Science: Chapter 16: Human Body

Ovulation

The ovulation is the release of a mature egg from the ovary. At puberty, a woman begins to ovulate.

White Blood Cells

White Blood Cells are part of your immune system. They help fight infections by destroying invaders like bacteria and viruses. Some White Blood Cells engulf invaders. Others produce antibodies that destroy invaders. Platelets are particles that prevent blood loss. When you cut or scrape your skin, platelets clump together in the damaged area and form a "plug." Floating in the plasma are red blood cells, white blood cells, and platelets. Blood is made of a fluid called plasma, two types of cells (red blood cells and white blood cells), and particles called platelets. White Blood Cells and platelets make up a tiny fraction of your body.

Breathing

Your breathing happens even when you don't think about it. When you breathe, you take in oxygen gas from the air and exhale carbon dioxide Your cells use oxygen for cellular respiration and produce carbon dioxide and water. When you breathe, air is inhaled through your nose and mouth. From there, it flows through the pharynx, or throat. The pharynx branches into two tubes. The esophagus leads to your stomach. The larynx, leads to your lungs. The larynx also contains your voice box. Next, air flows into the trachea, or windpipe. The trachea splits into two tubes called bronchi. One bronchus (singular) goes to each ling. Each bronchus branches into thousands of tiny tubes called bronchioles. Bronchioles end in tiny sacs called alveoli. Each of your lungs contains thousands of alveoli. Alveoli are sac-like structures surrounded by capillaries where the exchange of gases take place.

Circulatory System and Respiratory System

Your circulatory and respiratory systems work together to ensure that every cell in your body has the oxygen it needs to perform cellular respiration. The failure of any part can affect the entire system. For example, a person may die from a heart attack (failure of the heart). Smoking may lead to inefficient gas exchange in the lungs and cause cardiovascular disease. Blockage of blood vessels may lead to inefficient gas exchange in the brain and cause a stroke. To understand the system, we can trace the flow of blood, starting at the heart.

4 Chamber Heart

1. and 2.) Atria contract and pump blood to ventricles. (Blood from right atrium and blood from left atrium). 3.) Ventricles contract and pump blood out of the heart. (To body and to lungs). 4.) Heart muscle relaxes and blood flows back into atria. The heart has 4 chambers. Each chamber has an one-way valve at its exit. When each chamber contracts, the valve at its exit opens. When a chamber relaxes, the valve closes so that blood does not flow backwards. The heart contracts (or beats) in two stages. This causes the lub-dub sound you hear. In the first stage the atria contract together. This pumps blood to the ventricles. In the second stage, the ventricles contract together. This pumps blood out of the heart. Then the heart muscle relaxes before the next heartbeat. This allows blood to flow into the atria again.

Hormone

A hormone is a chemical that regulates body functions.

Sphygmomanometer

A sphygmomanometer is used to measure blood pressure. The cuff is pumped up with air to restrict blood flow in the arm. As the pressure in the cuff is released, blood starts flowing again. You can hear the flow in a stethoscope. The number at which blood starts flowing is the measure of the systolic pressure. Pressure in the cuff continues to release. The point at which no sound is heard indicates the pressure in the system when the heart is relaxed -- the diastolic reading.

Vas Deferans

A tube called the vas deferans passes from each epididymis into the body.

Blood

About 55% of your blood is plasma. Your blood circulates through about 90,000 kilometers of blood vessels in your body. Each heart beat pushes about 90 milliliters of oxygenated blood from the heart into the aorta, the body's largest blood vessel. From there, the blood flows to smaller arteries and then capillaries. Contractions of the heart generate blood pressure. The rhythmic change in blood pressure is called a pulse. Blood pressure keeps the blood flowing in the right direction. Valves prevent backflow of blood.

Labor

After 38 to 42 weeks, the fetus is ready to live outside of the mother. The mother goes through a series of contractions called labor. The fetus is pushed, headfirst, through her vagina. The baby is still connected to the placenta by the umbilical cord, birth is complete. The mother continues with labor until the placenta is pushed out of her body.

