BIO TEST REVIEW PDF

1. Anatomical Directional Terms Understand the anatomical directional terms and how they can be used to compare various parts: Superior: above Inferior: below Anterior/Ventral: front Posterior/Dorsal: back Lateral: toward the side Medial: toward the middle...

1. Anatomical Directional Terms Understand the anatomical directional terms and how they can be used to compare various parts: Superior: above Inferior: below Anterior/Ventral: front Posterior/Dorsal: back Lateral: toward the side Medial: toward the middle Superficial: (closer to) the surface of the body Deep: within the body; away from the surface Proximal: toward the point of attachment (primarily used in reference to limbs) Distal: away from the point of attachment (primarily used in reference to limbs) 2. Biological Organization of Humans Know the biological organization of humans, from least to the most complex: Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism 3. Body Cavities and Membranes Know the different body cavities, the membranes/fluids lining those cavities, and the organs found within those cavities: Ventral Cavity (divided by the diaphragm) Thoracic cavity: Lungs, Heart Abdominal cavity: Digestive organs Pelvic cavity: Rectum, Bladder, Reproductive organs Dorsal Cavity Cranial cavity: Brain Spinal cavity: Spinal cord Membranes: Mucous membranes: Line digestive, respiratory, and urinary organs; contain Goblet cells that secrete fluid; protect.  Serous membranes: Line thoracic and abdominal cavities; cover organs with serous fluid for lubrication. o Pleura: Thoracic cavity and lungs o Peritoneum: Abdominal cavity o Pericardium: Cardiac cavity Synovial membranes: Line freely movable joints and secrete synovial fluid for lubrication. Meninges: Protect the brain and spinal cord; secrete cerebrospinal fluid. 4. Types of Tissues (CMEN) Know the names and characteristics of the 4 types of tissues: 1. Connective Tissue Supports and bonds body parts Found throughout the body, binds organs together, and fills spaces 2. Muscle Tissue Composed of muscle fibers; responsible for movement (contract/relax) o Smooth Muscle: Involuntary, no striations, spindle-shaped, found in blood vessels and viscera. o Cardiac Muscle: Involuntary, striated with intercalated disks, found in the heart. o Skeletal Muscle: Voluntary, striated, cylindrical, multinucleated, attached to bones. 3. Epithelial Tissue Functions: Protection, Secretion, Absorption, Filtration, Excretion o Simple Squamous: Single layer of flattened cells; found in alveoli and blood vessels. o Simple Cuboidal: Single layer of cube-like cells; found in kidney tubules. o Simple Columnar: Single layer of column-like cells; found in small intestine, uterine tubes. o Pseudostratified/Ciliated Columnar: Appears layered but all cells touch the basement membrane; found in the trachea. o Stratified Squamous: Multi-layered flattened cells; found in the mouth, esophagus, and skin. 4. Nervous Tissue Neurons: Conduct electrical nerve impulses.  Neuroglia: Support, nourish, and protect neurons; examples include Astrocytes, Oligodendrocytes, Microglia, Ependymal cells. 5. Arrangement of Layers in Gastrointestinal Organs Know the arrangement of various layers found in the gastrointestinal organs: Mucosa → Submucosa → Muscularis → Serosa/Adventitia 1. Anatomy & Function of a Neuron: Anatomy: o A neuron consists of three main parts: the cell body, dendrites, and axon. § Cell body: Contains the nucleus and organelles. § Dendrites: Receive signals from other neurons. § Axon: Conducts nerve impulses away from the cell body and often ends in synaptic terminals. Function: o Neurons transmit electrical impulses (action potentials) across the nervous system, enabling communication between different parts of the body. 2. Steps Involved in Action Potential: a) What it is: An action potential is a rapid, transient electrical signal that travels along the axon of a neuron. It involves a change in membrane potential from negative to positive and back, which is essential for neural communication. b) Process and Amount of Electrical Current in mV for Each Step: 1. Resting Membrane Potential: o The neuron is at rest, with a membrane potential of -70 mV. This is maintained by the sodium-potassium pump and the differential distribution of ions (Na⁺ outside and K⁺ inside). 