Chapter 12: Human Physiology Flashcards
Digestion in Humans
Human digestive system has two functions: digestion and absorption.
Mouth
Tongue and teeth start the mechanical digestion. The salivary glands begin the chemical digestion of starch.
Esophagus
The epiglottis separates the windpipe and the esophagus, but no digestion occurs here.
Stomach
The stomach secretes gastric juice that starts the digestion of proteins.
Three types of cells assist in the digestion (chief cells and parietal cells).
Small Intestine
Digestion is completed here. Bile breaks down proteins, nucleus acid is hydrolysis by my leases, and lipase break down lipids. Has villi and lacteals.
Villi
Villi are fingerlike projections that absorb the nutrients from digestion. Contains lacteal, capillaries, and microvilli.
Lacteal: vessel of the lymphatic system.
Microvilli: greatly increase the rate of nutrient absorption by the villi
Large Intestine
Has three functions: egestion, vitamin production, and the removal of excess water.
Hormones of the Digestive System
Gastrin, secretin, and cholecystokinin.
Gastrin
Stimulates the secretion of gastric juice.
Secretin
Stimulates pancreas to release bicarbonate to neutralize acid in the duodenum.
Cholecystokinin
Stimulates pancreas to release pancreatic enzymes and gall bladder to release bile into the small intestine.
Respiration
The exchange of gasses: carbon dioxide and oxygen, through diffusion.
Gas Exchange in Humans
Air enters the naval cavity which moistens and filters it, which it then goes through the larynx to the bronchi, and the tiny bronchioles, and finally the alveoli where the gas exchange takes place.
Medulla and Gas Exchange
The medulla controls the breathing and sets the rhythm.. It monitors CO2 levels by sensing pH changes in the blood.
CO2 dissolves in the blood to become carbonic acid, so the higher the concentration of CO2, the lower the pH.
Hemoglobin
Carriers of oxygen in the blood stream. It is an allosteric molecule that exhibits cooperativity.
Hemoglobin is also sensitive to pH change. Because CO2 dissolves in the blood to make carbonic acid (making it have a lower pH), active muscles create a lot of CO2, which alerts the hemoglobin to go there and release oxygen/
Transport of Carbon Dioxide
Carbon dioxide is transported by plasma as part of the carbonic acid carbonate ion system, which keeps blood at the 7.4 pH.
Carbonic Acid Carbonate ion System
Bicarbonate ion is created in two steps:
- Carbon dioxide + H2O makes carbonic acid.
- Carbonic acid dissociates into a bicarbonate ion and a proton.
Closed Circulatory System
The human circulation system with arteries, veins, and capillaries.
Plasma
Liquid portion of blood, has clotting factors, hormones, antibodies, nutrients, dissolved gases, wastes.
Red blood cells
Carry hemoglobin and oxygen. Formed in the bone marrow and recycled in the liver.
White Blood Cells
Fight infection and formed in the bone marrow, as well as leukocytes produce antibodies.
Platelets
Cell fragments formed in the bone marrow that clot blood.
Arteries
Take blood away from the heart under great pressure, and made of thick, smooth muscle.
Veins
Take blood back to the heart under little pressure, and made of thin walls and valves to prevent back flow.
Capillaries
Allows for diffusion of nutrients and wastes, and only one cell thick.
Systolic Number
The measurement of the pressure when ventricles contract.
Diastolic Number
Measure of the pressure when the heart relaxes.
Coronary Circulation
Blood circulation through the heart.
Renal Circulation
Blood circulation through the kidneys.
Hepatic Circulation
Blood circulation through the liver.
Pulmonary Circulation
Includes the pulmonary artery, lungs, and pulmonary veins.