BIOL 144 EXAM 3 REVIEW

Osmosis

Diffusion of water across a selectively permeable membrane from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration (lower water concentration).

Diffusion

Spontaneous movement of a substance from one region to another, often with a net movement from a region of high concentration to one of low concentration (i.e., down a concentration gradient).

Hyperosmotic

Referring to a solution that has a higher solute concentration, and therefore a lower water concentration, than another solution.

Hyposmotic

Referring to a solution that has a lower solute concentration, and therefore a higher water concentration, than another solution.

Isosmotic

Referring to a solution that has the same solute concentration and water concentration as another solution.

Osmoregulation

The process by which an organism controls the concentration of water and solutes in its body.

Electrolytes

Any compound that dissociates into ions when dissolved in water. In nutrition, any of the major ions necessary for normal cell function.

Nitrogenous Wastes

Compounds excreted by animals to rid their bodies of excess nitrogen. Main types include ammonia, urea, and uric acid.

Nephron

One of many tiny tubules inside the kidney that function in the formation of urine.

Glomerulus

In the vertebrate kidney, a ball-like cluster of capillaries, surrounded by Bowman’s capsule, at the beginning of a nephron.

Bowman’s Capsule

The hollow, double-walled, cup-shaped portion of a nephron that surrounds a glomerulus in the vertebrate kidney.

Proximal Tubule

In the vertebrate kidney, the convoluted portion of a nephron into which filtrate moves from Bowman’s capsule. Involved in the largely unregulated reabsorption of electrolytes, nutrients, and water.

Distal Tubule

In the vertebrate kidney, the convoluted portion of a nephron into which filtrate moves from the loop of Henle. Involved in the regulated reabsorption of sodium ions and water.

Loop of Henle

In the kidneys of mammals and some birds, a long, U-shaped loop in a nephron that extends into the medulla. Functions as a countercurrent exchanger and multiplier in establishing and maintaining a medullary osmotic gradient that allows reabsorption of water from the collecting duct.

Collecting Duct

In the vertebrate kidney, a large, straight tube that receives filtrate from the distal tubules of several nephrons. Involved in the regulated reabsorption of water.

Filtration

A process of removing large components from a fluid by forcing it through a filter. Occurs in renal corpuscles of the vertebrate kidney, allowing water and small solutes to pass from the blood into the nephron.

Reabsorption

the process of __absorbing__ something again.

Bladder

An organ that holds urine until it can be excreted.

Urethra

The tube that drains urine from the bladder to the outside environment. In male vertebrates, also used for passage of semen during ejaculation.

Ureter

In vertebrates, a tube that transports urine from one kidney to the bladder.

ADH

A peptide hormone, secreted from the posterior pituitary gland, that stimulates water retention by the kidney.

Digestion

The mechanical and chemical breakdown of food into molecules that can be absorbed into the body of an animal.

Absorption

In animals, the uptake of ions and small molecules, derived from food, across the lining of the digestive tract.

Essential Amino Acids

Any amino acid that an animal cannot synthesize and must obtain from the diet. There are eight essential amino acids in adult humans: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Vitamins

Any of various organic micronutrients that usually function as coenzymes.

Essential Elements (Minerals)

Any chemical element, ion, or compound that is required for normal growth, reproduction, and maintenance of a living organism and that cannot be synthesized by the organism.

Phagocytosis

Uptake by a cell of small particles or cells by invagination and pinching off of the plasma membrane to form small, membrane-bound vesicles

Pharynx

the membrane-lined __cavity__ behind the nose and mouth, connecting them to the __esophagus__.

Amylase

Any enzyme that can break down starch by catalyzing hydrolysis of the alpha-glycosidic linkages between glucose residues.

Pancreatic Lipase

An enzyme produced by the pancreas that digests fats, releasing monoglycerides and fatty acids.

Emulsification

The dispersion of fat into an aqueous solution. Usually requires the aid of an amphipathic substance such as a detergent or bile salts, which can break large fat globules into microscopic fat droplets.

Pepsin

A protein-digesting enzyme secreted in inactive form (as pepsinogen) by chief cells in the stomach lining.

Esophagus

The muscular tube that connects the mouth to the stomach.

