n It is unlawful for an employer to fail or refuse to hire, to discharge, or otherwise discriminate because of age against individuals 40 years of age or older with respect to compensation, terms, conditions, or privileges of employment. n It is unlawful to forcibly retire an employee because of age 40+. n It is unlawful to give preference because of age to one person over another within the protected age Exceptions to the ADEA n Bona fide occupational qualifications (BFOQ) n Unequal impact on the protected age n Seniority systems Age as a BFOQ is permitted but extremely rare. Unequal Impact Job requirements with an unequal impact on the protected age are permitted if truly necessary. Pregnancy Discrimination Act of 1978 (PDA) n Women affected by pregnancy must be treated the same as other applicants and employees on the basis of their ability or inability to work. n Employers no longer require women to take leaves of absence or resign because of pregnancy. n Health insurance provided must cover expenses for pregnancy-related conditions on the same basis as expenses for other conditions. n Specific guidelines for pregnancy leave. PDA Guidelines for Pregnancy Leave Employers may NOT: n Use any employment practice (hiring, work duties, work schedule, promotion, firing, etc.) that discriminate against applicants or employees because of pregnancy, childbirth, abortion or a planned adoption. n Treat disabilities related to pregnancy or childbirth differently from other types of disabilities or medical conditions. Work parameters can be changed during pregnancy If pregnancy renders the employee unable to do the job or If pregnancy endangers the health and safety of others. An employee cannot be considered unable to do her job unless the particular skill affected must relate to the central mission of the job. The employer must treat her the same as temporarily disabled employees. If pregnancy endangers the health and safety of others the employee can be reassigned or put on mandatory leave. Does not apply to safety of employee or fetus - - only third parties. Family Medical Leave Act of 1993 (FMLA) n Requires employers of 50 or more workers to provide up to 12 weeks a year of unpaid, job-protected leave to take care of a newborn or newly adopted child.
o Function: Site of attachment of core sugar groups to proteins, site of cholesterol synthesis, and transport of membrane, secretory, and lysosomal proteins to Golgi Smooth ER-Membrane system of sacks without ribosomes o Function: Site of lipid metabolism, steroid synthesis, and drug detox Golgi apparatus-Membrane system of vesicles and stacked, flattened membrane sacs o Function: post translation modifications; segregation and packaging of proteins for secretion or incorporation into the PM or lysosomes Peroxisomes-Contain oxidase enzymes (catalase-breaks down peroxide) that function to detoxify substances Lysosomes-Contains acid hydrolases that mediate intracellular digest of molecules Centrioles-Paired, elongated star-shaped bodies comprised of triplets of microtubules that are part of the centrosome o Function: help organize microtubule network to form spindle during mitosis; form the base structures of cilia and flagella Ribosomes – particles containing protein and rRNA; site of protein synthesis 322 Cell Physiology Histology: Cell Physiology Christina Pereira Generation of a Resting Membrane Potential Membrane potential- a voltage across a membrane Resting Membrane Potential – voltage across the plasma membrane of a cell at rest (not stimulated or damaged) o Results from Na+ and K+ concentration gradients across the membrane and their different permeabilities o Resting membrane potential is maintained by active transport of ions o Ranges from -20 to -200 mV Purpose of membrane potential: to provide an electrochemical potential for: o Changes in membrane potential during excitation of neurons and muscle cells o For co-transport of substances into cells Membrane Receptors – diverse group of integral proteins and glycoproteins that serve as binding sites for ligands or other cells and function in cell signaling Cell Adhesion Molecules (CAMs) – plasma membrane receptors, usually glycoproteins, that: o Anchor cells to the extracellular matrix (ECM) and to each other § Are a component of desmosomes
