Module 4 Period 6 Notes - Doral Academy Preparatory School



Module 4 Period 6 Notes

B. Studying the Living Brain

During the past 10 years, researchers have developed several brain scanning techniques that can look through the thick skull and picture the brain with astonishing clarity.

MRI: Stands for magnetic resonance imaging. It involves passing non-harmful radio frequencies through the brain. A computer measures how these signals interact with brain cells and transforms this interaction into an incredibly detailed image of the brain, or body. MRI scans are used to study the structure of the brain.

fMRI: Stands for functional magnetic resonance imaging. These scans measure the activities of specific neurons that are functioning during cognitive tasks such as thinking, listening, and reading.

- MRI and fMRI scans use non harmful radio frequencies and give very detailed structures and functions living inside the brain.

PET scans: stands for positron emission tomography. This scan involves injecting a slightly radioactive solution into the blood and then measuring the amount of radiation absorbed by brain cells called neurons. The more active the neurons are, the more solution they absorb. The colors red and yellow indicate the maximum activity of neurons, while blue and green indicate minimal activity of neurons.

- fMRI scans are replacing PET scans since fMRI’s don’t require injecting slightly radioactive solutions into the blood.

- PET and fMRI scans are used to identify and map the living brain’s neural activity as a person performs complex behavioral and cognitive tasks, such as: seeing, moving, thinking, speaking, emphasizing, trusting, and even reacting to violence.

- Cognitive neuroscience identifies and maps differences in neural activity to understand the bases for cognitive functions.

- Researchers agree that the brain is genetically wired to place different things into different categories around the brain, hence, why you are able to remember thousands of different things.

Ex. Naming animals stirs activity in the back of the brain, while naming tools stirs activity in the front of the brain. You can name the animals based on size, shape, and colors, while you can name tools based on their function.

CONTROL CENTERS: FOUR LOBES

• Wrinkled cortex

– a thin layer of cells that essentially covers the entire surface of the forebrain

– Has a surface area of 18 inches

• Four lobes

– Frontal lobe

– Parietal lobe

– Occipital lobe

– Temporal lobe

• Frontal lobe

– involved with personality, emotions, and motor behaviors

• Parietal lobe

– involved with perception and sensory experiences

• Occipital lobe

– involved with visual processing

• Temporal lobe

– involved with hearing and speaking

• Frontal lobe: functions

– Phineas Gage

• Frontal Lobotomy

– A surgical procedure in which about one-third of the front part of the frontal lobe was cut away from the rest of the brain

• Frontal lobe: functions

– motor cortex

– narrow strip of cortex that is located on the back edge of the frontal lobe and extends down its side

– involved in the initiation of all voluntary movements

– right side controls left

– left side controls right

– organization and function of motor cortex

• Other functions of frontal lobe

– much knowledge of other frontal lobe functions comes from individuals who had damage to that area

– frontal lobes are involved in paying attention, organizing, planning, deciding, and carrying out various cognitive tasks and social-emotional behaviors

– executive function

• Parietal lobe: function

– location of somatosensory cortex

– narrow strip of cortex that is located on the front edge of the parietal lobe and extends down its side.

• Other functions of parietal lobe

– involved in several cognitive functions, including recognizing objects, remembering items, and perceiving and analyzing objects in space

• Temporal lobe: functions

– primary auditory cortex

– located on top edge of each temporal lobe, receives electrical signals from receptors in the ears and transforms these signals into meaningful sound sensations, such as vowels and consonants

• Temporal lobe: functions

– auditory association area

– located directly below the primary auditory cortex

– transforms basic sensory information, such as noises or sounds, into recognizable auditory information, such as words or music

• Temporal lobe: functions

– Broca’s area - frontal lobe

• located in left frontal lobe

• necessary for combining sounds into words and arranging words into meaningful sentences

• damage: Broca’s aphasia

– person cannot speak in fluent sentences but can understand written and spoken words

– Wernicke’s area

• located in the left temporal lobe

• necessary for speaking in coherent sentences and for understanding speech

• Damage: Wernicke’s aphasia

– difficulty in understanding spoken or written words and a difficulty in putting words into meaningful sentences

– Occipital lobe: functions

– vision

– primary visual cortex

– located at the very back of the occipital lobe

– receives electrical signals from receptors in the eyes and transforms these signals into meaningless basic visual sensations, such as lights, lines, shadows, colors, and textures

– Occipital lobe: functions

– visual association area

– transforms basic sensations, such as lights, lines, colors, and textures, into complete, meaningful visual perceptions, such as persons, objects, or animals

• Visual agnosia

– individual fails to recognize some object, person, or color

– has ability to see and even describe pieces or parts of some visual stimulus

• Neglect Syndrome

– refers to the failure of a patient to see objects or parts of the body on the side opposite the brain damage

– may dress only on one side of body

– may deny that opposite body parts are theirs

ORGANIZATION OF THE BRAIN

-Central nervous system is made up of the brain and spinal cord. Spinal cord, made up of neurons and bundle of axons and dendrites that carry information back and forth between the brain and the body.

-Peripheral nervous system includes all the nerves that extend from the spinal cord and carry messages to and from various muscles, glands, and sense organs located throughout the body.

