Download 1 I. Cell Structure B. DNA II. Types of Cells

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
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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
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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
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