Straub

How does cholecystokinin limit meal size?

hormone that limits meal size in two ways: 1. constricting the sphincter muscle between the stomach and duodenum, causing the stomach to hold its contents and fill more quickly than usual 2. stimulates the vagus nerve to send signals to the hypothalamus, causing cells there to release a neurotransmitter that is a shorter version of the CCK molecule itself

3. Describe the relationship of conscious decisions and movements. What may this relationship reveal about consciousness?

Behavior is driven by the subconscious mind tasks are preformed via the conscious mind, but most actions depend on the subconscious mind. They are same as reflex actions in certain ways, but vary. As far as physical reflex actions are concerned, actions or disturbances in and around you arise, and before you realize, your body responds to the disturbance. Right after your reflex action, you realize how your body responded. Yet when the subconscious mind takes control, your conscious mind is unaware you responded to the subconscious stimuli. The conscious mind is analytical and logical.

Describe how light resets the SCN

Light resets the oscillations in the SCN through a mechanism involving retinal ganglion cells that project directly to the SCN via the retino-hypothalamic tract. Through an indirect pathway, circadian information reaches the pineal gland where the hormone melatonin is produced, which also can shift the phase of oscillations in the SCN. Both melatonin and neural information from retinal ganglion cells can also directly act on the sleep-wake system itself. Thus, light input and the circadian system work together to modulate properties of the sleep-wake cycle.

Discuss the relationship between sleep and memory

Many studies have shown that sleep is an important factor to memory. The more sleep deprived a person is, the more delirious they become. Sleep deprivation decreases attention which in return decrease ones ability to memorize.

Describe the different causes and mechanisms of thirst.

Osmotic thirst occurs when solutes are more concentrated on the outside of the cell. This causes water to move from high concentration inside the cell to the outside that has a lot of solutes. For example if a person eats a salty meal, the stomach will detect high levels of sodium. The high levels of salt outside the cells increases osmotic pressure causing the cells to shrink as water leaves from inside the cell. This change is pressure is detected by cells in the hypothalamus (OVLT and SFO). The OVLT and SFO also stimulates the supraoptic nucleus and paraventricular nucleus of the hypothalamus. The PVN also stimulates the lateral preoptic area that causes individuals to feel thirsty and go to get a drink of water. The PVN of the hypothalamus also signals the release of vasopressin from the posterior pituitary. Vasopressin increases blood pressure by constricting blood vessels to compensate for decreased water volume in cells. Vasopressin also causes the kidneys to reabsorb water and excrete very concentrated urine. When an individual feels thirsty with osmotic thirst, they will drink pure water.

Describe the role of heredity and environment of violent behavior

Our genetic predispositions and our surrounding environments interact. Environments can trigger gene activity, and genetically influenced traits can evoke responses from others. The field of epigenetics studies the influences on gene expression that occur without changes in DNA.

5. Briefly describe the nature of parkinsons disease. Include discussion of its causes and possible treatments.

Parkinson's disease is a progressive nervous system disorder that affects how the person moves, including how they speak and write. Symptoms develop gradually, and may start off with ever-so-slight tremors in one hand. People with Parkinson's disease also experience stiffness and find they cannot carry out movements as rapidly as before. Parkinson's disease affects the way you move. It happens when there is a problem with certain nerve cells in the brain. Normally, these nerve cells make an important chemical called dopamine. Dopamine sends signals to the part of your brain that controls movement. Medication that increases dopamine levels is generally used to treat Parkinson.

Describe the mechanisms involved in temperature regulation

Pre Optic Area (POA) and Anterior Hypothalamus (AH) Temp regulation is one of the body's biological priorities.mechanisms maintain constant body temperature, including shivering, sweating, and changes in blood flow. You also rely on behav- ioral mechanisms, such as finding a cooler or warmer place, adding or removing clothing, POA: receives input from temp receptors throughout the body heating the pot -heat boosts aggression AH: leads to panting or sweating' cooling leads to shivering receives input from immune system Use temp to aid

Briefly describe how benzodiazepines work in the brain.

The benzodiazepines operate widely in the brain, affecting emotional reactions, memory, thinking, control of consciousness, muscle tone and coordination. The benzodiazepines enhance the action of the neurotransmitter, GABA(Gamma Amino Butyric Acid). Neurotransmitters are chemicals which enable the brain cells to transmit impulses from one to another. They are released from brain cells by electrical signals. Once released, the neurotransmitters signal inhibition or excitation of neighbouring brain cells. GABA is the major inhibitory neurotransmitter. The function of GABA is to slow or calm things down. Benzodiazepines increase the efficiency of GABA, thus causing greater inhibition or calming.

