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Life Functions 1 Objectives • Analyze the processes by which organisms representative of the following groups accomplish essential life functions including: – Unicellular protists, annelid worms, insects, amphibians, mammals, nonvascular plants, seed plants – Transport, excretion, respiration, regulation, nutrition, synthesis, reproduction, and growth and development. 2 • Transport : Life Functions how organisms deliver what they need to cells and move wastes from cells to organs of excretion. • Excretion: how organisms get rid of their waste and balance their fluids (pH, salt concentration, water). • Respiration: How organisms get oxygen from the environments and release carbon dioxide back to the environment and how plants exchange gases. • Regulation: how organisms control body processes—hormones, nervous system. • Nutrition: how organism break down and absorb foods. • Reproduction: sexual versus asexual, eggs, seeds, spores, placental, types of fertilization. • Growth and Development: metamorphosis, development in egg or in uterus, growth from seed or spore. 3 Life Functions Protists 4 Life Functions of Protists • The methods of transport, excretion, and gas exchange used by protists are generally the same at those used by cells in general: – – – – Diffusion/osmosis Active transport Facilitated diffusion Vesicular transport (endocytosis, exocytosis) 5 Life Functions of Protists • Nutrition – Animal-like protists: • Flagellates and Ciliates – Ingest food via endocytosis – Digestion is intracellular (within the cell) – Undigested materials are eliminated by exocytosis • Nonmotile (Sporozoans) are parasites that feed off the cells and fluids of their hosts. – Plant-like protists are photosynthetic autotrophs and make their own food. 6 Life Functions of Protists • Reproduction – Most protists reproduce asexually by cell division (fission). – Some may produce sexually. 7 Life Functions Animals 8 Life Functions: Animals • Transport – Complex animals have tissues that are several cell layers thick. • Making exchange of materials directly with the environment impossible. • Oxygen and nutrients must be transported to these body cells by a circulatory system. 9 Life Functions: Animals There are two types of circulatory systems. • Open circulatory system – In an open circulatory system, a heart pumps fluids containing oxygen and nutrients through a series of vessels out into the body cavity. – The fluid washes across the body’s tissues, supplying them with oxygen and nutrients. – The fluid collects in open spaces in the animal’s body and flows back to the heart. 10 Life Functions: Animals Open Circulatory System 11 Life Functions: Animals • Closed circulatory system – In a closed circulatory system, a heart pumps blood through a system of blood vessels. – The blood vessels provide a network that allows blood flow from the heart to all of the body’s cells and back again. – The blood remains in the vessels and does not come in direct contact with the body’s tissues. • Materials pass into and out of the blood by diffusing through the walls of the blood vessels. 12 Life Functions: Animals Closed Circulatory System 13 Life Functions Annelid Worms 14 Life Functions of Annelids • Segmented worms have a closed circulatory system. – Blood carrying oxygen to and carbon dioxide from body cells flows through vessels to reach all parts of the body. – The earthworm circulatory system consists of enlarged blood vessels that are heavily muscled. • When these muscles contract, they help pump blood through the system. 15 Life Functions of Annelids Earthworm Circulatory System 16 Life Functions of Annelids • Excretion – In each segment of the worm is a pair of excretory tubules called nephridia that remove wastes from the blood and fluid in the body cavity. – The nephridia lead to exterior pores through which the wastes are discharged. 17 Life Functions of Annelids Earthworm Excretory System 18 Life Functions of Annelids • Respiration – Annelids that live in water breathe through gills. • A gill is an organ specialized for exchange of gases under water. – Annelids that live on land exchange oxygen and carbon dioxide through their moist skin. 19 Life Functions of Annelids • Regulation (Nervous Control) – An earthworm has a system of nerve fibers in each segment. – The nerve fibers are coordinated by a simple brain that lies above the mouth. – The earthworm also has a nerve cord that runs along its belly. 