Biology Unit 5 Equilibrium

System

group of interacting component parts that act together to form a unified whole.

Emergent Properties

something that arises as you become more complex with new properties and behaviors that are not present at a lower level.

Central Nervous System

Made up of the brain and spinal cord; has relay neurons that do unconscious processing.

Peripheral Nervous System

Branches from the CNS; has sensory neurons and motor neurons to do unconscious and conscious processing.

Neurons

cells that carry rapid electrical impulses.

Synapse

the junction (connection) between two neurons.

Sensory neurons

Carries impulses from receptors to the central nervous system.

Motor neurons

Carries impulses to effector cells such as muscles and glands.

Relay neurons

Connects different cells of the central nervous system.

Nerve

A bundle of fibers (sensory or motor) in the body that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs.

Reflex Arc

a more rapid response that doesn't require the brain to prevent permanent damage; a "knee jerk" response.

Cerebellum

the part of the brain that is in control of voluntary movement (muscle contractions), balance, coordination, and posture.

Homeostasis

the tendency for an organism or cell to maintain a constant internal environment within tolerance limits.

Negative Feedback

the effect that is antagonistic (opposite) of the detected stimulus.

Receptor

notices a change in conditions.

Effector

initiates a corrective response.

Thermoregulation

if body temperature changes, mechanisms are induced to restore normal levels.

Circadian rhythms

the physiological and behavioral changes of an organism over a roughly 24-hour cycle.

Hypothalamus

section of the brain that links the nervous and endocrine systems in order to maintain homeostasis.

Pituitary gland

lies adjacent to the hypothalamus and is in direct contact due to a portal blood system; controls the secretion of other endocrine glands.

Autonomic Nervous System

your heart responds automatically to changes in body conditions.

Nephrons

functional units of kidneys.

Ligand

a chemical that binds to another specific molecule.

Specificity

The ability of the binding site of a receptor to bind specific ligands.

Hormones

chemical signals secreted from cells in endocrine glands that travel through the bloodstream to target any cell which has a receptor for the hormone.

Neurotransmitters

chemicals that transmit signals across a synapse, the junction between two neurons.

Cytokines

small signaling proteins that may affect the same cell it was secreted from, other nearby cells, or may act in a more systemic manner.

Calcium ions

used for signaling within muscle fibers and neurons.

Local Signaling

signaling molecules rely on diffusion between adjacent cells.

Distant Signaling

signaling molecules are transported through the blood to all parts of the body.

Transmembrane receptors

Cell surface receptors are integral membrane proteins; cannot cross the membrane barrier without help from a protein.

Intracellular receptors

those found inside the cell; can cross the membrane barrier without additional help to travel to the cytoplasm or nucleus.

Reception

Step 1 in chemical signaling; the process by which a cell detects a signal in the environment.

Transduction

Step 2 in chemical signaling; the process of activating a change within the cell.

Response

Step 3 in chemical signaling; the change that occurs in the cell as a result of the signal.

Obligate Intracellular Parasite

Viruses that must infect cells and reproduce inside them.

Capsid

the outer coating of viruses made of protein that contain nucleic acid.

Lysogenic cycle

the virus assimilates its genome within the host cell's genome to achieve replication without killing the host.

Lytic cycle

the virus reproduces and bursts out of the host cell, killing it.

Mutagen

anything that permanently changes genetic material, such as radiation, chemicals, and infectious agents.

Benign tumor

The cells in the tumor adhere to each other and remain in a single mass; do not cause cancer.

Malignant tumor

The cells in the tumor can detach and invade neighboring tissues, lymph vessels, or blood vessels; cause cancer.

Cancer

the disease caused by a malignant tumor; develops in 4 steps: Initiation, Promotion, Progression, and Metastasis.