Untitled Flashcards Set

The sinoatrial node acts as a pacemaker and regulates the heart’s ability to contract.

Sympathetic division speeds up the pacemaker and parasympathetic divison slows down the pacemaker. The pacemaker is regulated by hormones and temperature.

When blood comes out of the heart, it travels through the arteries to exchange gas at the capillary beds, and then returns to the venules.

The vertebrate circulatory system relies on blood vessels that exhibit a close match of structure and function.

In the artery, connective (epithelial) tissue lines the outside, the central lumen can be found in the middle, and the smooth muscle is the inner lining that contracts under motor control to contract and increase pressure.

Arteries have elastic and thick walls used to handle the high pressure of blood that is pumped from the heart.

Veins do not require thick walls because they return blood back to the heart at a significantly lower pressure

Blood flow slows as it travels from the arteries, to the arterioles, to the capillaries.

Endothelium minimizes resistance because it is smooth.

Decreased radius -> decreased volume -> increased pressure

Capillary beds have a smaller surface area than an artery, but have a much larger length that allows blood to flow slowly in capillary beds.

Venules have thin smooth muscle walls and contain valves to prevent the backward flow of blood.

The velocity of blood flow is determined by surface area.

When blood returns from the distal veins (found in the legs and feet), blood travels back to the right atrium. While the right atrium fills, it relaxes so the volume is able to increase and the pressure decreases. The right atrium is an example of a negative pressure pump.

Precapillary sphincters connect to arterioles and close when smooth muscle contracts so volume can decrease and pressure can increase. They are also able to open, and the closing/opening actions control whether or not blood enters the capillary beds.

Blood flow is regulated by nerve impulses, hormones, and other chemicals as well.

The exchange of substances between blood and interstitial fluid takes place across the thin endothelial walls of the capillaries.

When blood enters the venules and veins, the flow of blood speeds up as the total cross sectional area decreases.

Blood pressure flows from high to low pressure.

Blood pressure is a force exerted in all directions, including against the walls of blood vessels

Capillaries have thin walls, and the endothelium plus its basal lamina are used to facilitate the exchange of materials.

Capillaries found in major organs are usually filled to capacity,

Constriction and dilation of arterioles that supply the capillary beds regulate the distribution of blood.

Components of a negative feedback loop include a sensor (such as an oxygen sensor) that allow precapillary sphincters to open and close.

Nitric oxide is a major inducer of dialation.

Peptide endothelin is a potent inducer of vasoconstriction.

Vasoconstriction and vasodilation both change the output in blood pressure.

As blood moves into the capillary beds, there is a higher blood pressure as opposed to a lower osmotic pressure.

The lymphatic system returns fluid that leaks out from the capillary beds, and the fluid lost by the capillaries is known as lymph. 

Lymph nodes are organs that filter lymph and play an important role in the body’s defense.

Edema is caused by disruptions in the flow of lymph causing swelling.

Blood moves nutrients, oxygen, and carbon dioxide around the body to cells that need it.

Platelets are important for blood clotting.

White blood cells, known as lymphocytes, participate in the immune system.

Red blood cells are produced by stem cells, which have the ability to differentite, in bone marrow.

Erythrocytes do not have a nucleus, so they do not live very long and tend to have an average life span of 120 days.

Plasma is the connective tissue consisting of several kinds of cells suspended in a liquid matrix called plasma that contains inorganic salts.

Plasma proteins influence blood pH and help maintain osmotic balance between blood and interstitial fluid. Certain plasma proteins function in lipid transport, immunity, and blood clotting.

Sickle-cell disease is caused by abnormal hemoglobin proteins that form aggregates that can deform an erythrocyte into a sickle shape. These cells can rupture or block blood vessels, leading to organ swelling and pain. Leads to reduced numbers of red blood cells available to transport oxygen.

Coagulation is the form of a solid clot caused by a cascade of complex reactions that convert inactive fibrinogen to fibrin.

Atherosclerosis is the hardening of arteries caused by the accumulation of plaque, fatty deposits. Damage to the artery lining results in inflammation and leukocytes are attracted to the inflammed sites. When plaques rupture, they can trigger heart attacks or strokes.

Cholesterol is a steroid that is important for maintaining normal membrane fluidity in animal cells.

