Histology Fall 2009 Midterm

Front 1

Mesenchyme Cell

Back 1

-differentiate into cartilage cells forming a hyaline cartilage model

Front 2

How does the perichondrium convert to the periosteum?

Back 2

Blood vessels develop in the CT

-higher oxygen levels cause this converion

Front 3

Periosteal bone collar

Back 3

formed by osteoblasts in the periosteum that produce bone

Front 4

Primary ossification center

Back 4

-this in the center of the shaft (diaphysis)

Front 5

Periosteal bud

Back 5

-breaks through the bone collar bringing in blood vessels, osteoprogenitor cells, blood cells, and osteoclasts

Front 6

Osteoblasts

Back 6

deposit bone on pieces of calcified cartilage

Front 7

Osteoclasts

Back 7

resorb the calcified cartilage and newly formed bone, giving rise to a space, the marrow cavity

Front 8

Growth in LENGTH of bone occurs by

Back 8

-chondrocyte division (interstitial growth)

-this process of chondrocyte division, hypertrophy, osteoblast deposition, and osteoclast resorption becomes restricted to the ends of the bones (epiphysis)

Front 9

Growth in WIDTH

Back 9

-by appositional growth of osteoblasts from the periosteum

- marrow cavity enlarges due to osteoclast activity

Front 10

Secondary ossification center

Back 10

-forms at the ends of the bones (epiphysis) restricting the cartilage to a plate (growth plate, epiphyseal plate) or as a thin shell at the ends (articular cartilage)

-occurs postnatally

Front 11

When does growth in length end?

Back 11

-when bone replaces the cartilage in the epiphyseal plate

Front 12

When does growth in width end?

Back 12

-growth in width can continue throughout life from the periosteum

Front 13

Fracture repair

part 1

Back 13

-initially the damaged matrix and bone cells adjoing the fracture die, and damaged blood vessels form a blood clot. Macrophages remove the dead tissue and cells

Front 14

Fracture repair

part 2

Back 14

-primary bone is then formed by endochondral and intramembranous ossification

-irregularly formed bone trabeculae temporarily unite the extremities of the fracture bone, forming a bone callus

-the primary bone tissue of the callus is gradually resorbed and replaced by secondary lamellar bone

Front 15

Bone matrix turnover is primarily regulated by what two hormones?

Back 15

1. Calcitonin (Thyroid gland)

2. Parathyroid hormone

Front 16

Calcitonin

Back 16

-thyroid gland

-lowers blood Ca levels, inhibits bone resorption

Front 17

Parathyroid Hormone

Back 17

raises blood Ca levels, increases osteoclast activity

Front 18

Hyperparathyroidism

Back 18

results in excessive osteoclast activity

Front 19

Growth hormone

Back 19

-comes from the anterior pituitary

-stimulates bone growth in general and especially growth of the epiphyseal cartilage and bone

Front 20

3 Disorders involving GH

Back 20

1. Pituitary dwarfism--> decrease GH in children

2. Gigantism--> excess GH in children, abnormal increase in the length of bones

3. Acromegaly--> excess GH in adults, thickening of bones (growth from the periosteum)

Front 21

Achondroplasia

Back 21

the most common form of dwarfism, is a genetic disease in which cartilage is not converted into bone at the growth plate

Front 22

Vitamin D deficiency

Back 22

-leads to insufficient bone mineralization

A. Rickets - in children

B. Osteomalacia - in adults

Front 23

Osteoporosis

Back 23

common in postmenopausal women is characterized by an overall reduction in total bone mass although the bone matrix is normally mineralized. Osteoporosis is caused by an imbalance in bone turnover, with bone resportion exceeding bone formation

Front 24

Tumors of Connective Tissue

Fibroblasts

Back 24

Benign: Fibroma

Malignant (Sarcomas): Fibrosarcoma

Front 25

Tummors of CT--> Adipose

Back 25

Benign: Lipoma

Malignant (Sarcomas): Liposarcoma

Front 26

Tumors of Cartilage

Back 26

Benign: Chondroma, Osteochondroma

Malignant (Sarcomas): Chondrosarcoma

Front 27

Tumors of Bone

Back 27

Benign:
1. Osteoma
2.Osteoblastoma
3. Osteoid osteoma

Malignant (Sarcomas)
1. Osteogenic sarcoma
(Osteosarcoma)

Front 28

Tumors of Skeletal Muscle

Back 28

Benign: Rhabdomyoma

Malignant (Sarcomas): Rhabdomyosarcoma

Front 29

Tumors of Smooth Muscle

Back 29

Benign: Leiomyoma

Malignant (Sarcomas): Leiomysarcoma

Front 30

Sarcomas

Back 30

-greek for "flesh"

-are malignant tumors that arise from tissues derived from mesenchyme, including CT, adipose tissue, bone, cartilage and muscle

-may contain a mixture of tissue types and matrix

Front 31

Common features of all Muscle Types

Back 31

-consist of long, cylindrical cells or fibers
-specialized to shorten or contract
-have an acidophilic cytoplasm with oval or cigar shaped EUCHROMATIC nuclei
-contain large amounts of contractile filaments (myofilaments), especially actin and myosin
-are anchored to the CT by a basal lamina (secreted by muscle cell)
-are capable of enlarging (hypertrophy) or shrinking (atrophy)
-require a large vascular supply

Front 32

Skeletal Muscle

Light Microscopic Appearance

Back 32

1. Large unbranched, cylindrical fibers with visible CROSS-STRIATIONS in an acidophilic cytoplasm

2. Each fiber contains many nuclei (multinucleated) located PERIPHERALLY immediately underneath the sarcolemma

Front 33

Connective Tissue Wrappings (mysuims)

Back 33

Epimysium --> CT around gross muscle

Perimysium--> CT around bundle

Endomysium--> CT around a fiber

Front 34

EM Appearance and specializations of Skeletal Muscle

Back 34

Contractile filaments (myofilaments) fill the cytoplasm in a specialized arrangement

-Actin and myosin filaments are organized into repeating units called sarcomeres

-Contain light (I BAND) and dark (A BAND) regions

-actin filaments are anchored in a region called the Z LINE. Sarcomeres extend from Z line to Z line

-myofibrils are end to end sarcomeres

Front 35

Sarcoplasmic reticulum

Back 35

-smooth endoplasmic reticulum

-contains swollen ends called terminal cisternae which store and release Ca

Front 36

Transverse Tubules

T Tubules

Back 36

-invaginations of the sarcolemma (cell membrane) that carry excitation inward

Front 37

Triad

Back 37

-two terminal cisternae and one T-Tubule

-surrounds each sarcomere at the A/I band junction

Front 38

Innervation of Skeletal Muscle

Back 38

Lower motor neurons (LMN) from the spinal cord or brain stem innervate each skeletal muscle cell by a special junction called a synapse

Front 39

Skeletal muscle fibers contract ONLY...

