https://www.khanacademy.org/science/health-and-medicine/circulatory-system/heart-muscle-contraction/v/three-types-of-muscle 2023-09-10T17:11:17.624018169Z Three types of muscle Our bodies are equipped with three types of muscles: skeletal, cardiac, and smooth. Skeletal muscles, attached to bones and tendons, help us move voluntarily and quickly. Cardiac muscles, found only in the heart, work involuntarily and at a moderate speed to keep our heart beating. Smooth muscles, found in hollow organs and blood vessels, work slowly and involuntarily to control functions like digestion and blood flow. Each muscle type has a unique cellular structure. Rishi Desai video https://cdn.kastatic.org/googleusercontent/qqSkRyaST354-jfXhCgthZeGuHOaF01ho4EvSrXQXnEYLLjwZ0PCkjzg4w1m53dHsSBcwkbspvxJYiYyuN1lOQmG Three types of muscle Our bodies are equipped with three types of muscles: skeletal, cardiac, and smooth. Skeletal muscles, attached to bones and tendons, help us move voluntarily and quickly. Cardiac muscles, found only in the heart, work involuntarily and at a moderate speed to keep our heart beating. Smooth muscles, found in hollow organs and blood vessels, work slowly and involuntarily to control functions like digestion and blood flow. Each muscle type has a unique cellular structure. https://cdn.kastatic.org/ka-youtube-converted/bwOE1MEginA.mp4/bwOE1MEginA.mp4 689 Body systems in plants and animals https://www.khanacademy.org/science/mh-class-7-science-revision-course/x16e69e7a3344a1ee:week-3/x16e69e7a3344a1ee:untitled-318/e/identify-muscle-types-in-the-body 2026-04-20T07:20:46.893989224Z Identify muscle types in the body Let's practice vibhor exercise https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:from-cells-to-organisms/x230b3ff252126bb6:human-body-systems/a/hs-the-musculoskeletal-system-review 2026-04-26T16:30:39.382257956Z Learn: The musculoskeletal system review Learn about the organs and functions of the musculoskeletal system. article https://www.khanacademy.org/science/shs-biology-2/x2ea931c66bba6acd:unit-1-name/x2ea931c66bba6acd:skeletal-and-muscular-system/e/hs-the-musculoskeletal-system 2021-10-24T22:52:26.933018552Z The musculoskeletal system Test your knowledge on the musculoskeletal system! Ashley exercise https://www.khanacademy.org/science/bridge-course-class-10th-science/x37589313f9a4c197:untitled-78/x37589313f9a4c197:life-processes/v/human-digestive-system-in 2025-01-14T13:46:46.197485586Z Human Digestive System The fascinating journey of food through the human digestive system! From the mouth, where digestion begins with saliva, to the stomach, where gastric juices work their magic, and finally to the small and large intestines, where nutrients are absorbed and waste is processed—every step is an incredible process. Learn how organs like the liver, pancreas, and gallbladder play vital roles in breaking down food and supporting digestion. This video breaks down the complex digestive system into simple, easy-to-understand steps. Shankar Nair video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Human Digestive System The fascinating journey of food through the human digestive system! From the mouth, where digestion begins with saliva, to the stomach, where gastric juices work their magic, and finally to the small and large intestines, where nutrients are absorbed and waste is processed—every step is an incredible process. Learn how organs like the liver, pancreas, and gallbladder play vital roles in breaking down food and supporting digestion. This video breaks down the complex digestive system into simple, easy-to-understand steps. https://cdn.kastatic.org/ka-youtube-converted/2uL4b1yMhm8.mp4/2uL4b1yMhm8.mp4 492 Body systems in plants and animals https://www.khanacademy.org/science/bridge-course-class-11th-biology/xfa1bbeaa3bc88e64:plant-physiology/xfa1bbeaa3bc88e64:human-physiology/v/human-digestive-system 2024-12-29T07:21:40.948705593Z Secretions and functions of glands Let's explore the important enzymes and steps of the human digestive system Mahesh Shenoy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Secretions and functions of glands Let's explore the important enzymes and steps of the human