Human Body Systems

Human Body Systems A little about how our bodies work

The systems we will study…

Body Organization • Cells  Tissue  Organ  Organ System • ALL major body systems must work together to maintain homeostasis • What are the four types of tissue? Let’s look at the stomach • Epithelial – covers and protects underlying tissue, cells form a continuous sheet, Ex – stomach lining • Nervous – sends electrical signals through body, found in brain, nerves, and sense organs, Ex – controls acids, “full” feeling • Connective – joins, supports, protects, insulates, nourishes and cushions organs, literally keeps them from falling apart, Ex – collagen in walls • Muscle – made of cells that contract and relax to produce movement, Ex – layered so they help break-up food

Think it through… • Tanya went to a restaurant and ate a slice of pizza. Describe how Tanya used five organ systems to eat and digest her pizza. • Answer: The nervous system sends messages to Tanya’s muscular system to bite the pizza. Her jaws, which are part of the skeletal system, help grind the food. The food moves into Tanya’s stomach, which is part of the digestive system. The digestive system breaks down the food, and the circulatory system picks up nutrients and delivers them throughout the body. • Predict what would happen if the human body did not have specialized cells, tissues, organs and organ systems to maintain homeostasis. • Answer: The body would be unable to maintain homeostasis because the cells of the body would have too many jobs to do. The cells likely would not be able to do all of these jobs.

Digestive System • Major Organs – Mouth (teeth, salivary glands), esophagus, stomach, liver, gallbladder, pancreas, small intestine, large intestine, rectum, anus • Functions • Breaking down food so that the individual nutrients may be readily used by the cell’s of the body

Organs of the Digestive System • Mouth • Teeth – MD, grind food down into bits • Saliva – CD, released from salivary glands, enzymes that breaks a carbohydrate into simple sugars • Esophagus • The long straight tube connecting the pharynx and stomach • Peristalsis – rhythmic muscle contractions that squeeze food • Stomach • Muscular sac-like organ, attached between the esophagus and small intestine • Breaks down food into a liquid (chyme) by the actions of muscles (MD), enzymes and acids (CD)

Further down the digestive tract… • Liver • The large, reddish brown organ that makes bile to break up fat (CD) • Stores nutrients like glycogen (sugars) • Filters blood and breaks down toxins • Gallbladder • Sac-shaped organ that stores bile • Pancreas • Organ that lies behind the stomach and makes digestive enzymes and hormones that regulate sugar levels (insulin), involved in CD • Juices flow out of pancreas into the small intestine, these juices (bicarbonate) help to neutralize stomach acids in the chyme • Small Intestine • Organ between the stomach and large intestine, is a muscular tube 2.5 cm in diameter and about 6 meters long, food is MD and CD here • Villi – Finger-like projections, where nutrients are absorbed and whisked into the circulatory system

The end of the line… • See the villi  • Large Intestine • AKA colon • A wider and shorter portion of the intestines • Water is absorbed here so that solid waste materials can be discarded by the body • Rectum – the last part of the large intestine, stores feces until they can be expelled • Anus- the opening through which feces passes to the outside of the body

For each organ… 1. Label the organ 2. List the type of digestion (MD, CD) 3. Describe the function verbally

Think about it… • How would the inability to make saliva affect digestion? • Without saliva, swallowing would be more difficult and the chemical digestion of carbohydrates would not begin until the food reached the stomach. • How does the structure of the small intestine help achieve its functions? • The long length, folds and villi increase the surface area that comes in contact with the food that is being digested in the small intestine , allowing more nutrients to be absorbed.

Respiratory System • AKA cardiovascular system • Major Organs – Nose, Pharynx, Larynx, Trachea, Bronchi, Alveoli, Lung, Diaphragm • Functions • Respiration – breathing and cellular respiration • Exchange of O2 and CO2

Organs of the Respiratory System • Pharynx – the passage from the mouth to the larynx and esophagus, throat • Larynx – area of the throat that contains the voice box • Trachea – wind pipe, connects the larynx to the lungs • Bronchus – one of the two tubes connecting the trachea with the lungs • Alveoli – Tiny air sacs of the lungs where O2 and CO2 are exchanged, covered in capillaries • Diaphragm – A dome-shaped muscle beneath the lungs, inhale – moves down, exhale – moves up

More on respiration Breathing Cellular Respiration • Inhaling and exhaling air • The diaphragm causes you to breathe not your lungs, the lungs are for gas exchange • When the diaphragm contracts it moves down, the rib cage opens up, and air flows into the lungs • Exhaling is when the diaphragm relaxes, lifts upward and air is forced out of the lungs • When oxygen is used by cells to release energy stored in glucose • Occurs in the mitochondria of individual cells • RBC temporarily bind with and carry O2 in the bloodstream through the body to all cells via hemoglobin • O2 and sugars are broken down into CO2 and water during this process, while energy (ATP) is released

Label the respiratory organs…

Think about it… • If a respiratory disorder causes lungs to fill with fluid, how might this affect a person’s health? • The alveoli in the lungs are made for the exchange of gases, not liquids. Fluids in the lungs would prevent a person from getting all of the oxygen needed to maintain regular activity. The person might feel weak or tired. Also, the person could not get rid of the carbon dioxide from the cells, which might cause a problem, too. • Are breathing and respiration the same thing? • No, breathing is only one part of respiration. Respiration also includes cellular respiration.

