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what causes muscle contractions
nervous stimulation causes actin and myosin filaments to slide past each other in the muscle cell or fiber.
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what are muscle cells made up of?
myofibrils that consist of sarcomeres
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what must be present for a cell to contract?
calcium and ATP (adenosine triphosphate)
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explain the process of muscle contraction (cross-bridge cycle) from motor neuron
the motor neuron releases calcium from the sarcoplasmic reticulum. when the calcium binds to troponin on actin, tropomyosin moves out of the way so that actin and myosin can make a bridge formation. The bridge is strong when myosin contains ADP and Phosphate. When phosphate is released the myosin head pivots (contraction). When ATP comes, the cross bridge detaches. When ATP hydrolyzes, the energy to create ADP and phosphate puts the head back in its cocked position.
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explain how muscles work in pairs-prime movers and antagonist
what is the synergist
prime movers execute the movement, while the muscle that produces the opposite movement is the antagonist
the synergist helps by assisting the prime mover. works with it.
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what is the overall purpose of the nervous system
it makes all of our senses possible, helps us to think, makes movement possible by causing contraction, helps body functions operate
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what do all actions in the nervous system depend on
transmission of nerve impulses between neurons/nerve cells
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what are the function units of the nervous system?
neurons/nerve cells
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what are the 3 main parts of the nerve cell?
cell body, axon, dendrites
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what do axons do?
they transmit the impulse away from the cell body
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what do dendrites do?
they transmit the impulse toward the cell body
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what are the parts of the nervous system
- CNS-brain and spinal cord
- PNS-all the other neurons in the body
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what kind of neurons are sensory? what do they do?
afferent- send signals toward the CNS
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what kind of neurons are motor? what do they do?
efferent-send signals away from the CNS to muscles, glands, and organs
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what are 3 major parts of the brain
the cerebrum, cerebellum, and medulla oblongata
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what does the cerebum do?
associated with movement and sensory input
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what does the cerebellum do?
responsible for muscular coordination
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what does the medulla oblongata do?
controls many vital functions such as respiration and heart rate
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how long is the spinal cord?
18 inches long, stretching from the base of the skull (foramen magnum) to L1/L2
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how many spinal nerves exit the spinal cord?
62 or 31 pairs
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what are simple spinal reflexes
reflexes where nerve impulses travel through the spinal cord, but don't reach the brain
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how do most spinal reflexes work?
they work in ascending and descending pathways. sensory impulses enter the spinal cord through the dorsal horns, while motor impulses exit the spinal cord through the ventral horns.
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what is the purpose of the endocrine system?
it assists the nervous system in homeostasis and plays an important role in growth and sexual maturation
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where do the nervous and endocrine systems meet? explain their relationship.
they meet at the hypothalamus and the pituitary gland. the hypothalamus governs the pituitary gland, but is controlled by the feedback of hormones in the blood, coming from the pituitary.
the nervous and endocrine systems coordinate and control the body, but the endocrine system has more widespread and longer lasting effects
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what structure connects the hypothalamus and pituitary gland?
the infundibulum
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what are the 2 major portions of the pituitary gland? which is which?
the anterior lobe (adenohypophysis)
the posterior lobe (neurohypophysis)
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does the nervous or endrocrine system effect the body more?
the nervous and endocrine systems coordinate and control the body, but the endocrine system has more widespread and longer lasting effects
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what are 7 major endocrine glands?
hypothalamus, pituitary gland, thyroid, pancreas, adrenal glands, and gonads (testes & ovaries)
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what are hormones?
chemical messengers that control the growth, differentiation, and metabolism of specific target cells
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what are the 2 major groups of hormones? explain..
steroid- enter the target cells and have a direct effect on the DNA of the nucleus. their receptors are inside of the cell.
non steroid- their receptors are outside of the cell and they require a secondary messenger to effect the nucleus. they are usually amines or proteins, but can be fatty acids
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what is the most common second messenger?