Arteries

Arteries are blood vessels that carry blood away from the heart. With the exception of the pulmonary artery, they carry oxygen-rich blood. Each time the heart contracts, blood is pumped out at high pressure. Arteries are made of three layers of tissues that help them withstand that pressure. The lining is epithelial tissue. Next is a thick layer of smooth muscle that helps the artery withstand high pressure. The outer layer is made of elastic connective tissue that allows the artery to expand under pressure.

Blood Pressure

Blood Pressure is a measure of the force of blood pushing against the walls of the arteries. It is measured in millimeters of mercury (mm Hg). A pressure of 100 mm Hg means the pressure is great enough to push a narrow column of mercury 100 mm high. Normal blood pressure is 120/80 mm Hg. The top number is called the systolic pressure. Systolic Pressure is the maximum force exerted against artery walls each time the heart contracts. The lower number is called diastolic pressure. Diastolic Pressure is the force exerted on the arteries when the heart relaxes. Contractions of the heart generate blood pressure. The rhythmic change in blood pressure is called a pulse. Blood pressure keeps the blood flowing in the right direction.

Blood

Blood is a circulating connective tissue. It is made of a fluid called plasma, two types of cells (red blood cells and white blood cells), and particles called platelets. The main function of blood is to supply oxygen and nutrients to tissues and to remove waste products like carbon dioxide. Blood also transports hormones, enzymes, and immune cells between tissues and organs. Any interruption in the flow of blood can cause death in a matter of minutes. Interruptions in blood flow may be caused be a heart attack, stroke, or blood clots. You have about 5 liters of blood in your body. Blood enters the right side of the heart through two veins - the superior vena cava carries oxygen-poor blood from the upper body parts and the inferior vena cava carries oxygen-poor blood from the lower body parts.

Alveoli

Bronchioles end in tiny sacs called alveoli. Each of your lungs contains thousands of alveoli. Alveoli are sac-like structures surrounded by capillaries where the exchange of gases take place.

Capillaries

Capillaries are the smallest blood vessels where the exchange of materials with cells takes place. Capillary walls are only one cell thick and may be so narrow that blood cells must pass through in single file. They form a net-like structure throughout your tissues. Oxygen and other materials diffuse through capillary walls into the tissues and then into cells. From there, the blood flows to smaller arteries and then capillaries.

Penis

During sexual arousal, millions of sperm travel from the vas deferans, down the urethra, and are ejaculated out of the penis. Ejaculation is the abrupt discharge of semen. The urethra is a tube that runs through the penis. The penis is the organ that transfers sperm into the female's body.

Aorta

Each heart beat pushes about 90 milliliters of oxygenated blood from the heart into the aorta, the body's largest blood vessel.

Ejaculation

Ejaculation is the abrupt discharge of semen.

Fertilization (the menstrual cycle)

If fertilization occurs, the zygote moves down the fallopian tube and embeds in the thickened tissue. If fertilization does not occur, the egg deteriorates. Then, the tissue layer, along with the deteriorated egg, is discharged through the days. After menstruation, the tissue lining the uterus thickens again. Ovulation occurs about two weeks into the cycle. The entire process is called the menstrual cycle. It repeats each month puberty until late middle age.

Implantation

Implantation is the process in which an embryo becomes embedded in the lining of the uterus. Each month starting at puberty, the tissue lining the uterus thickens to prepare for pregnancy. Implantation is only successful about 30% of the time. Once the embryo is implanted, pregnancy begins. One of the first signs of pregnancy is that a woman's regular menstrual cycle stops. A pregnant woman may give birth to a baby between 38 and 42 week later which is the gestation period for humans. The fertilized egg then begins a 5 day journey down the fallopian tube toward the uterus. During the journey, the zygote undergoes many mitotic divisions. By the time it reaches the uterus, it is an embryo that looks like a tiny ball of cells. The next step is called implantation.

Diastolic Pressure

Normal blood pressure is 120/80 mm Hg. The lower number is called diastolic pressure. Diastolic Pressure is the force exerted on the arteries when the heart relaxes.

Systolic Pressure

Normal blood pressure is 120/80 mm Hg. The top number is called the systolic pressure. Systolic Pressure is the maximum force exerted against artery walls each time the heart contracts. The lower number is called diastolic pressure. The number at which blood starts flowing is the measure of the systolic pressure.