Back 39

when excited by the neuron

-completely dependent on the LMN for its function and survival

Front 40

Motor End Plate =

Neuromuscular junction or synapse =

Myoneural junction

Back 40

-consists of the axon terminal of the neuron, a small synpatic space, and the membrane of the muscle cell

-AP causes release of synaptic vesicles at the axon terminal

-ACh in the vesicles bind to the muscle membrane causing a depolarization or excitation

Front 41

Denervation

Back 41

results in an inability of the LMN to "tell" the muscle fiber to contract.

-this causes paralysis

-the muscle fiber atrophies and dies if not reinnervated

Front 42

Sensory neurons monitor the....

Back 42

stretch of the skeletal muscle

muscle spindle is the muscle stretch receptor

Front 43

Muscle Spindle

Back 43

-is the muscle stretch receptor

-consists of nerve endings and several small, modified muscle fibers surrounded by a CT sheath

Front 44

Muscle Fiber Typing

Back 44

-White vs Red vs Intermediate

-Fast-Twitch and Slow Twitch

-Type I and Type II

-determined by the neuron
-therefore all muscle fibers in a motor unit are the same fiber type

pg 68

Front 45

Use and Disuse of Muscle

Back 45

-increased use causes hypertrophy

-decreased causes atrophy

-denervation causes rapid atrophy

Front 46

Atrophy of Muscle

Back 46

-smaller fibres

-fat

-fewer fibrils

Front 47

Hypertrophy of Muscle

Back 47

-larger fibres, but same number

-more numerous fibrils

Front 48

Development of Skeletal Muscle



pg. 69

Back 48

1. Myoblasts- develop in mesenchyme

2. Myotubes- are multinucleated cells that develop by fusion

3. Myofibers

Front 49

Myofibers


pg. 69

Back 49

Are differentiated muscle cells that develop with innervation

-Sarcomeres, SER, T-tubules, and peripheral nuclei develop

-Muscle fibers that do not become innervated DIE

Front 50

Regeneration of Skeletal muscle



pg. 69

Back 50

-Mature muscle fibers CANNOT replicate

-small number of new fiber diffentiate from satellite cells

Front 51

Satellite Cells

Back 51

-Stem cells located between the sarcolemma and the basal lamina

-can differentiate into myoblasts in the adult

Front 52

Duchenne Muscular Dystrophy

Back 52

-X linked recessive disease

-affecting only males

-presence of a defective or absent actin binding protein (dystrophin) in the cell membrane leads to muscle destruction

Front 53

Cardiac Muscle

Light Microscropic Appearance

Back 53

1. Fibers are small, BRANCHED cells with striations. In x.s. they appear smaller and more variable in size than skeletal muscle fibers

2. Adjacent fibers are connected at their ends by specialized junctions, visible as a dark zigzagged line--> INTERCALATED DISC

3. Each fiber typically has an oval, euchromatic nucleus in the CENTER of the cell

4. Fibers are attached to the CT by a strong basal lamina. Large amounts of capillaries and lymphatic vessels are in the surrounding CT

Front 54

Cardiac Muscle

Electron Microscope Appearance and Specializations

Back 54

1. Cardiac Muscles like those of skeletal muscle contain:

a. Contractile filaments (actin and myosin), myofibrils, sarcomeres with A and I bands and Z lines

b. membranous specializations include SER with terminal cisternae and T-tubules

The membranous organelles are less developed than in skeletal m

Diads: one terminal cisternae one t-tubule at the Z line of each sarcomere

3. Myoglobin and mitochondria are abundant

4. individual cells are attached to each other with special junctions (intercalated discs)

Front 55

Intercalated Discs



pg 70 and 71

Back 55

-junctional complexes connecting adjacent cardiac muscle cells

Front 56

Fascia Adherens

Back 56

-type of intermediate junction

-hold adjacent cells together and transmit the force of contraction from cell to cell

-anchors actin filaments of the last sarcomere to the sarcolema

Front 57

Desmsomes

Back 57

hold adjacent cells together and transmit the force of contraction from cell to cell

are strong spot attachments that bind neighboring cells

Front 58

Gap or communicating junctions

Back 58

allow the diffusion of ions and electrical excitation between cells

-this spreads waves of excitation rapidly over the entire heart muscle

Front 59

Synctium

Back 59

-the mass of cells that contract together as a result of the individual cells structurally and ionically linked together

Front 60

Cardiac muscle cells are Autogenic

Back 60

-they exhibit a spontaneous rhythmic contraction

-the ANS, endocrine system, and specialized cardiac muscle fibers modify the pattern and rate of the intrinsic contraction of the cells

Front 61

Are there motor end plates in cardiac muscle?

Back 61

NO END PLATES

-cardiac muscle cells are sensitive to stretch (heart massage)

Front 62

Purkinje Fibers

Back 62

-specialized cardiac muscle cells located in the endocardium of the heart

-much larger than the typical cardiac muscle fibers and contain abundant glycogen with few myofibrils

-in slikdes the glycogen is disolved away leaving a pale, empty cytoplasm

Front 63

Purkinje Fibers

Back 63

-specialized to play a key role in coordinating the pattern of contraction in the heart.

-they help set the "pace" of the contraction by quickly conducting and spreading waves of excitation to other cardiac muscle fibers by gap junctions

Front 64

What can cardiac muscle not do?

What do they not have?

