Option H: Further Human Physiology

Option H: Further Human Physiology By Lunch Box only… because I have no friends / apparently no one likes Physiology.

H1: Hormone Control

H.1.1 State that hormones are chemical messengers secreted by endocrine glands into the blood and transported to specific target cells. • The endocrine system and the nervous system function to maintain homeostasis. • Hormones (chemical messengers) are secreted by endocrine glands. • Hormones are carried by the blood stream. • The Hormones are carried to target cells that have receptors that recognize the hormones.

H.1.2 State that hormones can be steroids, proteins, and tyrosine derivatives, with one example of each. • Hormones are characterized by their chemical composition. • Examples of Steroid: Testosterone, estrogen, progesterone • Example of Proteins: Insulin, ADH, FSH, LH • Example of Tyrosine Derivatives: Thyroxin

H.1.3 Distinguish between the mode of action of steroid hormones and protein hormones. • Steroid Hormones: • Pass easily through the lipid bilayer of plasma membranes. • Directly affect the expression of genes. • Protein Hormones: • Attach to a receptor protein (Glycoprotein) on outer cell membrane • This triggers action of a secondary messenger • The secondary messenger in the cytoplasm alters the action of the cell.

H.1.4 Outline the relationship between the hypothalamus and the pituitary glad. • Anterior Pituitary Lobe • The hypothalamus sends hormones to the anterior pituitary glad via the portal vein (a blood vessel) • The hypothalamus produces releasing hormones. (Ex. GnRH) • Hormones travel in blood through the portal vein to the anterior pituitary. • The releasing hormone caused the secretion of specific hormones. (Ex. LH or FSH)

H.1.4 Outline the relationship between the hypothalamus and the pituitary glad. CONTINUED. • Posterior Pituitary Lobe • The hypothalamus and the posterior pituitary lobe are connected by Neurosecretorycells. • The hormones that are secreted by the posterior pituitary love are produced in the hypothalamus. • Nerve impulses travel to the posterior pituitary through the axon. • These nerve impulses cause the release of the vesicles of hormones into the blood stream at the posterior pituitary (Ex. ADH, Oxytocin)

H.1.5 Explain the control of ADH (antidiuretic hormone or vasopressin) secretion by negative feedback. • ADH is produced by the hypothalamus and secreted by the posterior pituitary (where it is also stored). • If it IS secreted: the collecting duct becomes permeable to water and so the water will leave the collecting duct through osmosis into the medulla (of the kidney) so that the water is reabsorbed back into the bloodstream. • If it is NOT secreted the collecting duct remains impermeable and the water will not be reabsorbed, so the urine will contain high water content.

H.1.5 Explain the control of ADH (antidiuretic hormone or vasopressin) secretion by negative feedback. CONTINUED. • The hypothalamus detects the changes in blood plasma using osmoreceptors. • If the blood plasma is too CONCENTRATED: impulses are relayed to the neurosecretory cell and ADH is released and more water is reabsorbed • If the blood plasma is too DILUTE: no ASH is released and less water is reabsorbed. • This is an example of negative feedback.

H4: Functions of the Liver • Two Main Functions of the Liver: • To Detoxify! • To Regulate Blood Composition!

H.4.1 Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein. • The blood flowing to the liver is supplied from two major blood vessels; the hepatic artery and the hepatic portal vein. • Hepatic artery: delivers oxygenated blood from the aorta. • Hepatic portal vein delivers blood from the digestive tract (low in oxygen but high in levels of digested nutrients, though these levels will vary) • The blood (deoxygenated) leaves the liver through the hepatic vein and travels back ot the heart through the inferior vena cava.

H.4.1 Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein. CONTINUED. • Function of liver: • Remove and add substances to the blood. • Monitor and regulate concentration of nutrients before it flows through the rest of the body. • Hepatocytes (Liver Cells)- remove and add substances to and from the blood. • The liver is divided into many lobes. The hepatic portal vein branch into these lobes.

