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ECM
contains fluid transporting nutrients to cells, carrying away their wastes and secretory products
Epithelial tissue function
lining of body cavities, glandular secretion
CT function
structural support, nutrition, storage (fat, water, electrolytes), defense, repair, information
Most abundant CT cells?
Fibroblasts
Fibroblast function
synthesize and secrete fibers and ground substance, create and export factors to influence adjacent cell growth and proliferation
Adipocyte function
store fat, produce hormones and cytokines responsible for metabolism and immune health
What are macrophages derived from?
Monocytes
Macrophage function
phagocytize foreign particles, microorganisms, and damaged tissues, initiate immune response, initiate turnover of ECM
How do macrophages initiate immune response?
Present antigens to lymphocytes, secrete cytokines
What are cytokines?
Cell-signaling proteins
How do macrophages initiate ECM turnover?
Secrete hydrolytic enzymes (collagenase)
What are the four main cells in CT?
fibroblasts, adipocytes, macrophages, mast cells
What are mast cells
WBC commonly in CT
Mast cell functions
Chemical mediators of inflammatory response, allergic reactions
Chemical mediators of mast cells
histamine, heparin, eosinophil chemotactic factor, etc.
Collagen type I
thick collagen found in CT (tendons, skin, organs)
Collagen type III
reticular fibers, flexible meshwork (smooth muscle, endocrine glands, liver)
What do elastin fibers contain?
elastin and fibrilin
Elastin fiber locations
skin, trachea
Transient cells of CT
plasma, leukocytes (eosinophils, lymphocytes, neutrophils)
What is the most widespread CT?
Loose CT
Loose CT properties
ground substance/cells > fibers, contain collagen, reticular, and elastic fibers, loose irregular meshwork, flexible, vascularized, slight resistance to stress
Loose CT locations
Stomach/intestinal epithelia
Loose CT functions
cushions organs, storehouse of immune cells for many organs, can reduce inflammation
Dense Irregular CT properties
collagen fibers in 3D network, consist of mostly fibroblasts, resist pressure in many directions
Dense Irregular CT locations
dermis, gut, surrounding organs
Dense Irregular CT functions
give structural strength/flexibility to organs
Dense Regular CT properties
collagen fibers lay parallel to each other, primarily fibroblasts, resistant to pressure along one plane
Dense Regular CT locations
tendons, ligaments
What are the two types of adipose tissue?
unilocular (white), multilocular (brown)
White fat function
fat storage
Brown fat function
generates heat in newborns/fetuses
Elastin properties
dense, irregular elastic tissue
Elastin locations
Middle layer of large arteries, some ligaments
Reticular locations
hematopoietic bone marrow, lymph nodes, spleen
What is the major determinant of the properties of cartilage?
ECM composition
How is cartilage different from every other form of CT?
It is avascular and only has one type of cell (chondrocytes)
What is the most common form of cartilage?
Hyaline cartilage
Hyaline cartilage locations
Large airway walls, ends of bones in synovial joints, epiphyseal plates in youth
Hyaline cartilage function
Provide smooth gliding surfaces for bones, support body structures
Elastic cartilage function
facilitates speech, provides flexible support to larynx
Fibrocartilage locations
vertebrae, pubic symphysis, some tendon/ligament attachments
Fibrocartilage function
shock absorption, prevent bone to bone contact
Bone function
Provide structure of body, protect internal organs, act as lever for muscles to act on, house and protect CNS, form RBCs, reservoir of Ca2+
What are the four types of bone cells?
Osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
Osteoprogenitor cell function
stem cells to become osteoblasts
Osteoblast function
development of bone matrix (osteoid) and initial mineralization, which form osteocytes
How long can osteocyte cells live?
