revision grade 11

revision grade 11

• •Open & closed systems

  •Circulatory systems are either described as being open or closed

  •All vertebrates and many invertebrates have closed circulatory systems

  •In an open circulatory system, blood is not contained within blood vessels but is pumped directly into body cavities

  •Organisms such as arthropods and molluscs have open circulatory systems.

•Humans have CLOSED DOUBLE CIRCULATORY SYSTEM.

• A. closed In a closed circulatory system, blood is pumped around the body and is always contained within a network of blood vessels

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B. double circulatory system: in one complete circuit of the body blood passes through the heart (the pump) twice

•The right side of the heart pumps blood deoxygenated blood to the lungs for gas exchange;

•Blood then returns to the left side of the heart, so that oxygenated blood can be pumped efficiently (at high pressure) around the body;

Open Ended

why is human circulatory system refered to as closed double circulatory system.

•The human immune system is made up of the organs and tissues involved in destroying pathogens inside the body.

•There are 2 main groups of cells involved:

• phagocytes: ingest and digest pathogens or infected cells

• lymphocytes: 

- recognise specific pathogens through interaction with receptors in their cell surface membranes

- respond in one of several ways, for example by secreting antibodies

phagocytes

• •Phagocytes are white blood cells that are produced continuously in the bone marrow

  •They are stored in the bone marrow before being distributed around the body in the blood

  •They are responsible for removing dead cells and invasive microorganisms

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  •They carry out what is known as a non-specific immune response

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• •There are two main types of phagocyte, each with a specific mode of action.

  The two types are:

  •Neutrophils

  •Macrophages

  •As both are phagocytes, both carry out phagocytosis (the process of recognising and engulfing a pathogen) but the process is slightly different for each type of phagocyte