SUBDIVISIONS OF THE PERIPHERAL NERVOUS SYSTEM

Somatic nervous system

-Nerves in somatic have afferent and efferent fibers.

*Afferents carry information from sensory receptors in the skin, muscles, and other organs to the spinal cord and brain.

*Efferent fibers carry information from the brain and spinal cord to the muscle.

-Because of somatic nervous system, you can control your voluntary movements.

-You can control your muscles and know where your arms and legs are in space.

-It also maintains your balance and coordination because it sends signals back and forth to the brain.

Autonomic nervous system

-It regulates heart rate, breathing, blood pressure, digestion, and other functions.

-Has two divisions…

*Sympathetic division, triggered by threatening or challenging physical or psychological stimuli.

Example: When you see a frightening snake would trigger the sympathetic division, where then you would arouse for action such as fighting or feeling.

*Parasympathetic division turns the body to a calmer, relaxed state and is involved in digestion. When you feel calm, relaxed or digesting food your parasympathetic system is activated.

MAJOR PARTS OF THE BRAIN

Forebrain: The largest part of the brain with a left and right hemisphere. These are responsible for many functions like learning and memory, speaking and language, having emotional responses, experiencing sensations, initiating voluntary movements, planning and making decisions. Forebrain is the pinkish outer part.

Midbrain: Has a reward/pleasure center; areas for visual and auditory reflexes. It also had 3 different structures.

*Pons: transmits messages between the spinal cord and the brain.

*Medulla: A group of cells that control vital reflexes (Example: breathing, heart rate, blood pressure, etc.)

*Cerebellum: Coordinates motor movements, but not voluntary one; also in timed motor responses and reflexing/automatic learning.

Limbic System: The Old Brain

• group of about half a dozen interconnected structures that make up the core of the forebrain

• involved with regulating many motivational behaviors such as obtaining food, drink, and sex

• organizing emotional behaviors such as fear, anger, and aggression; storing memories

– Structures and functions

– Hypothalamus

– Amygdala

– Thalamus

– Hippocampus

• Hypothalamus

– regulates many motivational behaviors, including eating, drinking, and sexual responses; emotional behaviors such as arousing the body when fighting or fleeing, and secretion of hormones, such as occurs at puberty

• Amygdala

– located in the tip of the temporal lobe

– receives input from all the senses

– evaluates the emotional significance of stimuli and facial expressions, especially those involving fear, distress, or threat

• Thalamus

– gathers and processes information from the senses

– involved in receiving sensory information, doing some initial processing, and then relaying the sensory information to areas of the cortex

• Hippocampus

– curved structure inside the temporal lobe

– Involved in saving many kinds of fleeting memories by putting them into permanent storage in various parts of the brain

• Autonomic nervous system

– Sympathetic

– Parasympathetic

• Sympathetic

– triggered by threatening or challenging physical or psychological stimuli

• Physiological responses

– increased heart rate, increased blood pressure, and dilated pupils

– fight or flight

• Parasympathetic

– decreases physiological arousal

– returns the body to a calmer, more relaxed state

– stimulates digestion during eating

• Physiological responses

– decreases heart rate

– lowers blood pressure

– stimulate digestion

– body returns to more relaxed state

• Homeostasis

– sympathetic and parasympathetic systems work together to keep the body’s level of arousal in balance for optimum functioning

Section F. Endocrine System

Definition:

Endocrine system is made up of numerous glands that are located through the body. These glands secrete various chemicals called hormones, which affect organs , muscles , & other glands in the body

Pancreas :

Is an organ that regulates that level of sugar in the blood stream by secreting insulin.

Dysfunction :

Lack of insulin or a bad pancreas results in a dieses called diabetes while to much causes hypoglycemia (low blood sugar )

Control Center :

In many ways ,the hypothalamus which is located in the lower middle part of the brain ,controls much of the endocrine system by regulating the pituitary gland , which is located directly below and outside the brain. The hypothalamus is often called the control center of the endocrine

Thyroid :

This gland , which is located in the neck , regulates metabolism through secretion of hormones

Adrenal glands :

The adrenal cortex control hormones that regulate sugar and salt balances and help the body resist stress; they are also responsible for growth of pubic hair , a secondary sexual characteristic the adrenal medulla secretes 2 hormones that arouse the body to deal with stress and emergencies : adrenalines and non-adrenaline . lack of cortical hormones , the body’s responses are unable to cope with the stress

Pituitary gland :

A key component of the endocrine system . Divided into 2 (posterior & anterior pituitary )

- Posterior : regulates water & salt balance .

- lack of hormones causes on common form of diabetes .

Posterior pituitary :

Rear portion of pituitary regulates water and salt balances . lack of hormones is less common cause of diabetes .

Anterior pituitary :

Regulates growth through secretion of growth hormone and produces hormones that control adrenal cortex , pancreas , thyroid , and gonads , too little growth hormone produces dwarfism . to much cause gigantism.

Gonads :

- In females , the ovaries produce hormones that regulates sexual development ,ovulation , and growth of sex organs

- In male , the testes produce hormones that regulate sexual development ,production of sperm , and growth of sex organs

Dysfunction – lack of sex hormones during puberty results in lack of secondary sexual characteristics ( facial and body hair ,muscles in males and breasts in females).

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