Biology and Behavior Course Notes PDF

Taibah University College of Medical Rehabilitation Sciences Speech-Language Pathology and Audiology Department 1446 (2024-2025) Introduction to Psychology in Medical Rehabilitation Course (ASLP 213) Biology and Behavior...

Taibah University College of Medical Rehabilitation Sciences Speech-Language Pathology and Audiology Department 1446 (2024-2025) Introduction to Psychology in Medical Rehabilitation Course (ASLP 213) Biology and Behavior Dr. Naif Aljabri [email protected]  Biology and Behavior Behavior refers to how people change their actions in response to something happening around them. Our behavior is influenced by a mix of psychological and biological factors. The structure and functioning of our bodies play a significant role in how we act, affecting our tendencies, personalities, and chances of developing mental health issues. Psychological factors also impact how we behave, influencing our overall health and well-being. The nervous system is vital for behavior because it controls all our actions and reactions, including our thoughts and emotions. Understanding how the nervous system influences behavior is key to understanding different psychological disorders.  Role of the nervous system Our nervous system plays a role in everything we do. It helps you move, think and feel. It even regulates the things we do but don’t think about like digestion. The nervous system employs nerve cells, known as neurons (a neuron is a tiny single cell in the nervous system that transmits information.), to transmit signals or messages throughout the body. These electrical signals move between the brain, skin, organs, glands, and muscles. The signals facilitate movement and sensation, such as pain. The eyes, ears, tongue, nose, and peripheral nerves collect information about the environment, which is then relayed to and from the brain by the nerves. These signals control things like: Thoughts, Movements, Senses (how your brain Healing of memory, including processes what you wounds. learning, and balance and see, hear, taste, touch, emotions. coordination. and feel). Sleep patterns. Heartbeat and Response to Digestion. breathing stress, including rhythms. sweating.  Structure of the Nervous System Nervous System Peripheral Central Nervous Nervous System (PNS) System (CNS) Cranial Spinal Brain Spinal cord Nerves Nerves  Branches of the Nervous System The spinal cord is a large column of spinal nerves that transmits information between the brain and the peripheral nervous system (PNS)  Branches of the Nervous System The nervous system can be broken down into two main branches: - Central nervous system (CNS): it consists of the brain, which contains most neurons and does most of the “computing,” and the spinal cord. - Peripheral nervous system (PNS): The peripheral nervous system (PNS) is a part of the nervous system that extends beyond the brain and spinal cord. It includes all the nerves and neurons that lie outside the central nervous system (CNS).  Brain -The brain is composed of many parts that work together to organize our movements, create our thoughts, form our emotions, and produce our behaviors. The brain is supported by the nutrients and oxygen carried by blood vessels and protected by the bones of the skull and three layers of membranes (dura mater, arachnoid mater, and pia mater). These three layers are called “Meninges”. The fluid surrounding the brain acts as a shock absorber.  Brain The Brain is divided into three sections: 1. Forebrain: is home to sensory processing, endocrine structures, and higher reasoning. 2. Midbrain: plays a role in motor movement and audio/visual processing. 3. Hindbrain: is involved with autonomic functions such as respiratory rhythms and sleep. Cerebral Cortex Cerebral Cortex—the outermost and top layer of the brain; each cerebral hemisphere is divided into four lobes—the frontal, parietal, temporal, and occipital lobes—each of which is linked to specific functions. The right and left sides of the brain are linked by a bundle of nerve fibers called the corpus callosum. The frontal lobe is responsible for voluntary movement, reasoning, impulse control, language, and speech. Within the left frontal lobe, Broca’s Area plays a key role in speech production. The parietal lobe primarily handles the processing of touch sensations, limb positioning, and spatial awareness. The temporal lobe is primarily responsible for processing auditory information. Wernicke’s area, located in the temporal lobe, helps interpret sounds by translating various pitches and frequencies into meaningful information. Additionally, the temporal lobe works with the hippocampus to facilitate the formation of long-term memories. Within the left frontal lobe, Wernicke's area controls the ability to understand the meaning of words. The occipital lobe, positioned at the back of the cerebral cortex, serves as the brain's primary center for visual processing. It contains Brodmann Area 17, also known as the primary visual cortex, which is responsible for analyzing the size, shape, and location of objects within the visual field.  The Forebrain The forebrain is the largest part of the human brain. The structures in the forebrain include the cerebrum, thalamus, hypothalamus, pituitary gland, limbic system, and the olfactory bulb. The cerebrum is the area where most critical brain functions occur, including thinking, planning, reasoning, language processing, and interpreting sensory inputs like vision, touch, hearing, taste, and smell. The thalamus carries messages from the sensory organs like the eyes, ears, nose, and fingers to the cortex. The hypothalamus controls your pulse, thirst, appetite, sleep patterns, and other processes in your body that happen automatically The pituitary gland controls various bodily functions by producing hormones that influence growth, sexual and reproductive development, and the functioning of glands (such as the thyroid, adrenal glands, and gonads) as well as organs like the kidneys, uterus, and breasts. The limbic system plays a key role in behavioral and emotional responses, particularly those essential for survival, such as feeding, reproduction, caring for offspring, and the fight-or-flight response. The amygdala is a part of the limbic system, is responsible for processing and storing emotional responses, particularly those related to fear. The factory bulbs collect smell information from the nose and transmit it to the brain through the olfactory tracts.  