2. Depolarization: o Threshold: The membrane potential reaches -55 mV. o Sodium (Na⁺) channels open: Sodium ions rush into the neuron, causing a positive shift in membrane potential, peaking at about +35 mV. 3. Repolarization:  o Potassium (K⁺) channels open: Potassium ions leave the neuron, and the membrane potential begins to return toward its resting state, dropping back to around -70 mV. 4. Refractory Period: o During this period, the neuron cannot be re-stimulated until the membrane potential is restored. o The sodium-potassium pump actively restores the resting membrane potential by moving Na⁺ out and K⁺ back into the cell. 3. Three Classes of Neurons and Their Function: Sensory Neurons (Afferent Neurons): o Function: Bring sensory information from the peripheral body to the CNS. o Structure: Often have specialized receptors for stimuli like light, touch, or temperature. Interneurons (Relay Neurons): o Function: Connect sensory and motor neurons within the CNS. o Structure: Usually unmyelinated and form complex neural networks within the brain and spinal cord. Motor Neurons (Efferent Neurons): o Function: Transmit impulses from the CNS to muscles or glands, causing a response. o Structure: Often myelinated to speed up signal transmission. 4. Electrochemical Synapse: a) Why it is needed: Electrochemical synapses convert electrical signals into chemical signals. This is essential for communication between neurons, as the electrical signal in the axon cannot jump the synaptic gap. b) Steps Involved in the Process: 1. Action potential reaches the synaptic terminal: This triggers the opening of calcium channels. 2. Calcium influx: Calcium ions enter the pre-synaptic neuron, causing synaptic vesicles to move toward the synaptic membrane. 3. Neurotransmitter release: The vesicles release neurotransmitters into the synaptic cleft. 4. Neurotransmitter binding: Neurotransmitters bind to receptors on the post-synaptic neuron, leading to a change in its membrane potential.  Diagram labeling: Label the pre-synaptic neuron, post-synaptic neuron, synaptic vesicles, synaptic cleft, and neurotransmitter receptors. 5. Role of Neuroglial Cells in Supporting Neurons: CNS: o Microglia: Act as immune cells, clearing damaged neurons and pathogens. o Oligodendrocytes: Produce myelin in the CNS to insulate axons and speed up signal transmission. o Astrocytes: Provide structural support, transport nutrients, and maintain the blood-brain barrier. o Ependymal Cells: Produce cerebrospinal fluid (CSF), which cushions and nourishes the CNS. PNS: o Schwann Cells: Produce myelin in the peripheral nervous system by wrapping around axons. Each Schwann cell myelinates only one segment of an axon. o Satellite Cells: Support neuron cell bodies in the PNS, particularly in sensory and autonomic ganglia. 6. Different Types of Conduction in Unmyelinated vs. Myelinated Neurons: Unmyelinated Neurons: o Conduction: Action potentials move along the entire length of the axon, causing slower transmission. The impulse travels continuously. Myelinated Neurons: o Conduction (Saltatory Conduction): Myelin insulates the axon, causing the action potential to jump from node of Ranvier to node of Ranvier. This speeds up the impulse, making the transmission more efficient and conserving energy. 1. Anatomy & Function of a Neuron: Anatomy: o A neuron consists of three main parts: the cell body, dendrites, and axon. § Cell body: Contains the nucleus and organelles. § Dendrites: Receive signals from other neurons. § Axon: Conducts nerve impulses away from the cell body and often ends in synaptic terminals. Function: o Neurons transmit electrical impulses (action potentials) across the nervous system, enabling communication between different parts of the body. 2. Steps Involved in Action Potential: a) What it is: An action potential is a rapid, transient electrical signal that travels along the axon of a neuron. It involves a change in membrane potential from negative to positive and back, which is essential for neural communication. b) Process and Amount of Electrical Current in mV for Each Step: 1. Resting Membrane Potential: o The neuron is at rest, with a membrane potential of -70 mV. This is maintained by the sodium-potassium pump and the differential distribution of ions (Na⁺ outside and K⁺ inside). 