IB Biology Topic 6

pathogen

any disease-producing agent (especially a virus or bacterium)

antigen

any surface protein that may elicit an immune response or cell recognition

digestion

the process where food is converted into smaller molecules that can be absorbed into the body

enzymes

globular proteins that speed up chemical reactions in the body

amylase

enzyme found in saliva and pancreatic juice that breaks the chemical bonds in starches

protease

enzyme that speeds up the breakdown of proteins into amino acids. produced by the stomach, small intestine, and pancreas.

lipase

an enzyme secreted by the pancreas that catalyzes the breakdown of fats into individual fatty acids

stomach

An organ of the digestive system that contains acid, protease enzymes and churns food.

small intestine

organ that completes the chemical digestion of food and absorbs the nutrients

large intestine

the last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body

absorption

the process of absorbing nutrients into the body after digestion

assimilation

the process where cells absorb nutrients and use them for what the body needs

villi

fingerlike projections of the small intestine (illeum) that helps it absorb nutrients

heart

multi-chambered, muscular organ that pumps blood throughout the body

coronary arteries

arteries that supply oxygen-rich blood to the heart muscle

myogenic

Describes muscle tissue (heart muscle) that generates its own contractions.

pacemaker

a specialized bit of heart tissue that controls the heartbeat

nerves

any bundle of fibers belonging to the nervous system that transmits sensations and messages between the brain and other parts of the body

medulla

part of the brain nearest the spinal cord (base of brainstem) which controls breathing, heart rate and blood pressure.

adrenaline

affect sympathetic nervous system in stress response

arteries

thick walled, elastic blood vessels that carry blood away from the heart

capillaries

the smallest blood vessels which connect the smallest arteries with the smallest veins.
Diffusion can easily occur through the thin walls of capillaries

veins

blood vessels with valves, that carry blood back to the heart

plasma

liquid portion of blood made up of water, dissolved salts, proteins, hormones, etc.

erythrocyte

A red blood cell;
with hemoglobin, carries oxygen in the blood.

leucocyte

white blood cell
involved in immune response

platelet

a blood cell fragment that is important in forming blood clots

antibiotics

chemicals that inhibit the growth of microorganisms (bacteria and fungi)

virus

a nonliving, infectious particle composed of a nucleic acid and a protein coat.

bacteria

Prokaryotic, single celled organisms.

phagocytosis

a type of endocytosis in which substances are taken up by a cell, forming a vesicle.

antibodies

Protein that is produced by lymphocytes that attaches to a specific antigen which aids in destroying infectious diseases

HIV

the virus that causes acquired immune deficiency syndrome (AIDS); it replicates and kills Helper T-cells

AIDS

a syndrome caused by the human immunodeficiency virus (HIV) that renders immune cells ineffective, permitting opportunistic infections.

ventilation

the bodily process of inhalation and exhalation; of air - containing oxygen and carbon dioxide.

gas exchange

exchange of gases between air in alveoli and blood.
O2 for respiration and its waste product, CO2

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

trachea

The windpipe; a passage through which air moves in the respiratory system.

lungs

two spongy organs, located in the thoracic cavity enclosed by the diaphragm and rib cage.

bronchi

two short branches located at the lower end of the trachea that carry air into the lungs.

bronchioles

progressively smaller tubular branches of the airways

diaphragm

Large, flat muscle at the bottom of the chest cavity that helps with breathing

Central Nervous System

the brain and spinal cord;

Peripheral Nervous System

the sensory and motor neurons that connect the central nervous system to the rest of the body

dendrite

branching extensions of a neuron that receive messages and conduct impulses toward the cell body

axon

the extension of a neuron, which conducts impulses away from the cell body

myelin sheath

a layer of fatty tissue surrounding the fibers of many neurons;

motor end plates

Terminal filaments of motor neurons that form a synapse with a muscle cell

nerve impulse

the electrical discharge that travels along a nerve fibre

relay neuron

a neuron which connects sensory neurons to motor neurones in neural pathways

motor neuron

this carries impulses from the CNS to the muscles.

resting potential

the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse, -70mV

action potential

a neural impulse; the local voltage change across the membrane as a nerve impulse is transmitted.

endocrine system

collection of glands that secrete hormones into the blood which regulate growth, development, and homeostasis

homeostasis

process by which organisms maintain a relatively stable internal environment

negative feedback

a mechanism where the change in a physiological state triggers a response that reverses the initial change.

diabetes

a condition in which the pancreas fails to produce enough insulin or the body's cells cannot use insulin properly,

male reproductive system

Produces male sex cells (sperm) and mail hormones (e.g. testosterone), transfers sperm to the female

female reproductive system

produces female sex cells (oocytes) and female hormones (e.g. estrogen and progesterone); recieves sperm from male; site of fertilization of an oocyte; site of growth and development of an embryo and fetus.

FSH

Follicle Stimulating Hormone; a gonadotropic hormone that is secreted by the anterior pituitary and stimulates growth of Graafian follicles in female mammals, and activates sperm-forming cells in male mammals

LH

Luteinizing Hormone, a gonadotropic hormone that is secreted by the anterior pituitary; stimulates ovulation in female mammals and androgen release in male mammals

estrogen

female sex hormone, secreted by the ovary and responsible for typical female sexual characteristics

progesterone

A hormone produced by the ovaries which acts with estrogen to bring about the menstral cycle; prepares and maintains uterus for pregnancy

endometrium

the mucous membrane that lines the inner wall of the uterus

In Vitro Fertilization

The most common assisted reproduction procedure, in which a woman's eggs are mixed with sperm in culture dishes (in vitro) and then carefully inserted into a woman's uterus.

testosterone

the male sex hormone. testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty