CTAP Midterm

Osteoblasts

build bones/ bone-forming cells, consist of type 1 collagen fibers

Osteoclasts

break down bones/ bone-resorbing cells, formed by multinucleate cells (fusion of monocytes)

Osteon

structural unit of compact bone containing:

central canal: contains blood vessels (veins and arteries) and nerves

Lacunae: small spaces that house osteocytes

Canaliculi: tiny canals that connect the lacunae/osteocytes so they can communicate

Lamellae: concentric rings surrounding the central canal that the lacunae and canaliculi lay on top of

osteogenesis

creation of bone, two different types, intramembranous and endochondral

intramembranous ossification

when the osteoblasts differentiate from the mesenchyme and begin to secrete osteoid to create flat bones

endochondral ossification

when the mesenchyme turns into cartilage and then cartilage back to bone, process of long bone formation

3 Muscle Tissue Types

skeletal, cardiac, smooth

Skeletal

1 cell, very long (about the size of the muscle), due to their size they are multinucleated cells, they are voluntary, striated, and connected to bones, faster but weaker than smooth

Smooth

fusiform, single nucleus, overlapping each other due to their great length, smooth because there are no stripes or striations, slower but stronger than skeletal, found in organs & blood vessels

Cardiac

Involuntary, striated, intercalated discs for communication

Endomysium

surrounds individual muscle fibers/myofibril

Perimysium

surrounds muscle fascicles (group of muscle fibers)

Epimysium

surrounds the entire muscle

T-Tubules

Transmit action potentials deep into muscle fibers, triggering contraction

Sarcoplasmic Reticulum

Stores and releases calcium (Ca²⁺) for muscle contraction

A-band

Dark band where myosin & actin overlap

I-band

Light band, contains only actin

H-zone

Central region with only myosin

Z-line

Boundary of a sarcomere where actin filaments attach.

Duchenne's Muscular Dystrophy (DMD)

X linked recessive disorder of skeletal muscle, caused by a mutation in the dystrophin gene, leads to muscle weakness and degeneration, causes delayed ability to sit, stand, or walk, and difficulty learning to speak

Synapse

site where nerve impulse is transmitted from one neuron to another

Synaptic Communication

The process where neurons transmit signals to another neuron or an effector cell via neurotransmitters at the synapse

CNS Glial Cells

oligodendrocytes, astrocytes, microglia, ependymal cells

Oligodendrocyte

wraps around axons, produces myelin sheath on multiple segments (one oligodendrocyte myelinates multiple axons)

Astrocytes

long branching processes that create blood brain barrier, regulate nutrient/waste and regulate ion concentration (provide metabolic support)

Microglia

Phagocytic cells that clean up debris and pathogens

Ependymal cells

they line ventricles and produce cerebrospinal fluid (CSF)

PNS Glial Cells

Schwann and satellite

Schwann cells

Myelinate PNS axons (one Schwann cell per axon)

Satellite cells

form thin layer around cell body, support neuron cell bodies in ganglia, trophic, insulate, nourish, regulate microenvironment

White Matter

Consists of myelinated axons (fast transmission)

Gray Matter

Contains neuron cell bodies, dendrites, and synapses (processing & integration)

Myelinated Fibers

Have a myelin sheath, which increases conduction speed via saltatory conduction (jumping from node to node)

Unmyelinated Fibers

Lack a myelin sheath, leading to slower continuous conduction

Saltatory Conduction

The rapid transmission of an action potential along a myelinated axon, where impulses jump between Nodes of Ranvier

Depolarization

The influx of Na⁺ ions, making the inside of the neuron less negative and generating an action potential

Resting Membrane Potential

The electrical charge difference (-70mV) between the inside and outside of a neuron at rest, maintained by the Na⁺/K⁺ pump

Multiple Sclerosis (MS)

Autoimmune attack on CNS myelin, leading to nerve conduction impairment, suspect T cell reactive towards oligodendrocytes

Sclera of the eye

The white, tough outer layer that provides structural support

Retina

Contains rods (night vision) and cones (color vision)

Lens of the eye

Focuses light onto the retina for clear vision

Optic Disc

The blind spot where the optic nerve exits the eye (no photoreceptors)

Fovea centralis

The area in the retina with the highest concentration of cones (sharpest vision)

3 areas of the ear

External, middle, and internal

Middle Ear ossicles

Malleus, Incus, Stapes; transmit vibrations to the inner ear

Inner ear anatomy

Includes the cochlea (hearing) and vestibular system (balance)

Membranes of Inner Ear

Includes tectorial membrane (in cochlea, helps detect sound waves) and basilar membrane (supports Organ of Corti)

Myeloid stem cells

Stem cells in bone marrow that give rise to red blood cells (RBCs), platelets, and most white blood cells (WBCs) (except lymphocytes)

Megakaryocytes

Large bone marrow cells that produce platelets (for blood clotting) by shedding cytoplasmic fragments

Hematocrit

Percentage of blood volume occupied by red blood cells

Normal Hematocrit %

Male Adults: 42-52%

Female Adults: 36-48%

Children <15yo: 30-44%

Lymphoid stem cells

Stem cells that differentiate into lymphocytes (T-cells, B-cells, and natural killer (NK) cells)

Types of Leukocytes

Granular and Agranular leukocytes (Granulocytes & Agranulocytes)

Granulocytes

contain granules, Neutrophils, Eosinophils, Basophils

Neutrophils

First responders to bacterial infections, phagocytic

Eosinophils

Fight parasitic infections and involved in allergic reactions

Basophils

Release histamine during allergic responses

Agranulocytes

lack granules, Monocytes, Lymphocytes

Monocytes

Differentiate into macrophages, which engulf pathogens

Lymphocytes

Includes T-cells (immune response), B-cells (antibody production), and NK cells (destroy virus-infected/cancerous cells)

Reticulocyte

Immature red blood cell (RBC) released from the bone marrow before fully maturing

Blood plasma proteins

Includes albumin (osmotic pressure), globulins (immune function), fibrinogen (clotting factor)

Erythropoietin (EPO)

Hormone from the kidneys that stimulates RBC production in response to low oxygen levels

Vaso vasorum

Small blood vessels that supply the walls of large arteries and veins

Where vasoconstriction & vasodilation occur

In the arterioles, regulating blood flow and pressure

3 Layers of Centrifuged Blood

Plasma (top, 55%) - Water, proteins, nutrients

Buffy coat (middle, <1%) - WBCs & platelets

RBCs (bottom, ~45%) - Oxygen transport