Plasma

Plasma is the fluid part of the blood that contains water, dissolved nutrients, sugars, and proteins. Floating in the plasma are red blood cells, white blood cells, and platelets.

Platelets

Platelets are particles that prevent blood loss. When you cut or scrape your skin, platelets clump together in the damaged area and form a "plug."

Puberty

Puberty is the time of life when male and female sex organs become mature A women has an estimated 300 to 400 thousand eggs contained within her ovaries at the time of puberty. At puberty, a woman begins to ovulate. If fertilization occurs, the zygote moves down the fallopian tube and embeds in the thickened tissue. If fertilization does not occur, the egg deteriorates. Then, the tissue layer, along with the deteriorated egg, is discharged through the days. After menstruation, the tissue lining the uterus thickens again. Ovulation occurs about two weeks into the cycle. The entire process is called the menstrual cycle. It repeats each month puberty until late middle age.

Red Blood Cells

Red Blood Cells transport oxygen to your cells. Red Blood Cells are red because of a pigment called hemoglobin. Hemoglobin grabs onto the oxygen molecules you inhale and carries them to your cells. Floating in the plasma are red blood cells, white blood cells, and platelets. Blood is made of a fluid called plasma, two types of cells (red blood cells and white blood cells), and particles called platelets. About 45% of your blood is made up of red blood cells.

Respiration

Respiration is the entire process by which the body exchanges and uses gases. Respiration is made possible by the respiratory system. Your breathing happens even when you don't think about it. When you breathe, you take in oxygen gas from the air and exhale carbon dioxide Your cells use oxygen for cellular respiration and produce carbon dioxide and water.

Respiratory System

Respiratory System is the body system consisting of the lungs, and passageways that lead to the lungs.

Testes

Testes produce sperm and the male hormone, testosterone. The male reproductive system produces sperm and transfers it to the female reproductive system. The testes are stored in the external scrotum.

Testosterone

Testosterones regulates the development of male traits and the production of sperm (male sex cells).

Prostate Gland

The Prostate Gland produces some of the fluid that mixes with sperm as it travels through the vas deferans.

Circulatory System

The body system that circulates blood throughout the body and delivers essential substances to cells and removes wastes. It is sometimes called the cardiovascular system. The circulatory system consists of the heart, blood vessels, and blood. The circulatory system is a transportation system. Your body is made up of trillions of cells. Each cell needs oxygen and nutrients. As your cells carry out their functions, they need to get rid of wastes like carbon dioxide.

Epididymis

The epididymis temporarily stores mature sperm cells. A tube called the vas deferans passes from each epididymis into the body.

Fetus

The fetus is an embryo that has developed for 8 weeks and has formed the major structures. After the eighth week of pregnancy, the embryo has developed enough to be called a fetus. A human fetus develops from the end of the eighth week of the pregnancy (when the major structures have formed), until birth. The blood of the mother and fetus do not mix together. Oxygen and nutrients pass from the mother's blood to the fetus through the placenta and umbilical cord. Waste products like carbon dioxide pass from the fetus to the mother's blood for removal. Most drugs and alcohol can easily pass through the placenta and into the fetus, as well as many infections viruses such as the human immunodeficiency virus (HIV). After 38 to 42 weeks, the fetus is ready to live outside of the mother. The mother goes through a series of contractions called labor. The fetus is pushed, headfirst, through her vagina. The baby is still connected to the placenta by the umbilical cord, birth is complete. The mother continues with labor until the placenta is pushed out of her body.

Follicle

The follicle is a structure of the ovary where an egg matures. During ovulation, a mature follicle ruptures through the ovary wall. Once released, the egg travels down one of the fallopian tubes that lead to the uterus.

Heart

The heart is a hollow organ found in the middle of your chest. It is made mostly of cardiac muscle tissue. The heart contracts to pump blood throughout the body. A contraction happens when muscle tissue shortens. The right and left sides of the heart have separate functions. The right side of the heart collects oxygen-poor blood from the blood and pumps it to the lungs where it picks up oxygen and releases carbon dioxide. The left side of the heart then collects oxygen-rich blood from the lungs and pumps it to the body so that every cell in the body has the oxygen it needs. The heart pumps over two million liters of blood per year and weighs 300 grams. Heart contractions generates blood pressure. Contractions of the heart generate blood pressure. The rhythmic change in blood pressure is called a pulse. Blood pressure keeps the blood flowing in the right direction.