20 Life Functions of Annelids Earthworm Nervous System nerve cord brain 21 Life Functions of Annelids • Nutrition – Segmented worms have a complete internal digestive tract that runs the length of the body. – Food taken in by the mouth passes into the esophagus. – The food then moves through the crop, where it can be stored. – After that it moves through the gizzard where it is ground into smaller pieces. – Extracellular chemical digestion and absorption occurs along the intestine. 22 Life Functions of Annelids Earthworm Digestive System intestine esophagus pharynx mouth gizzard crop 23 Life Functions of Annelids • Reproduction – Most segmented worms are hermaphrodites, • Each individual contains both sexes. – Mating occurs when two worms join head to tail, exchanging sperm. – Later during egg laying, the clitellum (a thickened glandular ring) on each worm secretes a mucous cocoon. • Eggs are laid within the cocoon and fertilized externally with stored sperm as the worm withdraws from the cocoon. 24 Life Functions of Annelids Mating Earthworms 25 Life Functions Insects 26 Life Functions of Insects • Transport – Nutrients and other materials are transported through the body of a grasshopper by an open circulatory system. • A long blood vessel with a series of muscular “hearts” runs along the grasshopper’s back. Blood is pumped out of the open system and bathes the body tissues directly before returning to the heart. 27 Life Functions of Insects 28 Life Functions of Insects • Excretion – Insects have an excretory system that is composed of units called Malpighian tubules. – Malpighian tubules are slender, fingerlike extensions from the arthropod’s gut that are bathed by blood. – Water and small particles in the blood move through the tubules and into the gut. Metabolic wastes remain in the gut until they exit through the anus. 29 Life Functions of Insects • Malpighian Tubules (ant) 30 Life Functions of Insects • Respiration – The majority of terrestrial arthropods respire through a network of fine tubes called trachea. – Air enters the arthropod’s body through abdominal pores called spiracles and passes into the tracheae, delivering oxygen throughout the body. – Valves that control the flow of air through the spiracles and prevent water loss were a key adaptation for the first arthropods that invaded land more than 400 million years ago. 31 Life Functions of Insects • Tracheal system of a beetle 32 Life Functions of Insects • Grasshopper respiratory and circulatory systems. 33 Life Functions of Insects • Regulation (nervous system) – Senses • Insects have acute senses to detect movement, sound and chemicals. • Antennae detect touch and chemicals in the environment. They may also be used in communication. • Sensory hairs on the body may detect vibrations in the environment. • Eyes, simple or compound, are used to detect light or movement. 34 Life Functions of Insects • Regulation (nervous system) – Insects have a well developed nervous system that processes information coming from the sense organs. – It consists of: • A double nerve cord along belly. • A brain in the head. 35 Life Functions of Insects • Grasshopper nervous system 36 Life Functions of Insects • Nutrition – Insects have a complete digestive system with: • • • • • Mouth Stomach Intestine Anus Various glands that produce digestive enzymes – Mouthparts vary and are adapted for holding, chewing, sucking, or biting various foods. 37 Life Functions of Insects • Insect mouthparts 38 Life Functions of Insects • Anatomy of a Grasshopper 39 Life Functions of Insects • Reproduction – Most insect species have separate males and females and reproduce sexually. – Fertilization is usually internal. – Some species, including bees, ants and wasps, exhibit parthenogenesis, a form of asexual reproduction in which a new individual develops from an unfertilized egg. 40 Life Functions of Insects • Growth and Development Insect Life Cycle – The life cycles of most insects are complex, and often several molts are required before the adult stage is reached. – During the last molt, the young insect undergoes a dramatic physical change called metamorphosis. 