OPRETC Lecture One: Biomedical Sciences - Chapter 1

A vocabulary set of key terms and definitions from Lecture One covering the nervous, digestive, cardiovascular, and related systems.

Central Nervous System (CNS)

Brain and spinal cord; the control center for body functions.

Brain

CNS organ that processes information and coordinates cognitive and motor functions.

Spinal Cord

CNS structure that transmits signals between brain and body and coordinates reflexes.

Autonomic Nervous System (ANS)

Regulates involuntary functions and maintains homeostasis via autonomic branches.

Somatic Nervous System

Controls voluntary movements of skeletal muscles.

Cerebrum

Largest part of the brain; governs voluntary actions and some autonomic functions.

Brain Stem

Lower brain region (pons, medulla, midbrain) that regulates basic life processes.

Cerebellum

Coordinates movement, balance, and posture.

Thalamus

Sensory relay station; influences awareness and alertness.

Corpus Callosum

Fiber bundle that connects the two cerebral hemispheres.

Hypothalamus

Regulates homeostasis and coordinates endocrine and autonomic functions.

Hippocampus

Involved in memory formation and retrieval.

Pituitary Gland

Master endocrine gland regulating hormones throughout the body.

Cerebral Cortex

Outer brain layer responsible for higher cognitive functions.

Cerebrospinal Fluid (CSF)

Fluid that cushions the brain and circulates within the ventricles.

Blood–Brain Barrier (BBB)

Selective barrier between cerebral blood and CSF that restricts substance entry.

Dendrite

Neuron branch that receives signals.

Axon

Long projection that transmits signals away from the neuron’s cell body.

Myelin Sheath

Insulating layer around axons; speeds nerve impulse conduction.

Synapse

Junction where neuronal signals are transmitted to another cell.

Nodes of Ranvier

Gaps in the myelin sheath that enhance conduction speed.

Schwann Cell

Glial cell in the PNS that forms the myelin sheath around axons.

Nissl’s Granules

Rough endoplasmic reticulum in neurons involved in protein synthesis.

Wernicke’s Area

Temporal lobe region important for language comprehension.

Vestibular System

Reflex system that stabilizes head/eye position and posture.

Ingestion

Act of taking food into the mouth.

Digestion

Mechanical and chemical breakdown of food.

Absorption

Nutrients absorbed into the bloodstream from the small intestine.

Excretion

Elimination of waste via the large intestine.

Oral Mucosa

Mucous membrane lining the inside of the mouth.

Salivary Amylase

Enzyme in saliva that hydrolyzes starch and glycogen into maltose.

Esophagus

Muscular tube that moves food to the stomach by peristalsis.

Cardiac Esophageal Sphincter

Lower esophageal sphincter guarding entrance to the stomach.

Pyloric Sphincter

Sphincter guarding the stomach outlet.

Intrinsic Factor

Gland product essential for vitamin B12 absorption.

Parietal Cells

Stomach cells that secrete HCl and intrinsic factor.

Chief Cells

Stomach cells that secrete pepsinogen.

Pepsinogen

Zymogen that is converted to pepsin (protease) in the stomach.

Gastrin

Hormone released after meals that stimulates acid secretion.

Gastric Acid

Hydrochloric acid produced by parietal cells for digestion.

Gastric Emptying

Time for stomach contents to enter the small intestine; fastest when isotonic; fat slows it.

Liver

Organ receiving arterial and portal blood; produces bile and regulates metabolism.

Bile

Digestive fluid produced by the liver; emulsifies fats.

Gallbladder

Stores and concentrates bile; releases bile via the cystic duct.

Pancreas

Organ with exocrine digestive enzymes and endocrine hormones.

Insulin

Hormone that lowers blood glucose by promoting glucose uptake.

Glucagon

Hormone that raises blood glucose by promoting glycogen breakdown.

Somatostatin

Hormone that inhibits release of insulin and glucagon.

Secretin

Hormone stimulating pancreatic bicarbonate-rich secretion.

Pancreozymin

Hormone stimulating pancreatic enzyme secretion.

Duodenum

First part of the small intestine; major site of nutrient absorption.

Jejunum

Primary site of nutrient absorption; about 8–10 feet long.

Ileum

Last part of the small intestine; contains Peyer’s patches.

Large Intestine

Reabsorbs water and forms feces; houses gut bacteria.

Heart

Muscular organ that pumps blood through the circulatory system.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood toward the heart.

Aorta

Main artery distributing oxygenated blood to the body.

Right Atrium

Heart chamber that receives deoxygenated blood from the body.

Right Ventricle

Pumps deoxygenated blood to the lungs.

Left Atrium

Receives oxygenated blood from the lungs.

Left Ventricle

Pumps oxygenated blood to the systemic circulation.

Tricuspid Valve

Valve between the right atrium and right ventricle.

Mitral Valve

Valve between the left atrium and left ventricle.

Aortic Valve

Valve between the left ventricle and the aorta.

Pulmonary Valve

Valve between the right ventricle and pulmonary artery.

Systole

Contraction phase of the cardiac cycle.

Diastole

Relaxation phase of the cardiac cycle.

Cardiac Output

Volume of blood pumped per minute; CO = Stroke Volume × Heart Rate.

Stroke Volume

Amount of blood pumped by the heart in one beat (about 70 mL).

Heart Rate

Number of heartbeats per minute.

Central Nervous System (CNS)

Brain and spinal cord; the control center for body functions.

Brain

CNS organ that processes information and coordinates cognitive and motor functions.

Spinal Cord

CNS structure that transmits signals between brain and body and coordinates reflexes.

Autonomic Nervous System (ANS)

Regulates involuntary functions and maintains homeostasis via autonomic branches.

Somatic Nervous System

Controls voluntary movements of skeletal muscles.

Cerebrum

Largest part of the brain; governs voluntary actions and some autonomic functions.

Brain Stem

Lower brain region (pons, medulla, midbrain) that regulates basic life processes.

Cerebellum

Coordinates movement, balance, and posture.

Thalamus

Sensory relay station; influences awareness and alertness.

Corpus Callosum

Fiber bundle that connects the two cerebral hemispheres.

Hypothalamus

Regulates homeostasis and coordinates endocrine and autonomic functions.

Hippocampus

Involved in memory formation and retrieval.

Pituitary Gland

Master endocrine gland regulating hormones throughout the body.

Cerebral Cortex

Outer brain layer responsible for higher cognitive functions.

Cerebrospinal Fluid (CSF)

Fluid that cushions the brain and circulates within the ventricles.

Blood–Brain Barrier (BBB)

Selective barrier between cerebral blood and CSF that restricts substance entry.

Dendrite

Neuron branch that receives signals.

Axon

Long projection that transmits signals away from the neuron’s cell body.

Myelin Sheath

Insulating layer around axons; speeds nerve impulse conduction.

Synapse

Junction where neuronal signals are transmitted to another cell.

Nodes of Ranvier

Gaps in the myelin sheath that enhance conduction speed.

Schwann Cell

Glial cell in the PNS that forms the myelin sheath around axons.

Nissl’s Granules

Rough endoplasmic reticulum in neurons involved in protein synthesis.

Wernicke’s Area

Temporal lobe region important for language comprehension.

Vestibular System

Reflex system that stabilizes head/eye position and posture.

Ingestion

Act of taking food into the mouth.

Digestion

Mechanical and chemical breakdown of food.

Absorption

Nutrients absorbed into the bloodstream from the small intestine.

Excretion

Elimination of waste via the large intestine.