Excretory System • AKA urinary system • Major Organs – Kidneys (2), ureters, bladder, urethra • Functions • Removing waste from the blood in the form of urine, storing the urine, and eliminating the urine so that the body is not poisoned.

Organs of the Excretory System • Kidneys– a pair of organs responsible for cleansing the blood. Filter about 2000 L of blood per day in other words your blood cycles through your kidneys 350 times per day • Nephrons– Inside kidneys these are microscopic filters that remove waste and/or harmful substances from the blood. Urea is one waste product that is removed. Urea is created when cells use protein for energy, high in nitrogen. • Ureter– tube that whisks the urine from the kidney to the bladder • Bladder– a muscle that collects/stores urine • Urethra– tube used to expel urine from the bladder and body Nephrons

Kidneys as filtering agents Renal artery/Aorta Renal vein/Vena cava

Think about it… • When people have one kidney removed, their other kidney can often keep their blood clean. But the remaining kidney often changes, Predict how the remaining kidney may change to do the work of two kidneys? • The remaining kidney enlarges. By enlarging, the remaining kidney is able to clean much more blood. • Which of the following contains more water: the blood going into the kidney or the blood leaving it? • The blood going into the kidney contains more water. Though the kidney returns most of the water back to the blood vessels, some of the water leaves the bloodstream when the kidneys produce urine.

Circulatory System • AKA cardiovascular system • Major Organs – Heart, blood vessels (arteries, veins, capillaries), blood • Functions • Transport of gases, nutrients, waste, hormones, toxins and excess molecules • Protects the body for immune response and prevents leaks

Circulatory System Functions • Transport • Moves H2O and nutrients from the intestine to the cells or to a storage site • Moves O2 from the respiratory organ to the cells and CO2 from the cells back to the respiratory organ • Moves hormones from endocrine glands • Moves toxic or waste molecules to the excretory organ • Protection • of the organism from foreign invaders (immune system) • of itself from loss of blood (clotting mechanism)

Organs of the Circulatory System • Heart – • A pump the size of a fist with two atria (upper part) and two ventricles (lower part), valves separate the parts of this organ • Made of cardiac muscle that contracts and relaxes • Bottom of heart is tipped to the left side of the body, heart beat strongest • Beats 60-80 times per minute • The heart is actually two hearts side-by-side. The right side of our heart pumps blood to the lungs and the left side collects the blood from the heart and pumps the oxygenated blood to the entire body. • Lub-dub of sound of heart beat – “Lub” comes from contracting ventricles, “Dub” comes from aortic valve closing sharply

More on the heart… Our hearts have a thin walled right atrium which collects deoxygenated blood from the body. Blood is then sent to the right ventricle. After that blood flows on to the lungsvia the pulmonary arteries (with deoxygenated blood). The blood then flows through the capillaries surrounding the alveoli in the lung where CO2 is released and O2 is picked up. The capillaries then lead to the pulmonary vein (with oxygenated blood) which leads back to the left atrium. The blood then flows to the thicker walled left ventricle which pumps the blood under pressure to the body. ***The freshly oxygenated blood is sent first to the coronary arteries that supply the heart and to the aorta which branches into many arteries which in turn supply blood to all the organs and tissues. The carotid artery to the brain also branches off the aorta near its origin.

Blood flow through the heart…

Other Organs of the Circulatory System • Arteries – • Lead oxygenated blood AWAY from the heart, blood looks RED • Have thick, elastic walls containing smooth muscle, muscle contractions propel blood away from heart • Capillaries- • Arteries branch and become narrower until they meet a capillary bed • Found in ALL body tissues, help to control amount of heat lost from body • Are where the action is! These vessels are only one cell thick and are where gases, nutrients, hormones, toxic molecules, water, etc. can freely flow in and out or be exchanged (simple diffusion, no ATP needed) • Veins – • Have thin walls and valves to prevent backflow of blood • Contains waster from cells, low in oxygen so blood looks dark red or BLUE

More on circulation • Two types of circulation - • Pulmonary circulation – the flow of blood from the heart to the lungs and back to the heart through pulmonary arteries, capillaries and veins • Systemic circulation – the flow of blood from the heart to all parts of the body and back to the heart • Blood pressure – • Average BP is 120/80, BP varies from person to person, drops when asleep and increases when excited • Affected by: amount of blood, clogged blood vessels, rate of heart beat • Cardiovascular problems – • High blood pressure • Artherosclerosis – high cholesterol and clogged arteries • Heart attacks – muscle tissue dies, damaged, lack of O2 • Heart failure – heart can’t pump enough blood to meet body’s needs • When a person has a "coronary" we mean s/he has a block (usually an atherosclerotic plaque) in the coronary arteries that supply the heart with fresh oxygen. When this happens, some of the heart tissue is deprived of oxygen and dies (an MI or myocardial infarction).

