All Topics

Assessment 4

The fluid forced out of the blood plasma by hydrostatic pressure, which surrounds and bathes the body's cells and tissues.

Interstitial fluid

The force exerted by the blood against the wall of systemic capillaries, forcing blood plasma to leak out and bathe the surrounding tissues.

Hydrostatic pressure

Aggregated lymph nodes surrounding the opening to the respiratory and digestive tracts, which filter incoming air.

Tonsil

Bean-shaped structures that filter lymph and activate the immune system. There are 600 scattered throughout the body, with large clusters in cervical, mammary, axillary (armpit) and groin regions.

Lymph node

Gland that is a primary organ of the lymphatic system, found in the mediastinum, above the heart. Produces hormones thought to promote the maturation of T lymphocytes. Functional part is largest during childhood.

Thymus

Component of the spleen that removes worn out platelets and red blood cells, stores platelets, produces blood cells in the foetus.

Red pulp of spleen

A secondary organ of the lymphatic system located on left side of abdominal cavity below the diaphragm that primarily filters blood.

Spleen

Substance produced and released by the thymus, thought to promote the maturation of T lymphocytes.

Thymic hormone

Component of the spleen that carries out immune function and removes blood borne pathogens.

White pulp of spleen

Primary organ of the lymphatic system, responsible for the production of stem cells that eventually mature to form blood cells. Including red blood cells, white blood cells, and platelets.

Red bone marrow

A vessel that collects lymph from the right side of the head, neck, thorax, and right arm, and drains it into the bloodstream.

Right lymphatic duct

Specialized lymphatic capillaries located in the folds of the small intestine (villi) that absorb dietary fats and transport them to the bloodstream.

Lacteals

Also known as the thoracic duct, the largest lymphatic vessel in the body. It collects lymph from the left side of the head, neck, thorax, left arm, and lower body, and drains it into the bloodstream.

Left lymphatic duct

The fat-laden creamy-looking lymph fluid formed in the small intestine during digestion of fatty foods, absorbed and transported by lacteals.

Chyle

The pressure of a solution proportional to the concentration of the solute particles that cannot cross the membrane. For example, blood proteins can be too large to leave the capillaries, creating a gradient that pulls interstitial fluid back in.

Osmotic pressure

The body's non-specific response to injury or infection, characterized by redness, pain, heat and loss of function. Sets the scene for restoration and repair.

Inflammation

Fluid that circulates through the lymphatic system. It is derived from interstitial fluid and contains white blood cells, proteins, fats, and waste products. Main difference to interstitial fluid is the location, not composition.

Lymph fluid

The widening of the arterioles, which increases blood flow to tissues. It is a response to inflammation and helps deliver immune cells and nutrients to the affected area.

Vasodilation

An increase in blood flow to a specific area of the body, often in response to inflammation or injury. It helps deliver WBCs and chemicals. Provides extra heat, promoting metabolic rate of cells, and inhibiting migration of bacteria.

Hyperaemia

The movement of cells towards a chemical stimulus. It refers to the movement of WBCs towards areas of infection or inflammation.

Chemotaxis

The movement of WBCs out of the capillaries and into the surrounding tissues, due to increased permeability which occurs during inflammation. Allows defensive proteins such as antibodies and clotting factors to enter the injured area.

Emigration

Cells that engulf and digest pathogens, dead cells, and other debris. Examples are macrophages and neutrophils.

Phagocyte

A chemical released by mast cells that promotes vasodilation of local arterioles and increases the permeability of capillaries, as part of the inflammatory response to injury or infection.

Histamine

Key cell in inflammation, that releases histamine and other chemicals. Equivalent to the basophil cell in blood.

Mast cell

Ability to receive and respond to stimuli, e.g. electrical or chemical, and generate and action potential within itself.

Excitability

Ability to contract or shorten when stimulated.

Contractility

Ability to stretch or extend.

Extensibility

A white fibrous cord of dense regular connective tissue that attaches muscle to bone.

Tendon

Ability to return to its original shape after contraction or extension.

Elasticity

The end of the muscle tendon that is attached to a stationary bone.

Origin

The end of the muscle tendon that is attached to a movable bone.

Insertion

A muscle that has an action opposite that of the prime mover (agonist) and yields to the movement of the prime mover.