The Midbrain The midbrain is the topmost part of the brainstem, the connection central between the brain and the spinal cord. There are three main parts of the midbrain - the colliculi, the tegmentum, and the cerebral peduncles. Of the 12 cranial nerves, two thread directly from the midbrain - the oculomotor and trochlear nerves, responsible for eye and eyelid movement. 1. Colliculi are involved in processing visual stimuli, directing attention, and coordinating movements of the eyes and head. 2. Tegmentum plays a crucial role in various essential functions, including arousal, consciousness, sleep-wake cycles, coordination of specific movements, and cardiovascular regulation. 3. Cerebral peduncles serve as the primary pathway for signals traveling from the cortex to other parts of the central nervous system (CNS) and play a crucial role in coordinating body movements. The Hindbrain The hindbrain, found at the rear of the head and resembling a continuation of the spinal cord, includes the medulla oblongata, pons, and cerebellum, which together form the brainstem. This region primarily manages autonomic functions vital for survival. The hindbrain is composed of three key structures: the pons, cerebellum, and medulla. The majority of the 12 cranial nerves are located within this region. Pons: It functions as a coordination center for the signals and communication that pass between the two brain hemispheres and the spinal cord. Cerebellum: It connects sensations with muscle responses, allowing for most voluntary movements. It also processes signals from the inner ear and works with muscles to help maintain balance and posture. Medulla: It transmits signals between the spinal cord and the higher brain regions, while also regulating involuntary functions like swallowing sneezing, heartbeat, and respiration.  Left and Right Hemisphere of the Brain The Left Hemisphere contains language function, logic, problem-solving, and mathematical computation. The Right Hemisphere is concerned with imagination, art, feelings, and spatial relations. Both hemispheres of the brain are involved in most human activities and abilities.  Left and Right Hemisphere of the Brain The brain has specific areas that control different parts of your body, like your hands, feet, or face. The more precise and delicate the movements a body part can make, the more brainpower is dedicated to controlling it. For example, your fingers can do very detailed tasks, so a larger part of your brain is focused on them compared to something like your back, which doesn't need to move as precisely. Neurons Neurons are specialized cells designed to transmit information throughout the body. In contrast, a nerve is a whitish fiber or bundle of fibers composed of multiple neuron cells that carry sensory impulses to the brain or spinal cord and transmit signals from these areas to muscles and organs. The Nerves act like cables, carrying electrical impulses between your brain and the rest of your body. The Nerves are large bundles of many neuron fibers (called axons). Sensory Neurons - nerve cells that carry information received by the sense to the central nervous system. Motor Neurons - are nerve cells that carry information from the central nervous system to the muscles and the glands and influence their functioning.  Parts of the Neuron A neuron consists of three main components: dendrites, an axon, and a cell body, which can be compared to the branches, roots, and trunk of a tree, respectively. The Cell body, comparable to the tree trunk, houses the nucleus, which contains the neuron's DNA, and is the site where proteins are produced and then transported throughout the axon and dendrites. Dendrites, like tree branches, are where a neuron receives input from other cells. As they extend, dendrites branch out toward their ends, similar to how tree branches do, and they even have small, leaf-like structures called spines. The axon is a single threadlike structure that extends from and carries signals away from, the cell body to neighboring neurons, organs, or muscles. Neurotransmitters Neurotransmitters refer to about a dozen different chemicals that are made by neurons and then used for communication between neurons during the performance of mental or physical activities. Excitatory – stimulating the firing of messages, If more exist; messages are sent on their way Inhibitory – slowing the transmission of neural messages, If more exist; messages are slowed or stopped Neurotransmitters Neurotransmitters are often called the body's chemical messengers. They are molecules that the nervous system uses to send messages between neurons or from neurons to muscles. When two neurons communicate, it happens in a small gap called the “synaptic cleft”. In this gap, electrical signals that have traveled along the axon are temporarily changed into chemical signals by releasing neurotransmitters. These chemical signals then trigger a specific response in the receiving neuron.  Types of Neurotransmitters Acetylcholine: controls muscles, is used by the motor neurons of the spinal cord, and stimulates skeletal muscles. Dopamine: controls motor behavior, deficiency in chemical plays a role in Parkinson’s disease, & increase causes schizophrenia. Noradrenaline: prepares the body for action. Serotonin: controls emotional arousal and sleep. Endorphins: decrease the effects of pain during great bodily stress, such as an accident.  