Back 64

-NO regeneration

-Cells can NOT replicate

-NO stem cells

-if a portion of the heart dies (myocardial infarct), the muscle tissue is replaced by a CT scar

Front 65

Cardiac muscle CAN hypertrophy

Back 65

-example in hypertension, the increased functional demands on the heart to maintain the high BP leads to a massive increase in cell and heart size

Normal heart weight 350g

Hypertension Heart Weight 400-650g

*due to hypertrophy of left ventricle

Front 66

Smooth Muscle

Back 66

-found throughout the body, commonly in the walls of tubes (blood vessels, airways) and hollow organs (gut, uterus)

Front 67

Light Microscopic Appearance

Back 67

1. SMALL ACIDOPHILIC spindle shaped cells often arranged into layers

2. Each fiber has a single central nucleus

3. NO STRIATIONS

4. Individual cells are hard to distinguish

Front 68

Each Smooth Muscle Fiber is surrounded by?

Back 68

-a basal lamina and network of reticular fibers

Front 69

Smooth muscle cells, especially in blood vessels are capable of?

Back 69

Secreting large amounts of Type I collagen and elastic fibers

Front 70

Smooth Muscle Electronic Microscopic Appearance and Specializations

Back 70

1. Myofilaments (actin, myosin, and intermediate filaments) are present but NOT organized into myofibrils, sarcomeres, and A and I bands

-the filaments interconnect and are anchored to dense bodies that turn are anchored to the sarcolemma

Front 71

Smooth muscle cells do NOT have

Back 71

-specialized membrane systems (no specialized SER, terminal cisternae, or T-tubules)
***instead small invaginations of sarcolemma (caveolae) and pinocytotic vesicles are prevalent in the cytoplasm

-NO SPECIALIZE MOTOR ENDPLATES on smooth m fibers

Front 72

How does most Smooth M contract

Back 72

-most can spontaneously contract

-although the ANS and hormones of the endocrine system can modify the rate of contraction

Front 73

Smooth muscle fibers are often linked by?

Back 73

-gap junctions

-can contract as a single sheet of syncytium

-responsible for the wave-like contraction, such as peristaltic movment of the gut and male genital tract

-also sensitive to stretch (massage the uterus after childbirth)

Front 74

Smooth M and replication

Back 74

-can normally divide to maintain their number

-new smooth m cells develop from division of existing smooth m from undifferentiated stem cells or from pericytes associated with blood vessels

Front 75

Smooth muscle cells can undergo

Back 75

Hyperplasia and hypertrophy

-during pregnancy the smooth m fibers of the uterus increase massively in size (hypertorphy) and in number (hyperplasia)

Front 76

Atheroscelerotic Lesions in walls of blood vessels

Back 76

-Smooth muscle cell poliferation and extracellular matrix (fibers and proteoglycans) deposition play an important role

Front 77

Leiomyosarcomas

Back 77

-malignant tumors derived from smooth m

-most often found in the pelvic organs (especially the uterus) and blood vessels

-these rare tumors usually occur in adults

Front 78

Rhabdomyosarcomas

Back 78

-malignant tumors that resemble developing skeletal muscle cells

-usually occur in the arms and legs

-this rate tumor is typically present in children (1-6 y/o)

Front 79

Anatomically the NS is divided into two overlapping divisions

Back 79

1. CNS
-Brain, brainstem, spinal cord

2. PNS
-nerves and nerve roots, ganglia, nerve endings, receptors

Front 80

Neurons

Back 80

-one of two classes of nervous system cells

-excitable cells that receive and integrate stimuli, conduct electrical impulses along its processes, and pass on the "information" through specialized chemical junctions called synapses

-highly differentiated and are NOT able to replicate

-chains of neurons, linked together by synapses, carry information in one direction

Front 81

Glial

Back 81

-glue cells support the nuerons

-protect, surround, myelinate, and modulate the environment allowing the neurons to function efficiently

Front 82

Glia of the CNS vs PNS

Back 82

CNS:
oligodendrocytes, astrocytes, ependymal cells, microglia

PNS
Schwann and satellite cells

Front 83

Different Parts of Neurons

Back 83

Dendrites
Axons
Cell Body (soma)
Terminal

-some neurons are VERY big and have long axons that travel far away from their cell body

Front 84

CNS

Collection of cell bodies (plus axons)
vs
Collection of axons (no cell bodies)

Back 84

Gray matter (nuclei)

vs

White matter

Front 85

PNS

Collection of cell bodies (plus axons)
vs
Collection of axons (no cell bodies)

Back 85

Ganglia
-sensory; spinal, dorsal root ganglia (DRG)
-Autonomic: sympathetic or parasymathetic

vs

Nerves
-spinal, peripheral nerves most cranial nerves
-nerve roots

Front 86

Dendrites

Back 86

Short tapering processes

-may branch

-extension of cell body (same organelles)

-receives impulses

Front 87

Cell body (perikaryon, soma)

Back 87

-Nucleus plus cytoplasm

Cytoplasm contains
-microtubules, microfilaments, neurofilaments (intermediate) mitochondria (no glycogen), synaptic vesicles

-organelles to make new proteins
-golgi apparatus
-Ribosomes and RER (appear in LM as basophilic clumps called Nissl bodies)

-receives impulses

Front 88

Axon Hillock

Back 88

-Elevated region of cell body at beginning of axon

-stop protein making organelles from entering axon

Front 89

Nucleus of Neuron

Back 89

-large euchromatic nucleus with prominent nucleolus

Front 90

Axon

Back 90

-long process of constant diameter may be myelinated (wrapped by glia)

-may be gathered into bundles

-Does NOT contain organelles to make new proteins (no golgi, RER, ribosomes)

-moves material up and down axon

-conducts nerve impulses to terminal

-nerve fiber

Front 91

Axon Terminal

Back 91

-contains vesicles (synaptic) containing neurotransmitters

-releases vesicles on arrival of nerve impulse

Front 92

Axoplasmic Transport

Back 92

-continuous flow up and down

-guided by microtubules

Front 93

Anterograde transport

Back 93

-from cell body to terminal

-brings newly synthesized materials, i.e. synaptic vesicles down axon

-slow (bulk, 1.5 mm/day)

-fast (up to 400 mm/day)

Front 94

Retrograde Transport




pg. 79 (good picture)

Back 94

-from terminal to cell body

-only slow

Front 95

GOOD CHART PAGE 80

Back 95

Compares the SOMA, DENDRITES, and AXON

Front 96

General classification of neurons according to processes



pg. 81

Back 96

1. Multipolar

2. Bipolar

3. Pseudeounipolar

Front 97

Multipolar Neurons

Shape and Function

Back 97

-on axon, multiple dendrites

-Almost all neurons in CNS

-all motor neurons
LMN to skeletal muscle
Autonomic neurons
Sympathetic and parasympathetic neurons

