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Animal Physiology & Nutrition (Specialized organs (Digestion in the…
Animal Physiology & Nutrition
Evolution of Size and Shape
Natural selection often results in similar adaptations when diverse organisms face the same environmental challenge
Physical laws also influence animal body plans with regard to maximum size
As body dimensions increase, thicker skeletons are required to maintain adequate support,
As bodies increase in size, the muscles required for locomotion must represent an ever larger fraction of the total mass
Exchange with the Environment
Occurs as substances dissolved in an aqueous solution move across the plasma membrane of each cell
Rate of exchange is proportional to the body volume
Animals with Simple Internal Organization
Enables direct exchange between almost all their cells and the external environment
Single-celled Organism
Contains sufficient membrane surface area in contact with its environment to carry out all necessary exchange
Whales & other animals
Uses specialized surfaces that are extensively branched or folded that increases surface area
In humans - this is utilized for digestion, respiration, and circulation
Interstitial fluid
Animal Feedback
Regulator and Conformer
An animal is a regulator for an environment variable if it uses internal mechanisms to control internal change in the face of external fluctuation
An animal is a conformer for a particular variable if it allows its internal condition to change in accordance with external changes in the variable
Homeostasis
"Steady state" referring to the maintenance of internal balance
Animals maintain a relatively constant internal environment even when the environment changes significantly
Maintaining a variable such as body temperature or solute concentration at a
set point
Any fluctuation would be considered as a
stimulus
detected by a
sensor
Causes a response that helps return the variable to a set point
Negative Feedback
A control mechanism that reduces or "damps" the stimulus
Positive Feedback
A control mechanism that amplifies rather than reduces the stimulus
Thermoregulation
Endothermy
Meaning that they are warmed mostly by heat generated by metabolism
Can maintain a stable body temperature even in teh face of large fluctuations in the environmental temperature
Ectothermy
Meaning that they gain most of their heat from external sources
Tolerates larger fluctuations in their internal temperature
Integumentary System
Outer covering of the body, consisting the skin, hair, and nails
Insulation
Reduces the flow of heat between an animal's body and its environment
Most important to for marine animals
Circulatory Adaptations
Changes in the blood flow due to changes in the temperature
Relies on countercurrent exchange - transfer of solutes between fluids that are flowing in opposite directions
Energy Requirements
Energy Allocation and Use
Animals use chemical energy harvested from the food they eat to fuel metabolism and activity
Quantifying Energy Use
By measuring the rate at which an animal uses chemical energy and how this rate changes in different circumstances
Metabolic Rate
The sum of all the energy an animal uses in a given time interval
Typically measured in joules, calories, or kilocalories
Kcal = 1,000 calories/4,184 joules = Calorie
Animals must maintain a minimum metabolic rate for basic functions such as cell maintenance, breathing, and heartbeat
Basal metabolic rate (BMR)
Larger animals have more body mass and therefore require more chemical energy
The Need to Feed
Nutrition
Food being taken in, taken apart, and taken up
Herbivores, carnivores, omnivores
Essential Nutrients
Preassembled organic molecules and minerals
Includes essential amino acids, fatty acids, vitamins, and minerals
Serves as substrates, enzymes, coenzymes, and cofactors in biosynethtic reactions
Dietary Deficiencies
Malnutrition
A failure to obtain adequate nutrition
Insufficient intake of essential nutrients can cause deformities, disease, and even death
Undernutrition
the body uses up stored carbohydrates and fats and then begins breaking down its own proteins for fuel
Muscles begin to decrease in size
Brain becomes protein-deficient
Food Processing
Ingestion - act of eating or feeding
Digestion - food is broken down into molecules small enough for the body to absorb
Mechanical digestion breaks food down into smaller pieces, increasing the surface area available for chemical processes
Chemical digestion, because animals cannot directly use the proteins, carbohydrates, nucleic acids, fats, and phospholipids in food
Enzymatic hydrolysis - splitting of bonds through the addition of water
Absorption - the animals cells take up small molecules such as amino acids and simple sugars
Elimination - completes the process as undigested material passes out of the digestive system
Digestive Compartments
Intracellular Digestion
Food vacuoles
Hydrolysis of foods
Extracellular Digestion
The breakdown of food in compartments that are continuous with the outside of the animal's body
Gastrovascular cavity
Alimentary canal aka complete digestive tract
Specialized organs
Oral Cavity - where ingestion occurs
Salivary Glands - delivers saliva through ducts to the oral cavity
amylase hydrolyzes starches
Pharynx - throat region that leads to the trachea and esophagus
Digestion in the Stomach
Begins the digestion of proteins
Secretes a digestive fluid called gastic juice
Chemical Digestion
Protease/Pepsin
Digestion in the Small Intestine
Where most of enzymatic hydrolysis of the macromolecules from food occurs
Duodenum
Where chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder
Pancreas - aids in chemical digestion by producing an alkaline solution rich in bicarbonate as well as several enzymes
Liver - produces bile
Regulation of Energy Storage
@ liver and muscle cells - excess energy from the diet is stored in glycogen
Glucose Homeostasis
Synthesis and breakdown of glycogen are central not only to energy storage, but also to maintain metabolic balance
Relies predominantly on the antagonistic effects of two hormones, insulin and glucagon
Diabetes
Caused by a deficiency of insulin or decreased response to insulin in target tissues
Level of glucose in the blood may exceed the capacity of the kidneys to reabsorb nutrients
Presence of sugar in urine
Type 1: Insulin-dependent, an autoimmune disorder in which the immune system destroys the beta cells of the pancreas
Type 2: Non-insulin-dependent, characterized by a failure of target cells to respond normally to insulin