Low-density lipoprotein deliers cholesterol to cells for membrane production.

High-density lipoprotein scavenges excess cholesterol for return to the liver. 

A high LDL to HDL ratio increases risk of cardiovascular disease, and so does inflammation.

In a given volume, there is less O2 available in the water than in the air, so obtaining O2 from water requires greater efficiency. 

Skin, gills, trachae, and lungs are all respiratory surfaces that can be found in all types of animals.

Gills are outfoldings of the body that create a large surface area for gas exchange.

Ventilation moves the respiratory medium over the respiratory surface to maintain partial pressures of O2 and CO2.

Fish gills use a countercurrent exchange system where blood flows opposing water passage over the gills.

The tracheal system of insects consists of a network of branching tubes throughout the body, this tube supplies O2 directly to body cells.

Lungs are an infolding of the body surface.

Air passes through the pharynx, larynx, trachea, bronchi, bronchioles, to the alveoli where gas exchange occurs.

Alveoli are air sacs where gas exchange takes place and oxygen diffuses through the moist film of the epithelium into capillaries.

A mucus escalator lines the epithelium of the air ducts and moves particles up to the pharynx.

Mutualistic adaptations - the coexistence of humans and many bacteria involves mutualistic symbiosis.

The circulatory and ventillatory systems are an important part of gas exchange. Their main purpose is to move critical molecules from the external to the internal environments.

A circulatory system has circulatory fluid, a set of interconnecting vessels, and a muscular pump (heart).

In insects and arthropods, and some molluscs, circulatory fluid called hemolymph bathes the organs directly in an open circulatory system.

In a closed circulatory system, blood is confined to vessels and is distinct from the interstital fluid.

The circulatory system connects the fluid that surrounds cells with the organs that exchange ases, absorb nutrients, and dispose of waste.

Axolotl’s feathery gills appear red because of blood circulation. As they move around, they diffuse oxygen to the internal system. This allows axolotls to not spend a large amount of energy to acquire oxygen because the external surface is being used for gas exchange.

Animals that have a thin body wall have a complex gastrovascular cavity (flatworms), have a large surface area to volume ratio, and are small enough to not require a circulatory system.

Open circulatory systems are not efficient because there is no control over the delivery of hemolymph.

Closed circulatory systems are more efficient because hemolymph travels to a designated organ.

Small molecules move between cells and their surroundings by diffusion, which is random thermal motion that is only efficient over small distances because the time it takes to diffuse is proportional to the square of the distance.

Solutes move down a concentration gradient.

Gases move down a partial pressure gradient.

Ions move down an electrochemical gradient.

Some animals lack a circulatory system, like cnidarians that have gastrovascular cavities that help with both digestion and distribution of substances throughout the body.

Pressure and volume have an inverse relationship. P1V1=P2V2

When pressure decreases, fluid can be sucked up to increase the volume. This pressure gradient is a result of a changing volume in the heart.

Arteries branch into arterioles which carry blood away from the heart and into the capillaries.

Capillaries form networks that form capillary beds that allow for chemical exchange between blood and interstitial fluid.

High surface area is important for gas exchange.

Venules converge into veins and work to return blood from capillaries to the heart.

The two atria have relatively thin walls and serve as collection chambers for blood returning to the heart.

The ventricles have thickers walls and contract much more forcefully and at the same time. 

Fibrilitation occurs when the ventricles are not contracting at the same time, and this may result in a constant blood volume (and pressure.)

In vertebrates, hearts contain two or more chambers.

Sharks, rays, and bony fishes experience single circulation that results in a decreasing volume and increasing pressure (and vice versa).

Double circulation is experienced by amphibians, reptiles, and mammals. Oxygen poor blood is pumped from the right side in one circuit and oxygen rich blood is pumped from the left side in a separate circuit. 

Double circulation allows for a higher blood pressure and blood can be efficiently moved in a large organism so activity can be increased. However, since the ventricle is not anatomically divided, the mixing of dyoxgenated and oxygenated blood is possible.

In mammals, the ventricle is completely separated by a barrier, allowing mammals to generate different pressures in pulmonary circulation and systemic circulation. The higher pressure in the systemic circulation means we can move blood quickly.

Intermitten breathers include amphibians and many reptiles that can pass long periods without gas exchange, or they may rely on a different tissue for gas exchange such as the skin. This is common in animals who have a low metabolic rate. 