41 Life Functions of Insects • Growth and Development Complete Metamorphosis – Almost all insect species undergo “complete” metamorphosis. – In complete metamorphosis, the wingless, wormlike larva encloses itself within a protective capsule called a chrysalis. Here, it passes through a pupa stage, in which it changes into an adult. – A complete metamorphosis is a complex life cycle. The larvae can, however, exploit different habitats and food sources than adults. 42 Life Functions of Insects • Complete Metamorphosis 43 Life Functions of Insects • Complete Metamorphosis 44 Life Functions of Insects • Growth and Development Incomplete Metamorphosis – A smaller number of species develop into adults in a much less dramatic incomplete metamorphosis. – In these species, the egg hatches into a juvenile, or nymph, that looks like a small, wingless adult. – After several molts, the nymph develops into an adult. 45 Life Functions of Insects • Incomplete Metamorphosis 46 Life Functions of Insects • Incomplete Metamorphosis 47 Life Functions Vertebrates 48 Life Functions of Vertebrates • Transport – The vertebrate circulatory system is closed and consists of the following parts: • Heart • Blood • Blood vessels 49 Life Functions of Vertebrates • Heart – Pumps blood through lungs and body systems. – Has two types of chambers. • Atria—receive blood returning to the heart from body systems. • Ventricles—pump blood out of the heart to body systems. 50 Life Functions of Vertebrates • Blood vessels – Arteries • Carry blood away from the heart to lungs or body tissues. • Have thick, elastic walls – Capillaries • Smallest blood vessels • Walls one cell thick • Sites of materials exchange between blood and cells – Veins • Carry blood toward the heart • Have thin non-elastic walls • Have valves to prevent back flow 51 Life Functions of Vertebrates 52 Life Functions of Vertebrates 53 Life Functions of Vertebrates • Blood – Includes: • Plasma – the liquid portion of the blood composed of water, nutrients and wastes, salts, and proteins • Blood cells– Red blood cells – contain hemoglobin for transport of oxygen – White blood cells – defend the body against disease • Platelets – cell fragments involved in blood clotting 54 Life Functions of Vertebrates Amphibians 55 Life Functions of Amphibians • Transport – The adult amphibian’s circulatory system is made up of two loops and a three-chambered heart. – In the 3-chambered heart, • one chamber receives oxygen-rich blood from the lungs and skin, and another receives oxygen-poor blood from the body tissues.(these are the atria) • Blood from both chambers then moves into the third chamber (ventricle), which pumps blood to the body and lungs. 56 Life Functions of Amphibians • Amphibian heart structure 57 Life Functions of Amphibians • Frog heart and double-loop circulation 58 Life Functions of Amphibians • Excretion – Amphibians have specialized organs of excretion, the kidneys. The function kidneys will be discussed in detail with respect to mammals. • Respiration – Adult amphibians have lungs, a key adaptation for gas exchange on land. 59 Life Functions of Amphibians • Respiration – A lung is an internal, baglike respiratory organ that allows oxygen and carbon dioxide to be exchanged between the air and the bloodstream. – In amphibians, the lungs are hardly more than sacs with folds on their inner membrane that increase their surface area. – Many amphibians also obtain oxygen through their thin, moist skin. 60 Life Functions of Amphibians • Amphibian Lung Structure 61 Life Functions of Amphibians • Regulation (Nervous System) – The frog brain is about the same size as that of a fish but has a better developed area for smell. – The spinal cord extends down the back and is encased within the backbone. • Signals conducted between the body and brain travel along the spinal cord. – Sense Organs • The sense of smell, sight and hearing are well developed. 62 Life Functions of Amphibians • Nutrition (the Digestive System) – Most amphibians are small and so rely on insect or other small arthropods for food. – Their digestive system includes: pharynx, esophagus, stomach, liver, gallbladder, small intestine, large intestine and cloaca. • Cloaca is a common opening for the digestive, excretory, and reproductive systems. – The mechanisms of digestion will be discussed with the mammal digestive system. 63 Life Functions of Amphibians • Internal Anatomy of a Frog 64 Cloaca Life Functions of Amphibians • Reproduction – Amphibians depend on water to complete their life cycle. – Females release eggs into water and the males deposits sperm on them externally. • Growth and Development – Fertilized frog eggs hatch into swimming fishlike larvae called tadpoles. – Tadpoles develop into adult frogs through the process of metamorphosis. 