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I. Cell Structure A. membrane B. DNA C. cytoplasm II. Types of Cells A. Cells of the nervous system 1. neurons a) functions: produce and conduct (send) impulses (electrical messages) regulate glands sensing / perception thinking b) parts of a neuron cell body – contains nucleus (DNA inside) dendrites – receive impulses axon - produce and transmit impulses - only one per neuron - composed of axon terminals synaptic end bulbs synaptic vesicles c) types of neurons – by function sensory (afferent) neurons conduct impulses from receptors to CNS (brain and spinal cord) motor (efferent) neurons convey impulses from CNS (brain and spinal cord) to effectors association neurons convey impulses between motor and sensory neurons 2. neuroglia support and protect cannot conduct impulses Some types of neuoglia a) oligodendrocytes – produce myelin sheath in CNS b) Schwaan cells – produce myelin sheath in PNS c) astrocytes- part of blood-brain barrier d) ependymal cells – secrete cerebral spinal fluid e) microglia – type of immune cell for CNS 1 B. Cells of the reproductive system 1. function – sexual reproduction 2. types a) sperm (males only) produced in testes product of meiosis in males haploid cell b) ova (females only) produced in ovaries via meiosis product of meiosis in females haploid cell 3. meiosis – type of cell division reduces chromosome number in half produces sperm (in males) or ova (in females) creates unique gene combinations produces 4 unique haploid cells 4. other types of cell division a) mitosis cell replication – produces 2 identical daughter cells b) binary fission cell division for cells without a nucleus C. Cells of the endocrine system 1. function secrete hormones hormones: chemicals secreted outside of a cell regulate (control) cell activity (metabolism) of other cells bind to specific receptors on target cells i. internal receptors for hormones that can pass through cell membrane receptors may be in cytoplasm or in nucleus when hormone binds to receptor, usually activate genes – leads to production of proteins examples: estrogen, testosterone, glucocorticoids, mineralcorticoids ii. surface receptors for hormones that cannot pass through cell membrane 2 receptors on cell exterior when hormone binds to surface receptor, 2nd messenger is activated 2° messenger changes cell activity (metabolism) examples: insulin, glucagon, epinephrine and norepinephrine 2. types of endocrine cells a) within endocrine organs b) in non-endocrine organs hormone-producing cells in i. placenta ii. heart iii. small intestine and stomach ex: ghrelin iv. adipose tissue ex: leptin 3