Frogs and other amphibians have a 3 chambered heart, two atria and one ventricle. When the frog is underwater, blood flow to the lungs is nearly shut off to conserve energy and to prioritize the heart.

Turtles, snakes, and lizards have a 3 chambered heart, two atria and one ventricle partially divided by an incomplete septum.

Blood follows the path of least resistance, and how animals bypass the lungs is determined by the resistance.

Resistance is controlled by increasing or decreasing diameter of the vessels under neural control.

Mammals and birds have a 4 chambered heart with two atria and two ventricles that support a higher metabolic rate. The left side pumps and receives oxygen-rich blood, and the right side receives and pumps oxygen-poor blood.

Mammals and birds are endotherms and therefore require more O2 than exotherms.

Systole - contraction/pumping

Diastole - relaxation/filling

The cardiac cycle is a rhythmic cycle where the heart contracts and relaxes.

Cardiac output is the volume of blood pumped into the systemic circulation per minute and depends on both heart rate and stroke volume.

Heart rate is the number of beats per minute

Stroke volume is the amount of blood pumped in a single contraction.

Four valves prevent the backflow of blood in the heart.

The atrioventricular valves separate each atrium and ventricle.

The semilunar valves control blood flow to the aorta and the pulmonary artery.

The lub-dup sound of a heart beat is caused by the recoil of blood against the AV and then against the semilunar valves

The backflow of blood through a defective valve cuases a heart murmur

Some cardiac muscle cells are autorhythimic, meaning they contract without any signal from the nervous sytem

The sinoatrial node or pacemaker sets the rate and timing at which cardiac muscle cells contract

Impulses that travel during the cardiac cycle can be recorded as an electrocardiogram.

Impulses from the SA node travel to the AV node where the impulses are delayed and then travel to the purkinje fibers that make the ventricles contract.

Fat soluble vitamins do not need to be consumed constantly because they are stored. 

Water soluble vitamins do need to be consumed constantly because they are not stored.

Minerals are simple, inorganic nutrients that are usually required in small amounts, and consuming large amounts of minerals can easily upset the homeostatic balance.

Herbivores consume plants/algae

Carnivores consume mostly other animals

Omnivores regularly consume animals and plants/algae

Cod liver oil comes from the cod eating other fish, diatoms (algae) are making it.

Most animals are opportunistic feeders and broaden their diet when necessary. Animals will vary their diet based on their current nutritional needs.

Malnutrition is a failure to obtain adequate nutrition, and this can have negative impacts on health and survival.

Deficiencies in essential nutrients can cause deformities, disease, and death.

Some grazing animals can obtain missing nutrients by consuming concentrated sources of salt or other animals.

The nutrition of plants depends on what they’re growing in, sometimes animals use a salt lick to increase the nutrients in food.

In children, protein deficiency may arise when their diets shift from breast milk to food with little protein.

Undernourishment results when a diet does not provide enough chemical energy.

In an individual with undernourishment, they will use up stored fat and carbohydrates, break down their own proteins, lose muscle mass, suffer protein deficiency of the brain, and will die/suffer irreversible damage.

Many insights into human nutrition have come from epidemiology

Epidemiology - the study of human health and disease at the population level

Neural tube defects were found to be the result of a deficiency in folic acid in pregnant mothers. Based on this evidence, the US began to require that folic acid be added to enriched grain products in 1998.

Ingestion is the act of eating or feeding, and this can include four different mechanisms including filter feeding, substrate feeders, fluid feeders, and bulk feeders.

Filter feeding is common in aquatic animals, which sift small food particles from the surrounding medium and filter out material that isn’t food. However, they tend to ingest a lot of water.

Substrate feeders are animals that live in/on their food source, like a caterpillar in a leaf.

Fluid feeders suck nutrient-rich fluid from a living house like a fly feeding off of blood.

Bulk feeders eat relatively large pieces of food, and humans and snakes are examples of bulk feeders.

Digestion is the process of breaking food down into molecules that can be absorbed.

Mechanical digestion includes chewing or grinding to increase the surface area of food.

Chemical digestion uses amylase to split food into small molecules that can pass through cell membranes to be used towards the synthesis of larger molecules

In chemical digestion, enzymatic hydrolysis is the process that splits bonds in molecules when water is added.

