Animals Flashcards
How does digestion occur in the hydra (a cnidarian)?
Digestions occurs in the gastrovascular cavity which has only one opening. Cells of the gastrodermis secrete digestive enzymes into the cavity for extracellular digestion. Some specialized nutritive cells have flagella that move the food around and some have pseudopods that engulf food particles.
What is the gastrodermis of the gastrovascular cavity?
It is the lining of the gastrovascular cavity.
How does digestion occur in the earthworm?
The digestive tract is a long, straight tube. As the earthworm burrows in the ground, the mouth ingests decaying organic matter along with soil. This moves from the mouth through the esophagus and into the crop where it’s stored. Posterior to the crop is the gizzard which grinds up the food with the help of sand/soil and its own muscular walls. The rest of the digestive system consists of intestines, enhanced by typhlosole, aids in chemical digestion and absorption.
What is the function of the typhlosole in an earthworm’s digestion?
The typhlosole is a large fold in the upper surface of the intestines which enhances absorption by increasing surface area.
How does digestion occur in a grasshopper?
Similar to the earthworm, the digestive tract is a long tube consisting of a crop and gizzard. The grasshopper has a specialized mouth for tasting food and mechanical digestion. The grasshopper’s gizzard has plates made of chitin to grind up the food. The digestive tract also removes nitrogenous waste (uric acid).
Give an overview of digestion in humans.
The system has two important functions: digestion and absorption. The digestive tract is about 30 feet long and made of smooth (involuntary) muscles that pushes food along the digestive tract by a process called peristalsis.
Define digestion and what is digested in the human digestive system.
This is the breaking down large food molecules into smaller usable molecules. Fats are broken down to fatty acids and glycerol, starch into monosaccharides, nucleic acids into nucleotides and proteins into amino acids.
Define absorption.
This is the diffusion of smaller (already digested) molecules in the body’s cells. Vitamins and minerals are able to be absorbed without being digested.
How does digestion occur in the human mouth?
Mechanical digestion occurs with the tongue and the teeth. Teeth are indicative of an animal’s dietary habits. Incisors are for cutting, canines for tearing and molars for grinding. Salivary amylase is released by the salivary glands to being the chemical breakdown of starch.
How is digestion facilitated in the human esophagus?
After swallowing food is directed into the esophagus by the epiglottis and moves down by peristalsis. No digestion occurs in the esophagus.
What is the epiglottis?
This is a flap of cartilage in the back of the pharynx (throat). It directs food into the esophagus and not into the windpipe.
How does digestion occur in the human stomach?
Some mechanical digestion occurs and secretes gastric juice that begins digestion of proteins. The acidic environment creates pepsin and also kills germs. The stomach of all mammals contains rennin to aid in the digestion of he protein in milk.
What is gastric juice?
In the stomach this is a mixture of the enzyme pepsinogen and hydrochloric acid that begin the digestion of proteins. The acidic environment activates pepsinogen to becomes the active enzyme pepsin.
What is the cardiac sphincter?
It’s a ring of muscle at the top of the stomach that keeps food in the stomach from backing into the esophagus.
What is the pyloric sphincter?
It’s a ring of muscle at the bottom of the stomach that keeps food in the stomach long enough to be digested.
How do ulcers form in the stomach?
Excessive acid can cause an ulcer to form in the esophagus, stomach, or duodenum. Helicobacter pylori is a particular bacteria that can cause ulcers and can be treated with antibiotics.
How does digestion occur in the human small intestine?
Digestion is completed in the duodenum. Intestinal enzymes and pancreatic amylases hydrolyze starch and glycogen into maltose. Bile, which is produced in the liver and stored in the gallbladder, is released into the small intestine as an emulsifier to break down fats. Peptidases continue to break down proteins. Nucleases hydrolyze nucleic acids and lipases break down fats.
What are some peptidases present in the small intestine?
Trypsin and Chymotrypsin
How does absorption occur in the human small intestine?