Ovaries

The ovaries are the female organs that produce eggs and female hormones. Ovaries are also called oocytes. Ovaries also produce the female hormones estrogen and progesterone. the female hormones regulate the production and release of eggs and regulate the development of female traits. The vagina is the passageway that receives sperm during sexual intercourse. The female reproductive system produces eggs, ensures development of fertilized eggs, and gives birth.

Seminiferous Tubules

The scrotum is about 3 degrees celsius cooler than body temperature (37 degrees celsius). The cooler temperature allows sperm to develop. Sperm are produced in tightly-coiled tubes inside of the testes called seminiferous tubules.

Scrotum

The scrotum is about 3 degrees celsius cooler than body temperature (37 degrees celsius). The cooler temperature allows sperm to develop. Sperm are produced in tightly-coiled tubes inside of the testes called seminiferous tubules. The epididymis temporarily stores mature sperm cells. Each sperm cell has a flagellum.

Semen

The semen is a mixture of sperm and fluid that is ejaculated during sexual intercourse. The Prostate Gland produces some of the fluid that mixes with sperm as it travels through the vas deferans. A tube called the vas deferans passes from each epididymis into the body. During sexual arousal, millions of sperm travel from the vas deferans, down the urethra, and are ejaculated out of the penis. Ejaculation is the abrupt discharge of semen. The urethra is a tube that runs through the penis. The penis is the organ that transfers sperm into the female's body.

Bronchioles

The trachea splits into two tubes called bronchi. One bronchus (singular) goes to each ling. Each bronchus branches into thousands of tiny tubes called bronchioles.

Bronchus

The trachea splits into two tubes called bronchi. One bronchus (singular) goes to each ling. Each bronchus branches into thousands of tiny tubes called bronchioles. Bronchioles end in tiny sacs called alveoli.

Umbilical Cord

The umbilical cord contains arteries and veins that connect the embryo to the placenta. It contains arteries and veins that connect the embryo to the placenta. It enters the embryo's body at the umbilicus, or naval. Once the embryo is implanted in the uterus, the placenta begins to grow. Recall that the placenta supplies food and oxygen from the mother's blood to the developing embryo. It contains a network of blood vessels that links the embryo to the mother. By the fourth week of pregnancy, the embryo is about 2 millimeters long. It is surrounded by a thin, protective membrane called the amnion. Inside the amnion and surrounding the embryo, is amniotic fluid.

Uterus (the menstrual cycle)

The uterus is the organ where a baby grows and develops. Once released, the egg travels down one of the fallopian tubes that lead to the uterus. If fertilization occurs, the zygote moves down the fallopian tube and embeds in the thickened tissue. If fertilization does not occur, the egg deteriorates. Then, the tissue layer, along with the deteriorated egg, is discharged through the days. After menstruation, the tissue lining the uterus thickens again. Ovulation occurs about two weeks into the cycle. The entire process is called the menstrual cycle. It repeats each month puberty until late middle age.

Valve

The valve is a flap of tissue that prevents the backflow of blood. The heart has 4 chambers. Each chamber has an one-way valve at its exit. When each chamber contracts, the valve at its exit opens. When a chamber relaxes, the valve closes so that blood does not flow backwards. The heart contracts (or beats) in two stages. This causes the lub-dub sound you hear. In the first stage the atria contract together. This pumps blood to the ventricles. In the second stage, the ventricles contract together. This pumps blood out of the heart. Then the heart muscle relaxes before the next heartbeat. This allows blood to flow into the atria again. Valves prevent backflow of blood.

Veins

Veins are blood vessels that carry blood toward the heart. With the exception of the pulmonary veins, they carry oxygen-poor blood. Like arteries, veins have three tissue layers. But veins have thinner walls because they do not receive blood directly from the heart. The largest veins have one-way valves to keep blood flowing towards the heart.