Antagonist

The muscle directly responsible for producing a desired motion.

Agonist/Prime mover

Muscles that assist the prime mover by reducing undesired action or unnecessary movement, such as stabilising other joints.

Synergist

Muscles that stabilise the origin of the prime mover so that the prime mover can act more efficiently.

Fixator

Fibrous dense irregular connective tissue around [whole] muscles.

Epimysium

Small clusters of muscle fibres (cells).

Fascicle

Fibrous dense irregular connective tissue surrounding each fascicle.

Perimysium

Loose areolar connective tissue surrounding each muscle fibre (cell).

Endomysium

Also known as an efferent neuron. A type of nerve cell that transmits signals from the CNS to muscles and glands, causing them to contract or secrete substances.

Motor neuron

The cell membrane of a muscle fibre (cell), especially of a skeletal muscle fibre.

Sarcolemma

Threadlike structures extending longitudinally through a muscle fibre (cell) consisting mainly of thick filaments and thin filaments.

Myofibril

Small, cylindrical invaginations of the sarcolemma of striated muscle fibres (cells) that conduct muscle action potentials towards the centre of the muscle fibre.

Transverse tubule

A network of saccules and tubes surrounding myofibrils of a muscle fibre (cell), comparable to endoplasmic reticulum; functions to reabsorb calcium ions during relaxation and to release them to cause contraction.

Sarcoplasmic reticulum

The contractile protein that makes up the thick filaments of muscle fibres.

Myosin

A contractile protein that is part of thin filaments in muscle fibres.

Actin

Narrow, plate-shaped region of dense material that separates one sarcomere from the next.

Z disk

Dark, middle part of sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments.

A band

Lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments. A Z disc passes through centre of each I band.

I band

Narrow region in centre of each A band that contains thick filaments but no thin filaments.

H zone

Region in centre of H zone that contains proteins that hold thick filaments together at centre of sarcomere.

M line

Regulatory protein that is a component of thin filament; when calcium ions (Ca2+) bind to it, it changes shape, moving tropomyosin away from myosin-binding sites on actin molecules. Muscle contraction subsequently begins as myosin binds to actin.

Troponin

Contractile units in a striated muscle fibre (cell) extending from one Z disc to the next Z disc.

Sarcomere

Regulatory protein that is a component of thin filament; when skeletal muscle fibre is relaxed, it covers myosin-binding sites on actin molecules, thereby preventing myosin from binding to actin.

Tropomyosin

The narrow gap at a chemical synapse that separates the axon terminal of one neuron from another neuron or muscle fibre (cell) and across which a neurotransmitter diffuses to affect the postsynaptic cell.

Synaptic cleft

A synapse between the axon terminals of a motor neuron and the sarcolemma of a muscle fibre (cell).

Neuromuscular junction

Expanded distal ends of axon terminals that contain synaptic vesicles.

Synaptic end bulb

Formed when the myosin heads attach to actin during muscle contraction.

Cross-bridge

Neurotransmitter released by neurons (via synaptic vesicles) when stimulated by an action potential, that travels across the synaptic cleft and binds with specific receptors on motor end plate, triggering a muscle action potential.

Acetylcholine

Enzyme in the synaptic cleft that rapidly breaks down Acetylcholine (Ach) into acetyl and choline, which cannot activate the ACh receptor, ceasing the muscle contraction.

Acetylcholinesterase

The process during muscle contraction and relaxation whereby the thin filaments (actin) and the thick filaments (myosin) slide past each other.

Sliding filament mechanism

The steps that connect excitation (a muscle action potential propagating along the sarcolemma and into the T tubules) to contraction (sliding of the filaments).

Excitation-contraction coupling

State of partial contraction of muscles after death due to lack of ATP; myosin heads (cross-bridges) remain attached to actin, thus preventing relaxation

Rigor Mortis

A bone that has greater length than width, e.g. the humerus.

Long bone

A bone that is just as wide as it is long, e.g. trapezoid (wrist bone)

Short bone

A bone with a non-uniform shape, e.g. vertebrae or facial bones.

Irregular bone

A bone with a thin broad shape and structure. Primary role is to provide protection, e.g. sternum (breastbone) or mediastinum.

