Physiology Chapter - Hormones and Enzymes
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Questions and Answers

Which type of hormone can diffuse through the membrane of target cells due to being nonpolar?

  • Peptide hormones
  • Amine hormones
  • Amino acid-based hormones
  • Steroid hormones (correct)

What is a common characteristic of lipophobic messengers?

  • They are released by exocytosis. (correct)
  • They can be stored ahead of time in the cell.
  • They bind to intracellular receptors.
  • They diffuse through the cell membrane.

Which type of receptor is NOT found on the membrane of target cells for lipophobic messengers?

  • G protein coupled receptors
  • Intracellular receptors (correct)
  • Ligand-gated channels
  • Enzyme-linked receptors

Why can't lipophilic hormones be made and stored ahead of time within the cell?

<p>They would diffuse right out of the cell. (A)</p> Signup and view all the answers

Which of the following is an example of a lipophobic messenger?

<p>Peptide hormone (B)</p> Signup and view all the answers

What role do small activators and inhibitors play in enzyme regulation?

<p>They change the enzyme's affinity for the substrate. (A)</p> Signup and view all the answers

Which type of bond is primarily involved in allosteric regulation of enzymes?

<p>Hydrogen bonds (D)</p> Signup and view all the answers

What is the primary function of epithelial tissue?

<p>To form barriers between internal and external environments. (D)</p> Signup and view all the answers

How does covalent modification of enzymes affect their activity?

<p>It creates a stronger bond that results in longer-lasting changes. (D)</p> Signup and view all the answers

Which statement best describes connective tissue?

<p>It has scattered cells within an extensive extracellular matrix. (A)</p> Signup and view all the answers

What is the hierarchical structure of the body starting from the simplest level?

<p>Cells, tissues, organs, organ systems. (C)</p> Signup and view all the answers

Which type of gland is responsible for secreting hormones into the bloodstream?

<p>Endocrine gland (B)</p> Signup and view all the answers

In what way do enzymes contribute to speeding up reactions?

<p>By providing an alternative pathway with lower activation energy. (C)</p> Signup and view all the answers

What triggers the release of cortisol in the body?

<p>Stressful situations like surgery or illness (D)</p> Signup and view all the answers

Which hormones are responsible for regulating testosterone production?

<p>GnRH, LH, and FSH (D)</p> Signup and view all the answers

What is a key function of the seminiferous tubules in the male reproductive system?

<p>Production of sperm (A)</p> Signup and view all the answers

How many chromosomes do sperm and eggs each contain?

<p>23 chromosomes (D)</p> Signup and view all the answers

What is the role of cortisol during stress?

<p>To stimulate breakdown of proteins and fats for energy (C)</p> Signup and view all the answers

In which part of the male reproductive system does sperm maturation occur?

<p>Epididymis (A)</p> Signup and view all the answers

What can long-term stress result in with respect to the HPA axis?

<p>Stimulation of CRH secretion (C)</p> Signup and view all the answers

What is the consequence of stereotype threat on cognitive performance?

<p>Increased cognitive load and underperformance (C)</p> Signup and view all the answers

What is the equilibrium potential for K+ in millivolts?

<p>-90 mV (C)</p> Signup and view all the answers

What is the primary reason for the resting membrane potential to be around -70 mV?

<p>Continuous K+ leakage out of the cell (B)</p> Signup and view all the answers

What triggers the opening of voltage-gated ion channels during an action potential?

<p>Depolarization above a certain threshold (D)</p> Signup and view all the answers

What happens to Na+ channels during the action potential phase?

<p>They inactivate after about 1 millisecond (D)</p> Signup and view all the answers

What is hyperpolarization in the context of neuronal activity?

<p>Vm is more negative than the resting potential (B)</p> Signup and view all the answers

What is the role of the Na+/K+ pump in maintaining the negative membrane potential?

<p>Pumping 3 Na+ out for every 2 K+ in (A)</p> Signup and view all the answers

Why can action potentials travel long distances without decreasing in strength?

<p>The myelin sheath and Schwann cells (C)</p> Signup and view all the answers

Which of the following correctly describes the nature of action potentials?

<p>They are defined as all or nothing events (A)</p> Signup and view all the answers

What is the primary function of the SA node in the heart?