2. Depolarization: o Threshold: The membrane potential reaches -55 mV. o Sodium (Na⁺) channels open: Sodium ions rush into the neuron, causing a positive shift in membrane potential, peaking at about +35 mV. 3. Repolarization: o Potassium (K⁺) channels open: Potassium ions leave the neuron, and the membrane potential begins to return toward its resting state, dropping back to around -70 mV. 4. Refractory Period: o During this period, the neuron cannot be re-stimulated until the membrane potential is restored. o The sodium-potassium pump actively restores the resting membrane potential by moving Na⁺ out and K⁺ back into the cell. 3. Three Classes of Neurons and Their Function: Sensory Neurons (Afferent Neurons): o Function: Bring sensory information from the peripheral body to the CNS. o Structure: Often have specialized receptors for stimuli like light, touch, or temperature. Interneurons (Relay Neurons): o Function: Connect sensory and motor neurons within the CNS. o Structure: Usually unmyelinated and form complex neural networks within the brain and spinal cord. Motor Neurons (Efferent Neurons): o Function: Transmit impulses from the CNS to muscles or glands, causing a response. o Structure: Often myelinated to speed up signal transmission. 4. Electrochemical Synapse: a) Why it is needed: Electrochemical synapses convert electrical signals into chemical signals. This is essential for communication between neurons, as the electrical signal in the axon cannot jump the synaptic gap. b) Steps Involved in the Process: 1. Action potential reaches the synaptic terminal: This triggers the opening of calcium channels. 2. Calcium influx: Calcium ions enter the pre-synaptic neuron, causing synaptic vesicles to move toward the synaptic membrane. 3. Neurotransmitter release: The vesicles release neurotransmitters into the synaptic cleft. 4. Neurotransmitter binding: Neurotransmitters bind to receptors on the post-synaptic neuron, leading to a change in its membrane potential. Diagram labeling: Label the pre-synaptic neuron, post-synaptic neuron, synaptic vesicles, synaptic cleft, and neurotransmitter receptors. 5. Role of Neuroglial Cells in Supporting Neurons: CNS: o Microglia: Act as immune cells, clearing damaged neurons and pathogens. o Oligodendrocytes: Produce myelin in the CNS to insulate axons and speed up signal transmission. o Astrocytes: Provide structural support, transport nutrients, and maintain the blood-brain barrier. o Ependymal Cells: Produce cerebrospinal fluid (CSF), which cushions and nourishes the CNS. PNS: o Schwann Cells: Produce myelin in the peripheral nervous system by wrapping around axons. Each Schwann cell myelinates only one segment of an axon. o Satellite Cells: Support neuron cell bodies in the PNS, particularly in sensory and autonomic ganglia. 6. Different Types of Conduction in Unmyelinated vs. Myelinated Neurons: Unmyelinated Neurons: o Conduction: Action potentials move along the entire length of the axon, causing slower transmission. The impulse travels continuously.  Myelinated Neurons: o Conduction (Saltatory Conduction): Myelin insulates the axon, causing the action potential to jump from node of Ranvier to node of Ranvier. This speeds up the impulse, making the transmission more efficient and conserving energy. Introduction to the Human Brain Meninges: Protective layers around the brain and spinal cord. o Dura mater, arachnoid mater, pia mater are the three layers. o Cerebrospinal fluid (CSF) keeps these layers moist. Brain Structure: Speaker 1 compares the brain to a walnut, highlighting its two hemispheres. o Cerebrum: Largest part of the brain, outermost layer. Detailed Anatomy of the Brain Cerebrum: The largest and most superficial part of the brain. o Corpus callosum: Connects the left and right hemispheres. Diencephalon: Includes several critical structures. o Thalamus, hypothalamus, pituitary gland, pineal gland. Brainstem: Comprised of the midbrain, pons, and medulla oblongata, responsible for vital functions. Functional Roles of Brain Regions Cerebrum: Responsible for higher-level cognition and thinking. Brain Stem: Controls basic instincts such as breathing and heartbeat. Cerebellum: Coordinates movements and maintains balance. Cerebral Lobes and Their Functions 1. Frontal Lobe: Associated with thinking, decision-making, motor movements. 2. Parietal Lobe: Processes sensations like pain, temperature, and pressure. 3. Occipital Lobe: Responsible for vision. 