20-30 years
Osteoclast function
Removal and turnover of bone matrix by secreting bone degrading enzymes and hydrogen ions
Periosteum properties
Cover outer surface of bones, contain BVs and nerves, fibroblasts generate collagen fibers to link layers together, contain osteoprogenitor cells
Endosteum properties
Covers inner surface of bones, contains osteoprogenitors, inactive osteoblasts
Primary bone
Initial bone produced by osteoblasts
Secondary bone
Replaces primary bone, creating uniform layers of fibers and cells to create stronger bone
Bone collar
Initial bone created by intramembranous ossification
Primary ossification center creation
BVs penetrate bone collar, osteoprogenitors produce osteoblasts, deposits primary bone onto matrix, POC in center of bone
Secondary ossification center creation
BVs invade epiphysis after birth, SOC left by ends of long bone
Bone growth after birth
Epiphyseal growth plate provides matrix for primary and secondary ossification centers until it disappears
Steps to bone remodeling
Osteoblasts induce monocyte fusion to make osteoclasts
Osteoblasts regulate osteoclasts
Osteoclasts create tunnel in bone, osteoblasts produce matrix
BVs travel into tunnel to provide nutrition
How much of the body’s total calcium is stored in bones?
more than 90%
Two hormones responsible for Ca2+ regulation
parathyroid and calcitonin
Cycle of bone fracture
Ruptured BVs, loss of osteocytes and bone matrix
Blood clot forms
Periosteum and endosteum proliferate, osteoblasts secrete matrix
CT and hyaline cartilage callus forms, replaced with primary bone via endochondral ossification
Bone remodeling occurs to produce secondary bone
Individual muscle cells
Myofibers (myocytes)
3 layers of protective CT in muscles
epimysium, perimysium, endomysium
Epimysium properties
Dense CT, continuous with portions of perimysium, tendons, cover entire muscle
Perimysium properties
Dense CT (thinner than epimysium), surrounds fascicles, organizes myofibers
Endomysium properties
Thin CT layer, surround each myofiber
Myofibril
cylindrical array of actin and myosin filaments, run the length of myofiber
Sarcomere
contractile unit of myofiber, split myofiber and myofibrils into sections, provide striated appearance
When do humans reach their maximum number of myofibers?
Shortly after birth
How do muscles grow?
Muscles gain length naturally until body growth stops, supported by satellite cells, additional growth as a result of exercise also a result of satellite cells, creating additional myofibrils and larger myofibers
How do muscles repair?
Satellite cells provide limited healing by dividing and fusing with myofibers
What blocks myosin binding sites on actin?
Troponin
How do muscles contract?
ATP-driven myosin heads bind to actin, pulling it towards the middle of the myosin filament
How does the motor unit (neuromuscular junction) initiate muscle contraction?
Action potential arrive at NMJ, ACh released from neuron, diffuses into sarcolemma, opens ion channels and causes depolarization, Ca gets released and allows for contraction
Two types of nervous system cells?
Neurons and glial cells
Anatomic components of NS
central (CNS) and peripheral (PNS)
Two main organs of the CNS
Brain and spinal cord
PNS function
provide sensory information from outside world, deliver commands to effectors such as muscles and glands
CNS function
integrates sensory input, produced coordinated outputs
Two functional components of NS
Somatic (voluntary) and autonomic (involuntary)
Two branches of ANS
parasympathetic and sympathetic
Dendrites
Receive and integrate incoming signals
Neurofilaments
Extend from cell body, provide support throughout neuron
Axon
Connect cell body to terminal synapses, deliver signals from cell body to synapses
Synapse
Connection of axon terminal and dendrites of next neuron
How do neurons carry signals from one another?
Transmission accomplished by changes of resting membrane potential, decrease causes depolarization, release of neurotransmitters
Bilateral
both sides
Unilateral
one side
Ipsilateral
same side (action)
Contralateral
opposite side
Three classifications of joints
Fibrous, cartilaginous, synovial
Three types of fibrous joints
suture, syndesmosis, gomphosis
What are syndesmosis joints?
interosseous membranes betwen bones
Where are syndesmosis joints present?
radius and ulna, tibia and fibula
What are the types of cartilaginous joints
primary (synchondrosis), secondary (symphysis)
What type of cartilage is used in primary cartilaginous joints?
hyaline cartilage (slight bending)
What type of cartilage is used in secondary cartilaginous joints?
fibrocartilage
Where can primary cartilaginous joints be found?
epiphyseal plates, first sternocostal joint
Where can secondary cartilaginous joints be found?
intervertebral discs, pubic symphysis
Most common joint type in the body?
synovial