Absorption is the uptake of small molecules by body cells.

Elimination is the passage of undigested material out of the digestive system.

Most animals process food in specialized compartments that reduce the risk of an animal digesting its own cells.

Intracellular digestion - Food particles are engulfed by phagocytosis and liquids by pinocytosis. Food vacuoles fuse with lysosomes filled with hydrolytic enzymes used to break down molecules.

Sponges ingest all their food through intracellular digestion.

In most animals though, hydrolysis occurs by extracellular digestion which is the breakdown of food particles outside of the cell. Hydrolysis occurs in compartments that are continuous with the outside of an animal’s body.

Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrients.

More complex animals have a digestive tube with two openings, a mouth, and an anus. This digestive tube is called a complete digestive tract/alimentary canal. This tube has specialized regions that carry out digestion and absorption in a stepwise fashion.

In mammals, a number of accessory glands secrete digestive juices through ducts into the alimentary canal. Mammalian accessory glands include the salivary glands, pancreas, liver, and gallbladder.

Food processing begins in the oral cavity with teeth (that have specialized shapes) that cut, mash, and grind to break food into smaller pieces.

Salivary glands deliver saliva to lubricate food, and saliva contains mucus which is a viscous mixture of water, salts, cells, and glycoproteins.

The mouth has a neutral pH because our mouths secrete bicarbonate since enzymes in the stomach function best at a low pH. 

Movements by the tongue shape food into a bolus and help with swallowing. 

The throat, pharynx, is the junction that opens to both the esophagus and the trachea. The esophagus connects to the stomach and the trachea leads to the lungs.

Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract. 

Coughing/choking can occur when the swallowing reflex fails and food/liquids reach the windpipe.

Within the esophagus, food is pushed along from the pharynx to the stomach by peristalsis (alternative waves of smooth muscle contraction and relaxtion)

Valves called sphincters regulate the movement of material between compartments.

The stomach stores food and processes it into a liquid suspension that is mixed with grastric juice through a chruning action.

Chyme is the mixture of ingested food and gastric juice.

Gastric juice has a pH of 2, which kills bacteria and denatures proteins. This substance is low in pH because it is made of hydrochloric acid and pepsin, which is a protease that breaks peptide bonds to cleave proteins into smaller polypeptides.

Parietal cells secrete hydrogen and chloride ions separately into the lumen of the stomach where chief cells secrete inactive pepsinogen, which is activated to pepsin when mixed with hydrochloric acid in the stomach.

Mucus protects the stomach lining from gastric juice and cell divison adds a new epithelial layer every 3 days.

Coordinated contraction and reflaxation of stomach muscles churn the contents within the stomach, and sphincters prevent chyme from entering the esophagus and regulate its entry into the small intestine. 

If the sphincter at the top of the stomach allows movement of chyme back into the lower end of the esophagus, heartburn occurs.

The small intestine is the longest compartment of the alimentary canal where most enzymatic hydrolysis of macromolecules from food occurs.

The duodenum is the first section of the small intestine where chyme mixes with digestive fluids from the pancreas, liver, gallbladder, and small intestine.

The pancreaas produces protease, trypsin, and chymotrypsin. This solution is alkaline and neutralizes the acidic chyme.

Bile salts facilitate digestion of fats and are a majory component of bile. 

Bile is composed in the liver and stored/concentrated in the gallbladder. Bile destroys nonfunctional red blood cells.

Digestion is largely completed in the duodenum.

The small intestine has a huge surface area due to villi and microvilli that are exposed to the intestinal lumen. The microvillas’ surface creates a brush border that greatly increases the rate of nutrient absorption and allows transport across the epithelial cells to be passive or active, depending on the nutrient.

The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then finally to the heart.

The liver regulates nutrient distribution, creates many organic molecules, and detoxifies many organic molecules.

Epithelial cells absorb fatty acids and a monoglyceride (glycerol + fatty acid) and recombines them into triglycerides

Fats are coated with phospholipids, cholesterol, and proteins to form water-soluble chylomicrons which are transported into a lacteal (lymphatic vessel in each villus).

Lymphatic vessels deliver chylomicron-containing lymph to large veins that return blood to the heart.