The Spinal Cord The spinal cord is a long, tube-like structure that extends from the brain to the lower back. It serves as a pathway for nerve signals traveling between the brain and the rest of the body. These signals are essential for feeling sensations and controlling movement. Damage to the spinal cord can impact movement and bodily functions; Emotional and behavioral issues can arise or intensify following a spinal cord injury. It's common to experience a period of adjustment after such an injury, during which feelings of sadness or anxiety may emerge. Peripheral nervous system (PNS) The peripheral nervous system (PNS) is divided into two main parts: 1. Somatic Nervous System: is the network linking the spinal cord with the body and sense organs. These functions are managed through conscious thought and involve controlling voluntary movements such as Touch and Pain. 2. Autonomic Nervous System: is the collection of neurons that carry information to and from internal organs and glands. This regulates involuntary functions, such as heart rate, digestion, and breathing. It operates automatically without conscious control and is further divided into the sympathetic and parasympathetic nervous systems, which work together to maintain balance in bodily functions. 2.1. Sympathetic nervous system: a network of nerves that helps your body activate its “fight-or-flight” response. 2.2. Parasympathetic nervous system: a network of nerves that relaxes your body after periods of stress or danger.  Endocrine System The endocrine system is made up of glands that produce hormones, which are chemical messengers similar to neurotransmitters but with key differences: Hormones are released into the bloodstream, allowing them to reach and affect cells throughout the body that have the appropriate receptors. Unlike neurotransmitters, which act localized, hormones have widespread effects, are slower to take effect, and have longer-lasting impacts.  Endocrine System Glands Glands are specialized tissues in your body that produce and release substances. Endocrine glands specifically produce hormones and release them directly into your bloodstream. The major endocrine glands in your body include: Pineal gland: A small gland in the brain beneath the back of the corpus callosum that produces the hormone melatonin. Pituitary gland: A pea-sized gland at the base of the brain, below the hypothalamus, that releases eight hormones, some of which stimulate other endocrine glands to release hormones. Thyroid gland: A butterfly-shaped gland at the front of your neck that releases hormones involved in regulating metabolism. Parathyroid glands: Four small glands typically located behind the thyroid, releasing parathyroid hormone (PTH), which regulates blood calcium levels. Adrenal glands: Triangular glands on top of each kidney that release hormones important for metabolism, blood pressure, and stress response.  Endocrine System Organs Certain organs also produce and release hormones. An organ is a structure made up of different types of tissues working toget her to perform specific functions. The organs that are part of the endocrine system include: Hypothalamus: Deep within the brain, this structure links the endocrine and nervous systems, producing hormones like oxytocin and vasopressin, which are stored in the pituitary gland, as well as dopamine and somatostatin. Pancreas: Located in the back of the abdomen, it functions as both an organ and a gland, releasing insulin and glucagon, which are essential for regulating blood sugar levels. Adipose tissue (body fat): Found throughout the body, this connective tissue releases hormones such as leptin, angiotensin, and adiponectin. Ovaries: Small, oval-shaped glands on either side of the uterus that produce eggs and release sex hormones regulating the menstrual cycle and pregnancy. Testicles (testes): Small, round organs in the scrotum that produce sperm and sex hormones, especially testosterone. The relationship between hormones and behavior is bidirectional, with behaviors influencing hormone levels just as hormones affect behavior.  Brain Scans Electroencephalogram (EEG) An EEG is a test that identifies irregularities in brain waves or electrical activity in the brain. During the procedure, electrodes are attached to the scalp. An EEG is utilized to assess various brain disorders. In cases of epilepsy, seizure activity shows up on the EEG as rapid spiking waves. Individuals with brain lesions, which can occur due to tumors or strokes, might exhibit very slow EEG waves, depending on the lesion's size and location. The test helps diagnose other conditions that affect brain activity, such as Alzheimer’s disease, certain psychoses, and the sleep disorder narcolepsy. Computed Tomography (CT) Brain Scan A brain CT scan is a noninvasive imaging technique that uses specialized X-ray measurements to create horizontal or axial images, often referred to as slices, of the brain. These scans offer more detailed information about brain tissue and structures than standard head X-rays, making them more effective in detecting brain injuries or diseases.  Brain MRI (magnetic resonance imaging) scan A brain (head) MRI scan is a painless procedure that generates highly detailed images of the structures within the head, primarily the brain. Healthcare providers utilize brain MRIs to assess, diagnose, and monitor various medical conditions affecting the brain or other structures in the head.  Positron emission tomography (PET) Positron emission tomography (PET) scans are used to identify early indicators of cancer, heart disease, and brain conditions. The process involves injecting a safe radioactive tracer that aids in detecting diseased cells. References: 1. Coon, D., Mitterer, J. O., & Martini, T. (2021). Introduction to Psychology: Gateways to Mind and Behavior (16th ed.). Cengage. 2. Frese, M., & Sabini, J. (2021). Goal directed behavior. Taylor & Francis. 3. O’Kane, D. (2023). Psychology: An introduction for health professionals. Elsevier Health Sciences. 4. World Health Organization. (2022). Mental health. World Health Organization. 5. https://www.who.int/news-room/fact-sheets/detail/mental-health-strengthening-our-response