65 Life Functions of Amphibians • Life Cycle of a Frog 66 Life Functions of Amphibians • Life Cycle of a Frog 67 Life Functions Mammals 68 Life Functions of Mammals • Transport – Mammals have a four-chambered heart and doubleloop circulatory system. – In this system, oxygen-rich and oxygen-poor blood are kept completely separate. 69 Life Functions of Mammals • Excretion – Excretion is the process that rids the body of toxic chemicals, excess water, salts, and carbon dioxide while maintaining osmotic and pH balance. – The lungs, the kidneys, and the skin all function as excretory organs. – In the liver, ammonia is converted to a less toxic nitrogen waste called urea, which is transported to the kidneys, then removed from the blood 70 Life Functions of Mammals • Organs of Excretion 71 Life Functions of Mammals • Excretory System 72 Life Functions in Mammals • Excretion Kidneys – The kidneys are a pair of bean-shaped, reddish brown organs located in the lower back. – The kidneys regulate the amount of water and salts contained in blood plasma. They play a vital role in maintaining homeostasis. 73 Life Functions of Mammals • Excretion Kidneys – Each kidney is composed of blood-filtering units called nephrons. The kidneys filter out toxins, urea, water, and mineral salts from the blood. The body reabsorbs useful molecules and water. – Urine is formed from the remaining water, urea, and salts. Ureters are tubes that carry the urine from the kidney to the urinary bladder. 74 Life Functions of Mammals • Human Kidney Structure 75 Life Functions of Mammals • Excretion – The ureters direct the urine into the urinary bladder, a hollow, muscular sac that stores urine. – Urine leaves the bladder and exits the body through a tube called the urethra. The elimination of urine from the body through the urethra is called urination. 76 Life Functions of Mammals • Respiration – During aerobic respiration, cells must take in oxygen to oxidize glucose and make ATP. – Cells must also release carbon dioxide, a waste product of aerobic respiration. 77 Life Functions of Mammals The Path of Air – From the nose, air passes through a muscular tube in the upper throat called the pharynx. The air flows through a passageway for air called the larynx. – Air then passes into the trachea. The trachea divides into two smaller tubes, the bronchi, which lead to the lungs. Within the lungs, gas exchange occurs in clusters of tiny sacs called alveoli. 78 Life Functions of Mammals • Human Respiratory System 79 Life Functions of Mammals • Alveoli 80 Life Functions of Mammals • Gas Exchange in the Lungs 81 Life Functions of Mammals • Gas Transport – In the lungs, hemoglobin molecules in the blood pick up oxygen. The blood travels to the heart, then to the rest of the body. – In body tissues, oxygen diffuses into the cells for use during aerobic respiration. Carbon dioxide diffuses from the cells into the blood. In the lungs, carbon dioxide is released. 82 Life Functions of Mammals O2 and CO2 in the blood 83 Life Functions of Mammals • Regulation (Nervous System) 84 Life Functions of Mammals • The nervous system consists of cells and organs that: – Detect stimuli in the internal and external environment. – Control and coordinate responses. – Integrate the activities of organ systems. • The basic functional unit of the nervous system is the nerve cell or neuron. • Neurons are specialized cells that transmit 85 information throughout the body. Life Functions of Mammals • Neurons carry information by conducting electrical signals called nerve impulses. • Structure of a neuron: – Dendrites – often short, numerous extensions from the cell body that receive information from other cells. – Cell Body (soma) – the largest part of the cell, it contains the nucleus, most of the organelles and most of the cytoplasm. – Axon – long, slender process that conducts impulses away from the cell body. 86 Life Functions of Mammals 87 Life Functions of Mammals • Nervous tissue consists of neurons and supporting cells. • A nerve is a bundle of axons. • The nervous system is divided into two structural components – Central nervous system • Brain • Spinal cord – Peripheral nervous system • Nerves and sensory structures outside the central nervous system. 