Circulatory System

By: Francisco Colina-Salas


Transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce.

Arteries, Veins, and Capillaries

Arteries have a thick outer layer of longitudinal collagen and elastic fibers to avoid leaks and bulges. They have a thick wall which is essential to withstand the high pressures. They also have thick layers of circular elastic fibres and muscle fibres to help pump the blood through after each contraction of the heart.

Veins are made up of thin layers with a few circular elastic fibres and muscle fibres. This is because blood does not flow in pulses and so the vein walls cannot help pump the blood on. Veins also have thin walls which allows the near by muscles to press against them so that they become flat. This helps the blood to be pushed forwards towards the heart. There is only a thin outer layer of longitudinal collagen and elastic fibres as there is low pressure inside the vein and so little chance of bursting. Finally, a wide lumen is needed to accommodate the slow flowing blood due to the low pressure.

Capillaries are made up of a wall that is only one cell layer thick and results in the distance for diffusion in and out of the capillary being very small so that diffusion can occur rapidly. They also contain pores within the their wall which allow some plasma to leak out and form tissue fluid. Phagocytes can also pass through these pores to help fight infections. In addition, the lumen of the capillaries is very narrow. This means that many capillaries can fit in a small space, increasing the surface area for diffusion.

Blood passage through our Veins

Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. As the atrium contracts, blood flows from your right atrium into your right ventricle through the open tricuspid valve.

Composition of Blood

Plasma is the liquid part of the blood. Approximately half of your blood is made of plasma. The plasma carries the blood cells and other components throughout the body. Plasma is made in the liver.

Erythrocyte: A cell that contains hemoglobin and can carry oxygen to the body. Also called a red blood cell (RBC).

Leukocytes or white blood cells, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders.

Platelets are parts of the blood that help the blood clot.

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  1. High blood pressure, occurs when a high force of blood presses against the artery walls over time.

  2. No symptoms

  3. More than 3M US cases per year

  4. ACE Inhibitor, channel blocker, diuretic, heat medication


  1. The build-up of fats, cholesterol, and other substances in and on the artery walls

  2. More than 3M US cases per year

  3. Pain in the chest, can occur in the leg while exercising. Also common: shortness of breath, heart attack, transient ischemic attack, poor wound healing, erectile dysfunction, or stroke.

  4. Blood thinners, diabetes medication, heart medication.

Reproductive System


Producing new lives so species don't die.


It's a process in which spermatozoa are produced from male primordial germ cells by way of mitosis and meiosis. The initial cells in this pathway are called spermatogonia, which yield primary spermatocytes by mitosis.


  • Oogenesis describes the production of female gametes (ova) within the ovary
  • The process begins during fetal development, when a large number of cells (oogonia) are formed by mitosis before undergoing a period of growth
  • These cells begin meiosis but are arrested in prophase I until puberty
  • At puberty, some follicles continue to develop each month is response to FSH secretion
  • These follicles complete the first meiotic division to form two cells of unequal size
  • The cell with less cytoplasm is a polar body (which degenerates), while the larger cell forms a secondary oocyte
  • The secondary oocyte begins the second meiotic division but is arrested in prophase II (until fertilization)
  • It is released from the ovary (ruptured follicle develops into corpus luteum) and, if fertilization occurs, will complete meiosis
  • The second meiotic division will produce an ovum and a second polar body



  1. A disorder in which tissue that normally lines the uterus grows outside the uterus
  2. Pain: in the lower abdomen, vagina, rectum, pelvis, or lower back, can occur while defecating or during sexual intercourse, can be sharp, severe or mild. Menstrual: irregular menstruation, spotting, heavy menstruation, or painful menstruation. Gastrointestinal: inability to empty bowels, bloating, or constipation. Abdominal: abdominal fullness or cramping. Also common: nausea, abnormal vaginal bleeding, irregular uterine bleeding, sensitivity to pain, or infertility
  3. More than 3M US cases per year
  4. Hormones and medicine


  1. Condition in which the opening of the urethra is on the underside of the penis, instead of at the tip.
  2. Opening of the urethra at a location other than the tip of the penis. Downward curve of the penis. Hooded appearance of the penis because only the top half of the penis is covered by foreskin. Abnormal spraying during urination.
  3. More than 3M US cases per year
  4. Surgery