C875 Combined from PA, Quizlet

Mix of Pa and quizlet flashcards

Superior

Toward the head or upper part of a structure or the body; above.

Inferior

Away from the head or toward the lower part of a structure or the body; below.

Dorsal

Toward the back side of the body; posterior.

Ventral

Toward the belly or front side of the body; anterior.

Superficial

Closer to or on the body surface.

Deep

Farther from the body surface; more internal.

Proximal

Closer to the point of attachment of a limb to the trunk.

Distal

Farther from the point of attachment of a limb to the trunk.

Medial

Toward the midline of the body.

Lateral

Away from the midline of the body.

Anterior

Toward the front of the body; ventral.

Posterior

Toward the back of the body; dorsal.

Cell

Basic structural and functional unit of life.

Tissue

Group of similar cells that perform a common function.

Organ

Structure composed of at least two tissue types that performs a specific function.

Organ system

Group of organs that work together to accomplish a common purpose.

Epidermis

Superficial layer of skin made of stratified squamous epithelium that provides a protective barrier.

Dermis

Deep connective-tissue layer of skin containing blood vessels, nerves, and glands.

Hypodermis

Subcutaneous layer of adipose and areolar tissue that anchors skin and insulates the body.

Melanocyte

Pigment-producing cell in the epidermis that synthesizes melanin.

Keratin

Tough, waterproofing protein found in epidermal cells.

Sweat gland

Skin gland (eccrine or apocrine) that secretes perspiration for thermoregulation.

Sebaceous gland

Oil gland associated with hair follicles that secretes sebum.

Arrector pili muscle

Small smooth muscle that elevates hair, producing ‘goosebumps.’

Thermoregulation

Physiological control of body temperature via mechanisms like sweating and vasoconstriction.

Cartilage

Flexible connective tissue with chondrocytes; cushions joints and forms parts of the skeleton.

Endochondral ossification

Process in which cartilage models are replaced by bone during development and growth.

Bone marrow

Soft tissue in bones; red marrow forms blood cells, yellow marrow stores fat.

Osteon

Structural unit of compact bone consisting of concentric lamellae around a central canal.

Periosteum

Dense connective-tissue membrane covering the outer surface of bone.

Skeletal muscle

Striated, multinucleated muscle attached to bones; under voluntary control.

Smooth muscle

Non-striated, single-nucleated muscle in walls of hollow organs; involuntary.

Cardiac muscle

Striated, branched muscle of the heart with intercalated discs; involuntary.

Sarcolemma

Plasma membrane of a muscle fiber.

Sarcomere

Contractile unit of muscle fiber between two Z lines.

Sarcoplasmic reticulum

Specialized smooth ER in muscle fibers that stores and releases calcium.

T-tubule

Invagination of the sarcolemma that conducts action potentials into the muscle fiber interior.

Tendon

Dense regular connective tissue cord attaching muscle to bone.

Ligament

Dense regular connective tissue band connecting bone to bone.

Aponeurosis

Broad sheetlike tendon connecting muscles to bones or other muscles.

Actin

Thin filament protein that interacts with myosin during muscle contraction.

Myosin

Thick filament motor protein that pulls actin to shorten sarcomeres.

Troponin

Regulatory protein on actin that binds calcium to initiate contraction.

Tropomyosin

Protein that covers actin’s binding sites when the muscle is relaxed.

Neuromuscular junction

Synapse between a motor neuron and a skeletal muscle fiber.

Acetylcholine

Neurotransmitter released at neuromuscular junctions to trigger muscle contraction.

Central nervous system (CNS)

Brain and spinal cord; integrates and processes information.

Peripheral nervous system (PNS)

All neural tissue outside the CNS; carries information to and from the CNS.

Neuron

Excitable cell that transmits electrical impulses.

Dendrite

Branched neuronal process that receives incoming signals.

Axon

Long neuronal process that carries impulses away from the cell body.