88 Life Functions of Mammals 89 Life Functions of Mammals • The Endocrine System 90 Life Functions of Mammals • The endocrine system regulates body functions through the production of hormones. • Hormones are substances secreted by cells that act to regulate the activity of other cells in the body. • The functions of hormones include the following: – Regulate growth, development, behavior and reproduction. – Coordinate the production, use and storage of energy. 91 – Maintain homeostasis Life Functions of Mammals • The endocrine system consists a number of recognizable endocrine glands and tissues scattered throughout the body. 92 Life Functions of Mammals • The hypothalamus is an area of the brain that coordinates the activities of the nervous and endocrine systems. • It controls many body functions by using hormones to communicate with the pituitary gland. 93 Life Functions of Mammals • The pituitary gland secretes many hormones that control other endocrine glands. • The secretions of these hormones is directed by hormonal signals from the hypothalamus. 94 Life Functions of Mammals • The thyroid gland is located in the neck, just below the larynx. • Thyroid hormones are primarily involved in the regulation of metabolic rate in the body. 95 Life Functions of Mammals • The parathyroid glands are located within the thyroid glands. • Parathyroid hormone (PTH) helps to regulate the levels of calcium in body fluids. – If blood calcium levels get too low, the parathyroid gland is stimulated to release PTH. – The effect of PTH is to raise calcium levels 96 Life Functions of Mammals • The pancreas contains clusters of specialized cells called islets of Langerhans that secrete endocrine hormones. • The hormones are: insulin and glucagon • These hormones help regulate blood glucose levels – Insulin stimulates body cells to take up glucose thereby lowering levels in the blood. – Glucagon has the opposite effect, by causing the liver to release glucose into the blood. 97 Life Functions of Mammals • The Adrenal Glands are located above the kidneys. • One of the chief functions of adrenal hormones is to prepare the body for “fight or flight” responses in time of stress. • The hormones epinephrine and norepinephrine (sometimes called adrenaline) cause increased heart rate, blood pressure, and blood glucose levels. 98 Life Functions of Mammals • Nutrition (The Digestive System) 99 Life Functions of Mammals • Functions: – Ingestion of water and food – Chemical digestion and absorption – Elimination of food residues • Includes: – – – – – – – Mouth (tongue, teeth, salivary glands) Esophagus Stomach Small intestine Large intestine Liver and gall bladder Pancreas 100 Life Functions of Mammals • Mouth – Chewing accomplishes physical breakdown of food – Tongue move food over teeth, mixes it with saliva, and pushes it to throat for swallowing – Salivary glands secrete saliva, which • moistens and softens the food • contains enzymes the begin the breakdown of starch • contains mucus for lubrication 101 Life Functions of Mammals • The esophagus – Transport food from throat to stomach – Uses wavelike muscle contractions called peristalsis. • Stomach – Temporarily stores food – Churning further contributes to physical breakdown – Gastric juices contain enzymes and acids that begin the chemical breakdown of proteins 102 Life Functions of Mammals • Small Intestine – Most nutrient digestion a absorption occur here – Enzymes from pancreas and bile from liver contribute to the chemical digestion of carbohydrates, lipids, and proteins – Finger-like projections of digestive epithelium increase surface area for absorption of digested nutrients. 103 Life Functions of Mammals • Villi in the Small Intestine 104 Life Functions of Mammals • Cross Section of the Small Intestine 105 Life Functions of Mammals • Large Intestine – Absorbs water – Microbes here synthesize vitamins K and B – Undigestible wastes are compacted into feces 106 Life Functions of Mammals Reproduction • All mammals reproduce sexually through internal fertilization. • Mammals are divided into three subclasses based on their method of reproduction. – Monotremes (egg-laying mammals): There are only three surviving species of montremes (2 spiny anteaters and the platypus) – Marsupials (pouched mammals): have a short period of development inside the mother’s body. After that, they experience a period of development inside a 107 pouch on the outside of the mother’s body. Life Functions of Mammals – Placental mammals: • give birth to young that have developed inside the mother’s uterus until their body systems are fully functional. • During development the young receive nourishment through the placenta. • The placenta is an organ made of uterine and embryonic tissues that passes nutrients and oxygen to and removes wastes from the developing embryo. 