digestive system https://cdn.kastatic.org/ka-youtube-converted/wIN_OwWT2Kk.mp4/wIN_OwWT2Kk.mp4 412 Body systems in plants and animals https://www.khanacademy.org/science/mh-class-7-science-revision-course/x16e69e7a3344a1ee:week-3/x16e69e7a3344a1ee:untitled-318/e/parts-of-the-digestive-system 2026-06-15T02:00:46.78238584Z Parts of the digestive system Let's practice vibhor exercise https://www.khanacademy.org/science/in-in-class-10-biology/in-in-life-processes/in-in-nutrition-in-human-beings/e/human-digestion 2026-06-08T05:00:48.378277506Z Human digestion Let's learn how human digestion occurs in the mouth, stomach, small, and the large intestine. Saiyem exercise https://www.khanacademy.org/science/health-and-medicine/circulatory-system/circulatory-system-introduction/v/flow-through-the-heart 2020-09-09T23:28:12Z Flow through the heart Learn how blood flows through the heart, and understand the difference between systemic and pulmonary blood flow. Rishi is a pediatric infectious disease physician and works at Khan Academy. Rishi Desai video https://cdn.kastatic.org/googleusercontent/oZ6EhbCXlLF8nqwCrKPR1Z4ftBWhk54hdKa9fGwBCm5IRu2rqouGgpU9MTWst9rAQJyZW_7WHiSxn0aIX6dVYHZr Flow through the heart Learn how blood flows through the heart, and understand the difference between systemic and pulmonary blood flow. Rishi is a pediatric infectious disease physician and works at Khan Academy. https://cdn.kastatic.org/ka-youtube-converted/7XaftdE_h60.mp4/7XaftdE_h60.mp4 471 Body systems in plants and animals https://www.khanacademy.org/science/mh-grade-8-science/x0f256b8de9c7cf34:human-body-and-organ-sysytem/x0f256b8de9c7cf34:circulatory-system/v/heart 2025-06-04T07:06:07.855810958Z Heart Let's explore how the heart works as a double pump and helps in circulating blood through out the body. We will also get quick overview of the cardiac cycle. Mahesh Shenoy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Heart Let's explore how the heart works as a double pump and helps in circulating blood through out the body. We will also get quick overview of the cardiac cycle. https://cdn.kastatic.org/ka-youtube-converted/_4DhswbhR0M.mp4/_4DhswbhR0M.mp4 272 Body systems in plants and animals https://www.khanacademy.org/science/health-and-medicine/circulatory-system/blood-vessels/v/arteries-vs-veins-what-s-the-difference 2023-09-10T17:11:17.624018169Z Arteries vs. veins - what's the difference? Explore the roles of arteries and veins in the circulatory system. Uncover common misconceptions about oxygenated and deoxygenated blood, and learn the true distinction: arteries carry blood away from the heart, while veins transport blood towards the heart. Delve into the high-pressure nature of arteries and the low-pressure, high-volume characteristics of veins. Rishi Desai video https://cdn.kastatic.org/googleusercontent/x2Vu8mDkRGVuCk7yG7tz8kKSROmZuOQ0BQtmxuIV3PM8BZLr_r1Aygs2JLAhiuV_8WXT_XPSDdR4eHmqW6_TO5ffIQ Arteries vs. veins - what's the difference? Explore the roles of arteries and veins in the circulatory system. Uncover common misconceptions about oxygenated and deoxygenated blood, and learn the true distinction: arteries carry blood away from the heart, while veins transport blood towards the heart. Delve into the high-pressure nature of arteries and the low-pressure, high-volume characteristics of veins. https://cdn.kastatic.org/ka-youtube-converted/lXkfZYlnwl4.mp4/lXkfZYlnwl4.mp4 464 Body systems in plants and animals https://www.khanacademy.org/science/biology/human-biology/circulatory-pulmonary/a/components-of-the-blood 2024-03-27T09:57:43.690871742Z Components of blood The different components that make up blood. Plasma, white blood cells, red blood cells, platelets. article https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:from-cells-to-organisms/x230b3ff252126bb6:human-body-systems/a/hs-the-circulatory-system-review 2026-04-26T16:30:39.382257956Z Learn: The circulatory system review Learn about the organs and functions of the circulatory system. article https://www.khanacademy.org/science/health-and-medicine/circulatory-system-diseases/x6e556f83:quizzes/e/heart-quiz 2026-04-07T23:55:07.30621384Z Introductory circulatory system quiz Rishi