List and describe enzymes involved in the digestion of macromolecules. Flashcards
Enzymes involved in the digestion of macromolecules.
Each digestive enzyme is specific for a specific food type. For example Lipase is an enzyme specific for lipid molecules, and amylase is specific for starch.
Salivary Amylase: begins carbohydrate digestion by breaking down starch and glycogen to disaccharides.
Pepsin: begins protein digestion
Pancreatic lipase: breaks down fats into fatty acids and glycerol.
Peptidase: breaks down peptides into amino acids.
Importance of digestion for absorption and transport of nutrients.
Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Transport mechanisms used by Epithelial cells to absorb Nutrients:
(Passive mechanism- no ATP) Simple Diffusion: Direct movement through the cell membrane following a concentration gradient. Ex: very small molecules and nonpolar molecules such as fatty acids dissolve through phospholipid layer of the membrane.
Passive mechanism: facilitated Diffusion: Movement through a cell membrane following a concentration gradient, but the molecule must travel through a protein channel because of its size and polarity (glucose and amino acids)
Active movement ATP expended- Membrane Pumps: Molecules moved against the concentration gradient by certain proteins using ATP to pump the molecule across the membrane. Ex: glucose and amino acids
Active mechanisms: Endocytosis (pinocytosis and phagocytosis: molecules are trapped in an infolding of the membrane and pass through the other side of the membrane as a vesicle. Ex: some macromolecules that have not been fully digested.
Peristalsis in the digestive process.
Peristalsis is used in the stomach to mix food with digestive secretions, including a protein-digesting enzyme. This movement is called churning. In the rest of the alimentary canal, peristalsis causes a contraction just behind the food mass and this keeps it moving through the canal, as well as helping to mix the food with a variety of enzymes. The peristaltic movement is relatively fast within the esophagus and slows dramatically in the intestines (absorption).
Importance of the pancreas and the pancreatic enzymes.
The pancreas is a multipurpose organ that produces two important hormones (insulin and glucagon) involved in glucose metabolism, the pancreas produces three enzymes involved in digestion: lipase, amylase, and a protein-digesting enzyme known as an endopeptidase.
These three enzymes are part of fluid known simply as pancreatic juice that is released into the first portion of the small intestine through a duct.
This duct allows the three enzymes to enter the lumen (cavity) of the small intestine, where partially digested food from the stomach is being released. **bile from the liver is also released here from the gallbladder.
Adaptations and functions of the small intestine.
The cells in the inner lining of the small intestine make up what is called the mucosa. This has many small folds or projections called villi. Each villus is composed of many small cells whose job is selectively absorbing molecules found in the lumen of the small intestine.
The absorption occurs through cells in an epithelial layer in direct contact with the nutrients. The epithelial cells have tiny membrane projections called microvilli that extend into the lumen of the intestine. The villi and microvilli greatly increase the surface area for absorption within the small intestine. The interior of each villus contains a capillary bed for nutrient absorption and transport of digested monomers by the bloodstream.
Contrast vessels- arteries, arterioles, capillaries, venules and veins!
Arteries- carry blood away from the ventricles of the heart
Arterioles- receive blood from the arteries and carry blood to the capillaries
Capillaries- sites of exchange of substances between the blood and the body cells.
Venules- receives blood from the capillaries
Veins- carry blood toward the atria of the heart.
Pulmonary vs. Systemic circuits of flow
Pulmonary circulation on the right side of the heart moves blood between the heart and the lungs.The oxygenated blood then flows back to the heart. Along this route, the capillary beds are found in your lungs, where the blood picks up oxygen and releases carbon dioxide.
Systemic circulation on the left side of the heart, moves blood between the heart and the rest of the body. It sends oxygenated blood out to cells and returns deoxygenated blood to the heart. The artery that emerges from the heart at the beginning of this route is the aorta. Branches of the aorta carry blood to almost every organ and cell type in your body. Along this route, the capillary beds are found in your organs and tissues, where the blood picks up carbon dioxide and releases oxygen
Importance of the SA node and AV node in cardiac cycle regulation.