Front 98

Bipolar Neurons

Shape and Function

Back 98

one axon, one dendrite at opposite poles

-Special sensory only
vision (retina)
hearing and balance (inner ear)
smell (olfactory mucosa)
taste

Front 99

Pseudounipolar Neurons

Back 99

-one axon that divides close to the cell body into tow long processes (one to periphery, one to CNS)
-only tips by periphery function as dendrites

-General sensory
touch pain, vibration, position sense, etc

present in DRG

present in some cranial ganglia sensory in function (Trigeminal ganglia)

Front 100

General Organization of the PNS

Back 100

Ganglia- collection of cell bodies (and attached axons)

Nerves-collection of Axons (NO cell bodies)

Glial cells of the PNS:
Schwann cells surround ALL axons (may form myelin)

Satellite cells surround cell bodies in the ganglia

Front 101

General Organization of the PNS



pg 82 and 83

Back 101

1. Dorsal root ganglion
-sensory-afferent (pseudounipolar)

2. Lower motor neuron LMN
Somatic motor-efferent
motor end plate, skeletal muscle, multipolar

3. Sympathetic ganglion
Autonomic - visceromotor
smooth m, cardiac m, glands
multipolar

4. Parasympathetic

Front 102

Motor End Plate or NMJ



pg 84

Back 102

Specialized synapse between a LMN and a skeletal muscle fiber

LMN (cell body in CNS)---> Axon in PNS nerve----> Terminal forms synapse on skeletal muscle fibers

Front 103

Sensory Nerve Ending




pg 84

Back 103

-distal tips of sensory neurons (nerve "beginning") that respond to sensory stimuli by initiating a nerve impulse

-converts sensation into electrical impulses

Front 104

Naked or Free Endings

Back 104

-touch, pain, and temperature

-common but hidden in CT and epithelium

Front 105

Encapsulated receptors -endings with fancy CT

Back 105

-Meissner's Touch corpuscle

-Pacinian corpuscle--vibration

-Muscle spindle--stretch receptor

Front 106

Ganglia in the PNS



pg. 85

Back 106

-cell body of neuron, satellite cell (glia), fibroblasts in CT wrapping, Schwann cells (glia) around axons

ALL GANGLIA CONTAIN:
-cell bodies of neurons
(and attached axons)

Glia cells
-satellite cells around cell bodies
Schwann cells around axons
CT and blood vessels

Front 107

Dorsal Root Ganglion






pg. 85

Back 107

-Spinal, Sensory (somatic), and some cranial ganglia (tridgeminal)

-pseudounipolar, no synapses

-Big, 4-10X

Front 108

Sympathetic ganglion





pg. 85

Back 108

-Paravertebral (chain), superior cervical ganglia, prevertebral (collateral)

-Multipolar synapses

-Big 4-10X

***Motor, Visceral

Front 109

Parasympathetic






pg. 85

Back 109

Paarasympathetic ganglion

-teeny tiny, at least 40X

-motor, visceral

Front 110

Axons and Schwann Cells

Back 110

-ALL axons in the PNS are surrounded by Schwann cells (glial cell)

-Schwann cells can repeatedly wrap around an axon and form a myelin sheath

Front 111

Schwann cells surround axons in one of 2 ways:


pg86

Back 111

1. Wrap around a single axon over and over forming a myelin sheath

2. Surround several axons

Front 112

Myelin



pg 86

Back 112

composed primarily of multiple layers of the Schwann cell membrane (lipid bilayer)

-Since each Schwann cell myelinates only a small segment of a single axon, it takes a long series of Schwann cells to cover the entire axon

-the myelin sheath electrically insulates the axon and increases the speed of nerve impulse conduction

Front 113

Node of Ranvier



pg. 86

Back 113

The myelin free region at the junction between adjacent Schwann cells

Front 114

EACH axon in the PNS is surrounded by



pg 86

Back 114

1. Schwann cells (+/-) myelin)
2. Basal lamina secreted by the Schwann cell
3. CT wrapping (endoneurium

-2 and 3 important in regeneration

Front 115

Peripheral Nerves




pg 87

Back 115

composed of bundles of axons (myelinated and unmyelinated, big and small, motor and sensory) with their supporting Schwann cells, all held together by several layers of CT (and blood vessels)

Front 116

Nerves have 3 layers of CT



pg. 87

Back 116

1. Endoneurium (around 1 axon)

2.Perineurium (around bundle, individual fascicle)

3. Epineurium (around gross nerve)

Front 117

Perineurium

Back 117

Made of specialized fibroblasts linked together forming part of blood-nerve barrier

Front 118

All peripheral nerves are mixed in function


pg. 88

Back 118

-Mixed = motor + sensory


-look at diagrams on this page

Front 119

Damage to peripheral nerves

Structurally


pg 88

Back 119

-axons are severed and separated from their cell bodies, the separated portion degenerates

-there is a possibility that the portion connected to the cell body can sprout, grow, and reconnect with the receptors and/or muscle fibers

-this regeneration or regrowth of the severed axons is guided by the Schwann cells and fibroblasts of the endoneurium

***ALL FUNCTIONS carried by the axons are lost, both sensory and motor. Function may return with successful regeneration

Front 120

ANS



pg 90

Back 120

-subdivision of the nervous system, based upon function (control of cardiac muscle, smooth muscle and glands)

-its two divisions include parts of the CNS and PNS

Front 121

PREganglionic cell bodies in CNS

Sympathetic


pg. 90

Back 121

thoracic and upper lumbar spinal cord segments

-T1-L2 Spinal cord

Front 122

POSTganglionic cell bodies in the PNS

Sympathetic

Back 122

1. Paraveterbral (chain) ganglia including superior, middle, inferior cervical ganglia

2. Prevertebral (collateral) includes celiac, superior, inferior mesenteric ganglia

Front 123

PREganglionic cell bodies in CNS

Parasympathetic

Back 123

Sacral spinal cord (S2-S4)
Brain stem

Front 124

POSTganglionic cell bodies in the PNS

Parasympathetic


pg. 90

Back 124

1. Small terminal ganglia in or near target

2. Otic, submandibular, pterygopalatine, ciliary ganglia, near brain stem

Front 125

CNS is divided into?



