Module 8 Intro

Module 8—Circulation, Immunity, and Excretion

Module Glossary

 

aldosterone: a hormone that causes the tubules of the kidneys to retain sodium and water

 

This increases the volume of fluid in the body, and drives up the blood pressure.

 

antibody: a protein in the blood that identifies and neutralizes foreign invaders, such as bacteria or viruses

Each antibody is specific to a particular invader.

 

antidiuretic hormone: a hormone in all mammals that stimulates increased water reabsorption by the kidneys; also called vasopressin

 

arterial pressure: the pressure blood exerts on artery walls

 

bladder: the organ where urine is stored before being discharged by the urethra

 

Bowman’s capsule: a caplike formation at the top of each nephron that serves as a filtration structure; surrounds the glomerulus

 

cell-mediated immunity: involves the activation of white blood cells, specifically macrophages, neutrophils, monocytes, and T-cells rather than the production of antibodies

 

coagulation: the process where a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel

 

congenital: appearing at birth due to a heredity/genetic abnormality or from complications during a pregnancy

 

connective tissue: the material between the cells of the body that gives tissues form and strength

 

This tissue is also involved in delivering nutrients.

 

countercurrent heat exchange: a mechanism used to transfer heat from one flowing current of fluid to another across a semi-permeable membrane

Birds use countercurrent heat exchange between blood vessels in their legs to keep heat concentrated within their bodies.

 

dehydration: a relative deficiency of water molecules in relation to other dissolved solutes; can be caused by blood loss, vomiting, excess exertion, or malnutrition

 

diabetes insipidus: a condition characterized by the excretion of large amounts of severely diluted urine, which cannot be reduced when fluid intake is reduced

 

It denotes an inability of the kidney to concentrate urine. DI is caused by a deficiency of antidiuretic hormone (ADH), also known as vasopressin.

 

diastole: the relaxation of the heart

 

distal tubule: the tubular portion of the nephron that lies between the loop of Henle and the proximal tubule

 

The distal tubule’s main function is the reabsorption of water and solutes and the secretion of various substances.

 

endocardium: the innermost layer of tissue that lines the chambers of the heart

 

This sheet of shiny white tissue also lines the body’s blood vessels to help form a continuous lining through the circulatory system. This lining helps blood flow smoothly and prevents the formation of clots.

 

fibrin: a mesh-like protein involved in the clotting of blood

 

glomerulus: a fine network of capillaries within Bowman’s capsule arising from the renal artery

 

helper T-cell: arises from the thymus

 

These T-cells recognize an antigen on the surface of an invading pathogen and stimulate B-cells to produce antibodies.

 

hydrostatic pressure: the pressure exerted by a fluid on any contacting surface, such as the force exerted by blood on a capillary wall

 

Hydrostatic pressure is greater on the arteriole end of a capillary.

 

hypothalamus: a gland located above the brain stem and connects the nervous system with the endocrine system by relaying messages to the pituitary gland; it is the size of an almond

 

kidneys: two organs that filter wastes from the blood and adjust the concentration of salts in the blood

The waste is excreted in the urine.

 

killer T-cell: also known as a cytotoxic T-cell

 

It kills other target cells, such as cells infected with viruses, parasites, or cancer. These T-cells monitor all the cells of the body and are ready to destroy any cells that express foreign antigen fragments on the surface.

 

loop of Henle: a tubular portion of the nephron

 

It is an extension of the proximal tubule that loops into the medulla of the kidney and its main function is the reabsorption of water and ions.

 

memory T-cell: a lymphocyte that carries receptors for a specific foreign antigen encountered in an earlier infection or through vaccination; it quickly promotes an immune response if the same antigen is re-encountered in a subsequent infection

 

mitral stenosis: a heart valve disorder that narrows or obstructs the mitral valve opening

Narrowing the mitral valve prevents the valve from opening properly and obstructs the blood flow from the left atrium to the left ventricle. This can reduce the amount of blood that flows forward to the body.

 

myocardial fibres: a specialized cardiac muscle that can contract as well as conduct electrical impulses; not found anywhere else in the body

 

osmoreceptors: a sensor found in the hypothalamus of the brain that detects changes in osmotic pressure

 

osmotic pressure: hydrostatic pressure produced by a solution that is separated by a semi-permeable membrane

 

The pressure is created due to different concentrations of solutes. It is required to maintain equilibrium with no net movement of solvent. In other words, osmotic pressure stays the same at all times unless there is a problem. You can think of osmotic pressure as the pressure required to prevent water from leaving.

 

pathogen: a germ or foreign-invading substance that can cause illness/disease

 

proximal tubule: the tubule connected to Bowman’s capsule

 

Its main function is the reabsorption of water and solutes as well as the secretion of hydrogen ions.

 

pulmonary: having to do with the lungs

 

Purkinje fibres: specialized fibres that transmit electrical impulses to the cardiac muscles in the heart to induce rhythmic muscle contraction

 

Rh factor: a group of antigens found in most red blood cells; people with Rh antigen on their blood cells are Rh+

 

shock: a serious, life-threatening condition where insufficient blood flow reaches the body tissues

As the blood carries nutrients and oxygen around the body, reduced flow hinders the delivery of these components to the tissues, and can stop the tissues from functioning properly.

 

sphygmomanometer: a device used to measure blood pressure

 

stem cells: undifferentiated cells that can theoretically divide without limit to replenish other cells

When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function. This can be, for example, a muscle cell, a red blood cell, or a brain cell.

 

stethoscope: an acoustic medical device designed to listen to internal sounds of the human body

 

suppressor T-cell: slows and suppresses the process of cellular immunity to ensure that normal tissue does not get destroyed

 

systemic: a body system in general

 

systole: a contraction of the heart

 

undifferentiated cells: not yet reaching the stage where specific biological roles are formed

These cells show no visible separation into their different structural parts.

 

ureter: in mammals, a pair of muscular tubes that carry urine from the kidneys to the bladder

 

urethra: the tube through which urine exits the bladder and the body

 

vasoconstriction: the constriction of blood vessels resulting from muscular contraction in blood vessel walls

 

When blood vessels constrict, the flow of blood is restricted or slowed. It is the opposite of vasodilation, the widening of blood vessels.

Biology 20 © 2008 Alberta Education