HSCI 210 Final Exam Study Guide

Vocabulary practice cards covering neurons, glial cells, brain structures, blood composition, the endocrine system, and specialized tissue functions based on the HSCI 210 final exam guide.

Myelin sheath

A fatty tissue layer that surrounds nerves in both the Central Nervous System (CNS) and Peripheral Nervous System (PNS). Its primary functions include protecting the nerves and enhancing the speed of impulse transmission. This is crucial for efficient communication between nerve cells.

Dendrite

The portion of a neuron that receives signals from other neurons. Dendrites have a tree-like structure, allowing them to establish numerous connections and increase the surface area for receiving synaptic inputs.

Soma

The cell body of a neuron that contains the nucleus and processes incoming information. It maintains the health of the neuron and integrates incoming signals to determine if they will trigger an action potential.

Axon

A tail-like portion of a neuron responsible for transmitting signals to other neurons or target tissues. Axons can vary in length; they are often insulated by myelin sheath, facilitating faster signal transmission.

Unipolar neurons

Sensory neurons primarily responsible for touch, temperature, and pain. They possess a single process that bifurcates into the peripheral and central branches, enabling direct transmission of sensory information.

Bipolar neurons

Sensory neurons specialized for vision, hearing, smell, taste, and equilibrium. Bipolar neurons have two distinct processes: one acts as a dendrite and the other as an axon, facilitating efficient communication of sensory signals.

Multipolar neurons

Neurons that receive and integrate information, facilitating motor control and sensory perception. They are characterized by multiple extensions from the soma and are the most common type found in the brain and spinal cord.

Afferent neurons

Sensory neurons that transmit information toward the brain. These neurons convey sensory stimuli from the periphery to the central nervous system (CNS) for processing.

Efferent neurons

Motor neurons that transmit information away from the brain. They carry commands from the CNS to muscles and glands, eliciting responses such as movement or secretion.

Interneuron

A relay neuron found only in the CNS that connects afferent and efferent neurons. Interneurons are essential for reflexes and complex reflex arcs, processing sensory input before generating motor output.

Epineurium

The connective tissue layer that surrounds the entire nerve and contains adipose and blood vessels. This protective layer ensures the nerve's structural integrity and provides nourishment.

Perineurium

A thicker connective tissue layer that surrounds the fascicle within nerves, helping to protect against compression injury. It provides a barrier crucial for maintaining ionic balance necessary for nerve function.

Endoneurium

The connective tissue layer surrounding individual axons within fascicles, which contains capillaries, collagen, and Schwann cells. It provides structural support and protection to each axon within a nerve.

Synapse

The region where nerves communicate, using electrical signals via gap junctions or chemical neurotransmitters across a synaptic cleft. Synapses are crucial for transmitting signals between neurons, facilitating complex networks necessary for brain function.

Electrical Synapse

found in CNS–both brain and spinal cord + smooth and cardiac muscle

• Direct (continuos) propagation; slower

• Saltatory Propagation; quicker

Chemical Synapse

most common; found in both CNS and PNS—at neuromuscular junctions + synapses with glands

Glial Cells

support cells - provide structural and metabolic support to neurons in both CNS and PNS

Oligodendrocytes

Glial support cells in the CNS responsible for creating myelin. They extend their processes to multiple axons, providing insulation and support to several neurons concurrently.

Schwann cells

Glial support cells in the PNS responsible for making myelin. Each Schwann cell wraps around a single segment of an axon, playing an integral role in the regeneration of damaged nerves.

Neuroglia

nerve helper cells

• CNS - oligodendrocytes: make myelin

• PNS - Schwann cells: make myelin

Peripheral nueropathy

nerve damage; nerves not functioning properly

• damage to myelin sheath; loss of feeling

• lack of blood flow

Multiple Sclerosis

An auto-immune disorder in which the body attacks its own myelin around nerves, resulting in symptoms like numbness, tingling, and vision problems. This demyelination disrupts normal neuronal communication.

White Brain Matter

• Mostly heavily myelinated axons

• Connect various brain regions to assist with functions related to learning, attention, and motor control.

• The myelin gives this tissue its characteristic white color, facilitating rapid signal transmission.

