BIO 191 CH 38 HW

Which part of the eye contains the densest concentration of cone cells? Fovea. Lens. Cornea. Opsin.

Fovea The fovea, located in the center of the retina, has the densest concentration of cone cells.

Which of the following statements does not describe a vertebrate eye? It contains cells that are sensitive to either dim light or color. It contains many light-sensing columns called ommatidia. It acquires images by focusing light on receptor cells. It contains photoreceptors that are either rod- or cone-shaped.

It contains many light-sensing columns called ommatidia. Ommatidia are only found in compound eyes.

Which part of the eye bends light to focus it on the retina? Lens. Optic nerve. Sclera. Fovea.

Lens The lens focuses light onto the retina.

True or false? The "blind spot" in vertebrate eyes is a region of the retina that contains no photoreceptors.

True The blind spot contains no photoreceptors.

The peripheral nervous system (PNS) transmits information to and from the central nervous system (CNS) and plays a role in regulating an animal's movements and internal environment. Determine which of the following statements about the PNS are true. Select the four statements that are true.

-Neurons in the parasympathetic division release neurotransmitters that act on receptors that slow heart rate. -Stimulating the organs of digestion is a parasympathetic response. -The sympathetic division of the PNS prepares the body for physical exertion in stressful situations. -Parasympathetic nerves are associated with the cranial and sacral regions of the spinal cord, whereas sympathetic nerves are associated with the thoracic and lumbar regions. The autonomic nervous system of the PNS regulates the body's internal environment. It consists of the parasympathetic division and the sympathetic division. The parasympathetic division controls "rest and digest" functions, whereas the sympathetic division controls "fight or flight" functions. This table lists some of the opposing actions of each division. Parasympathetic division "rest and digest" constricts pupils slows heart rate stimulates activity of pancreas and gallbladder stimulates activity of intestines promotes emptying of bladder Sympathetic division"fight or flight" dilates pupils increases heart rate inhibits activity of pancreas and gallbladder inhibits activity of intestines inhibits emptying of bladder

The vertebrate nervous system can be organized into two main systems: the central nervous system (CNS) and the peripheral nervous system (PNS). Which of the following terms and phrases describe structures or actions of the CNS? Which describe structures or actions of the PNS? Drag each word or phrase to the appropriate bin. If the word or phrase applies to both the central nervous system and peripheral nervous system, drag it to the "both CNS and PNS" bin.

Central Nervous System: -Brain and spinal cord -Initiates signals to muscles and organs -Process information received from sense organs Peripheral Nervous System: -Afferent and efferent neurons -Carries sensory information toward the spinal cord -Carries signals to muscles and organs -Cranial nerves and spinal nerves Both CNS and PNS: -Reflexes -Enables voluntary locomotion The central nervous system (CNS) is comprised of the brain and spinal cord. The CNS processes information received from sense organs and initiates signals that produce responses in muscles and organs. The peripheral nervous system (PNS) includes the neurons that are outside of the CNS. Afferent neurons transmit information to the CNS, whereas efferent neurons carry impulses from the CNS to a target organ. Both reflexes and voluntary movements result from the interaction of the CNS and PNS.

True or false? Cone cells are color photoreceptors that use different retinal molecules to absorb different wavelengths of light.

False Although it is true that cone cells are the color photoreceptors in the eye, they use different opsin (not retinal) molecules in their opsin-retinal complexes to absorb different wavelengths of light.

Which part of the eye is the opening through which light initially passes? Sclera. Retina. Pupil. Fovea.

Pupil The pupil is the small opening in the center of the iris through which light initially passes.

Which of the following statements about photoreception is true? Rhodopsin is found in cone cells. Rod cells are responsible for color vision. Cone cells are sensitive to dim light. The retinal molecule changes shape when it absorbs light.

The retinal molecule changes shape when it absorbs light. The retinal molecule is the light-sensitive portion of the retinal-opsin complex.

The central nervous system consists of the spinal cord and the brain, which is one of the most complex organs in animals. On the diagram below, label the parts of the human brain and identify one function of each part of the brain. Drag the labels to their appropriate locations on the diagram, following these steps. Drag blue labels onto the blue targets to identify the structures of the brain. Drag pink labels onto the pink targets under each structure to identify one function of that part of the brain.

a. cerebrum b. diencephalon c. working a crossword puzzle d. sending signals from the senses to the appropriate brain region e. communicating between left and right cerebral hemispheres f. brainstem g.cerebellum h.regulating a person's resting heart rate i. maintaining balance while walking The brain, part of the central nervous system, is the most complex organ in the human body. The brain has four major regions, each with specialized functions. The cerebrum is the largest part of the brain and is responsible for thought, information processing, and memory. The diencephalon acts as an integrating center for sensory information and controls homeostasis. The cerebellum coordinates movement and balance (e.g., hand-eye coordination). The brainstem, which is continuous with the spinal cord, functions in some autonomic responses and relays information to and from higher brain centers.