exercise https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology/lung-introduction/v/meet-the-lungs 2024-04-04T15:34:20.714536152Z Meet the lungs! Breathing in through the mouth or nose, air travels down the throat, through the Adam's apple or voice box, and into the lungs. The lungs, which look like an upside-down tree, direct air to tiny sacs called alveoli. Oxygen from the air enters the bloodstream, while waste carbon dioxide exits into the alveoli and is exhaled. This process is vital for human survival. Rishi Desai video https://cdn.kastatic.org/googleusercontent/uH7kTzlYMjpw2kX36_nrlBZ_1Q4BmB8OwW_tVhTLOdAD8DsUUgNrol2mUSTQgJpc4c3xwRT1iOcP2YQpTDjw5zqn Meet the lungs! Breathing in through the mouth or nose, air travels down the throat, through the Adam's apple or voice box, and into the lungs. The lungs, which look like an upside-down tree, direct air to tiny sacs called alveoli. Oxygen from the air enters the bloodstream, while waste carbon dioxide exits into the alveoli and is exhaled. This process is vital for human survival. https://cdn.kastatic.org/ka-youtube-converted/qGiPZf7njqY.mp4/qGiPZf7njqY.mp4 576 Body systems in plants and animals https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology/lung-introduction/v/people-and-plants 2020-10-23T19:02:14Z People and plants Learn more about photosynthesis and cellular respiration through a classic story: Jack and the Beanstalk. Rishi is a pediatric infectious disease physician and works at Khan Academy. Rishi Desai video https://cdn.kastatic.org/googleusercontent/M528gtuXOmw1M8uUHtRUM9OfnysksNbzGe8j_drTTrTiAWLiIygjGPBq7e6tYaLica49WqwdShuKG6OQZmnlVcE People and plants Learn more about photosynthesis and cellular respiration through a classic story: Jack and the Beanstalk. Rishi is a pediatric infectious disease physician and works at Khan Academy. https://cdn.kastatic.org/ka-youtube-converted/lzWUG4H5QBo.mp4/lzWUG4H5QBo.mp4 570 Body systems in plants and animals https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology/lung-introduction/v/inhaling-and-exhaling 2023-08-17T23:33:36.770424498Z Inhaling and exhaling Find out exactly why air goes in and out of the lungs. Discover how changes in lung volume affect air pressure, leading to the movement of air molecules in and out of the lungs. This process, crucial for respiration, is explained using a simple jar analogy. Rishi is a pediatric infectious disease physician and works at Khan Academy. Rishi Desai video https://cdn.kastatic.org/googleusercontent/SQkfgiCLzTh4R0AaTjEc2gRwVwDpZBjzLDmWoFgNl9aRs3O6Zzk9Im888XuR9CAHjiXnSAlgQiKv7AtZJGWNK39hkQ Inhaling and exhaling Find out exactly why air goes in and out of the lungs. Discover how changes in lung volume affect air pressure, leading to the movement of air molecules in and out of the lungs. This process, crucial for respiration, is explained using a simple jar analogy. Rishi is a pediatric infectious disease physician and works at Khan Academy. https://cdn.kastatic.org/ka-youtube-converted/mykrnTh1tz8.mp4/mykrnTh1tz8.mp4 779 Body systems in plants and animals https://www.khanacademy.org/science/health-and-medicine/respiratory-system/respiratory-system-introduction/e/lung-quiz 2026-04-07T23:17:37.123726494Z Introductory respiratory system quiz Questions Rishi Desai exercise https://www.khanacademy.org/science/revision-up-science-class-6-full-term/x00110b31861f2508:week-1/x00110b31861f2508:diversity-in-the-living-world/v/diversity-in-plants 2026-02-09T11:47:20.44246785Z Diversity in Plants In this video we dive into the plant world by studying the different parts of plants (root, shoot, leaf, stem, flower and fruit) and classify plants into different types on the basis of their structure (trees, shrubs, herbs and vines). Joel Prakash Stephen video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Diversity in Plants In this video we dive into the plant world by studying the different parts of plants (root, shoot, leaf, stem, flower and fruit) and classify plants into different types on the basis of their structure (trees, shrubs, herbs and vines). https://cdn.kastatic.org/ka-youtube-converted/qpDOWitPKUY.mp4/qpDOWitPKUY.mp4 385 Body systems in plants and animals