pg. 91

Back 125

1. Gray matter-->
contains CELL Bodies, axons, dendrites, glial cells and synapses

2. White matter-->
-containing AXONS and glial cells
-appears white in fresh dissection due to large amount of myelinated (lipid) fiber

Front 126

Glial Cells of the CNS

Back 126

-mechanically support and maintain the proper environment of the neurons

-they are greater in number than neurons and most are capable of proliferating

-in the adult, primary brain tumors are derived from glial cells

Front 127

Oligodendrocytes

Back 127

-myelinate axons

-can form a myelin sheath around segments of up to 50 axons

-major component of white matter

Front 128

Astrocytes

Back 128

-contain intermediate filaments (glial fibrillary acidic protein)
-modulate ionic environment of neurons
-cell processes surround capillaries
-involved in blood brain barrier
-proliferates when damaged, forming a glial scar (gliosis) that inhibits regeneration

Front 129

Ependymal cells

Back 129

-ciliated cells that line the ventricles (cavities) of the brain and the central canal of the spinal cord

-modified ependymal cells form the epitheilia lining of the choroid plexus

Choroid plexus secretes cerebrospinal fluid (CSF) into the ventricles

Front 130

Microglia - immune cell

Back 130

-active in antigen sensing

-active in phagocytosis

-derived from monocytes in the blood (mesoderm)

-prominent after injury

Front 131

Glial cell tumors

Back 131

-gliomas

-are the common primary brain tumors of the adult.

-include glioblastomas, astrocytomas, ependymomas, and oligodendrogliomas

Front 132

Cerebral Cortex

Back 132

-cerebrum

-thin outer gray layer of the cerebrum

-organized into 3-6 layers of cells

-the PYRAMIDAL cell is the largest cell in the crebral cortex

Front 133

Cerebellar Cortex

Back 133

Thin outer gray area of the cerebellum organized into 3 laysers

-Purkinje cell is the largest cell in the cerebellar cortex

Front 134

Development of the Nervous System



pg. 94

Back 134

-during the 3rd week, the surface ECTODERM thickens, folds, and invaginates downward to form the:

1. Neural Tube
2. Neural Crest

Front 135

Neural tube



pg. 94

Back 135

-hollow tube initially, opens at both ends

forms most of the CNS including:
-neurons of the CNS (brain, spinal cord)
-glia (astorcytes, oligodendrocytes, and ependyma)
-the neural retina
-posterior pituitary

Front 136

Neural Crest



pg. 94

Back 136

-collection of cells NOT incorporated into the tube, eventually migrate away

-cells migrate and give rise to most of the PNS including all ganglionic cells (DRG, sympathetic and parasympathetic postganglionic neurons)
-glial cells of the PNS (Schwann and satellite cells)
-the meninges

Front 137

Other neural crest derivatives include



pg. 94

Back 137

-adrenal medulla cells,
-melanocytes
-scattered endocrine cells
-diverse structures in the head and neck
(CT, bones, conotruncal septum of heart, odontoblasts)

Front 138

How to remember which cells is from neural tube?

Back 138

1. If the CELL BODY is in the CNS then it is derived from the NEURAL TUBE

-also CNS glia - oligodendrocytes, astrocytes, ependyma (not microglia)

EVERYTHING in the brain and cerebellum is from the neural tube

Front 139

How to remember which cell is from the NEURAL CREST?



pg 95

Back 139

IF the CELL BODY is in the PNS (ganglia) then it is derived from NEURAL CREST

-also PNS glia - Schwann and satellite cells

Front 140

More examples of CNS



pg 96

Back 140

-Spinal Cord (Gray and White matter)

-Cerebral Cortex (pyramidal cell)

-Lower motor neuron (LMN)

-Cerebellar Cortex (Purkinje cell)

Front 141

More Examples of PNS



pg 97

Back 141

-Dorsal root or Spinal ganglion
-Pacinian corpuscle
-Meissner's touch corpuscle
-sympathetic ganglion
-Muscle spindle
-Motor End-plate
-Peripheral nerve
1. axons
2. Schwann cells
3. Myelin
4. Node of Ranvier
5. Perineurium

Front 142

General Structure of the Vasculature



pg 98

Back 142

-a generic blood vessel is a tube lined on the inside with endothelium
-the wall of the vessel is composed of histologically discernible layers or tunics
-the composition and abundance of the vessels into arterial, miscrovascular, and venous types

Front 143

Layers or Tunics of the blood vessel walls from lumen outwards:

Back 143

Tunica Intima

Tunica Media

Tunica Adventitia

Front 144

Tunica Intima

Back 144

-Innermost layer consists of:

-simple squamous epithelium = endothelium
-markers-LM: Factor VII, fucose, E-selectins
-basement membrane*
-loose connective tissue* and sparse longitudinal smooth muscle*

*variable with vessel type

Front 145

Tunica Media

Back 145

Middle layer consists of:

-internal elastic lamina*
-elastic CT (sheets, fibers in loosely spiraling layers)*
-collagenous CT (bundles, fibers)*
and/or smooth (majority!!!) or cardia muscle cells*

*variable with vessel type

Front 146

Tunica Adventitia

Back 146

Outer Layer
-loose connective tissue* anchoring the vessel to its surroundings
-smooth m* walls of larger vessels are two thick for adequate sustenance solely by diffusion from the lumen. these vessels have their own blood supply, the vasa vasorum

*variable with vessel type

Front 147

Endocardium

Back 147

-the intima of the heart

-interior lining consists of endothelium, and CT reinforcing this inner layer

Front 148

Myocardium

Back 148

-media of the heart

-composed of cardiac muscle

-thickness and fiber orientation varies with the individual chamers

-atrial fibers are smaller and thinner than ventricular fibers

Front 149

Epicardium

Back 149

-Adventitia of the heart

Front 150

Pericardim

Back 150

-the fibrous sack that envelops the heart
-line with mesothelium

-permits almost frictionless movement of the heart during contraction and relaxation

Front 151

Purkinje Fibers

Back 151

-the heart's pacemaker and conductive system for its inherent rhythmic contraction

-Sino-atrial node (SAN)

-atrio-ventricular node (AVN)