Millions of fingerlike projections called villi and microvilli, in conjunction with the lacteal, absorb all the nutrients that were previously released.
What is the structure of the villus in the small intestine?
The capillaries of the villus absorb amino acids, vitamins, and monosaccharides. The lacteal (contained in the villus) is a small vessel of the lymphatic system which absorbs fatty acids and glycerol. Each epithelial cell has microscopic microvillus that increase nutrient absorption.
What function does the human large intestine play in absorption?
The large intestine or colon serves three main functions: egestion, vitamin production, and removal of excess water. If too much water is removed constipation occurs and diarrhea is occurred is too little water is removed.
Define egestion.
Egestion is the removal undigested waste.
Describe the last 7-8 inches of the human gastrointestinal tract?
That last 7-8 inches are called the rectum. It stores feces until their release and the opening at the end of the tract is called the anus.
What is respiration and how does it occur?
Respiration is the exchange of oxygen and carbon dioxide between the external environment and the cell of body. It occurs passively through diffusion.
What conditions must respiratory surfaces meet?
Respiratory surfaces must be thin, moist and have large surface areas.
How do simple animals such as sponges and hydra complete gas exchange?
Gas exchange occurs over the entire surface of the organism wherever cells are in direct contact with the environment.
How does an external respiratory surface in earthworms and flatworms work?
This means that diffusion of O2 and CO2 occurs at the skin. Oxygen is carried by hemoglobin dissolved in blood.
How does an internal respiratory system work in arthropods and crustaceans?
Air enters the body through spiracles and travels through a system of tracheal tubes into the body, where diffusion occurs in sinuses or hemocoels. In arthropods, oxygen is carried by hemocyanin which is similar to hemoglobin but with copper at its core atom instead of iron.
How do gills work?
They take advantage of concurrent exchange to maximize the diffusion of respiratory gases.
What is the pathway through which air enter the lung?
Air enters the nasal cavity where is is moistened, warmed and filtered, From there the air passes through the larynx and down the trachea and into the bronchi.
How does air pass through the lungs?
From the bronchi air moves to the tiniest bronchioles and end in microscopic air sacs called alveoli where diffusion of gases occurs.
How does air get drawn into the lungs?
As the rib cage expans, the diaphragm contracts and lowers which causes the chest cavity to expand. The internal pressure in the lungs is lower than the atmospheric pressure. Thus, the air is drawn in by negative pressure.
How do CO2 levels affect breathing rates?
The medulla in the brain, contains the breathing control center, sets the rhythm of breathing and monitors CO2 levels in the blood by sensing changes in pH of the blood. CO2 dissolves in the blood to form carbonic acid therefore the higher the CO2 concentration the lower the pH. A blood pH lower than 7.4 causes the medulla to increase the rate of breathing.
What is hemoglobin?
It is an allosteric molecule. The respiratory pigment that can combine loosely with four oxygen molecules forming oxyhemoglobin and carry it through the blood. The closer it binds to the oxygen the more difficult it is to unload.
Describe how hemoglobin binds to oxygen.
It exhibits cooperativity, meaning once it binds with one oxygen molecule it binds more easily to 3 other molecules. In addition, it is sensitive to pH because a drop in pH lowers the affinity for oxygen.
What is the Bohr shift?
CO2 dissolves in water to form carbonic acid and actively respiring tissue which release large quantities of CO2 and lower the pH of its surroundings. This induces hemoglobin to release its oxygen at the cells where needed.
Explain the saturation-dissociation curves for hemoglobin.
The further to the right the curve is, the less affinity the hemoglobin has for oxygen.
How is carbon dioxide transported?
Very little is transported by hemoglobin. Most CO2 is carried in the plasma as part of the reversible blood buffering carbonic-acid-bicarbonate ion system.
What is the carbonic-acid-bicarbonate ion system?
First, CO2 combines with water to form carbonic acid, this is catalyzed by carbonic acid anhydrase in red blood cells. Second, carbonic acid dissociates into a bicarbonate ion and a proton. The protons are given up in the plasma and lowers the blood pH or taken up by bicarbonate ion which raises blood pH.