H.4.1 Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein. CONTINUED. • Blood from the vessels flows through the sinusoids of the liver and then drain into wider vessels that then lead to the hepatic vein. • In the sinusoids: exchange of materials between blood and the hepatocytes. • Sinusoids are lined with gapped endothelial cells which facilitate the exchange of materials. • Sinusoids contain Kupffer cells- aid in the breakdown of worn out red blood cells -they receive a mixture of oxygenated and deoxygenated blood.

H.4.2 Explain the role of the liver in regulation levels of nutrients in the blood. • The levels of nutrients in blood rise and fall depending on how recently a meal was ingested and the rate that the body is using the nutrients. • The Hepatocytes absorb and store excess nutrients as blood passes through the sinusoids (Ex. Glucose). • These nutrients can be released back into the blood when nutrient levels drop too low in the blood. • For Glucose: Insulin and Glucagon are produced by the pancreas to help the liver maintain blood glucose levels. Insulin- stimulates the hepatocytes to absorb glucose when levels are too high. Glucagon- stimulates the hepatocytes to convert glycogen into glucose and release it when the levels are too low.

H.4.3 Outline the role of the liver in storage of nutrients in the blood. • When levels of certain nutrients are too high in the blood, the hepatocytes absorb and store the nutrients. • When levels of certain nutrients are too low in the blood, the hepatocytes release them. • Ex. Carbohydrates, Iron, Vitamin A, Vitamin D.

H.4.4 State that the liver synthesizes plasma proteins and cholesterol. • The plasma proteins are produced in the rough endoplasmic reticulum of the hepatocytes. There are several types of plasma proteins. • Ex. Albumin, Fibrinogen, Prothrombin, and Globulins. • Most of the cholesterol required by the body is manufactures by the liver (but also is taken in as a part of diet).

H.4.5 State that the liver has a role in detoxification. • The hepatocytes also absorb toxic substances. • Ex. Ethanol, Food Preservatives, Pesticides, Herbicides • These toxic substances are converted into non-toxic of less toxic substances.

H.4.6 Describe the process of erythrocyte and hemoglobin breakdown in the liver, including phagocytosis, digestion of globin and bile pigment formation. • Erythrocytes (red blood cells): have a short life span and do not contain nucleus and thus cannot undergo mitosis so they must be replaced by new cells from the bone marrow. • The plasma membrane eventually ruptures and releases the hemoglobin into the blood plasma. • The hemoglobin is absorbed by phagocytosis (mainly in the liver)

H.4.6 Describe the process of erythrocyte and hemoglobin breakdown in the liver, including phagocytosis, digestion of globin and bile pigment formation. CONTINUED. • Kupffer cells (cells in the walls od the sinusoids that are phagocytic). • These cells split the hemoglobin into two groups: Heme groups and globins. • Globins are hydrolysed to amino acids and enter the blood. • Iron is removed from the heme groups leaving bile pigment or bilirubin. Both are released into the blood. • The iron is carried to to bone marrow, where it is used to produce hemoglobin in new red blood cells. • The bile pigment is absorbed by hepatocytes and forms part of the bile. • Hemoglobin  Globin  Amino Acids • Heme Groups  Iron  Bile Pigment

H.4.7Explain the liver damage caused by excessive alcohol consumption. • Alcohol is absorbed from the small intestine and enters the blood stream. • From the blood stream it enters the Liver. • The Liver cells absorb the alcohol and break it down. • It may have to pass through the sinusoids many times before it can all be absorbed into the hepatocytes. • This can lead to breakdown of hepatocytes. • The hepatocytes are replaced by fatty tissue. • Liver cells cannot be replaced.

H.4.7 Explain the liver damage caused by excessive alcohol consumption. CONTINED. • Three Primary Effects on the Liver • Cirrhosis: irreversible damage to the liver tissue. Normal tissue (blood vessels and hepatocytes) is replaced by scar tissue. • Fat Accumulation: Fatty deposits build up in place of normal liver tissue. • Inflammation (Alcoholic Hepatitis): Liver tissue swells due to overexposure to alcohol. .

The End!

Option H: Further Human Physiology