The majority tissue that makes up the heart is muscle (cardiac muscle)
Cardiac muscle spontaneously contracts and relaxers without any control by the nervous system known as myogenic muscle contraction. However the myogenic activity of the heart does need to be controlled in order to make the timing of the contractions unified and useful.
Within the right atrium, there is a mass of specialized tissue that has properties of both muscle and nervous system cells within its walls; this tissue is called the SA node. The SA node acts as the pacemaker for the heart by sending out an electrical signal to initiate the contraction of both atria.
Also within the right atrium is another mass of specialized muscle tissue, known as the AV node. The AV node receives the signal from the SA node, delays for approximately 0.1 seconds and then sends out another electrical signal. This second signal goes to the thick muscular ventricles and results in their contraction.
Systole vs. Diastole for atria and ventricles
Heart valves open and close depending on the pressure of the blood on each side of the valve.
The term used for a chamber of the heart that is not contracting is diastole
The term used for a chamber of the heart that is contracting is systole.
Explain the importance and efficiency of alveoli in the respiratory system.
Alveoli in the lungs are found as clusters at the ends of the smallest bronchioles. Each alveoli has one or more surrounding capillary beds. The air first enters your trachea, then your right and left primary bronchi. Then your smaller branches of the bronchi. Then very small branches called bronchioles and finally the air enters the small air sacs in the lungs called alveoli.
oxygen diffuses from the air and reaches the alveolus through the membranes, which is only through two cells. The first of these is a single cell making up the structure of the alveolus, the second is a single cell making up the wall of the capillary.
Carbon diffuses in the opposite direction through the same two cells. As long as a person continues breathing, and refreshing the gasses in alveoli, the concentration gradients of these two gasses will ensure diffusion of each gas in the direction the body needs.
Contrast inspiration vs. expiration.
Inspiration is breathing in and expiration is breathing out.
Steps of inspiration that are in opposite order for expiration:
1. The diaphragm contracts, and external intercostal muscles and a set of abdominal muscles help to raise the rib cage. These actions increase the volume of the thoracic cavity.
2. Because the thoracic cavity has increased its volume, the pressure inside the cavity decreases. This leads to less pressure ‘pushing on’ the passive lung tissue.
3. The lung tissue increases its volume because there is less pressure exerted on it.
4. This leads to a decrease in pressure inside the lungs, also known as a partial vacuum.
5. Air comes in through your open mouth or nasal passages to counter the partial vacuum within the lungs, and fills the alveoli.
➢multiple choice:
Tidal Volume (TV)—volume moved in or out of the lungs during a respiratory cycle (500mL)
Residual Volume (RV)—volume that remains in the lungs at all times (1200mL)
Vital Capacity (VC)—maximum volume of air that can be exhaled after taking the deepest possible breath (4600mL)
Total Lung Capacity (TLC)—total volume of air the lungs can hold (5800mL)
Differentiate between pneumocytes I and pneumocytes II.
Type I pneumocytes- very thin with a very large membrane surface area, well designed for diffusion. If damaged, these cells are incapable of mitosis for replacement.
Type II pneumocytes- cuboidal in shape and has relatively little membrane surface area. These cells produce and secrete a solution that acts as a surfactant. This reduces the surface tension of the moist inner surface of alveoli, and prevents the sides of the alveoli from sticking to each other. Type II pneumocytes are capable of mitosis for replacement of both types of alveolar cells if they are damaged
Describe emphysema.
Emphysema is a disease whereby the alveoli in the lungs are progressively destroyed. The leading cause of this is smoking. This disease is chronic, and it turns healthy alveoli into large, irregularly shaped structures with gaping holes. This reduces the surface area for gas exchange, and so less oxygen reaches the bloodstream.
