Introduction to Anatomy and Physiology — Key Terms (Bones, Vertebrae, and Homeostatic Regulation)

Vocabulary flashcards covering bone types, key bone and vertebrae structures, and the core concepts of homeostasis and feedback mechanisms.

Flat bone

One of the basic bone types; thin, flat plates (e.g., many skull bones) that protect organs and provide broad surfaces for muscle attachment.

Irregular bone

Bone with a complex shape that doesn’t fit the other categories (e.g., most vertebrae).

Long bone

Bone type with a shaft (diaphysis) and ends; densest, strongest part for weight bearing.

Short bone

Cube-like bones (e.g., bones of wrists and ankles).

Sesamoid bone

Small round bone embedded in a tendon, often improving leverage (e.g., patella).

Osteon

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

Lacunae

Small cavities within bone tissue housing osteocytes.

Canaliculi

Tiny channels in bone that connect lacunae for nutrient and waste exchange.

Lamellae

Concentric layers of bone matrix surrounding the central canal within an osteon.

Central canal

The Haversian canal in an osteon that contains blood vessels and nerves.

Atlas (C1)

First cervical vertebra; supports the skull, lacks a vertebral body, has an anterior tubercle.

Axis (C2)

Second cervical vertebra; carries the dens (odontoid process) enabling head rotation.

Intervertebral disc

Cartilaginous joint between most adjacent vertebrae; no disc between C1 and C2.

Vertebral arch (neural arch)

The bony arch formed by pedicles and lamina that surrounds the spinal cord.

Pedicle

Part of the vertebral arch connecting the body to the arch, forming the sides of the vertebral foramen.

Lamina

Part of the vertebral arch forming the posterior portion; together with pedicles forms the arch.

Spinous process

Posterior projection of a vertebra; in thoracic region, often directed inferiorly.

Transverse process

Lateral projections from a vertebra; provide attachment points and, in thoracic vertebrae, rib articulation.

Superior articular processes

Pairs of projections that articulate with the vertebra above.

Inferior articular processes

Pairs of projections that articulate with the vertebra below.

Transverse foramen

Openings in cervical vertebrae through which the vertebral artery passes.

Vertebral artery

Artery supplying the brain; travels through the transverse foramina of the cervical spine.

Cervical vertebra

Vertebrae of the neck (C1–C7) with distinctive features such as transverse foramina.

Thoracic vertebra

Vertebrae of the chest (T1–T12) characterized by rib facets and typically a long, inferiorly directed spinous process.

Lumbar vertebra

Lower back vertebrae (L1–L5) with large bodies and strong processes for supporting weight.

Head of rib

Articulates with the costal facets on the vertebral body of a thoracic vertebra.

Costal tubercle

Part of the rib that articulates with the transverse process facet on the thoracic vertebra.

Costal facet

Facets on the vertebral body that articulate with the head of a rib.

Sacrum

Fused sacral vertebrae (S1–S5) forming part of the pelvis; typically one bone in adults.

Coccyx

Tailbone formed by fused coccygeal vertebrae in adults; historical note links name to the cuckoo bird.

Set point

The desired value range that a physiological variable should maintain to sustain homeostasis.

Receptors

Sensors that detect changes in a controlled condition and relay information to the control center.

Control center

Neural or hormonal center that interprets signals and determines the appropriate response.

Effectors

Organs or tissues that respond to the control center’s commands to restore homeostasis.

Negative feedback

A regulatory mechanism that counteracts a change to bring a variable back toward its set point.

Positive feedback

A regulatory mechanism that amplifies a change in the same direction, usually episodic (e.g., childbirth).

Autonomic nervous system

Part of the nervous system regulating involuntary functions (sympathetic and parasympathetic components).

Baroreceptors

Pressure sensors in blood vessels that detect changes in blood pressure and help regulate it via the brainstem.

Blood pressure

The force exerted by circulating blood on vessel walls; tightly regulated by autonomic and hormonal systems.

Homeostasis

Stable internal conditions maintained by balanced physiological processes (receptors, control centers, effectors, and feedback).