Systems Physiology - AP Biology

The tiny gaps in between myelin sheaths are referred to as nodes of Ranvier. The action potential will jump from node to node as it moves down the axon.

If an axon existed without these gaps (the entire length was covered in myelin), it would be unable to conduct an action potential.

The cerebellum is mainly responsible for fine tuning the motions of the body, including balance and coordination. As a result, damage to this region would cause difficulty walking straight and maintaining balance.

Each answer corresponds to one lobe of the cerebrum. The frontal lobe is responsible for conscious thought, as well as many other functions. The parietal lobe is responsible for integrating tactile information. The temporal lobe has the functions of interpreting smell and sound. The occipital lobe is associated with processing visual information.

The eye is divided into two chambers by the lens: the anterior and posterior chambers. The anterior chamber is filled with aqueous humor, while the posterior chamber is filled with vitreous humor. Aqueous humor nourishes the eye and maintains intraocular pressure. Aqueous humor is also important in the refraction of light, which allows humans to distinguish clear images and colors.

Hippocratic and Galen humor do not exist. Hippocrates and Galen were two ancient physicians who would use the four humors (yellow bile, black bile, phlegm, and blood) to diagnose and treat patients.

Unmyelinated nervous system components make up grey matter, while myelinated axons make up white matter. The cerebral cortex on the surface of the brain contains unmyelinated neural tissue, namely the cell bodies of neurons in the central nervous system. This region is rich in connections. Below its surface lie many myelinated axon tracts to inner nuclei, the cerebellum, other areas of the cortex, and the spinal cord.

In the blind spot, there is a lack of photoreceptors as the optic nerve exits the optic disk. We normally overcome this automatically when our brains use the information of the surrounding visual field and "fills in" the blind spot.

The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of any nerves or ganglia, not including the brain and spinal cord. The prefrontal cortex is a structure in the cerebrum of the brain, and is thus part of the central nervous system.

General nerves throughout the body are part of the peripheral nervous system.

The spinal cord and vertebrae is broken down into four regions: cervical, thoracic, lumbar, and sacral. There are seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, and five sacral vertebrae. Cervical vertebrae are located in the neck, thoracic vertebrae in the trunk or upper back, lumbar vertebrae in the lower back, and sacral vertebrae in the gluteal region. The sacral vertebrae are fused into a single unit known as the sacrum.

The spinal cord consists of functional horns that help send information to the brain, as well as to the parts of the body. The dorsal horns send sensory information to the brain, while the ventral horns contain motor neurons.

A neuron receives input from other neurons at the dendrites. Neurotransmitters released by other neurons bind to receptors on the dendrites, which carry the signal to the cell body. The signal is then amplified in the cell body before being transferred to the axon. Once the signal transitions to the axon, it is considered an action potential. The signal eventually reaches the end of the axon, where the synaptic vesicles are located, and stimulates release of neurotransmitters to the next neuron's dendrites.

The correct order of the spinal meninges from superficial to deep (outside to inside) is dura mater, arachnoid mater, and pia mater. The dura mater is the most outer layer that is closely associated with the skill and vertebral column. Deep to the dura mater is the arachnoid mater, which contains the cerebrospinal found in the subarachnoid space. Underneath the subarachnoid space lies the pia mater, which is very closely associated with the brain and spinal cord.

The correct answer is dura mater, arachnoid and lastly the pia mater. The meninges surround the brain and spinal cord in the central nervous system and are made up of three layers. The outermost layer is the dura mater, beneath it lies the arachnoid and below that is the pia mater.

Mast cells contains secretory granules, rich in histamine and other hormonal mediators, that promote inflammation and other allergy symptoms in response to antigen exposure.

Germ layers are primary layers of cells that form during embryogenesis. In mammals, they are the endoderm, ectoderm, and mesoderm. In embryo development, the germ layers differentiate during gastrulation.

The mesoderm is a primary germ layer that forms during gastrulation. The mesoderm develops into most of the organ systems of the human body, including the muscular system, circulatory system, and excretory system.

A woman is said to be “full term” when she is at 39 to 41 weeks of pregnancy. Medical intervention to induce labor during this time is not ideal.

During the generation of an action potential, the cell will undergo two refractory periods. The first is referred to as the absolute refractory period, during which no stimulus, regardless of size, will generate another action potential. This is followed by the relative refractory period, during which an action potential will be generated only if an abnormally large stimulus is encountered. During the relative refractory period, the cell is hyperpolarized due to the removal of potassium ions from the cell interior, which results in a more negative membrane potential than the cell would have at rest.

By pumping two positively-charged potassium molecules in for every three positively-charged sodium molecules that are pumped out of the cell, the sodium-potassium pump maintains a resting potential of –70mV relative to outside of the cell. This function is important for creating an electrochemical gradient along the neuron.

Remember that sodium flows down its gradient to enter the cell during depolarization, while potassium flows down its gradient to exit a cell after an action potential, causing hyperpolarization during the refractory period.

After the sodium channel is opened, sodium rushes into the cell down its concentration gradient (as previously created by the sodium-potassium pump). This causes depolarization of the membrane as its potential reaches a value of +35mV, which is eventually lowered by the opening of the potassium channels. This leads to hyperpolarization, which prevents the signal from traveling backwards.