the baby is the umbilical cord which is made of of two different vessicles, the umbilical vein, which delivers
oxygenated and nutrient rich blood from the placenta to the fetus. And the umbilical Artery, which carries
deoxygenated blood from iliac arteries
out to the placenta. The umbilical veins send blood to the venous duct, which bypasses the liver and send the blood to the posterior and inferior vena cava. Since the lungs are not in use yet, the blood goes from the right atrium to the Foramen ovale which bypasses the lungs. The arteriole duct sends the blood from the pulmonary artery to the aorta where the umbilical artery carries the deoxygenated blood back to the placenta.