Front 152

Bundle of His

Back 152

-consists of purkinje fibers

-divides and extens from the AVN to the ventricles

-through its fibers the paced AP is delivered to the ventricular muscle fibers

Front 153

Cardiac Valves

Back 153

-of the heart muscle are anchored into a CT skeleton

-this dense CT forms rings between atria and ventricles and extends into the heart valves as their core

-line by endocardium

Front 154

Arterial System



p. 100

Back 154

-distributes blood from the heart to the capillaries (high pressure)

1. Elastic Arteries
2. Muscular Arteries
3. Arterioles

Front 155

Elastic Arteries

Back 155

-aorta
-common carotid
-subclavian
-large pulmonary

Front 156

Structure of Elastic Arteries



pg. 100

Back 156

T. intima--> complete, well defined

T. media--> thick concentric layer of elastic, fenestrated sheets, interspersed with collagenous CT and smooth muscle

T. Adventitia--> a distinct layer of collagenous and elastic CT, vasa vasorum (own blood vessels)

Front 157

Function of Elastic arteries

Back 157

-have low resistance bc they have large lumina and their media expands in response to increased systolic pressure to further increase their lumen

-the store systolic energy is then released in the recoil of the elastic media facilitating and even blood flow downstream

Front 158

Muscular Artery Structure

Back 158

-all large arteries extending from elastic arteries to arterioles

T.intima--> thin with a prominent internal elastic lamina (membrane) separates it from media
-nuclei of endothelial cells bulge into the lumen when the muscular vessel contract

T.media--> thick concentric layer of Smooth m cells (>2), intermixed with elastic sheets and collagenous fibers. External elastic lamina is more diffuse, but discernible with elastin stain

T. adventitia
-variable with location and size of the artery, contains collagenous and elastic fibers, vasa vasorum

Front 159

Muscular Artery Function

Back 159

muscular arteries distribute blood to large areas of the body and having muscular T. media responsive to both neural and hormonal stimulation may be constricted or dilated to suit the capacitance or blood delivery to an organ or body part

Front 160

Structure of Arterioles



pg 101

Back 160

T.intima--> consists of endothelium, (nuclie of these cells often bulge into the lumen) the basement membrane CT fibers and an incomplete or absent internal elastic lamina

T. media--> consists of 1-2 concentrically arranged smooth muscles cells; no internal elastic lamina

T. Adventitia--> collagenous and elastic fibers form a network layer approximately equal to media thickness

-1-2 layers smooth muscle

Front 161

Function of Arterioles



pg 101

Back 161

-small arteries connecting muscular arteries to capillary networks

major resistance segment of the vascular system

-by very minute local changes, the arteriolar luminal diameter, they regulate blood flow through capillary networks

-general constriction or relaxation of the arteriorles respectively increases or decreases peripheral reistance and thus they play the effector role in regulation of maintenance of they systemic BP

Front 162

Capillaries



pg 101

Back 162

-thin walled vessels with small lumen
***1 layer of endothelial and little bit of CT
-these vessels comprise the micorcirculation, a dense, highly branched network between arterial and venous systems

Front 163

General Structure of Capillaries



pg 101

Back 163

Tubes linned by endothelium, a simple squamous epithelium characteristically containing numerous pinocytotic vesicles resting on basement membrane, surrounded by scant CT
***lack smooth muscle

Front 164

Pericyte



pg 101

Back 164

-a mesenchymal cell with high potential to differentiate
-contractile proteins and lysosomes were shown in their cytoplasm indicating their contractile and phagocytic character

-enveolped with basement membrane of the capillary

*lots or research about cancer with depriving cancer cells of blood b/c they need vasculature to live

Front 165

3 Major Groups of Capillaries



pg 102

Back 165

1. Continuous (non-fenestrated)

2. Fenestrated

3. Discontinous (sinusoids)

Front 166

Continuous (non-fenestrated) Capillaries

Back 166

-endothelial cells are .3-.8 um thick, joined to each other by tight junctions (zonula occludens)

-cytoplasm contain numerous pinocytotic vesicles, which may form transendothelial channels

-a continuous basement membrane is present and envelops pericytes adjacent to capillaries

-found in muscle, skin, testis, and ovary

Front 167

Continuous capillaries in the thymus, spleen, CNS, and lung

Back 167

-specialized
-thinner endothelial cells (.1-0.2 um)
-fewer pinocytotic vesicles
-participate in forming blood-specific tissue barriers (ie. blood-brain barrier)

Front 168

High Endothelial Vessels

Back 168

-variation of non-fenestrated endothelium found in lymph nodes

-lined with cuboidal cells

-specialized region allows specific lymphocyte migration from blood to lymphatic tissue

Front 169

Fenestrated Capillaries

Back 169

-Endothelial cells are locally attenuated (80 nm) and have in such areas numerous pores (bridged by a diaphragm of plasmalemma)
-basement membrane is continous pericytes are rare

-found in endocrine glands, intestines and kidney

Front 170

Discontinous Capillaries
(sinusoids)


pg 102

Back 170

-endothelial cells are perforated and discontinuous (.5 - 3.0 um)
-basment membrane is largely absent
-vessesl conform their shape to the surrounding tissue
-in liver, bone marrow, adrenal cortex, and adenohypophysis

-spleen a high discontinous endothelial lining venous sinuses

Front 171

Glomera

Back 171

-modified arterioles with numerous layers of richly innervated smooth muscle

-lacking internal elastic lamina involved with flow control in menstruation, erection, and thermo and BP regulation

Front 172

Metarterioles

Back 172

-arterioles branch into vessels with discontinous muscular coat, able to partially diminish flow, adding a regulator control to the vascular beds

Front 173

Precapillary sphincters

Back 173

-at the orgigin of capp channels in some tissues a single muscle cell sphincter has been proposed

-show to intermittently shut down the downstream capillaries

Front 174

Aterioventous Anastomoses



pg 103

Back 174

connecting arterial vascular channels to venules without passing through a capillary bed

Front 175

Arterial portal system

Back 175

-a vascular arrangement where arterial blood passes through two cap beds in series

-glomerular and renal parenchymal caps in liver

Front 176

Venous Portal System



pg 103

Back 176

-A vascular formation where venous blood which already went through a cap bed passes through another one and then enters a venule (venous portal system in the liver)

Front 177

Venous System

Back 177

collects and stores blood from the capillaries and returns it to the heart

-low pressure

-thin walled vessels, many have valves for back flow

-high lumen to wall thickness ratio

-in extremities skeletal muscle contraction aids the blood propulsion toward heart

