bio 4

Energy Balance and Metabolism

• Overview: Energy balance refers to the relationship between energy intake and energy expenditure, which is crucial for maintaining body weight. Metabolism encompasses all biochemical processes that convert food into energy, regulated by hormones and influenced by factors such as exercise and temperature.

• Blood Glucose Regulation:

  • Mechanisms to increase blood glucose during postabsorptive state.

  • Role of liver in gluconeogenesis and glycogenolysis.

• Insulin and Glucose Relationship:

  • Insulin's role in lowering blood glucose levels.

  • Reciprocal changes in insulin and glucose concentrations.

• Exercise and Energy Demands:

  • Increased energy requirements during physical activity.

  • Activation of metabolic pathways to meet energy needs.

• Basal Metabolic Rate (BMR):

  • Definition: The rate of energy expenditure at rest.

  • Measurement methods: Indirect calorimetry or direct calorimetry.

• Hormonal Regulation:

  • Hormones like insulin, glucagon, leptin, and ghrelin influence metabolism and appetite.

  • Interaction of hormones with receptors to regulate energy balance.

• Temperature Effects on Metabolism:

  • Impact of temperature on chemical reactions and metabolic rates.

  • Changes in protein function and membrane structure due to temperature variations.

Excretory Systems

• Overview: Excretory systems are responsible for the removal of nitrogenous wastes and regulation of water and electrolyte balance in organisms. They involve complex processes such as filtration, reabsorption, secretion, and excretion, primarily carried out by the kidneys and urinary system components.

• Nitrogenous Wastes:

  • Forms include ammonia, urea, and uric acid.

  • Vary based on the organism's habitat and evolutionary adaptations.

• Filtration Processes:

  • Involves glomerular filtration in kidneys.

  • Key processes: filtration, reabsorption, secretion, and excretion.

• Kidney Structure:

  • Composed of nephrons, the functional units.

  • Common structural features across vertebrates include renal cortex, medulla, and pelvis.

• Urinary System Components:

  • Major components: kidneys, ureters, bladder, and urethra.

  • Human kidney anatomy includes renal arteries, veins, and nephron structures.

• Hormonal Regulation of Urine Composition:

  • Hormones like aldosterone and antidiuretic hormone (ADH) regulate sodium and water reabsorption.

  • ADH increases water permeability in collecting ducts, affecting urine concentration.

Endocrine Systems

• Overview: The endocrine system is a network of glands that produce and secrete hormones to regulate various bodily functions, including metabolism, growth, and mood. It works in conjunction with the nervous system to maintain homeostasis through chemical signaling.

• Hormone Classes:

  • Peptide Hormones: Water-soluble, made of amino acids (e.g., insulin).

  • Steroid Hormones: Lipid-soluble, derived from cholesterol (e.g., cortisol).

  • Amine Hormones: Derived from single amino acids (e.g., epinephrine).

• Receptor Locations:

  • Lipid-Soluble Hormones: Receptors located inside target cells (cytoplasm or nucleus).

  • Water-Soluble Hormones: Receptors located on the cell membrane.

• Hypothalamus and Pituitary Function:

  • Hypothalamus regulates hormone release from the pituitary gland.

  • Anterior pituitary produces hormones like ACTH, TSH, and GH; posterior stores and releases oxytocin and ADH.

• Posterior Pituitary Hormones:

  • Oxytocin: Stimulates uterine contractions and milk ejection.

  • Antidiuretic Hormone (ADH): Regulates water balance by promoting water reabsorption in kidneys.

• Pancreas and Adrenal Glands Hormones:

  • Pancreas: Produces insulin (lowers blood glucose) and glucagon (raises blood glucose).

  • Adrenal Glands: Produce cortisol (stress response), aldosterone (regulates sodium/potassium), and adrenaline (fight-or-flight response).

• Diabetes Mellitus Distinctions:

  • Type 1 Diabetes: Autoimmune destruction of insulin-producing beta cells; requires insulin therapy.

  • Type 2 Diabetes: Insulin resistance; often managed with lifestyle changes and medications.

Nervous System

• Overview: The nervous system is a complex network that coordinates actions and sensory information by transmitting signals between different parts of the body. It consists of two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS), which work together to process and respond to stimuli.

• Central Nervous System (CNS):

  • Comprises the brain and spinal cord.

  • Responsible for processing information and coordinating responses.

• Peripheral Nervous System (PNS):

  • Consists of all nerves outside the CNS.

  • Connects the CNS to limbs and organs, facilitating communication.

• Neuron Structure:

  • Key components include dendrites, cell body, axon, and axon terminals.

  • Each part has a specific function related to signal transmission.

• Neurons Types:

  • Sensory Neurons: Transmit sensory information to the CNS.

  • Motor Neurons: Convey commands from the CNS to muscles and glands.

  • Interneurons: Connect neurons within the CNS, processing information.

• Reflexes:

  • Automatic responses to stimuli, crucial for survival.

  • Involve sensory input, interneuron processing, and motor output.

• Membrane Potential:

  • Refers to the voltage difference across a neuron's membrane.

  • Essential for generating action potentials and neuronal signaling.

• Action Potential:

  • A rapid change in membrane potential that propagates along the axon.

  • Initiated at the axon hillock when threshold potential is reached.

• Synapse Structure:

  • Junction between neurons where neurotransmission occurs.

  • Composed of presynaptic terminal, synaptic cleft, and postsynaptic membrane.

• Neurotransmitters:

  • Chemical messengers released at synapses to transmit signals.

  • Classes include excitatory (e.g., glutamate) and inhibitory (e.g., GABA) neurotransmitters.

• Receptor Types:

  • Ligand-gated Ion Channels: Open in response to binding of neurotransmitters.

  • Voltage-gated Ion Channels: Open in response to changes in membrane potential.