Gray Brain Matter

• Unmyelinated tissue primarily consisting of mostly neuronal cell bodies

• Processes and transmits information, muscle control, sensory perception, memory, emotions, and speech.

Dura Mater

The outermost protective connective tissue layer of the meninges located between the skull and brain. It offers a sturdy protective barrier against mechanical injury.

Arachnoid Mater

The thin middle layer of the meninges that acts as a loose cushion and forms the subarachnoid space, which contains cerebrospinal fluid (CSF). This cushioning is essential in protecting the brain from impacts.

Pia Mater

The innermost layer of the meninges, tightly bound to the brain and spinal cord. It contains blood vessels that supply necessary nutrients to the nervous tissue.

Reflex Arc

• Reflex: An automatic, rapid response to a stimulus

• involuntary, involves both CNS and PNS

• receptor sense stimulus—> afferent neuron sends message to dorsal root ganglion—> message sent through dorsal spine—> message sent through ventral spine—> efferent neuron sends message away from body—> effector produces quick response.

• This pathway allows quick reactions to stimuli without direct brain intervention.

• receptors: detect and respond to stimuli (sensors)

• effectors: respond to signals from nervous system with muscle contraction or gland secretion (responders)

Cerebrospinal fluid (CSF)

within the subarachnoid mater of spinal cord meninges

Choroid plexus

• Cells located in the ventricles that produce cerebrospinal fluid (CSF).

• This fluid is crucial for making the brain weigh less by suspending it

Corpus Callosum

• The structure that connects the two hemispheres of the brain, facilitating the crossing of impulses between them.

• Integrates information

Homunculus

• gyrus and sulcus

• Maps representing sensory and processing areas on the cerebral cortex, depicted by gyri and sulci

Somatomotor cortex

• The primary motor cortex, located in the precentral gyrus

• responsible for planning and initiating voluntary movements.

Somatosensory cortex

• The primary sensory cortex located in the postcentral gyrus

• processes tactile information regarding touch, pressure, pain, and temperature.

Central Gyrus

the fold that divides the cerebrum into anterior and posterior halves

Central canal

• the passageway through the spinal cord

• circulates cerebrospinal fluid which is formed in the choroid plexus (cells in the ventricle

Hydrocephalus (big headed baby)

• A medical condition characterized by the accumulation of cerebrospinal fluid (CSF) inside the head, typically due to a blocked aqueduct.

• caused by congenital malformations, brain injuries, infections, tumors, and strokes

Basal ganglia

• A group of nuclei situated deep within the brain, including structures such as the Substantia Nigra

• Facilitates voluntary movement, habit formation, emotions, learning, and eye movements

Parkinson’s Disease

• A neurodegenerative disorder characterized by the progressive loss of dopamine-producing cells in the Basal Ganglia/Substantia Nigra, leading to symptoms like tremors, rigidity, and bradykinesia.

• heredity, age, and males

Cerebellum

involved in coordination of movement, posture and balance, but also fine motor skills, emotional processing, learning and hand/eye coordination

Arbor Vitae

• The white matter located in the cerebellum that transmits information to various parts of the cortex.

• Its unique tree-like structure plays a crucial role in coordinating motor control and maintaining balance.

Cerebellar Dysfunction

• neurological impairment with coordinations and tremor, lack of voluntary muscle control

• caused by genetic mutations and hereditary factors or other medical conditions like multiple sclerosis

Medulla Oblongata

A vital section of the brainstem responsible for regulating essential autonomic functions such as heart rate, blood pressure, and breathing.

Ataxia

damage to the cerebellum can cause a “drunken gait”

Pons

A prominent structure in the brainstem that regulates sleep, facial movement, and hearing. It serves as a relay station between different parts of the brain.

Peripheral Nervous System (PNS)

• connects central nervous system to organs, limbs, and skin

• carries sensory and motor information to and from CNS

• allows brain and spinal cord to receive and send information to the body

• somatic (voluntary

  • sensory (afferent)

  • motor (efferent)

• autonomic (involuntary)

  • sympathetic (fight/flight)

  • parasympathetic (rest/digest)

Spinal cord

Superior—>inferior anatomy

• cervical spine, thoracic spine, lumbar spine, sacrum, coccyx

• disruptions in flow will lead to spinal cord infarction

• PNX plexus: complete network of interwoven nerve fibers formed around spinal nerves

  • cervical plexus, brachial plexus, lumbar plexus, sacral plexus

Dermatomes

Areas of skin that are innervated by the cutaneous branches from a single spinal nerve.