Interphase o G1 – vigorous growth o S – growth and DNA synthesis o G2 – more growth and preparation for cell division o G0 – cells that permanently cease dividing; normal metabolic activity Mitotic Phase (Cell Division) o Mitosis – nuclear division o Cytokinesis – division of the cytoplasm Control of Cell Division · Surface to volume ratio of cells · Chemical signals such as growth factors and hormones · Contact inhibition · Cyclins and cyclin-dependent kinases (Cdks) complexes Developmental Aspects of Cells All cells of the body contain the same DNA but develop into all the specialized cells of the body Cell specialization (also called cell differentiation) is determined by the kind of proteins that are made in that cell due to different genes being turned off or on. in various parts of the embryo are exposed to different chemical signals that channel them into specific differentiation pathways Cell aging o Wear and tear theory attributes aging to chemical insults and formation of free radicals that have cumulative effects throughout life o Genetic theory attributes aging to cessation of mitosis that is programmed into our genes 322 Cell Physiology Histology: Histology Z Liu Histology: The science concerned with the minute structure and organization of cells and tissues in relation to their function
Osteoclasts-bone destroying (reabsorption-reabsorbs minerals into the blood) maintain bone matrix made by osteoblasts In osteoporosis, bone degradation (reabsorption) outpaces bone deposition. Bone is degraded and Ca +2 released in response to a need for calcium in the body; this is controlled by parathyroid hormone (PTH) Fig 6.12 PTH stimulates osteoclasts PTH also stimulates kidney to convert Vit D to active form (calcitrol) which increases Ca+2 absorption from the intestine. Calcium salt deposit in bone is stimulated by calcitonin-produced in the thyroid when calcium levels are high Muscular System A. Functions of the Muscular system a. Movement b. Heat generation c. Maintenance of posture d. Stabilization of joints B. Muscle Tissue/Muscles a. Common properties of the 3 different muscle types: i. Comprised of cells called ‘muscle fibers’ ii. Contain myofilaments (thick, thin, elastic) iii. Function in movement C. Skeletal Muscles: Fig 9.2 a. Voluntary muscle, striated, made of muscle cells, CT wrapping, blood vessels, and nerves. a. Muscles are wrapped in a CT covering called the epimysim. b. Bundles of skeletal muscle cells (called fasicles ) are wrapped in a CT covering called the perimysium. a. Individual skeletal muscle cells (muscle fibers) are wrapped in the CT covering called the endomysium (surrounds plasma membrane of the cell). Microscopic anatomy of skeletal muscle Fig 9.3, 9.5 1. Skeletal muscle cells (muscle fibers)-long cylindrical cells with multiple nuclei formed by fusion of embryonic cells; contain myofibrils. 2. Sarcolemma-specialized plasma membrane of skeletal muscle invaginates into t-tubules at the A-band I-band junction 3. Sarcoplasm-cytosol of a muscle cell. 4. myofibrils- (an organelle) rod-like structures comprised of proteins (actin, myosin, nebulin, titin, tropomysin, troponin) contained within skeletal muscles cells that re the contractile elements. Composed of myofilaments (3 types) a. filament-comprised of myosin, with ‘head’ and ‘tail’ regions.
o Motor Division-efferent  Somatic-aka Voluntary Nervous System-motor neuron impulses from CNS to skeletal muscle  Visceral-aka Autonomic Nervous System (ANS)-visceral motor neuron impulses that regulate smooth, cardiac muscle, and glandular tissue  Sympathetic-Fight or flight  Parasympathetic-Rest and digest Cellular Components  Neuroglia-Non-neural cells of the CNS and PNS that control the chemical environment of the CNS and PNS and insulate, protect, and promote the growth of neurons o CNS  Astrocytes- starshaped; most abundant cell type in the CNS; function to control chemical environment ; part of the blood-brain barrier (BBB)  Ependymal-line central cavities of the brain and spinal cord-epithelial cells  Oligodendrocytes-myelinate long axons  Microglia-protective role-macrophages of the NS o PNS cells  Schwann cells-myelinate axons-also function in peripheral nerve regeneration  Satellite cells-surround neuron cell bodies in ganglia-control chemical environment  Neurons-highly specialized cells of the PNS and CNS that conduct info in the form of electrical impulses (depolarization of the PM) o Types  Function  Sensory-conducts impulses from receptors in peripheral body parts into the brain or spinal cord  Interneuron-transmits impulses between neurons within the brain and spinal cord  Motor-conducts nerve impulses from the brain or spinal cord out to effectors  Structure-multipolar, bipolar, unipolar o Characteristics  Long-lived; amitotic (non-dividing), highly differentiated; high metabolic continuous and abundant supply of glucose o Structure  Cell body (soma) and plasma membrane  Neuronal processes-cytoplasmic extensions of neurons (covered by PM)  Dendrites-Afferent-tapered, branching processes that serve as the main receptive, or input regions of a neuron; transmit signals toward the cell body; usually many per neuron  Axon-Efferent-output process of a neuron; carries signals away from the cell body; usually 1 per neuron; aka “nerve fiber” o Axon hillock-transition region o Axon collaterals-branches along the axon o Terminal branches-branches at the end of the axon o Boutons-axon terminals-make synapses