The alimentary canal ends with the large intestine which includes the colon, cecum, and rectum. The colon leads to the rectum and anus, and the cecum aids in the fermentation of plant material and connects where the small and large intestine meet.

The human cecum has an extension called the appendix, which plays a minor role in immunity.

The colon completes the recovery of water that began in the small intestine.

Feces, the wastes of the digestive system, become more solid as they move through the colon.

The community of bacteria living on unabsorbed organic material in the colon contributes to about ⅓ of the dry weight of feces.

Feces are stored in the rectum until they can be eliminated through the anus, and two sphinceters between the rectum and anus control bowel movements.

Digestive systems of vertebrates are varied, with many adaptations linked to an animal’s diet.

Dentition, an animal’s assortment of teeth, is an example of structural variation reflecting diet.

The success of mammals is due in part to their dentition, which is specialized for different diets.

Nonmammalian vertebrates have less specialized teeth, though exceptions exist like the teeth of poisonous snakes are modified as fangs for injecting venom.

Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

Thermogenesis is the adjustment of metabolic heat production to maintain an ideal body temperature, and can be increased by muscle activity such as moving or shivering. 

Pythons use shivering thermogenesis to incubate their eggs, and their eggs have to be incubated at a higher temperature because the heat speeds up the necessary chemical reactions needed for the offspring to develop. 

Nonshivering thermogenesis occurs when hormones cause mitochondria to increaase their metabolic activity. 

When energy is converted from one form into another form, heat is lost to the environment. 

The impact of heat loss on a food web - if autotrophs are being consumed by an organism, the amount of heat lost is small because there was only one level of chemical transformation. Every time there is an additional layer, or an additional consumer, in the food web, more energy is lost in the form of heat. This means as food webs continue to branch out, energy transformation becomes less efficient.

Some mammals have tissue called brown adipose tissue (BAT) that allows for rapid heat production. BAT can be found in many mammalian infants as well as in adult mammals that hibernate such as bears. 

In humans, BAT is most abundant around our back, neck, and shoulders.

The quantity of BAT found in human adults has been found to vary depending on the temperature of the surrounding environment. Additionally, a high surface area to body ratio is correlated to abundant brown adipose tissue.

When organisms have a higher brown adipost tissue content, they require more energy. 

Birds and some other nonavian reptiles can also raise body temperature through shivering. 

Birds and mammals can adjust their insulation to acclimatize to seasonal temperature changes, and this adjustment is important to animals whose temperatures vary. 

The lipid composition of the cell membrane may change temperatures, and for this reason, when temperatures are subzero, some ectotherms produce antifreeze compounds to prevent ice formation in their cells.

If fish do not adjust their lipid composition, their bilayer will not perform properly. Think of the lipid bilayer like butter, it hardens when temperature gets too cold!

Ice fish live in cold climates, so they produce antifreeze compounds to prevent death.

Since cell membranes are made of lipids, they are temperature dependent. 

Mammals have sensors responsible for thermoregulation concentrated in a region of the brain called the hypothalamus (found in the brainstem), which triggers heat loss (ex. evaporation through sweating or panting) or heat generation (thermogenesis) mechanisms.

Animals, especially humans, have a lot of heat sensors in our hands that allow information to go through sensory neurons into the hypothalamus.

Fevers are a response to infection that increases body temperature and set point. 

Using a fever to treat an infection is a tradeoff. Fevers tend to kill bacteria by denaturing their proteins, but they also kill off healthy cells in an organism.

Some ectotherms seek warmer environments to increase their body temperatures in response to infections.

Bioenergetics is the overall flow and transformation of energy in an animal, and this determines the animal’s nutritional needs, and it relates to an animal’s size, activity, and enviornment. 

Developing eggs use biosynthesis where food is turned into energy to grow. Animals that hibernate eat more than they need to at the current moment to store nutrients for later.

Organisms can be classified by how they obtain energy.

Energy containing molecules from food are used to make ATP, which powers cellular work. After the needs of staying alive are met, remaining food molecules can be used in biosynthesis in the form of body growth, repair, synthesis of storage molecules such as fat, and production of gametes.

Metabolic rate is the sum of all energy an animal uses in a unit of time, and can be determined by heat loss, O2 consumed/CO2 produced, and the energy content of food consumed and lost in waste products.