Myotomes

Segments of spinal nerve roots, where each segment innervates more than one muscle.

Cranial nerves

• PNS also includes cranial nerves

• considered peripheral even if they come off the brain directly

Red Blood Cells/Erythrocytes

• Red blood cells making up about 44% of blood composition.

• They contain hemoglobin, which is essential for oxygen binding and transport from the lungs to body tissues.

Erythropoiesis

• RBC production

• produced in the bone marrow and is a response to different signals

• kidneys release erythropoietin in response with hormones

Anemia

body does not have enough healthy RBC to deliver enough oxygen to tissues

Sickle Cell Anemia

• mutated hemoglobin molecules because sickle-shaped RBCs that can’t fit through capillaries well anymore

• hereditary

Polycythemia

• hematocrit and hemoglobin levels exceed normal thresholds

• leading to increased blood viscosity (thicker blood) and a higher risk of clot formation and complications like hypertension.

White Blood Cellls/Leukocytes

• White blood cells that defend the body against pathogens, destroys cancer cells, and neutralize toxins

• comprising less than 1% of blood. They are key components of the immune response.

Types of leuokcytes

Never Let Monkeys Eat Bananas

• neutrophils(60-70%) - first to arrive at injury site.

• lymphocytes(20-40%)

• monocytes(3-10%)

• eosinophils(1-4%)

• basophils(1%)

Plasma

• 55% of blood composition

• contains hormones, glucose, enzymes, waste products

Platelets (Thrombocytes)

• Broken fragments of megakaryocytes

• forming scabs and halting bleeding by initiating the clotting process.

Inflammation

• inflammatory responses:" WBCs migrate to region, targeting microbes immediately after an injury/infection

• neutrophils: release enzymes to kill bacteria/pathogens

• extravasation: when WBCs migrate from bloodstream—> local damages/infected tissue

Diapedesis

The final phase of extravasation process during which white blood cells exit the bloodstream by squeezing through the capillary endothelium to reach sites of infection or injury.

Platelets

• <1% of blood

• made in bone marrow

• forms scabs to stop cuts from bleeding

• aka thrombocytes

  • when signaled, platelets migrate to source of bleeding and aggregate to “fill the hole” and form a clot

Lymph

• collects waste products, including damaged cells and bacteria

• carry extra protein and fluid from tissues and fats from intestines and bring them back to bloodstream

  • contains lymphocytes

  • only flow TO the heart

Lymphocytes

primary lymphoid organs produces lymphocytes from immature progenitor cells

secondary lymphoid organs - holding tank for mature lymphocytes

B Cells

• Type of lymphocytes that are produced in the bone marrow.

• They learn to recognize pathogens and generate specific antibodies,

T Cells

• Type of lymphocytes that originate in the bone marrow but mature in the thymus.

• Helps to destroy cancer cells quickly and prevent auto-immune reactions

NK Cells

• Type of lymphocytes that work to kill viruses and cancer cells quickly without having to recognize them first due to prior exposure

Thymus

• produces and matures T cells

• secretes hormones (thymosin and thymulin) —> play roles in immunity regulation

  • anterior to heart, deep to sternum

  • contains 2 lobes

  • large and active during childhood —> aging —> replaced with fat

Mononucleosis

• swollen lymph nodes

• transmitted by contact with saliva from an infected person

Lymphedema

• any blockage or removal of the lymphatic vessels/nodes will cause the corresponding body part to swell

  • primary lymphedema: due to hyperplasia, hypoplasia, or aplasia of the vessels

  • secondary lymphedema: due to any damage done to the vessels/nodes from surgery, inury, or disease

Cysterna chyli

• A secondary lymphoid organ

• drains lymph and absorbs fat from the intestines

• serves as the origin for the thoracic duct

Lymphatic duct

• A secondary lymphoid organ

• drainage reservoir for lymph coming from the right side of the head, neck, and upper body