Blood • Blood is complex tissue containing - • Plasma, RBC, WBC, and cell fragments called platelets (help create clots) • Functions – • O2 from lungs to cells, CO2 from cells to lungs • Circulates nutrients from intestines to cells • Removes waste and excess substances (toxins) via kidney • Location of immune and hormonal responses • Blood cells – • RBC – live 120 days, 2.4 million destroyed every second and created in bone marrow at equal rate, contain hemoglobin • WBC – lifespan varies as needed, help fight infection, created in marrow, lymph nodes/glands • Blood types – • A, B, AB (universal receiver), O (universal donor) • Rh factor – protein found in blood, inherited

Think about it… • How is the structure of capillaries related to their function? • Capillaries are very small and have thin walls, which lets them be near every cell to allow oxygen, nutrients in and carbon dioxide, and wastes out of cells into the bloodstream. • How does the body use the circulatory system to help maintain proper body temperature? • As blood circulates in the body, it picks up heat from the cells and carries it through blood vessels close to the skin’s surface, the heat leaves the blood and goes into one’s surroundings.

Skeletal System • Major Organs – Bones and connective tissues (tendons, ligaments, and cartilage) • Functions • Protection • Storage • Blood Cell Formation • Movement & Support

Bone functions revealed Protection Storage Blood Cell Formation Movement • Ribs protect heart and lungs, the skull protects the brain, vertebrae protect the spinal cord • Bones store minerals that help the nerves and muscles function properly • The marrow in bones is responsible for making blood cells • Bones have muscles attached to them that contract and relax to make movement • Without bone you would not be able to stand, crawl, walk or even sit • Bones provide support for your body’s structure against gravity, • Tendons are tough inelastic bands that attach muscle to bone, ligaments are strong elastic bands cover the ends of bones and connect bones at a joint • Your skeleton is strong but light

More on bones Structure of a Bone Injuries and Diseases Keeping Bones Healthy • The outer layer of bone is hard or compact and very strong, dense and tough • The inside layer of bone is spongy, like honeycomb, lighter and slightly flexible • The middle portion of a bone is jelly-like bone marrow, where new blood cells are constantly being produced • Broken bones are known as fractures • When broken, bones produce new cells to rebuild themselves, these cells cover both ends of the broken part and close the break • Sprains, osteoporosis, arthritis • Bones need regular exercise to stay as strong as possible • Strengthen your skeleton by consuming calcium, which helps bones harden and become strong

Joints • Joints are places where two or more bones meet • Ligaments hold joints together • Three types of joints: • Gliding – bones glide over each other to allow for flexibility, Ex – Wrist, ankle • Ball and socket – allows the appendage to move freely in ALL directions, Ex – Shoulder, hip • Hinge – enables bones to flex and extend, Ex – Knee, elbow

Think it through… • Human bones and bird bones are quite different. Compare the bones of these two animals and assess why birds have hollow bones. • Answer: Human bones are dense and filled with marrow which adds weight to bones. Most birds fly so additional weight would hinder them; therefore, they have hollow bones. • Red bone marrow produces blood cells. Children have red bone marrow in their long bones, while adults have yellow bone marrow, which stores fat. Why might adults and children have different bone marrow? • Answer: Children are still growing, so they need more blood cells as their bodies get bigger. After children become adults, they don’t need as many new blood cells, so long bones store fat instead.

Muscular System • Major Organs – 3 types of muscles • Functions • To move things in and through the body • To allow for body movement

Types of Muscle Skeletal muscle – allows bones to move, protects inner organs Smooth muscle – moves food through the digestive system, makes walls of blood vessels Cardiac muscle – makes the heart, pumps blood around the body

Movement • Muscles attach to bones via tendons • Ex – where the bicep muscle attaches to the shoulder and forearm • Skeletal muscles work in pairs: • Flexors – muscle that bends part of the body, Ex - biceps • Extensors – muscle that straightens part of the body, Ex – triceps

Exercise & Injury • Exercise • Use it or lose it, muscle atrophy • Aerobic vs anaerobic exercise • Injury • Strain – muscle torn or stretched too far • Tendinitis – inflammation of a tendon

Think it through… • Describe some of the muscle action needed to pick up a book. Include the terms flexor and extensor in your description. • Answer: An extensor in the back of my arm straightens out my arm as I reach for the book. Flexors in my hand allow me to close my fingers on the book, and a flexor in my arm bends my arm as I pick up the book. • If aerobic exercise improves heart strength, what likely happens to heart rate as the heart gets stronger? • Answer: As the heart gets stronger it will pump more blood with each beat. The heart will not need to work as hard to pump the same amount of blood, so heart rate decreases.