Peristalsis

Rhythmic waves of muscular contraction. In the digestive tract, pushes food along. In animals with hydrostatic skeletons, enables crawling.

Sphincter

A muscular valve that can close off a tube, as in a blood vessel or a part of the digestive tract.

Colon

The portion of the large intestine where feces are formed by compaction of wastes and reabsorption of water.

Lumen

The interior space of any hollow structure (e.g., the rough ER) or organ (e.g., the stomach).

Stomach

A tough, muscular pouch in the vertebrate digestive tract between the esophagus and small intestine. Physically breaks up food and begins digestion of proteins.

Crop

In animal anatomy, a storage organ in the digestive tract of certain vertebrates.

Gizzard

a muscular, thick-walled part of a bird's stomach for grinding food, typically with __grit__.

Liver

A large, complex organ of vertebrates that performs many functions, including storage of glycogen, processing and conversion of food and wastes, and production of bile.

Gallbladder

A small pouch that stores bile from the liver and releases it as needed into the small intestine during digestion of fats.

Small Intestine

The portion of the digestive tract between the stomach and the large intestine. The site of the final stages of digestion and of most nutrient absorption.

Villi

Small, fingerlike projections of the lining of the small intestine 

Microvilli

Tiny protrusions from the surface of an epithelial cell that increase the surface area for absorption of substances.

Rumen

The largest champer of a four-chambered stomach specialized for digestion of plant cellulose.

Large Intestine

The posterior portion of the vertebrate digestive tract, consisting of the cecum, colon, and rectum. Its primary function is to form feces by absorbing water from and compacting the wastes delivered from the small intestine.

Diabetes Mellitus

A disease caused by a defect in insulin production (type 1) or in the response of cells to insulin (type 2). Characterized by abnormally high blood glucose levels and large volumes of glucose-containing urine.

Negative Pressure Ventilation

Ventilation of the lungs by expanding the rib cage so as to “pull” air into the lungs.

Positive Pressure Ventilation

Ventilation of the lungs by using increased pressure in the mouth to “push” air into the lungs.

Alveoli

Any of the tiny, air-filled sacs of a mammalian lung.

Bronchus

In mammals, one of a pair of large tubes that lead from the trachea to each lung.

Diaphragm

An elastic, sheetlike structure. In mammals, the muscular sheet that separates the chest and abdominal cavities. It contracts and moves downward during inhalation, expanding the chest cavity.

Trachea (tetrapods)

In terrestrial vertebrates, the airway connecting the larynx to the bronchi.

Tracheae (insects)

In insects, any of the small, air-filled tubes that extend throughout the body and function in gas exchange.

Hemoglobin

An oxygen-binding protein consisting of four polypeptide subunits, each containing an oxygen-binding heme group. The major oxygen carrier in mammalian blood.

Open Circulatory System

A circulatory system in which the circulating fluid (hemolymph) is not confined to blood vessels; occurs in most invertebrates.

Closed Circulatory System

A circulatory system in which the circulating fluid (blood) is confined to blood vessels and flows in a continuous circuit; found in vertebrates.

Heart

A hollow muscular organ that pumps the blood through the circulatory system by rhythmic contraction and dilation.

Capillaries

In a closed circulatory system, any of the many small, thin-walled blood vessels that permeate all tissues and organs and allow exchange of gases and other molecules between blood and body cells.

Arteries

Any thick-walled vessel that carries blood (oxygenated or not) under relatively high pressure away from the heart to organs of the body.

Veins

Any blood vessel that carries blood (oxygenated or not) under relatively low pressure from the rest of the body toward the heart.

Valves

In circulatory systems, any of the flaps of tissue that prevent backward flow of blood, particularly in veins and in the heart.

Systole

The portion of the cardiac cycle during which the atria or ventricles of the heart are contracting.

Diastole

The portion of the cardiac cycle during which the atria or ventricles of the heart are relaxed.

Hypertension

Abnormally high blood pressure.

Neuron

An animal cell that is specialized for the transmission of nerve impulses. Typically has dendrites, a cell body, and a long axon that forms synapses with other neurons.

Glia

Collective term for several types of cells in nervous tissue that are not neurons and do not conduct electrical signals but perform other functions, such as providing support, nourishment, or electrical insulation.

