Exam 1 Objectives Flashcards
Basic functions of all cells
- Exchange of substances across cell membranes (active/passive transport, facilitated diffusion, endo/exocytosis)
- Energy transfer (fuel substrate -> ATP, CO2, H20)
- Synthesis of proteins/macromolecules (replaces worn out cell components, adaptive, growth/repair)
- store genetic material
- responds to chemical messengers
- Replication/Repair
continuous replication
Replication of epithelial cells occurs in a steady state in areas subjected to mechanical or chemical stresses. Epithelial cells can rapidly divide when injured (e.g., hepatogenesis with liver damage). Smooth muscle cells can undergo mitosis (e.g., in pregnant woman’s uterus).
Structures with continuous replication: skin, GI, epithelial cells, smooth muscle cells
Fixes post-mitotic state
cells can’t reproduce themselves; cardiac/skeletal muscle cells, neurons (most neurons are in fixed post-mitotic state, but injured peripheral neurons can regenerate injured axons provided that there is an ideal environment for repair)
tissue
formed from aggregated cells
organ
tissues come together in specific patterns
organ system
maintains homeostasis/internal environment of the body
cells -> tissues -> organs -> organ systems
cell function interdependence
cell types arrange themselves into structural and functional units (tissue), thus the formation of muscle, nervous, epithelial, and CT. Thus, their functions are mutually dependent since each type of tissue is composed of an aggregate of cells and a surrounding ECM
Collective function of the organ systems
maintain homeostasis, the “internal environment of the body.” Dynamic constancy of the internal environment is maintained by combined action of reflexes and local mechanisms
Biological rhythms
add an anticipatory component to the homeostatic system; allows/enables homeostatic mechanisms to be used immediately (allows for a quick response) when there’s a perturbation
example: circadian cycle -> sleep cycle based on light and dark
cell types
epithelial, CT, neurons, muscle
Epithelial cells
continuous layer of cells that lines the surfaces of organs; replication at a steady state in areas subjected to mechanical or chemical stresses; functions - selectively permeable, protection (from dehydration, chemical, and mechanical damage), secretion of substances (i.e., mucus, water, hormones, enzymes, etc.)
Muscle cells
generate mechanical force, specialized for contraction and movement, contain large amounts of actin a myosin
skeletal muscle
function is to move the skeleton, growth via hypertrophy but NO hyperplasia, fixed post-mitotic, innervated by somatic NS, voluntary control
cardiac muscle
function is to propel blood in the vasculature, growth by hypertrophy, fixed post-mitotic, innervated by ANS, involuntary control
smooth muscle
located in hollow tubes and organs, function is to propel contents, cell growth via hyperplasia and hypertrophy, can undergo mitosis, innervated by ANS, involuntary control
neurons
specialized for initiation and conduction of AP, most are fixed post-mitotic, can be modified in CNS (plasticity), peripheral neurons have potential to regenerate in ideal environment
connective tissue
medium for exchange of nutrients, blood gases, and waste products between the cells and the vasculature; defense against foreign microorganisms and toxins, through the production and activation of immune system and the formation of a physical barrier to prevent the spread of infection; trophic and morphogenetic roles in tissue development/repair; structural support- forms a continuum between itself and the other tissues of the body, it is critical for the development and maintenance of the body
Glands
complex structures composed of epithelial cells
exocrine glands
secrete onto external surfaces through ducts, such as GI enzymes and salivary glands
endocrine glands
ductless glands that secrete messengers into the blood; pancreatic secretion of insulin, hormones
paracrine glands
secrete substances into the extracellular fluid compartment (EFC)
CT cell classification
- special skeletal type
- general type
a. resident
b. transient
Special skeletal type
CT cells, consists of cartilage and bone, stuck in matrix they secrete; includes chondrocytes, osteocytes, osteoblasts, osteoclasts
General type
CT cells
- Resident: stay in fixe location of body (includes fibroblasts, adipocytes, macrophages, pericytes, mast cells)
- Transient: originate in bone marrow, circulate in blood, then enter CT when needed, must be replenished often since short lived (includes B/T lymphocytes, neutrophils, macrophage, etc.)
Intracellular fluid compartment
fluid in all cells of body
extracellular fluid compartment
fluid in blood (plasma) + spaces around cells (interstitial fluid)
Extracellular Matrix (ECM) Structure
non-living macromolecules in extracellular space; made of soluble fibers (long carbohydrate chains linked to proteins which bind to water) and insoluble protein fibrils (collagen and elastin); basement membrane = basal lamina + reticular lamina
Basement membrane of ECM function
mechanical anchor, has metabolic role, influences rate of cell division, helps in growth/repair, forms selectively permeable barrier
Basal lamina
inner layer of basement membrane of ECM; transmembrane and extracellular glycoproteins + collagen
reticular lamina
outer layer of basement membrane of ECM; made of collagen
Function of ECM
distribute stresses of movement/gravity and maintains structural integrity; allows two muscle fibers to shorten, even if one is not activated, preventing shear
Components common to all reflex arcs
1) Sensory receptor
2) Afferent pathway
3) integrating center: compares change to ‘set point’
4) efferent pathway
5) visceral target site
ANS Major integrating center
hypothalamus
Areas of CNS that can function as integrating center for ANS responses
Reflex integrating centers: brain, brainstem, spinal cord
somatic motor system
single axon arises from ventral horn of grey matter in spinal cord; alpha motor neurons are large in diameter and myelinated; innvervation target = muscle fiber; NT = ACh (cholinergic transmission) and nicotinic receptor (nacho) is found at the NMJ; nAChr is ligand gated and allows for flux of cations (EPP = excitatory)
preganglionic neuron of ANS (visceral motor system)
soma from lateral horn of spinal cord, sends axon (myelinated, cholinergic) to synapse onto ganglion cell; ACh binds to nicotinic receptor (ligand-gated) on ganglion cell resulting in an EPSP
postganglionic neuron of ANS (visceral motor system)
comprised of ganglion cell and unmyelinated axon that innervates peripheral visceral sites; close to the zone of transmission (where NT released), terminal end branches and contains varicosities (swellings) that store and release NT; cholinergic/nonadrenergic (NE), but may also release other chemicals such as ATP, serotonin, NO; M receptors for ACh; adrenergic receptors that bind NE are either alpha or beta
innervation targets of ANS (visceral motor system)
cardiac, smooth, glands, adipose, lymph
parasympathetic NS
- origin: craniosacral; cranial nerves III, VII, X(Vagus nerve), S2, S3, S4 (pelvic splanchnic nerves)
- NT: ACh
- Receptors: N on Ganglion, M on visceral sites
- Parasympathetic ganglia lie within, or very close to, the organs that the postganglionic neurons innvervate