How do animals with no circulatory system function?
This is true for sponges and hydra; all their cells are in direct contact with the environment.
How do animals with a closed circulatory system function?
This is true for earthworms and humans; the blood is pumped by the heart through arteries, veins and capillaries.
How do animals with open circulatory systems function?
This is true for grasshoppers - anthropod blood is colorless and don’t carry oxygen; after blood is pumped by the heart into an artery it leaves the vessel and seeps through spaces called sinuses/homocoels as it feeds body cells then, blood moves back to veins and then the heart
Component of Blood: Plasma
Liquid portion of the blood that contains clotting factors, hormones, antibodies, nutrients, dissolved gases and wastes. It maintains the proper osmotic potential of the blood; 300 mosm/L.
Component of Blood: Red Blood Cells
Erythrocytes; Carry hemoglobin and oxygen. They don’t have a nucleus and live about 120 days. They’re formed in the bone marrow and recycled in the liver.
Component of Blood: White Blood Cells
Leukocytes; Fight infection and are formed in the bone marrow. They dies fighting infection and are a component of pus. One type - B lymphocyte - produces antibodies.
Component of Blood: Platelets
Thrombocytes; These are cell fragment formed in the bone marrow from megakaryocytes. They clot blood.
Blood Clotting
It begins with the release of clotting factors from platelets and damaged tissue. Then, complex interactions such as the activation of inactive plasma proteins occur. Anticlotting factors normally circulate in the plasma and prevent the formation of a clot or thrombus which can cause damage is there is no injury.
Artery and Arteriole
Function: carry blood away from the heart under enormous pressures
Structure: walls made of thick, elastic, smooth muscle
Vein and Venule
Function: carry blood back to the heart under very little pressure
Structure: thin walls with valves to prevent back flow; they are located within skeletal muscle, which propels blood upward and back to heart as the body moves
Capillary
Function: allows for distribution of nutrients and wastes between cells and blood
Structure: walls are on-cell thick and so small that blood cells travel single file
Heart
It is located beneath the sternum is about the size of a clenched fist. It beats about 70 beats per minute and pumps about 5 quarts of blood per minute.
Heart: Structure
Two atria receive blood from the body cells and two ventricles pump blood out. Cardiac muscles cells have the ability to contract even when removed from the heart.
Sinoatrial Node
This pacemaker sets the timing of contractions in the heart. It’s locates on the wall of the right atrium and generates electrical signals to the atrioventricular that trigger ventricles to contract. It’s influenced by two sets of nerves, hormones such as adrenaline and body temperature.
Electrocardiogram
EKG: It detects electrical impulses that travel through the cardiac and body tissues to the skin.
Blood Pressure
It is lowest in the veins and highest in the arteries. Normal, resting, adult blood pressure is 120/80.
Systolic Pressure
Measurement of the pressure when the ventricles contract.
Diastolic Pressure
A measure of the pressure when the heart relaxes.
Pathway of Blood in the Heart
Right Atrium → Right atrioventricular valve (tricuspid) → Right Ventricle → Pulmonary semilunar valve → Pulmonary artery → Lungs → Pulmonary Vein → Left Atrium → Bicuspid (left AV) Valve → Left Ventricle → Aortic Semilunar Valve → Aorta → To Cells in the Body
Pathway of Blood in the Body
It circulates through the coronary circulation, renal circulation (kidneys) and hepatic circulation (liver). The pulmonary circulation includes the pulmonary artery. lungs and pulmonary vein.
Chemical Signals
The endocrine system releases hormones and the nervous system releases neurotransmitters. There;s some overlap for example epinephrine functions as both a fight-or-flight hormone and a neurotransmitter.
Hormones
Produced in ductless (endocrine) gland and move through the body to a specific target cell.
Adrenaline
Hormone that produces and immediate, short-lived response.
Edysone
Alters the development of insects by regulating metamorphosis.
