Human Anatomy and Physiology Quiz

Human Physiology IB Biology 12th

• Unit Guiding Questions:
  • What are the roles of nerves and hormones in integration of body systems?
  • What are the roles of feedback mechanisms in regulation of body systems?

System Integration

• Definition: When components communicate and coordinate.
• Levels of Organization: Organelles, cells, tissues, organs, organ systems, and organisms.
• Emergent Properties: Individual parts combined create new functions.

Cells, Tissues, Organs, and Body Systems

• Hierarchy: Cell organelles -> cells -> tissues -> organs -> organ systems -> organisms
• Emergent Properties: Complex systems have functions that simple components alone do not possess. Examples include muscle cells, liver tissue, epithelium, heart, circulatory system, and the mammal.

Tissue

• Definition: A group of two or more different types of specialized cells with specific structures and functions working together and communicating.
• Example: Type I and Type II pneumocytes in alveolar tissue (lungs) performing gas exchange.

Organ

• Definition: A group of two or more types of tissues working together to perform a specific function in life.
• Example: Lung (alveolar tissue, cartilage tissue, ciliated epithelium tissue); Spongy and palisade mesophyll tissue in a leaf.

Organ System

• Definition: A group of organs working together to perform a function of life.
• Example: Digestive system (esophagus, stomach, intestines, pancreas, and other organs for digestion and nutrient absorption).

Organism

• Definition: A living thing made up of multiple integrated and interdependent systems.
• Example: Humans have 11 organ systems.

Integration of Organs

• Coordination: Requires:
  • Communication:
    • a. Hormones: Chemical substances released by the endocrine system, traveling through the bloodstream to affect target cells.
    • b. Nerves: Electrical impulses rapidly transmitted by neurons to a specific location on muscle or glands.
  • Transport of Materials: Blood/circulatory system carries substances between parts.

Hormones

• Definition: Chemical substances released by the endocrine system.
• Transport: Through bloodstream to the whole body.
• Action: Affect any cell with the proper receptor (target cell).
• Duration: Lasts until the hormone is broken down; slower than nervous signals.

Nervous Signals

• Definition: Electrical impulses (100 m/s) transmitted by neurons.
• Location: Specific muscle or glands.
• Speed: Rapid.
• Duration: Very short.
• Components: The nervous system consists of neurons (dendrites, axon, nucleus, soma, etc.) and synapses.

The Nervous System

• Composition: Neurons that carry electrical impulses, dendrites, motor end plates, and muscle cells.
• Typical Motor Neuron: Includes cell body, cytoplasm, nucleus, axon, impulse, myelin sheath, and synapse.

The Brain

• Central Information Integration:
  • Receives information
  • Stores information
  • Processes information
  • Sends signals to effectors if necessary.

The Spinal Cord

• Two Parts: Central Nervous System and Nerves
• CNS Function: Comprised of brain and spinal cord.
• White Matter Function: Transmits signals - from sensory receptors to the brain, and from the brain to other organs.
• Grey Matter Function: Contains cell bodies and synapses, processing information, decision making, and unconscious processes (e.g., digestive tract movement).

Transport of Materials and Energy

• Blood/Circulatory System: Transports materials throughout the body.
• Example: The digestive system passes intermediate products to other organs.

Involuntary Peristalsis (Intestine)

• Control: The enteric nervous system (ENS)

Sensory Receptors

• External Receptors: Touch, heat, light
• Internal Receptors: Stretch receptors, chemoreceptors

Brain Output

• Different Brain Parts Affect Different Organs: Many neurons in specific brain areas transmit to different effector organs.

Nerves

• Definition: Bundles of nerve fibers surrounded by a sheath.
• Function: Transmit signals in one direction only.
• Components: Sensory and motor neurons.

Reflex Arc (Example: Pain Reflex)

• Definition: Involuntary, rapid response to a stimulus.
• Process: Stimulus, receptor, sensory neuron, interneuron, motor neuron, effector organ.

Cerebellum

• Function: Coordination center that controls timing of muscle contractions, balance, posture, things that require muscle memory.

Homeostasis and Hormones

• Homeostasis: Maintaining stability in the internal environment between specific limits. Limits include pH, CO2, glucose levels, body temperature, and water balance.
• Endocrine System: Glands releasing hormones transported in blood.

Melatonin

• Gland: Pineal gland.
• Function: Controls circadian rhythms (sleep/wake cycles).
• Activity: High levels promote sleep, inhibited by light.

Hormone to Prepare for Vigorous Activity

• Hormone: Epinephrine (adrenaline).
• Adrenal Glands: Release epinephrine to prepare body for "fight or flight," increasing glucose, oxygen supply to skeletal muscles.
• Effects: Hydrolysis of glycogen = glucose. Increased diameter of bronchi/bronchioles: ventilation rates and tidal volume increase; Increase blood flow to liver and muscles; Decrease blood flow to gut and kidneys.

Hypothalamus and Pituitary Gland

• Connection: Hypothalamus attached to pituitary gland, connecting the nervous system and the endocrine system.
• Input: Receives input from other parts of the brain, temperature sensors, and blood glucose/solute concentrations.