Dendrites

A short extension from a neuron’s cell body that receives signals from other neurons.

Axon

A long projection of a neuron that can propagate an action potential.

Cell Body

The part of a neuron that contains the nucleus; where incoming signals are integrated. 

Membrane Potential

A difference in electric charge across a cell membrane; a form of potential energy.

Resting Potential

The membrane potential of a cell in its resting, or unstimulated, state.

Depolarization

A change in membrane potential from its resting negative state to a less negative or a positive state; a normal phase in an action potential.

Action Potential

A rapid, temporary change in electrical potential across a membrane, from negative to positive and back to negative. Occurs in cells, such as neurons and muscle cells, that have an excitable membrane.

Voltage-gated Channels

A type of ion channel that opens or closes in response to a change in membrane voltage.

Positive feedback

A physiological mechanism in which a change in some variable stimulates a response that increases the change. Relatively rare in organisms but important in a few processes, such as generation of an action potential.

Sodium-potassium pump

A transmembrane protein that uses the energy of ATP to move sodium ions out of the cell and potassium ions into the cell, normally against their electrochemical gradients.

Synaptic Vesicles

A small neurotransmitter-containing vesicle inside the end of an axon that releases neurotransmitters into the synaptic cleft by exocytosis.

Neurotransmitters

A molecule that transmits signals from one neuron to another neuron or to a muscle cell or gland cell. Examples are acetylcholine, dopamine, serotonin, and norepinephrine.

Central Nervous System

An aggregation of large numbers of neurons into clusters called ganglia in bilaterian animals. In vertebrates, it consists of the brain and spinal cord.

Peripheral Nervous System

All the components of a nervous system that are outside the central nervous system. In vertebrates, includes the somatic nervous system and autonomic nervous system.

Dorsal nerve cord (spinal cord)

A bundle of nerves running the length of the body. A characteristic feature of chordates.

Myelinated Neurons

Multiple layers of myelin, derived from the cell membranes of certain glial cells, wrapped around the axon of a neuron and providing electrical insulation.

Somatic Nervous System

The part of the vertebrate peripheral nervous system that controls skeletal muscles and is under voluntary control.

Autonomic Nervous System

The part of the vertebrate peripheral nervous system that controls internal organs and involuntary processes, such as stomach contraction, hormone release, and heart rate. Includes parasympathetic and sympathetic nerves.

Parasympathetic Nervous System

The part of the autonomic nervous system that triggers responses for conserving or restoring energy, such as reduced heart rate and stimulated digestion.

Sympathetic Nervous System

The part of the autonomic nervous system that stimulates fight-or-flight responses, such as increased heart rate, increased blood pressure, and slowed digestion.

Effector

Any cell, organ, or structure with which an animal can respond to external or internal stimuli. Usually functions, along with a sensor and an integrator, as part of a homeostatic system.

Sensory Neurons

A nerve cell that carries sensory signals to the central nervous system.

Motor Neurons

A nerve cell that carries signals from the central nervous system to effector cells in a muscle or gland.

Pitch

The sensation produced by a particular frequency of sound.

Hair Cells

A pressure-detecting mechanoreceptor cell in vertebrates that has tiny hairlike structures (stereocilia) jutting from its surface. Found in the inner ear, lateral line system, and ampullae of Lorenzini.

Stereocilia

One of many stiff projections from the surface of a vertebrate hair cell that are involved in detection of sound or of waterborne vibrations.

Tympanic Membrane

The membrane separating the middle ear from the outer ear in terrestrial vertebrates.

Ear ossicles

Bony ossicles called the malleus, incus, and stapes.

Cochlea

The organ of hearing in the inner ear of mammals, birds, and crocodilians. A coiled, fluid-filled tube containing specialized pressure-sensing cells (hair cells) that detect sounds of different pitches.

Basilar Membrane

One of the membranes in the vertebrate cochlea between which the hair cells are located. Vibrates when sound waves travel through the fluid in the cochlea.

Tectorial Membrane

A membrane located in the vertebrate cochlea; takes part in the transduction of sound by bending the stereocilia of hair cells in response to sonic vibrations.

Compund Eye

An eye formed of many independent lenses, each associated with a light-sensing columnar structure (ommatidium); occurs in arthropods.