BIO Exam #6

Axial Skeleton

Skull, vertebral column, ribs, sternum

Dendrite

Slender extensions of the cell body that receive information from receptors or incoming impulses from other neurons. Interneurons and motor neurons have numerous dendrites that are fairly short and extend in many directions from the cell body. Sensory neurons are an exception, because their dendrites connect directly to an axon.

Myelin

A fatty insulating material produced by Schwann cells; Schwann cells wrap themselves around a short segment of an axon many times as a sort of insulating blanket, creating a shiny white protective layer around the axon (myelin sheath); neurons that have axons wrapped in a sheath of myelin are called myelinated neurons.

Axon

A long, slender tube of cell membrane containing a small amount of cytoplasm. Axons are specialized to conduct electrical impulses. Axons of sensory neurons originate from a dendrite, whereas the axons of interneurons and motor neurons originate from the point of union with the cell body, called the axon hillock. At its other end, the axon branches into slender extensions called axon terminals. Each axon terminal ends in a small, rounded tip called an axon bulb.

Fovea

A small depression in the retina of the eye where visual acuity is highest. The center of the field of vision is focused in this region, where retinal cones are particularly concentrated.

Hypothalamus

A small region at the base of the forebrain that coordinates some automatic functions of the pituitary gland, such as water and solute balance, temperature control, carbohydrate metabolism, and production of breast milk. It plans an important role in regulating homeostasis because it monitors sensory signals relating to sight, smell, taste, noise, and body temperature. "hunger center," "thirst center."

Cupula

A soft, gel-like dome in the ampula. Hairs of mechanoreceptor sensory neurons are embedded in the cupula.

Osteoclast

Bone-dissolving cells; Cut through mature bone tissue, dissolving the hydroxyapatite and digesting the osteoid matrix in their path. The released calcium and phosphate ions enter the blood. The areas from which bone has been removed attract new osteoblasts, which lay down new osteoid matrixes and stimulate the deposition of new hydroxyapatite crystals.

Otolith

Bonelike material in the itricle and saccule. These are embedded in the gel near the gel's surface, unattached to the bone wall of the vestibule. These produce impulses in nearby sensory neurons that are transmitted to the brain for interpretation.

Malleus/Incus/Stapes

Bones in the middle ear which vibrate from the eardrum to vibrate the oval window. This amplifies sound.

Corpus Callosum

Bridges the two cerebral hemispheres

Organ of Corti

Combination of hair cells and the tectorial membrane that converts pressure waves to impulses.

Inner Ear

Consists of the cochlea, vestibular canal, tympanic canal, cochlear duct, basilar membrane, hair cells, tectorial membrane, organ of Corti, round window-sorts sounds by tone and converts them into impulses-semicircular canals, ampulla, cupula, hair cells-senses rotational movements and converts them into impulses-vestibule, utricle, saccule, otoliths, and hair cells-sense static (non-moving) position and linear acceleration and deceleration; converts them into impulses.

Middle Ear

Consists of the eardrum, malleus, incus, stapes, oval window, auditory tube; Amplifies sound.

Outer Ear

Consists of the pinna and auditory canal; receives and channels sound

RAS

Controls levels of sleep and wakefulness; a group of neurons in the reticular formation. Some neurons transmit a steady stream of action potentials to the cerebrum, keeping us awake and alert. A "sleep center" releases the neurotransmitter serotonin, which induces sleep by inhibiting the neurons that arouse the brain. Norepinephrine inhibits the effects of serotonin and makes us feel more alert. Can be measured by EEGs.

Olfaction

Detection of odors with olfactory receptor cells that are located in the upper part of the nasal passages. These receptor cells are sensory neurons with a modified dendritic ending that branches to become several olfactory hairs. These extend into a layer of mucus covering the surface of the nasal passages. Olfactory receptor cells synapse with olfactory neurons in a nearby area of the brain called the olfactory bulb, where information is partially integrated and then passed to higher brain centers.

Utricle/Saccle

Each contain mechanoreceptor hair cells, gel, and hard crystal of bonelike material called otoliths. These sense head position and acceleration.

Synovial Joints

Have liquid lubrication and are movable; ball and socket is most freely movable; some joints only allow movement in one plane

Fibrous Joints

Immovable; sutures in skull

Pineal

Influences reproductive function and melatonin; determines our most complex behavior, including emotions and conscious thought. Part of the forebrain.