Osmoregulation

• Senses: Detects solute concentration/osmolarity.
• Response: Prompts pituitary to release ADH to increase reabsorption in kidneys.
• Hormones: ADH (vasopressin)

Heart Rate Feedback

• SA Node: Connected to the medulla oblongata via the vagus and sympathetic nervous system.
• Feedback Loops: Chemoreceptors (sense pH, increase heart rate if pH is low); Baroreceptors (sense blood pressure, increase heart rate if blood pressure is low); Epinephrine can over ride these.

Ventilation Rate Feedback

• pH of blood: Normal = 7.35-7.45. Low pH = high CO2; drop in pH causes nerve signals to diaphragm and intercostals.
• Negative feedback loop: Relates to changes in ventilation rate during exercise.
• Spirometry used for measurements of rate and tidal volume during exercise.

Peristalsis Control

• Voluntary: Initiated by the central nervous system (CNS), swallowing and defecation (later in life).
• Involuntary: Controlled by the enteric nervous system (ENS), moving food and defecation (early in life).

Neural Signaling

• Nerve Impulse: Electrical signal passed between cells, along the same neuron or between neurons.
• Components: Axon of transmitting neuron, receiving neuron, chemical synapse, synaptic vesicle, neurotransmitter, synaptic cleft, receptor, axon terminals, soma, unmyelinated axon, terminal button, dendrites.

Membrane Potential

• Definition: Voltage created by imbalance of charges(ions).
• Rest: Inside of neuron is relatively negative (-70 mV); sodium ions on the outside.
• Action Potential: Reversal/restoration of electrical potential across plasma membrane.

Nerve Impulse

• Resting Potential: Electrical potential across a cell membrane when not propagating an impulse.
• Action Potential: Reversal/restoration of electrical potential between the inside and outside of a neuron.

Propagation of Action Potential (Nerve Impulse)

• Self-Propagating: Depolarization in one part triggers depolarization in the next due to the opening of voltage-gated channels in a one-way direction.
• Different Propagation Speeds: Myelinated neurons are faster (100 m/s) due to saltatory conduction, while unmyelinated neurons are slower (1 m/s).

Myelination and Saltatory Conduction

• Myelin Sheath: Acts as an insulator, forcing action potentials to "jump" between nodes of Ranvier.
• Saltatory Conduction: Action potentials jump from node to node in myelinated axons, which speeds up transmission.

Synaptic Transmission

• Synapse: Gap between cells where signals (neurotransmitters) are passed.
• Process: Electrical impulse to chemical neurotransmitter, neurotransmitters diffuse across the synapse, bind to the receptor, changes in ion channels, sufficient ion entry can cause action potential; neurotransmitter is removed.

Acetylcholine

• Neurotransmitter: Found between neurons and muscle cells; 2 parts: Acetyl (from respiration) and Choline (from diet).
• Breakdown: Acetylcholinesterase breaks it down quickly, choline reabsorbed to make more acetylcholine.

Threshold Potential

• Critical Level: Membrane potential must reach to initiate an action potential.

Propagation of Action Potential

• Local Currents: Movement of sodium ions between polarized and depolarised regions; causes depolarization in adjacent regions.
• Oscilloscope: Measures membrane potentials through electrodes.

Saltatory Conduction

• Mechanism: Jumping of the nerve impulse in myelinated neurons from node to node. Increases impulse speed.
• Schwann Cells: Act as insulators, carrying currents more quickly between nodes of Ranvier.

Exogenous Chemicals

• Nicotinoids: Insecticide similar to nicotine; irreversible binding to acetylcholine receptors causing paralysis/death in insects.
• Cocaine: Blocks dopamine reuptake causing dopamine buildup and euphoria.

Inhibitory Neurotransmitters

• Action: Some neurotransmitters make the membranes even more negative making it harder to send nerve impulses.

Synaptic Summation

• Excitatory/Inhibitory Summation: Excitatory inputs summate to reach the threshold, inhibitory inputs prevent.

Pain Perception

• Sensory Neurons: Have free nerve endings in the skin.
• Stimulus: Pain is detected; action potential generated.
• Pathway: Impulse travels to spinal column, then to brain.
• Response: Brain sends impulses to motor neurons to affect behavior.

Consciousness

• Definition: Simultaneous awareness of many things.
• Conditions: Reduced consciousness occurs during sleep and/or anesthesia.

Transport in Plants

• Water Transport:
  • Transpiration (evaporation within the leaf)
  • Osmosis (roots absorb water)
  • Cohesion
  • Adhesion
  • Xylem Vessels: Dead, hollow vessels to move water;
    • strengthened by lignin;
    • transferred between cells through pits.
  • Mass Flow - water transported as a continuous stream.

Adaptations of Plants' Transport Structures

• Xylem Vessels: Specialized for efficient water transport, being dead and hollow along with thickened walls of cellulose and lignin.
• Root hairs: Increased surface area for water absorption.

Coronary Artery Occlusion (Causes/Consequences)

• Atherosclerosis: Hardening and narrowing of arteries due to cholesterol deposits. Atheromas develop causing a reduction in vessel diameter.
• Occlusion Consequences: Myocardial tissue death; myocardial infarction(heart attack) due to restricted blood flow- oxygen/nutrient deprivation.
• Risk Factors: Smoking, obesity, lack of exercise, genetics, high blood pressure, diet high in saturated fats/salt, and age.
• Treatment: Bypass surgery, stent placement.