Thoracic duct

• A secondary lymphoid organ

• drainage reservoir for the left side of the head, neck, body, including the right lower quarter and leg

Hormone signaling

• Hormones are chemicals that help control and coordinate body functions

• Made in glands and travel through bloodstream target organs and tissues

Hormonal Stimuli (Hypothalamus)

• most common stimuli type

• glands get activated by other hormones

  • secretes hormones that stimulate anterior pituitary gland to secrete hormones that stimulate other endocrine glands to secrete hormones in their respective places

• terminated by negative feedback loop

Humoral Stimuli (Parathyroid Gland)

• response to altered levels of ions/nutrients (chemical)

• caused by altered levels of ions or nutrients

• Low concentration of ions stimulates capillaries that go to the parathyroid glands which get stimulated to secret parathyroid hormones.

• terminated by negative feedback loop

Neural Stimuli (Adrenal Gland)

• response to neural signal (electrical

• Release caused by electric signals

• SNS fiber stimulates adrenal cells that travel through the CNS spinal cord and go to the adrenal glands, which then go to the capillary to secrete hormones.

Hypothalamus

• releases tropin hormone to anterior/posterior pituitary

  • tyrotropin

  • corticotropin

  • gonadotropin

  • growth hormone

• produces hormones—> store in posterior pituitary

  • vasopressin/antidiuretic

Pituitary gland/hypophysis

Pineal Gland

Thyroid gland

• regulates metabolism, increases metabolism, heart rate, body temperature, and cell growth

Parathyroid gland

• produces and releases PTH

  • stimulates release of calcium from bones into bloodstream

  • decreases excretion of Ca2+ from kidneys and increases reabsorption in small intestine

Thymus

Kidneys

Adrenal Glands

• responding to stress

• produces adrenaline and cortisol

  • increases heart rate, breathing —> fight or flight

Pancreas

• blood sugar balance

• digestive and endocrine

  • produces insulin = controls amount of glucose in your blood —> improper amount of insulin can lead to diabetes

• exocrine: acinar cells that secrete digestive enzymes into small intestines

• endocrine: islets of langerhans are bodies that contain endocrine cells

  • beta cells make insulin

  • alpha cells secrete glucagon—> tells liver to release glucose

Calcitriol

A hormone produced in the proximal convoluted tubule (PCT) that signals the intestines to increase calcium absorption. It plays a critical role in regulating calcium and phosphate balance.

Islets of Langerhans

Clusters of endocrine cells located in the pancreas, including alpha and beta cells. These islets are responsible for producing vital hormones such as insulin and glucagon, which are integral to glucose homeostasis.

Type 1 Diabetes

A chronic condition characterized by the body's inability to produce sufficient insulin due to autoimmune destruction of pancreatic beta cells. It requires lifelong insulin therapy for management.

Acromegaly

A disorder resulting from excess growth hormone in adults after the completion of bone fusion. It causes abnormal enlargement of bones and tissues, leading to various health complications.

Bony labyrinth

A complex of cavities located in the temporal bone that contains perilymph molecules. It includes the cochlea, vestibule, and semicircular canals, all of which are essential for hearing and balance.

Iris

colored part of the eyes

pupil

aperture that can change size and amount of light entering the eyes

Sclera

outer whites of the eyes; fibrous membrane where eye muscles attach

• cornea: anteriormost portion of sclera

Lens

thick, biconcave, transparent disc —> changes shape to allow light to focus on different parts of the retina

Retina

tissue at the posterior portion of the eye; changes light signals —> electrical impulses (afferent signals)

• photoreceptors: converts light —> electrical impulses —> processed in brain

Macula Lutea

middle, posterior pole of eye; responsible for sharp vision

• fovea centralis: center of macula lutea, contains cones

  • cones: detects wavelengths of light —> allows for color vision

Optic Disc

small elevation where nerves gather to exit as the optic nerve

• blind spot—> lacks photoreceptors —> light focused in this area can’t be perceived

Aqueous Humor

thin, watery fluid between cornea and iris that helps keep the eyeball’s shape

• balances production and drainage —> manages pressure

Vitreous Humor

gel-like substance (water, collage, other proteins) that fills the space behind lens and front of retina

• helps maintain eye’s shape

• medium for light to pass through to retina