Ch. 13: Animal Form and Function Flashcards
How are cells organized?
tissues: group of similar cells performing common function, ex. muscle and nervous tissue
organs: groups of different kinds of tissues working together; ex. heart
organ system: two or more organs working together; ex. digestion includes mouth, stomach, intestines, pancreas, liver
Feedback mechanism
assesses product of an activity to determine if the need for that activity has been satisfied
Ex. negative feedback, positive feedback
Negative feedback
change in condition is detected and metabolic process is initiated to return to original state, whereupon the process is terminated
helps maintain homeostasis, keeps conditions around baseline
Ex. humans sweat when it’s hot to cool the body, which returns it to its set point temp. and sweating stops, when humans are cold they shiver to return to set point temp. and shivering stops
Homeostasis
maintenance of stable, internal conditions within narrow limits
Positive feedback
change in condition initiates process that intensifies condition so that it’s driven further beyond normal limits
Ex. during childbirth, oxytocin is released which stimulates more contractions which releases more oxytocin
As size of animal increases…
amt. of energy required per unit weight decease
Structure of neuron
- cell body
- dendrite: receives stimuli
- axon: sends nerve impulses
Sensory neurons (afferent neurons)
receive initial stimulus
Ex. sensory neurons in eyes stimulated by touch
Motor neurons (efferent neurons) (effectors)
stimulate effectors, target cells that produce some kind of response
Ex. motor neurons stimulate muscles or sweat glands (to cool body)
Interneurons (association neurons)
located in spinal cord/ brain and receive impulses from sensory neurons/ send impulses to motor neurons
are integrators: evaluate impulses for appropriate response
Transmission of nerve impulse (steps)
- Resting potential and graded potentials: -70mv resting potential is depolarized (more + on inside, -60mv) or hyper-polarized (more - on inside, -80mv) by a stimulus that opens/ closes gated ion channel
- Depolarization and action potentials: voltage-gated ion channels let Na+ from outside into cell to depolarize cell and if threshold is passed, more Na+ floods in to create action potential (+30mv) then Na+ channels inactivate, but active their neighbors
- Repolarization: in response to inflow of Na+, K+ voltage gated ion channels open to allow K+ on inside to exit
- Hyperpolarization: more K+ ions have moved out than necessary so membrane is like -90mv
- Refractory period: reestablishment of original location of Na+ on outside and K+ on inside by Na+/ K+ pump
Transmission across synapse
action potential begins in dendrites and reaches end of axon, opening Ca2+ gates which facilitate releasing of neurotransmitter into synaptic cleft, neurotransmitter diffuses across synapse and binds with receptor proteins on postsynaptic membrane (other neuron)
Acetylcholine, Neuromuscular junction
neurotransmitter commonly secreted at neuromuscular junctions (gaps between neurons and muscle cells) to stimulate muscles to contract
at other junctions may cause inhibitory postsynaptic potential
Epinephrine
adrenaline
neurotransmitter, hormone, drug
used w/ allergic reactions
GABA
inhibitory neurotransmitter among neurons in brain
Reflex arc
rapid, involuntary response to stimulus
sensory to motor neuron, sometimes interneuron
brain does not integrate the sensory/ motor activities
Forebrain, Cerebrum, Corpus callosum
includes:
- cerebrum: largest and most visible part of brain, folded area divided into two halves (cerebral hemispheres)
- speech, thinking, control of muscles, left controls right
- left brain is language, math, logic; right brain is images
- corpus callosum connects two halves of cerebrum
Hypothalamus/ Pituitary gland
sources of regulatory hormones
develop from the forebrain
Limbic system
network of neurons associated w/ emotions
forms in and around cerebrum
Midbrain
forms upper portion of brainstem, which connects spinal cord w/ cerebrum
Hindbrain, Cerebellum
contributes formation of cerebellum
cerebellum: evaluates body movements and coordinated these movement w/ sensory stimuli; ex. hand-eye coordination
3 levels of human defense
- nonspecific first line of defense: skin, mucous membrane
- nonspecific second line of defense: phagocytes, interferons, inflammatory response
- third line of defense, immune response: targets specific antigens
Human first line of defense
- Skin: physical barrier w/ oily and acidic sweat secretions
- Antimicrobial proteins: like lysozyme (breaks bacterial cell walls) contained in saliva, tears
- Cilia: line airway to get invaders out of lungs
- Gastric juice in stomach kills most microbes
- Symbiotic bacteria
Phagocytes (second line of defense), Monocytes, NK cells
white blood cells (leukocytes) that engulf pathogens by phagocytosis
include neutrophils and monocytes
monocytes enlarge into large phagocytic cells called macrophages
natural killer (NK) cells attack abnormal body cells like tumors
Complement (second line of defense)
group of ~20 proteins that “complement” defense reactions
help attract phagocytes to feign cells and help destroy foreign cells by promoting cell lysis
Interferons (second line of defense)
substances secreted by cells invaded by viruses that stimulate neighboring cells to produce proteins that help then defend against the virus
Inflammatory response (second line of defense), Histamine, Vasodilation, Phagocytes, Complement
Ex. Skin is damaged
- Histamine secreted by mast cells
- Vasodilation (white blood cell dilation), stimulated by histamine, increases blood supply to damaged area and allows for easier movement of white blood cells through blood vessel walls; also causes redness, increase in temp. (stimulate white blood cells and make environment inhospitable to pathogens), and swelling
- Phagocytes arrive and engulf pathogens/ damaged cells
- Complement helps phagocytes destroy foreign cells and stimulates histamine release
Immune response (third line of defense), Antigen
differs from inflammatory response in that it targets specific antigens (any molecule identified as foreign, like a toxin, protein coat of virus or molecule unique to bacteria)
Major histocompatipility complex (MHC)
mechanism by which immune system is able to differentiate between self and nonself cells
collection of unique glycoproteins that exist on membrane of all body cells, different in each person so other cells with other MHC seen as foreign
Lymphocytes (definition and types)
primary agents of immune response
leukocytes that originate in bone marrow, but concentrate in lymphatic tissues like lymph nodes, thymus gland, and spleen
Types: B cells, T cells
B cells
lymphocytes that originate and mature in bone marrow
respond to antigens
plasma membrane is characterized by specialized antigen receptors, called antibodies
Plasma cells
daughter B cells produced when B cells encounter antigens that specifically bind to their antibodies
release specific antibodies, which then circulate through the body, binding to antigens
Memory cells
daughter B cells produced when B cells encounter antigens that specifically bind to their antibodies
long-lived B cells that do not immediately release their antibodies, but respond quickly to subsequent invasion by same antigen
provides immunity to many diseases after first occurrence
Antibodies (immunoglobulins)
proteins specific to a particular antigen
5 classes each associated w/ a particular activity, determined by differing amino acid sequences
antibodies inactive antigens by binding to them, which is followed by macrophage phagocytosis and stimulation of complement proteins that will lyse pathogens
T cells
lymphocytes that originate in bone marrow but mature in thymus gland
have antigen receptors that are recognition sites for molecules displayed by nonself cells
Distinction between self and nonself cells
- MHC markers on plasma membrane
- invaded body cells display combination of self/ nonself markers