AMP- adenosine monophosphate
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how do most hormones effect the cell
by effecting the rate of protein synthesis
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what is the function of the endocrine glands
name other organs that arent endocrine glands that produce hormones
to produce hormones
the stomach, small intestines, and kidneys
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what glands release cortisol and other hormones during stress
adrenal cortex, anterior and posterior pituitary, and the hypothalamus
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what effect does cortisol released from the adrenal cortex have on the body
reduces inflammation, raises blood sugar level, and inhibits the release of histamine
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what gland is called "the master gland"
the pituitary
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what are hormones of the adenophypophysis called? why?
trophic hormones
because they act mainly on other endocrine glands
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list major adendohyophysis tropic hormones
5
- -somatotropin hormone (STH), or growth hormone (GH)
- -adrenocorticotropic hormone (ACTH)
- -thyroid-stimulating hormone (TSH)
- -follicle-stimulating hormone (FSH)
- -luteinizing hormone (LH)
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list 2 hormones released from the neurohypophysis
- oxytocin (the labor hormone)
- antidiuretic hormone (ADH)
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what is whole blood made up of?
- 55% blood plasma
- 45% erythrocytes (red blood cells), leukocytes (white blood cells), and platelets
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where are the erythrocytes, leukocytes, and platelets formed?
from stem cells in bone marrow
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function of erythrocytes
transport oxygen that is bound to protein hemoglobin
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how many types of leukocytes are there
5
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what percentage of blood plasma contains ions, waste, nutrients, and hormones? where do they go?
10%
they dissolve into the water
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the heart is a double pump system? explain purpose
the pulmonary circuit-sends blood to the lung for oxygenation
the systemic circuit-pumps blood to the rest of the body
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describe the pulmonary and systemic circuits PATHWAYS (i.e. how the heart works)
deoxygenated blood enters the superior and inferior vena cava into the rt atria, rt ventricle, and out of the rt and lt pulmonary arteries to the lungs where they get oxygenated (pulmonary)
- then the newly oxygenated blood goes through the rt and lt pulmonary veins, to the lt atria, lt ventricle, and out of the aorta to the body (systemic)
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what are the 4 valves in the heart and where?
- tricuspid valve-between the rt atria and rt venticle
- pulmonary valve-between the rt ventricle and pulmonary arteries
- bicuspid (mitral) valve-between the lt atrium and lt ventricle (diastole)
- aortic valve-between the lt ventricle and the aorta
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which valves are the semilunar valves?
the pulmonary and aortic valves
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what is the name of the actual heart MUSCLE
myocardium
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what initiates the intrinsic beat of the heart
the SA, or sinoatrial node in the rt atrium
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what defines a cardiac cycle?
the period of one ventricular contraction to the end of the next ventricular contraction
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what happens during the systole phase?
contraction of the left ventricle
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what happens during the diastole phase?
relaxation in the left ventricle
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what does the vascular system consist of?
the arteries that carry oxygenated blood awat from the heart, veins that carry deoxygenated blood to the heart, and capillaries
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what is the function of capillaries in the vascular system? how big are they compared to other vessels?
they exchange water, nutrients, and waste products between the blood and the surrounding tissues.
they are the smallest vessels
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which arteries are considered systemic?
the vessels beginning with the aorta through the branches of the rest of the body
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what happens when arteries move further away from the heart? what are these called?
they become thinner
arterioles (the veins that run parallel usually have the same name)
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characteristics of the walls and pressure of arteries
the walls are thick and elastic; they operate under high blood pressure
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what is vasodilation and vasoconstriction? what are the effects?
relaxation and contraction of the arterial walls (smooth muscle)
this influences the blood pressure and blood distribution to the tissues
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characteristics of the walls and pressure of veins
the walls are thinner and less elastic, and they carry blood under low pressure
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do deflections of an ECG reflect the systole and diastole of the heart? why?
- no.
- they reflect the electric activity that happens right before (the initiation) the relaxation and contraction happens
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