4. Temporal Lobe: Involved in hearing and understanding language. Language and Speech Areas Broca's Area (Frontal lobe): Controls speech production and motor aspects of speaking. Wernicke's Area (Temporal lobe): Responsible for understanding language and speech perception. Charting these functions is essential for memorization. Diencephalon and Limbic System Thalamus: Acts as a sensory relay station. Hypothalamus: Regulates homeostasis (temperature, water balance, hunger, etc.). Pituitary Gland: Controls hormone release. Pineal Gland: Regulates sleep-wake cycles. Limbic System: Includes amygdala (emotion) and hippocampus (memory). Brain Stem and Its Functions Midbrain: Connects cerebellum and cerebrum; controls reflexes. Pons: Involved in relaxation and urination. Medulla Oblongata: Manages heart rate, breathing, and other life-sustaining functions. Neuroplasticity and Memory Neuroplasticity: Brain’s ability to form new neural connections. Hippocampus: Converts short-term memory to long-term memory. Olfaction: Plays a role in memory, with interconnected sensory areas. Impact of Brain Injuries and Dementia Brain injuries can affect functions like hearing, language, and memory. Dementia affects multiple brain regions, not just the hippocampus. 1. Arrangement of White and Gray Matter: o Gray Matter: Located centrally in the spinal cord, shaped like a butterfly or the letter "H." It contains cell bodies of motor neurons, interneurons, and synapses. It is responsible for processing sensory and motor information. o White Matter: Surrounds the gray matter and contains myelinated axons that carry information to and from the brain. It is organized into ascending (sensory) and descending (motor) tracts. 2. Dorsal and Ventral Fibers:  oDorsal Root: Contains sensory fibers that transmit sensory information from the body to the spinal cord (afferent). o Ventral Root: Contains motor fibers that transmit motor commands from the spinal cord to muscles and glands (efferent). o Dorsal Horn: Located in the gray matter; it receives sensory input from the dorsal roots. o Ventral Horn: Located in the gray matter; it sends motor output to muscles via the ventral roots. 3. Composition of a Spinal Nerve: o A spinal nerve is formed by the merging of the dorsal (sensory) and ventral (motor) roots at the spinal cord. o It is a mixed nerve, meaning it carries both sensory and motor information. o Spinal nerves are classified into different segments: cervical, thoracic, lumbar, sacral, and coccygeal. Somatic Reflex Arc 1. Involvement of Neurons in Somatic Reflexes: o Sensory Neuron (Afferent): Detects a stimulus (e.g., pain) and sends the signal to the spinal cord. o Interneuron: In the spinal cord, the interneuron processes the signal and connects the sensory and motor neurons. o Motor Neuron (Efferent): Transmits the motor response from the spinal cord to the muscle, causing an action (e.g., muscle contraction in response to pain). o The somatic reflex arc bypasses the brain to provide a rapid response. The sensory neuron triggers a motor response via the spinal cord's interneuron, allowing a fast, involuntary movement (e.g., pulling hand away from a hot object). Autonomic Nervous System (ANS) 1. Difference Between Sympathetic and Parasympathetic Nervous Systems: o Sympathetic Nervous System: § Fight-or-flight response. § Increases heart rate, blood pressure, and respiration rate. § Dilates pupils, inhibits digestion. § Activates adrenaline (epinephrine) release from adrenal glands. § Example: Increased heart rate during physical exertion or stress. o Parasympathetic Nervous System: § Rest-and-digest response. § Lowers heart rate, blood pressure, and respiration rate. § Stimulates digestion and decreases blood flow to muscles.  § Example: Decreased heart rate and digestion after eating or relaxing. 2. Examples of How Each Division Affects Different Organs: o Sympathetic System: § Heart: Increases heart rate and force of contraction. § Lungs: Dilates bronchioles to increase airflow. § Pupils: Dilates pupils to improve vision in low light. § Gastrointestinal Tract: Inhibits peristalsis, reduces digestive activity. o Parasympathetic System: § Heart: Decreases heart rate. § Lungs: Constricts bronchioles to reduce airflow. § Pupils: Constricts pupils to limit light entry. § Gastrointestinal Tract: Stimulates peristalsis and secretion of digestive enzymes.