Front 178

Venules

Back 178

-post capillary and collecting venules have large lumen than capillaries, their wall is the same as capillaries

-collecting venules have often pericytes surrounding the endothelial cells

-vessels comprise an important segment of the circulation, the sluggish flow here allow inflammatory cell attachment to endothelium and traffic across the fascular wall into the CT during inflammation

Front 179

Venules Structure



pg 104

Back 179

-endothelium
-basement membrane
-thin CT layer comprise the wall

-lack the smooth muscle but often have pericytes

Front 180

Small and Med sized veins



pg 104

Back 180

-often irregular lumen, collapsed from lack of structural support

-valves

-tin tunica media and thick tunica adventitia

-often run with arteries but can be distinguished as a result of wall thickness

Front 181

Small and Med sized veins Structure



pg 104

Back 181

-T. intima is indirect

-T. media is relatively thin and contains smooth muscle

-T. adventitia often the thickes layer, becomes very loose on the periphery and is often the site of fluid accumulation in edema

Front 182

Large Vein Structure



pg. 104

Back 182

-vena Cava, mesenteric vein

-T.intima is thin

-T.media contains smooth muscle interspered with CT

-T. adventitia contains longitudinally oriented smooth muscle bundles
-the longitudinal bundles of smooth muscel are most distinct in large abdominal vessels

Front 183

Teeth



pg 106

Back 183

-made up of 3 calcified, avascular tissues surrounding a soft CT filled space (pulp cavity)

-embedded in and attached to the alveolar processes of the maxilla and mandible

Front 184

Calcified tissues of teeth in order of hardness


pg 106

Back 184

Enamel

Dentin - living tissue

Cementum

Front 185

Teeth are divided into two parts



pg 106

Back 185

1. Crown
a. Anatomical crown - portion covered by enamel

b. Clinical crown - portion projecting above gum line (gingiva)
***DENTIN AND ENAMEL

2. Root portion covered by cementum, attached to bone by a thick CT (peridontal lig)
***DENTIN and CEMENTUM

Front 186

Gingiva

Back 186

-specialized oral mucosa

-stratified squamous CT

-attached to tooth by epithelial attachment, slightly keratinized

Front 187

Pulp Cavity

Back 187

-space within tooth

-occupied by dental pulp, a LCT with abundant blood vessels and nerves

Front 188

Odontoblasts

Back 188

-cells that secrete dentin

-forms a simple columnar epithelial layer on the inner wall of dentin

-odontoblastic processes are in the dentinal tubules

-continues to secrete dentin

***Neurocrest derivatives

Front 189

Periodontal Ligament

Back 189

-dense CT that anchors tooth in socket

-collagen fibers of the ligament extend from the cementum to the alveolar bone

Front 190

Enamel

Back 190

-acellular, mineralized tissue covering the dentin in the crown region

-98% hydroxyapatite, hard substance in the body

-arranged as enamel rods

-completely removed in decalcified sections

-produced by ameloblasts, which degenerate when the tooth erupts

Front 191

Dentin

Back 191

-minneralized tissue froming the bulk of the tooth, in the crown and root, surrounds pulp cavity

-odontolasts secrete dentin, throughout life

-contains odontoblastic processes in dentinal tubules

-odontoblasts line the inner portion of dentin

-sensitive to heat, cold, and mechanical stimuli

Front 192

Cementum

Back 192

-thin layer of mineralized tissue covering the dentin in the root

-collagen fibers of the periodontal lig are embedded in the cementum

-produced by cementocytes
**closest to bone in structure

-cemenotcytes, ike osteocytes are trapped in lacunae with canaliculi

Front 193

Cellular cementum

Back 193

-contains cementocytes in lacunae

Front 194

Alveolar bone

Back 194

-mostly spongy bone, softer not well formed bone

Front 195

Three major paired salivary glands

Back 195

1. Parotid
2. Submanidbular
3. Sublingual

-produce saliva, a mixture of serous and mucous secretions, water and electrolytes, and antibodies produced by plasma cells

Front 196

Ducts of the Salivary Gland



pg 109

Back 196

1. Intralobular Duct
A. Intercalated Duct
B.Striated Duct

2.Excretory duct

Front 197

Intrecalated Duct



pg 109

Back 197

-intralobular duct

-small, teeny tiny duct
-line with clear staining, simple squamous or cuboidal epithelial cells
-adds bicarbonate ions to secretion

Front 198

Striated (Secretory) Duct



pg 109

Back 198

-intralabular duct

-lined by simple columnar epithelium

-Acidophilic cytoplasm

-Nuclei towards lumen

-Basal striations due to parallel rows of mitochondria in folds of the cell membrane

-active in ion transport, reabsorb sodium addition of potassium to secretion

Front 199

Excretory Duct



pg 109

Back 199

-larger ducts surrounded by more and more CT

-line with simple columnar to stratified squamous epithelium

-main excretory duct empties into oral cavity

Front 200

Parotid gland



pg 110

Back 200

-pure serous gland

-many intercalated and striated ducts

-excretory ducts

Front 201

Submandibular Gland



pg 110

Back 201

-Salivary gland

-mixed gland mostly serous

-many intercalated and striated ducts

-excretory ducts

Front 202

Sublingual gland



pg 110

Back 202

-Salivary gland

-mixed gland, mostly mucous

-NO intercalated and a very few striated ducts
(serous demilunes)

-excretory

Front 203

Pancreas (exocrine)



pg 110

Back 203

-pure serous gland

-many intercalated ducts and NO striated ducts

-excretory

Front 204

Memory Tactic for Glands

SS

EE

Back 204

SS:
Striated ducts are only in Salivary glands

EE
Everyone has excretory ducts

Front 205

Pancreas



pg 111

Back 205

two glands in one:
An exocrine gland (serous gland)
An endocrine gland (islets of Langerhans)

-fenestrated capillaries
-intercalated ducts
-centroacinar cell
-serous acini
-secretory vesicles (zymogen granules)

Front 206

Exocrine Pancreas

Serous Cells (acinar or zymogen cells)

Back 206

-Compound tubulo-alveolar PURE SEROUS gland

-Euchromatic nucleus
-Basophilic cytoplasm (RER) w/ secretory (zymogen) granules
-Secrete digestive enzymes including trypsinogen, chymotrypsinogen, amylase, lipase, deoxyribonuclease, etc
-enzymes are secreted from the serous cells in an inactive porenzyme form
-become active in duodenum