Animals acquire energy by synthesis (autotrophs) or eating (heterotrophs), turning it into energy through digestion/absorbtion processes, where nutrient molecules can enter cells to create energy or create new molecules for the body to use such as proteins. In each process, some energy is lost as heat.

Metabolic rate and oxygen consumption are used often because of the stochiometric equation between glucose and oxygen / carbon dioxide and water.

In animals, a lot of energy that is converted from a food form into a chemical form releases heat into the enviornment.

Basal metabolic rate is the metabolic rate of an endotherm at rest, with an empty stomach, and not experiencing stress. BMR represents the mimimum an animal needs to survive, and this is measured under a comfortable temperature range.

BMR will never be measured at 0 because your body is constantly doing processes even if you aren’t actively doing anything.

Standard metabolic rate is the metabolic rate of a fasting, non-stressed ectotherm at rest under an ideal temperature.

Animals working at a higher intensity cannot continue to function for long because of the high cost of metabolic energy. 

Ectotherms have a much lower metabolic rate than an endotherm at a similar size. 

Metabolic rates are affected by endo/ectotherms, age, sex, size, activity, temperature, and nutrition.

Metabolic rate is roughly proportional to body mass to the power of ¾ 

Smaller animals have higher metabolic rates per gram than larger animals

The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater relative blood volume compared to a larger animal (think of your cat/guinea pigs and how they breathe much faster!) This impacts the evolution of body plans

As body size increases, energy costs per gram of tissue decreases, but a larger fraction of the body tissue is needed for exchange, support, and locomotion.

Activity greatly affects metabolic rate for both endotherm and ectotherm

In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity

For most terrestrial animals, the average daily rate of energy consumption is 2-4x BMR (endotherms) or SMR (ectotherms)

The fraction of an animal’s energy budget devoted to activity depends on factors such as the environment, behavior, size, and thermoregulation. 

Bats use a lot of energy to maintain their body temp, and as a result, they will drop their metabolic rate to maintain homeostasis. This is an example of torpor, which is a good strategy to use if there are restrictions on energy.

Torpor is a physiological state of decreased activity and metabolism, and enables animals to save energy while avoiding dangerous and difficult situations.

Daily torpor is exhibited by many small mammals/birds and seems adapted to feeding patterns (increased food intake decreases torpor)

Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity.

Metabolic rates during hibernation can be 20% lower than if the animal attempted to maintain normal body temperature

Hibernation and summer torpor reduces the amount of energy, oxygen, food, and water needed to survive.

Summer torpor is called estivation, and enables animals to survive long periods of high temperatures and scarce water.

In the European hamster, the molecular components of the cicadian clock cease operation during hibernation.

There are some fundamental similarities in the evolutionary adaptations of plants and animals.

Mechanical breakdowns (chewing) and increasing the surface area (breaking down food into smaller parts) allows acids and enzymes to break the food down.

Protective secretions along digestive pathways prevent enzymes and acids from hurting your cells.

An adequate diet must supply chemical energy for cellular processes, organic building blocks for macromolecules, and essential nutrients which are required materials for animals that cannot assemble these from simple organic molecules themselves.

Essential nutrients must be obtained from an animal’s diet and cannot synthesize it themselves (such as vitamin c in humans) there are four classes including essential amino acids, essential fatty acids, vitamins, and minerals.

All organisms require 20 amino acids, but plants and microorganisms can normally produce all 20. Animals can synthesize about half from macromolecules in their diets and the remaining amino acids, but the essential amino acids must be obtained from food in a prefabricated form.

Meat, eggs, and cheese provide all the essential amino acids and are thus “complete” proteins.

Most plant proteins are incomplete in amino acid composition, so vegetarians can easily obtain all essential amino acids from eating a varied diet of plant proteins (combining grains and legumes, assuming whole grain and whole legumes)

Animals can synthesize many of the fatty acids they need, but the essential fatty acids must be obtained from diet and include unsaturated fatty acids (a fatty acid with one or more double bonds)

Animals typically obtain ample amounts of essential fatty acids from seeds, grains, and vegetables in their diet. Some are concentrated in animals that ate grains and vegetables (diatoms that fish ate)

Vitamins are organic molecules required in the diet in very small amounts, and 13 vitamins are essential for humans. Vitamins can be either fat or water soluble.