Nervous System • The nervous system acts like a telephone system. Information is transmitted from and to the brain, the brain receiving information from the sensory nerves, and from the motor nerves. Information about our environment is received by the sensory nerves, then sent to our brain. At the same time, information about our bodies (Ex. We are hungry) is received by the motor nerves, and it too is sent to the brain. • Major Organs – Brain, spinal cord, nerves, neurons • Functions • Gathers and interprets information inside/outside the body • Responds to stimuli from inside/outside the body

The Nervous System The nervous system can be broken into two (2) parts, the central nervous system (CNS) and the peripheral nervous system (PNS). Further more, the brain and the spinal cord makes up the CNS, while the sensory nerves and the motor nerves makes up the PNS. The PNS is composed of the sense organs (e.g. the eye, the ear, touches nerve cells, taste buds, and olfactory nerve cells). The somatic nervous system and the autonomic nervous system are the parts of the motor nerves.

Peripheral Nervous System • PNS covers a large portion of the body, see pink in picture… • Involuntary movement, such the beating of our hearts, does not need our brain to work. But we when we run, our bodies need more oxygen, so our brain tells the autonomic nervous system that controls our heart to beat faster. One very easy difference to see between the two nervous system's is that the autonomic nervous system act much faster.

PNS continued… • A nerve cell, or neuron acts exactly like a phone line or a computer cable. It conducts electrons, just like wires and electricity. For these electrons to be able to move from one cell to another, they must pass through across a gap or space lying between two nerve cells called a synapse. But electrons cannot move across a gap. So a neurotransmitter carries these electrons across the synapse, in the form of Na+ and K+. As the neurotransmitter move across the synapse, they are caught by a receptor protein on the next nerve cell. • Nerve cells never touch each other, or other cells. If they did, the nervous system would short out like an unprotected wire. So nerve cells are coated by a myelin sheath, which insulates it from other cells in our body, exactly like the plastic coating on an electrical wire, or computer cable. This myelin sheath prevents the nerve cells from shorten out, and keeps our bodies working properly.

Central Nervous System • Brain is the main control center • Brain has three parts: • Cerebrum – largest part, looks like a mushroom cap, has hemispheres, where memories are stored • Cerebellum – second largest part, processes sensory info from body such as skeletal muscles and joints relaying info about balance • Medulla – smallest, can’t live w/out it, controls involuntary processes like heart rate and body temperature • Our brain controls how our body acts. Voluntary movement is initiated by our brain, and sent to the somatic nervous system, which controls our biceps, triceps and other voluntary muscles. • Spinal cord is made of bundles of neurons and axons that relay impulses from the brain • Nerve fibers in the spinal cord allow the brain to send/receive messages from neurons all over the body • Humans have sensory and motor neurons

Think it through… • Some medications slow a person’s nervous system. These drugs are often labeled “May cause drowsiness.” Explain why a person needs to know about this side effect. • Answer: A drug that causes drowsiness may affect the way that impulses travel in neurons. Affecting the impulses may increase the time it takes a message to get to the brain or the time it takes a message to get from the brain to muscles. It is important to be aware of this side effect so that activities that requires a fast reaction time, such as driving, can be avoided. • Explain how your life would change if your autonomic nervous system suddenly stopped working. • Answer: If my autonomic nervous system suddenly stopped working, I would not be able to digest food, my eyes would not adjust to light or darkness, my heart rate and blood pressure couldn’t change as they need to, and my lungs wouldn’t work properly.

Integumentary System • The integumentary system covers your body and helps you maintain homeostasis. It is composed the dermis (inside) and epidermis (outermost layer). • Major Organs – Skin • Functions • Protects you by keeping water in your body and foreign particles out. • Keeps you in “touch” with the outside world. Nerve endings (sensory neurons) let you feel things around you. • Skin helps you regulate body temperature. You sweat to help cool your body • Skin also releases small amounts of liquid waste.

Think about it… • When and why do dogs pant? How is this related to the function of skin? • Answer: Dogs pant on hot days or after they have had physical activity. Dogs do not sweat to cool down the way humans do. As a result, dogs pant to regulate their body temperature. • The epidermis on the palms of your hands and soles of your feet is thicker than anywhere else on your body. Why might this skin need to be thicker? • Answer: The epidermis forms a protective covering of dead cells. The hands and feet are areas of the body that are often used, so the epidermis in these areas needs to be thicker for better protection.

Human Body Systems