Pons

Just above and partially surrounding the medulla oblongata that connects higher brain centers and the spinal cord; contains groups of axons that extend from the cerebellum to the rest of the CNS, and is important in coordinating the flow of information between the cerebellum and higher brain centers; aids the medulla oblongata in regulating respiration.

Retina

Layers at the back and sides of the eye; comprising primarily photoreceptor cells, neurons, and a few blood vessels. Between the retina and the sclera at the back of the eye lies the choroid, consisting of pigmented cells and blood vessels. Absorbs light and converts in into impulses.

Pupil

Light passes though which is an adjustable opening in the center of the iris.

Cornea

Light passes through from the sclera; bends incoming light (focuses light).

Iris

Light strikes from the aqueous humor; a colored disk-shaped muscle that determines how much light enters the eye

Cerebellum

Located just behind the medulla oblongata that coordinates the basic body movements that are below the level of conscious control; Ensures that antagonistic muscles do not contract at the same time; stores and replicates whole sequences of skilled movements, such as tying a shoe, shifting a car, or hitting a home run. To coordinate these activities, receives sensory input from many sources, including joint and muscle receptors, balance and position receptors in the ear, and visual receptors.

Osteocyte

Mature bone cells that maintain the structure of bone; Extracellular deposits of calcium phosphate enclosing and surrounding living cells. They are arranged in rings in cylindrical structures. Osteocytes nearest the center of an osteon receive nutrients by diffusion from blood vessels that pass through a central canal.

Aqueous Humor

Nourishes and cushions cornea and lens

Sensory Neuron

Of the PNS; specialized to respond to a certain type of stimulus, such as pressure or light. They transmit information about this stimulus to the CNS in the form of electrical impulses. In other words, sensory neurons provide input to the CNS.

Motor Neuron

Of the PNS; transmits impulses away from the CNS. They carry the nervous system's output still in the form of electrical impulses, to all of the tissues and organs of the body.

Cones

Our ability to distinguish a variety of colors is due to the way the brain interprets the rations of impulses coming from the ganglion cells connected to the three types. When all three types are activated by all different wavelengths, we perceive white light. The perception of black is no light at all. Also responsible for visual acuity; require stronger light to be activated because the photopigments are much less sensitive to light than the rhodopsin in rods

Cerebral Cortex

Outer layer of the cerebrum; is primarily gray matter, consisting of CNS neurons with unmyelinated axons and their associated neuroglial cells. The inner portion of the cerebrum is mostly white matter containing myelinated nerve axons that connect lower brain areas to the cerebral cortex.

Appendicular Skeleton

Pectoral and pelvic limbs and girdles

Rods

Photoreceptors responsible for black-and-white vision in dim light. They all have the same photopigment called rhodopsin. This is much more sensitive to light than the photopigments in cones, and therefore in dim light our vision is dependent primarily on rods. Do not give us color vision, which is why objects appear less colorful in dim light.

Tympanic Membrane

Receives sound from the auditory canal and serves as a partition between the outer and middle ears. (Eardrum)

Thalamus

Receives, processes, and transfers information; located just above the hypothalamus. Integrates and relays some outgoing motor activity as well, accepts sensory signals from other parts of the body and brain and channels them to the cerebrum to be interpreted. As sensory information like pain and pressure arrives, we are conscious of the sensation but cannot identify where it originates. We become aware of which part of the body is experiencing the sensation.

Celly Body

The main body of a neuron that has a nucleus that has DNA, along with mitochondria and other cell organelles.

Hair Cell

The mechanoreceptor cells of the ear; have hairlike projections that are embedded in an overhanging structure called the tectorial membrane, which is composed of a firm, gelatinous, noncellular material. Together, they are the Organ of Corti, the organ that converts pressure waves to impulses.

Vitreous Humor

Transmits light to retina

Pinna

Visible portion of the ear; Sound waves arrive at the pinna and are directed into the auditory canal.

Semicircular Canals

Within cochlea; Vestibular Canal, Tympanic canal, and Cochlear Duct; where sound is converted. Sense rotational movement.

Osteoblast

Young bone-forming cells that cause the hard extracellular matrix of bone to develop; Secrete a mixture of proteins called osteoid, which forms a matrix that provides internal structure and strength to bone. Osteoblasts also secrete enzymes that facilitate the crystallization of hard mineral salts of calcium phosphate, known as hydroxyapatite, around and between the osteoid matrix. As more and more hydroxyapatite is deposited, the osteoblasts become embedded in the hardening bone tissue. In mature compact bone, approximately one-third of the structure is osteoid and two-thirds is crystals of hydroxyapatite.