Front 207

Exocrine Pancrease

Ducts

Back 207

1. Intercalated Ducts
-usually line by clear, simple cuboidal cells
-secrete bicarbonate and water to make the secretion alkaline
CENTROACINAR CELLS are the first duct cells, seen in the middle of the secretory acinus
b. Excretory ducts
-usually similar colummar

Front 208

Pancreatic cacinoma (adenocarcinoma)

Back 208

-4th leading cause of cause of cancer death

Front 209

Islets of Langerhans

Back 209

-clusters of endocrine cells scattered among the serous cells and ducts
-separated from serous cells by a delicate CT
-lighter staining than serous cells
-secrete hormones that regulate glucose, lipid, and protein metabolism

FENESTRATED capillaries carry away the hormones

Front 210

Secrete hormones that regulate glucose, lipid, and protein metabolism

Back 210

Beta cell (70%) - secrete insulin, lowers blood glucose, Diabetes (Type I) - loss of Beta cells

Alpha cell (20%) secretes glucagon, raises blood glucose

Delta cell - secrete somatostatin

PP cell - secretes pancreatic polypeptide

Front 211

How to differentiate between the two PURE serous glands, the Pancreas and Parotid gland?


pg 112

Back 211

Parotid - has lots of visible ducts, many striated ducts, and lots of CT

Pancreas- has few visible ducts, NO striated ducts, very little CT and if visible, Islets of Langerhans
-the pancreas has many intercalated ducts but they are too small to use for ID

Front 212

Exocrine functions of the Liver

Back 212

-secretion of BILE into ducts which eventually empty into the duodenum

-bile contains salts that emulsify fats in the small intestine

-bile contains bilrubin an unwanted byproduct of hemoglobin breakdown, eliminated in feces

Front 213

Liver modification and filtration of BLOOD


pg 113

Back 213

a. metabolism and storage of food products in the blood absorbed from the intestines

b. secretion of plasma proteins, including albumen, blood clotting factors (fibrinogen and prothrombin)

c. removal of toxic substances from the blood (alcohol and lipid soluble drugs, barbiturates)

d. removal of breakdown products (RBCs) and other debris from the spleen

Front 214

Dual blood supply to liver



pg 113

Back 214

Hepatic artery - brings fresh oxygenated blood (25%)

Hepatic portal vein - brings blood from capillaries (75%)

Intestines (food laden)
Pancreas (hormones)
Spleen (RBC breakdown products)

Venous portal system
Cap --> vein --> cap

Front 215

Structural organization:
The liver lobule



pg 113

Back 215

-blood flows from portal triad to central vein

-hepatocytes arranged as plates

-sinusoidal capillaries

PORTAL TRIAD-->
hepatic artery
hepatic portal vein
bile duct

Front 216

Hepatocytes



pg 114

Back 216

-secrete bile into canaliculi, tiny channels formed by tight junctions between hepatocytes

-bile flows along the canaliculi to the edge of the lobule where they empty into true epithelial lined ducts, the biled ducts

-lined by simple cuboidal or in larger ducts, simple columnar

Front 217

BILE FLOW



pg 114

Back 217

-Hepatocytes -->
Bile Canaliculi-->
Bile ductules-->
Bile ducts-->
Hepatic duct

***bile is kept separated and flows in a direction opposite the blood flow

Front 218

BLOOD FLOW



pg 114

Back 218

Hepatic artery and hepatic portal vein--> sinusoids --> central vein ---> vena cava

Front 219

Branches of the hepatic portal vein and artery in the CT at the edge of the lobule, empty their blood into:

Back 219

-the liver sinusoids which are lined by endothelial and Kupffer cells (macrophages)

-Hepatocytes bordering the sinusoids modify the blood as it flows along the sinusoids

-blood leaves the lobule when it reaches the central vein

-central veins in all the lobules eventually form the hepatic vein which empties into the inferior vena cava, returing blood to the heart

Front 220

Hepatocytes

Back 220

-acidophilic cuboidal epithelial cells with euchromatic nuclei

-cytoplasm contains abundant mitochondria, Golgi, RER, free ribosomes, SER, vesicles

-modifies and secretes substance in the blood

-bile is secreted into small pockets formed by tight junctions (zonula occludens) between adjacent hepatocytes

-can divide if stimulated and regenerate the liver

Front 221

Inusoids

Back 221

-the sinusoidal capillaries of the liver are discontinous with fenestrations in the endothelial cells and large gaps between cells

-basal lamina is incomplete or absent

-unlike sinusoids in other organs, the hepatic sinusoids are lined not only by endothelial cells but also by the phagocytic, Kupffer cell

Front 222

Kupffer cells

Back 222

-macrophages in the liver

-phagocytic, engulfing old RBCs, debris, and bacteria as it flows through the sinusoid

Front 223

Perisinusoidal space (space of disse)

Back 223

-space between the hepatocytes and the sinusoids

-blood fluids readily pass through the endothelial fenestrations and gaps into this space

-contains only small amounts of CT (usually reticular fibers)

Front 224

Ito cells (fat storing cell of Ito)

Back 224

-are a small population of cells hidden in the perisinusoidal space

-they store (Vitamin A) in lipid droplets

-with inflammation, the Ito cell produces excess Type I and Type III reticular collagen, causing liver scarring or cirrhosis

Front 225

Different Types of Liver Lobules

Back 225

1. Classic liver lobule

2. Liver Acinus --relates zones to blood supply
-Zone 1 -best supplied
-Zone 3 - poorest

3. Portal lobule - emphasizes Bile secretion

Bile duct is in the center

Front 226

Cirrhosis

Back 226

-CT deposition (fibrosis) and scarring of the liver

-the liver becomes subdivided into nodules of regnerating hepatocytes surrounded by scar tissue

-the Ito cell is the major source of excess collagen

-cirrhosis is commonly caused by alcohol abuse or chronic hepatits

Front 227

Gall bladder

Back 227

-Tubular organ that receives, stores and concentrates bile, and discharge it into the duodenum

- line by simple columnar epithelium with tight junctions and microvilli

-smooth muscle in the wall helps dispel bile

-gallbladder will be revisited in the GI section