Myelin sheath

Lipid-rich covering around some axons that speeds impulse conduction.

Astrocyte

Star-shaped glial cell that supports neurons and forms the blood–brain barrier.

Oligodendrocyte

CNS glial cell that forms myelin sheaths around axons.

Microglia

Phagocytic glial cell that removes debris and pathogens in the CNS.

Ependymal cell

Ciliated glial cell lining brain ventricles; produces and circulates cerebrospinal fluid.

Synapse

Junction where a neuron communicates with another cell via neurotransmitters.

Presynaptic cell

Neuron that releases neurotransmitter into a synapse.

Postsynaptic cell

Cell that receives and responds to neurotransmitter at a synapse.

Synaptic cleft

Narrow gap between pre- and postsynaptic membranes.

Neurotransmitter

Chemical messenger that transmits signals across a synapse.

Action potential

Rapid electrical impulse that travels along the membrane of an excitable cell.

Cerebrospinal fluid (CSF)

Clear fluid that cushions the CNS and circulates nutrients; produced by the choroid plexus.

meninges

Three protective membranes—dura mater, arachnoid mater, pia mater—surrounding the CNS.

Pons

Brainstem region that relays signals between cerebrum and cerebellum and helps regulate breathing.

Medulla oblongata

Brainstem region that controls vital reflexes such as heart rate and respiration.

Cerebellum

Brain region that coordinates movement, posture, and balance.

Thalamus

Brain relay station for sensory information headed to the cerebral cortex.

Hypothalamus

Brain region that regulates homeostasis, autonomic functions, and endocrine activity.

Cerebrum

Largest brain region responsible for conscious thought, memory, and voluntary action.

Frontal lobe

Cerebral lobe for motor control, planning, reasoning, and personality.

Parietal lobe

Cerebral lobe processing somatosensory information.

Occipital lobe

Cerebral lobe that processes visual information.

Temporal lobe

Cerebral lobe involved in hearing, language, and memory.

Afferent (sensory) nerve

Carries impulses toward the CNS from receptors.

Efferent (motor) nerve

Carries impulses away from the CNS to effectors.

Dorsal root

Posterior spinal cord root carrying sensory (afferent) fibers.

Ventral root

Anterior spinal cord root carrying motor (efferent) fibers.

Sympathetic nervous system

Autonomic division active during ‘fight-or-flight’ situations.

Parasympathetic nervous system

Autonomic division active during ‘rest-and-digest’ conditions.

Cornea

Transparent front layer of the eye that refracts incoming light.

Lens

Biconvex eye structure that focuses light onto the retina.

Retina

Innermost eye layer containing photoreceptors.

Photoreceptor

Retinal cell (rod or cone) that converts light into nerve impulses.

Rod

Photoreceptor sensitive to low light and responsible for black-and-white vision.

Cone

Photoreceptor responsible for color vision and sharp detail.

Vitreous humor

Gel filling the posterior eye that maintains shape.

Aqueous humor

Clear fluid in the anterior chamber of the eye that nourishes cornea and lens.

Pupil

Opening in the iris that regulates the amount of light entering the eye.

Hair cell

Mechanoreceptor in the cochlea and vestibular apparatus that detects sound or movement.

Semicircular canals

Three fluid-filled loops in the inner ear that detect rotational movement.

Utricle

Vestibular sac that detects horizontal acceleration.

Saccule

Vestibular sac that detects vertical acceleration.

Static equilibrium

Sense of head position relative to gravity.

Dynamic equilibrium

Sense of rotational or angular movement.

Negative feedback

Control mechanism in which the response reduces or shuts off the original stimulus.

Humoral stimulus

Hormone release triggered by changing blood levels of ions or nutrients.

Hormonal stimulus

Hormone release triggered by other hormones.

Neural stimulus

Hormone release triggered by nervous system input.

Growth hormone (GH)

Anterior pituitary hormone that stimulates tissue growth and repair.