4. Briefly describe the cellular organization of the cerebellum.

The cerebellum receives input from the spinal cord, from each of the sensory systems by way of the cranial nerve nuclei, and from the cerebral cortex. That information eventually reaches the cerebellar cortex, the surface of the cerebellum. • The neurons are arranged in a precise geometrical pattern, with multiple repetitions of the same units. • The Purkinje cells are flat (two-dimensional) cells in sequential planes, parallel to one another. • The parallel fibers are axons parallel to one another and perpendicular to the planes of the Purkinje cells. • Action potentials in parallel fibers excite one Purkinje cell after another. Each Purkinje cell then transmits an inhibitory message to cells in the nuclei of the cerebellum (clusters of cell bodies in the interior of the cerebellum) and the vestibular nuclei in the brainstem, which in turn send information to the midbrain and the thalamus.

Briefly describe the role of the HPA axis and the autonomic nervous system in the stress response

The hypothalamus in the brain is in charge of the stress response. When a stress response is triggered, it sends signals to two other structures: the pituitary gland, and the adrenal medulla. These short term responses are produced by The Fight or Flight Response via the Sympathomedullary Pathway (SAM). Long term stress is regulated by the Hypothalamic Pituitary-Adrenal (HPA) system. The hypothalamus stimulates the pituitary gland The pituitary gland secretes adrenocorticotropic hormone (ACTH) ACTH stimulates the adrenal glands to produce the hormone corticosteroid Cortisol enables the body to maintain steady supplies of blood sugar Adequate and steady blood sugar levels help person to cope with prolonged stressor, and helps the body to return to normal

Describe the major brain mechanisms of eating and hunger.

The hypothalamus regulates feeding behavior. One section, the arcuate nucleus, initiates the feeling of hunger using the neurotransmitter ghrelin when the stomach sends a signal that the body requires nutrients. The lateral hypothalamus is associated with the sensation of taste, which reinforces eating behaviors. It also secretes insulin so that glucose can be transferred into cells. When satiated, the paraventricular nucleus of the hypothalamus inhibits the lateral hypothalamus so that feeding behaviors cease and over-eating is prevented. Finally, the ventromedial region of the hypothalamus affects the timing of feeding.

Briefly describe the role of the locus coeruleus in arousal and attention

The locus coeruleus (LC) is small structure in the pons whose axons release norepinephrine to arouse various areas of the cortex, and increase wakefulnees. The LC is dormant during sleep. Certain areas of the hypothalamus stimulate arousal by releasing the neurotransmitter histamine, which produces excitatory effects throughout the brain. Antihistamine drugs produce drowsiness if they cross the blood-brain barrier. A different group of axons from the lateral nucleus of the hypothalamus release the peptide neurotransmitter orexin (also known as hypocretin). Orexin stimulates acetylcholine-releasing cells in the basal forebrain to stimulate neurons responsible for wakefulness and arousal. The basal forebrain is an area just anterior and dorsal to the hypothalamus. Some of the axons from the basal forebrain release GABA and are essential for sleep. These neurons receive input from the anterior and preoptic areas of the hypothalamus.

1. Describe the area and major functions of the primary motor cortex (include the relevant areas near to the motor cortex).

The primary motor cortex or M1 is one of the principal brain areas involved in motor function. M1 is located in the frontal lobe of the brain, along the precentral gyrus. The role of the primary motor cortex is to generate neural impulses that control execution of movement. Signals from M1 cross the bodys midline to activate skeletal muscles on the opposite side of the body. Every part of the body is represented in the primary motor cortex.

2. Describe the significance of mirror neurons.

The significance of mirror neurons is that they help in understanding actions of others (empathy, interpretation, non verbal communication), they help form new motor skills, imitate others and helps refine motor skills.

Discuss the leading theories on the biological perspectives on dreaming

The two major biological perspectives on dreaming are the clinico-anatomical hypothesis and the activation-synthesis hypothesis. The activation-synthesis hypothesis states that a dream is a representation of the brain effort to sparse and distorts information. Dreams start off as spontaneous activity in the pons and PGO waves activate some of the cortex, but not other parts. The cortex combines the input with whatever activity that was occurring and it synthesizes a story that makes sense based of the information. The clinico-anatomical hypothesis is based on clinical studies of individuals with brain damage. Clinico-anatomical place emphasizes on the belief that dreams being with arousal stimuli and then are interpreted from the recent memories and the sensor information the brain receives just as the activation-synthesis hypothesis, the clinico-anatomical hypothesis states that dreaming is a form of thinking that takes place during uncharacterized conditions. A reason for this is said to be dues to the lack of information the brain is receiving from organs and the V1 and auditory areas of cortex have lower than usual activity. The clinic-anatomical doesn't place emphasizes on the pons or the PGO wave. The clinico-anatomical hypothesis explains that either external or internal stimulation activates parts of the occipital, parietal, and temporal cortex. No visual information overrides the stimulation and no criticism of the prefrontal cortex censors it, so it develops into hallucinatory perceptions. The activation-synthesis hypothesis explains that during sleep, many brain regions become activated so the brain creates a story to try and make sense of all of this activity.

Describe brain function during REM sleep.

The whole brain is active during dreams, from the brain stem to the cortex. Most dreams occur during REM (rapid eye movement) sleep. This is part of the sleep-wake cycle and is controlled by the reticular activating system whose circuits run from the brain stem through the thalamus to the cortex.