Flat bone

A small bone that is found within connective tissue (usually tendons) where there is considerable friction, e.g. the patella (kneecap).

Sesamoid bone

The ends of long bones, usually larger in diameter than the shaft.

Epiphysis

The shaft of a long bone.

Diaphysis

A visible line on the bone, indicating the point where the epiphysis and metaphysis meet, when the epiphyseal plate ossified.

Epiphyseal line

Bone tissue that contains few spaces between osteons, forms the external portion of all bones and the bulk of the diaphysis (shaft) of long bones; is found immediately deep to the periosteum and external to spongy bone.

Compact bone

Bone tissue that consists of an irregular latticework of thin plates of bone called trabeculae; spaces between trabeculae of some bones are filled with red bone marrow; found inside short, flat, and irregular bones and in the epiphyses (ends) of long bones.

Spongy bone

The space within the diaphysis of a bone that contains yellow bone marrow and the nutrient artery.

Medullary Cavity

The membrane that covers bone and consists of dense fibrous connective tissue, and is essential for bone growth, repair, and nutrition.

Periosteum

A highly vascularised connective tissue located in microscopic spaces between trabeculae of spongy bone tissue, primarily responsible for producing red blood cells, white blood cells and platelets.

Red bone marrow

Found in the medullary cavity (hollow interior) of long bones and consists mainly of adipose cells, which store triglycerides. The stored triglycerides are a potential chemical energy reserve.

Yellow bone marrow

Hyaline cartilage attached to articular bone surfaces, which keeps bone ends from getting crushed, provides a smooth surface and acts as a shock absorber.

Articular cartilage

The membrane that lines the medullary cavity of bones.

Endosteum

The basic unit of structure in adult compact bone, consisting of a central canal with its concentrically arranged lamellae, lacunae, osteocytes, and canaliculi.

Osteon

Irregular latticeworks of thin plates of spongy bone tissue. Fibrous cords of connective tissue serving as supporting fibres by forming a septum extending into an organ from its wall or capsule

Trabeculae

Small, hollow spaces where osteocytes are found.

Lacunae

Concentric rings of hard, calcified extracellular matrix found in compact bone.

Lamellae

Networks of small channels or canals in bone tissue, containing the processes of osteocytes. Provide routes for nutrients to reach osteocytes and for wastes to leave them.

Canaliculi

Mature bone cells that maintain the daily activities of bone tissue.

Osteocyte

Bone-building cells. They synthesise and secrete collagen fibres and other organic components needed to build the extracellular matrix of bone tissue, and they initiate calcification.

Osteoblast

Large, multinuclear cells that resorb (destroy) bone matrix, using lysosomes.

Osteoclast

Stem cells that have the ability to differentiate into an osteoblast.

Osteoprogenitor cell

The hyaline cartilage plate in the metaphysis of a long bone; site of lengthwise growth of long bones.

Epiphyseal plate

Hormone secreted by the chief (principal) cells of the parathyroid glands that stimulates osteoclasts to increase blood calcium level.

Parathyroid hormone

Hormone produced by the parafollicular cells of the thyroid gland that can lower the amount of blood calcium and phosphates by inhibiting bone resorption and by accelerating uptake of calcium and phosphates into bone matrix.

Calcitonin

A joint formed of dense fibrous connective tissue and generally either immoveable (synarthrosis) or slightly moveable (amphiarthrosis). E.g. sutural joints, syndesmoses or interosseous membranes.

Fibrous joint

Joints without a synovial (joint) cavity where the articulating bones are held tightly together by cartilage, allowing little or no movement. E.g. synchondrosis (hyaline cartilage joins two bones together) or symphysis (i.e. the pubic symphysis).

Cartilaginous joint

Fully movable joints in which a synovial cavity is present between the two articulating bones.

Synovial joint

A slightly movable joint.

Amphiarthroses

A freely movable joint.

Diarthroses

An immovable joint.

Synarthroses

An immovable fibrous joint that joins skull bones.

Suture

A fibrous joint that permits little or no movement, e.g. gomphosis, where a cone-shaped peg fits into a socket (i.e. teeth in gums).

Syndesmosis

The deeper of the two layers of the articular capsule of a synovial joint, composed of areolar connective tissue that secretes synovial fluid into the synovial cavity.

Synovial membrane