108 Life Functions of Mammals The Reproductive System: • The Male Reproductive System consists of: – Internal organs including • • • • Testis Epididymus Vas deferens Seminal vesicles • Prostate gland • Bulbourethral glands • Urethra – External organs including • Penis • Scrotum • Urethra 109 Life Functions of Mammals • Testes – Located in the scrotum • Scrotum is an external skin pouch that helps regulate the temperature of the testes – Produce sperm – Contain cells that secrete testosterone hormones necessary to maintain male secondary sex characteristic. • Epididymus – Coiled tube on testis where sperm finish maturing and become able to move. 110 Life Functions of Mammals • Vas deferens – Tube through which sperm move to reach the urethra. • Seminal vesicles – Produces a sugary fluid that sperm use for energy. It is slightly alkaline to neutralize acids in prostate fluid and the vagina. • Prostate gland – Produces a slightly acid fluid that contributes 20-30% of semen volume. 111 Life Functions of Mammals • Bulbourethral gland – Secrete a thick, alkaline mucus – Helps neutralize urinary acids in urethra and lubricates the glans (tip of the penis) • The secretions of the seminal vesicle, prostate, and bulbourethral gland mixed with sperm form the semen. 112 Life Functions of Mammals • The urethra passes through the penis. • The penis deposits the semen into the female reproductive system. 113 Life Functions of Mammals The Male Reproductive System 114 Life Functions of Mammals • The Female Reproductive System consists of : – Ovaries – Oviducts – Uterus – Vagina • Ovaries – Produce eggs (ova) – Secrete hormones (estrogen, progesterone) • Maintain female secondary sex characteristics • Regulate menstrual cycle 115 Life Functions of Mammals • Oviducts provide a passageway through which ovum moves toward uterus. • Uterus—hollow, muscular organ within which development takes (if egg has been fertilized) • Vagina—muscular tube that leads from uterus to outside of body. – Receives the penis during sexual intercourse – Serves as “birth canal” during labor and delivery. 116 Life Functions of Mammals Female Reproductive System 117 Life Functions of Mammals Fertilization • If sperm are present in the female reproductive system within a few days after ovulation, fertilization may occur. 118 Life Functions of Mammals Cleavage and Implantation • In the first week after fertilization, the zygote undergoes a series of internal divisions known as cleavage. • Cleavage continues as the embryo moves toward the uterus. By the time it reaches the uterus, the embryo is a hollow ball of cells. • About six days after fertilization, the embryo burrows into the lining of the uterus in an event called implantation. 119 Life Functions of Mammals Early Zygote Development 120 Life Functions of Mammals Pregnancy • Human development takes about 9 months—a period known as gestation, or pregnancy. • The 9 months of pregnancy are often divided into three trimesters, or 3-month periods. • For the first 8 weeks of pregnancy, the developing human is called an embryo. 121 Life Functions of Mammals First Trimester • In the second week after fertilization the embryo grows rapidly. • Embryonic membranes interact with the uterus to form the placenta. • The placenta is the structure through with the mother nourishes the embryo. 122 Life Functions of Mammals Structure of the Placenta 123 Life Functions of Mammals • By the end of the fourth week, all the major organs begin to form and the heart begins to beat. • From the eighth week until childbirth the developing human is called a fetus. • A fetus has recognizable body features. 124 Life Functions of Mammals Second and Third Trimesters • During these trimesters, the fetus grows rapidly as its organs become functional. • By the end of the third trimester, the fetus is able to exist outside the mother’s body. • After about 9 months of development, the fetus leaves the mother’s body in a process called labor. 125 Life Functions of Mammals 126