Histology Unit 3 Review

What organs make up the CNS?

Brain and spinal cord

What organs make up the PNS?

Cranial and spinal nerves with their associated ganglia

What is the Soma?

cell body; contains nucleus and organelles

What are dendrites?

receive input from other neurons and from external environment and carry it to cell body

what are Axons?

carry information from cell body to another neuron or effector cell

What are Synapses?

cell-to-cell junctions utilizing chemical messengers (neurotransmitters)

Describe Multipolar Neurons

most common type; has numerous branched Dendrites and 1x Axon

describe Bipolar Neurons

1x Dendrite + 1x Axon

describe Pseudo-unipolar Neurons

Appears to have 1x process from Soma—Dendrite + Axon fused @ Soma (false appearance of 1 process instead of 2)

describe Neuroglia

supporting but non-conducting cells that are in apposition to neurons

what type of Glia does CNS have?

Oligodendrocytes, Astrocytes, Microglia, and Ependymal cells

what type of Glia does PNS have?

Schwann cells and Satellite cells (capsule cells)

describe Astrocytes

main aid in bld brain barrier; surrounds Somas and processes of neurons

what’s significant of foot processes of Astrocytes on bld-brain barrier?

restricts passage of substances b/w bld and cerebral spinal fluid (CSF): limited diffusion and active transport

describe Oligodendrocytes

1 cell creates Myelin sheath for multiple axons or axon segments

describe Ependymal cells

columnar cells—similar functions to epithelial cells; lines central canal of spinal cord & ventricles of brain

Stem cell for other neuroglia:

Ependymal cells

describe Microglia

smallest neuroglia; macrophages resident to CNS (Phagocytic); only Nuclei are visible unless special stain is used

describe Schwann cells

produces lipid-rich myelin sheath the surrounds axons; 1 cell insulates 1 segment of 1 axon; surrounds unmyelinated fibers, too; clears debris & guide regrowth of PNS axons

describe Myelin sheath

speeds up rate of conduction of Action potential; not all Neurons are surrounded by it; appears as white ring around axons unless stained

describe Satellite (Sc) & Capsule cells (Cc)

small, flat cells that surround neurons of (PNS) ganglia; Soma structural support; insulate neurons; reg. exchange of metabolic substances

in the Brain, Gray matter is located where?

the outer covering

in the Brain, the White matter is located where?

the inner core

in the Spinal cord, where is the White matter located?

in the outer covering

in the Spinal cord, where is Grey matter located?

in the inner core

in the Spinal cord, what does its Grey matter contain?

somas of multipolar neurons & neuroglia nuclei

in the Spinal cord, what does its White matter contain?

collection of myenlinated axons w/ neuroglia nuclei

describe Peripheral neve of PNS

Many axons (nerve fibers) that carry sensory and motor information between organs/tissues and brain/spinal cord; Surrounded by connective tissue
sheaths—like muscle

describe Ganglia of PNS

small accumulations of neuron cell bodies & glia surrounded by CT capsule

describe Endoneurium

loose CT + reticular fibers surrounding each indv nerve fiber (axon) and Schwann cells

describe Perineurium

specialized CT + epithelial-like cells and tight junctions surrounding each nerve fascicle (diffusion barrier)d

describe Epineurium

dense irregular CT that surrounds peripheral nerve (blood vessels; adipose)

what are Nodes of Ranvier?

space b/w adjacent Schwann cells

what type of neurons are Dorsal root ganglion (snesory)

pseudo-unipolar neurons

what type of neuron is Sympathetic ganglion (motor)

multipolar neutronsw

what type of neurons is Parasympathetic ganglion?

multipolar neurons

describe Tunica intima

Endothelium, Basement mbrane, & thin layer Loose CT

describe Tunica media

layers of Smooth muscle cells + Elastic fibers—thicker layer in Arteries

describe Tunica adventitia

longitudinal Collagenous tissue that merges w/ Loose CT around Vessels—thinker layer in Veins

describe Large/ elastic Arteries fucntion

recoil of numerous Elastic fibers allows for BP created by Heart to propel bld through vessels

which type of arteries make the majority of arteries in body?

Medium/ muscular (distributing) Arteries

describe Small arteries & arterioles function

control bld flow by altering diameter of Lumen

describe Small Arteries & Arterioles

only 1-2 layers of smooth muscle cells in tunica media for arterioles; Gap junct found bw endothelium and smooth muscle; Tunica adventitia thin & blends w surrounding CT

which bld vessels have the smallest diameter?

Capillaries

describe Capillaries

1x layer of endothelial cells + basement mbrane; fluid exchange network(s)

describe Continuous capillaries

most common; 8-10 um diameter

describe Fenestrated capillaries

occurrence of filtration/ absorption; 30-40 um diameter

describe Discontinuous capillaries (sinusoids)

cells can pass through vessel wall; 60-80 um diameter

where are Cont. capillaries found in the body?

Muscle lung, CT, and CNS

where are Fenestrated capillaries found in the body?

Endocrine glands, Gall bladder, Kidney, and Intestinal tract

where are Discont. capillaries found in the body?

Liver, spleen, bone marrow

describe Veins

thinner wall & larger Lumen diameter vs. arteries; Valves present to prevent backflow in larger veins

describe Venules & small veins

Postcapillary venules small diameter and limited Tunica media with very few Smooth muscle cells

describe Medium veins

up to 10mm diameter; Valves appear to prevent backflow

describe Large veins

>10mm diameter; thin Tunic media but thick Adventitia (collagen/ elastic fibers; long. smooth muscle cells)”

“Vessels of the Vessels” is referring to what?

Vasa vasorum

describe Vasa vasorum

small bld Vessels that provide nutrients to Tunic media and adventitia of larger Arteries and veins whom have thick walls

Lymphatic caps are sinusoids, describe this:

More permeable than bld Capillaries; Unidirectional flow of fluid from tissues → veins; Collect excess protein-rich fluid from interstitial fluid called Lymph

what does Lymph vessels NOT carry?

bld, presence of bld means internal issues occurring

describe Aneurysm

damage to bld vessels which weakens its wall, bld pools in defected area and is no longer confined to its vessel(s); if left untreated, rupture of vessels causes internal bleeding and potential death

Valves in the heart separate chambers for what purpose?

it’s to prevent backflow

describe Heart wall layer: Endocardium

endothelium lining Artia & Ventricles

describe Heart wall layer: Myocardium

thick layer of cardiac muscle fibersdescribe Heart wall layer:

describe Heart wall layer: Epicardium

Mesothelium (simple squamous) + CT

describe Purkinje fiber

non-contractile: send electrical signal to contractile cardiac muscle fibers; clear cytoplasm; no Intercalated disks w/ less myofibrils but larger in diameter

where are Purkinje fibers found?

in the Endocardium of the Heart

what kind of tissue is found in the Epidermis?

Epithelial tissue

what kind of tissue is found in the Dermis & Hypodermis?

Connective tissue

what kind of muscle tissue is found near hair follicles?

Smooth muscle

describe Epidermis and its derivatives

keratinized stratified squamous epithelium; nonvascular

describe Dermis and its derivatives

dense irregular CT, provides mechanical support, strength, and thickness; vascularized

describe Hypodermis and its derivatives

deep to dermis (subcutaneous/subcutis), composed of variable amounts of adipose tissue lobules and dense irregular CT