Hesi A2 anatomy study guide
• Mitosis is necessary for growth and repair. In this process the DNA is duplicated and distributed evenly to two daughter cells.
• Meiosis is the special cell division that takes place in the gonads that is the ovaries and testes. In the process of meiosis, the ...
Mitosis is necessary for growth and repair. In this process the DNA is duplicated and distributed
evenly to two daughter cells.
Meiosis is the special cell division that takes place in the gonads that is the ovaries and testes. In
the process of meiosis, the chromosome number is reduced from 46 to 23 so when the egg and
the sperm unite in fertilization the zygote will have the correct number of chromosomes.
The skin consists of two layers: epidermis (the outer layer) and dermis (the underlying layer of
connective tissue with blood vessels, nerve endings, and the associated skin structures).
The layers of the epidermis from outer layer to inner layer are the stratum corneum, the
stratum lucidum, the stratum granulosum, and the inner most stratum germinativum (which
includes stratum Basale and stratum spinosum), this is where mitosis occurs.
Functions of the skeletal system include support, movement, blood cell formation(hemopoiesis)
protection of internal organs, detoxification (removal of poison) provision for muscle
attachment and mineral storage (particularly calcium and phosphorus.
A long bone has irregular epiphysis at each end composed mainly of spongy bone and a shaft or
diaphysis composed mainly of compact bone. The cells that form compact bone are called
osteoblast when they become fixed in the dense matrix they stop dividing but continue to
maintain bone tissue as osteocytes.
The axial skeleton consists of the skull, vertebral column, twelve pairs or ribs and a sternum.
When including the 6 bones of the ear, the skull is comprised of 28 bones, 14 facial bones, and
14 cranial bones. The facial bones include two nasal bones two maxillary bones, two zygomatic
bones, one mandible (the only moveable bone of the skull), two palatine bones, one vomer, two
lacrimal bones, and wo inferior nasal conchae.
The vertebral column is divided into five subsections. There are 7 cervical vertebrae, 12 thoracic
vertebrae, 5 lumbar vertebrae, 5 sacral vertebrae (which fuse to form the sacrum), and
coccygeal vertebrae (known tailbone).
The appendicular skeleton includes the gridles and the limbs. The upper portion consist of the
pectoral of shoulder gridle the clavicle and scapula, and the upper extremity. The lower portion
of the appendicular skeleton is made up of the pelvic gridle or so coxae. Each of the os coxae
consist of a fused ilium, ischium, and pubis.
Muscle contraction results from the sliding together of actin and myosin filaments within the
muscle cell or fiber. Each muscle cell consists of myofibrils which turn made up of still smaller
units called sarcomeres. Calcium and adenosine triphosphate (ATP) must be present for a
muscle cell to contract
The skeleton muscles which make up the muscular system are also called voluntary muscles
because they are under conscious control.
Skeletal muscles must work in pairs: the muscle that executes a given movement is the prime
mover, whereas the muscle that produces the opposite movement is the antagonist. Other
muscles known as synergists may work in cooperation with the prime mover.
Flexors reduce the angle at the joint, whereas extensors increase the angle. Abductors draw a
limb away from the midline, and adductors return the limb back toward the body.
The main parts of a neuron are the cell body, axon and dendrites. Dendrites transmit the
impulse toward the cell body and the axons transmit the impulse away from the cell body.
, The nervous system may be divided structurally into a central nervous system (CNS) and the
peripheral nervous system (PNS). The CNS is compromised of the spinal cord and brain, while
the PNS is composed of all other neurons in the body. Sensory (afferent) neurons transmit nerve
impulses toward the CNS. Motor (efferent) neurons transmit nerve impulses away from the CNS.
The major parts of the brain are the cerebrum (associated with movement and sensory input),
the cerebellum (responsible for muscular coordination), and the medulla oblongata (controls
many vital functions such as respiratory and heart rate).
The endocrine system assists the nervous system in homeostasis and plays important roles in
growth and sexual maturation.
Hormones are chemical messengers that control the growth, differentiation and metabolism of
specific target cells. There are two major groups of hormones, steroid and nonsteroidal
hormones. Steroids hormones enter the target cells and have a direct effect on the DNA of the
nucleus. Some nonsteroidal hormones are protein hormones. Many protein hormones remain at
the cell surface and act through a second messenger usually a substance called adenosine
monophosphate (AMP). Most hormones affect cell activity by altering the rate of protein
synthesis.
The pituitary gland is nicknamed the master gland. It is attached to the hypothalamus by a stalk
called the infundibulum. The pituitary gland has two major portions: the anterior lobe
(adenohypophysis) and the posterior lobe (neurohypophysis). Hormones of the
adenohypophysis are called the trophic hormones because they act mainly on the other
endocrine glands. Somatotropin hormone (STH) of growth hormone (GH), adrenocorticotropic
hormones (ACTH), thyroid-stimulating hormone (TSH), follicle stimulating hormone (FSH),
luteinizing hormone (LH). Hormones released from the posterior lobe of the pituitary include
oxytocin (the labor hormone) and antidiuretic hormone (ADH)
Whole blood consists of approximately 55% plasma and 45% formed elements: erythrocytes
(red blood cells), leukocytes (white blood cells), and platelets. All the formed elements are
produced from stem cells in red bone marrow. Erythrocytes are modified for transport of
oxygen. Most of this oxygen is bound to the pigmented protein hemoglobin.
White blood cells are active in phagocytosis (neutrophils and monocytes) and antibody
formation (Lymphocytes). Platelets are active in the process of blood clotting.
Blood serves to transport oxygen and nutrients to body cells and to carry away carbon dioxide
and metabolic wastes. Plasma contains approximately 10% proteins, ions, nutrients, waste
products, and hormones, which are dissolves or suspended in water.
The heart is a double pump that sends blood to the lungs for oxygenation through the
pulmonary circuit and to the remainder of the body through the systemic circuit. Blood is
received by the atria and is pumped into circulation by the ventricles.
Tricuspid Valve is on the right side. Bicuspid Valve is on the left side.
Semilunar valve is found at the entrances of the pulmonary trunk and the aorta.
Blood is supplied to the heart to the heart muscle (the myocardium) by the coronary arteries.
Blood is drains from the myocardium directly into the right atrium through the coronary sinus.
The heart has an intrinsic beat initiated by the sinoatrial node and transmitted along a
conduction system through the myocardium. This wave of electrical activity is what is measured
on an electrocardiogram (ECG). The cardiac cycle is the period from the end of one ventricular
contraction to the end of the next ventricular contraction.
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