<p>To initiate the heartbeat (C)</p> Signup and view all the answers

Which type of valve is located between the atria and the ventricles?

<p>Atrioventricular valve (C)</p> Signup and view all the answers

What structure allows direct and rapid spread of ions between cardiac muscle cells?

<p>Gap junctions (B)</p> Signup and view all the answers

Why do veins have one-way valves?

<p>To prevent backflow of blood (D)</p> Signup and view all the answers

Which of the following correctly describes the sequence of blood flow through the heart chambers?

<p>Atria → Ventricles → Arteries (C)</p> Signup and view all the answers

How do action potentials in pacemaker cells differ from those in neurons?

<p>They involve different types of voltage-gated channels. (B)</p> Signup and view all the answers

Under which condition do the AV valves open?

<p>When Patria &gt; Pvent (A)</p> Signup and view all the answers

What role do desmosomes play in cardiac muscle cells?

<p>Provide strong cell adhesion (A)</p> Signup and view all the answers

What effect does bronchoconstriction have on airflow in the respiratory system?

<p>Decreases airflow by contracting smooth muscles (D)</p> Signup and view all the answers

During gas exchange in the lungs, what is the direction of oxygen diffusion?

<p>From the alveoli into the blood (A)</p> Signup and view all the answers

Which of the following conditions would shift the hemoglobin saturation curve to the right?

<p>Increased CO2 levels (D)</p> Signup and view all the answers

What percentage of oxygen is typically unloaded to tissues at rest?

<p>25% (C)</p> Signup and view all the answers

What is the primary mechanism by which CO2 is transported in the blood?

<p>Converted to bicarbonate (B)</p> Signup and view all the answers

What does the term 'partial pressure' refer to in the context of gases?

<p>The pressure exerted by a specific gas in a mixture (B)</p> Signup and view all the answers

What occurs during bronchodilation?

<p>Sympathetic nervous system stimulates relaxation of smooth muscle (B)</p> Signup and view all the answers

Which factor does NOT influence hemoglobin's affinity for oxygen?

<p>Total blood volume (D)</p> Signup and view all the answers

Flashcards

Lipophobic Messengers

Signaling molecules that cannot cross the cell membrane due to their polarity. They rely on membrane receptors for interaction with the target cell.

Lipophilic Messengers

Signaling molecules that can readily cross the cell membrane due to their non-polar nature. They interact with receptors inside the target cell.

Ligand-gated Channel (Ionotropic Receptor)

A type of membrane receptor that directly opens an ion channel upon ligand binding, altering the flow of ions across the cell membrane.

Enzyme-linked Receptor

A type of membrane receptor that activates an enzyme upon ligand binding, initiating intracellular signaling cascades.

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G Protein-coupled Receptor (Metabotropic Receptor)

A type of membrane receptor that activates a G protein upon ligand binding, triggering downstream signaling pathways.

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What do enzymes do?

Enzymes are proteins that speed up chemical reactions in cells by lowering the activation energy required to start the reaction.

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What is the active site of an enzyme?

The active site is the specific part of an enzyme where the substrate binds.

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How do cells regulate enzyme activity?

Cells can control enzyme activity by increasing or decreasing the amount of enzyme present, or by using activators or inhibitors.

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What is allosteric regulation?

Enzymes can be regulated by small molecules called activators or inhibitors that bind to a site outside the active site, called the allosteric site.

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What is covalent modification?

Covalent modifications, such as adding a phosphate group, can change an enzyme's activity and are often longer lasting than allosteric regulation.

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What is epithelial tissue?

Epithelial tissue forms continuous sheets of cells that line the inside of body tubes, separate the internal environment from the external environment, and make up glands.

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What is connective tissue?

Connective tissue provides structural support for the body and is made up of scattered cells in an extracellular matrix. Examples include blood, bones, tendons, and fat.

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What is muscle tissue?

Muscle tissue is specialized for contraction and is responsible for movement. There are three types: skeletal, smooth, and cardiac.

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HPA axis

The hypothalamic-pituitary-adrenal (HPA) axis is a complex neuroendocrine system that regulates the body's response to stress. It involves the hypothalamus, pituitary gland, and adrenal glands, working together to release hormones like corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and cortisol.

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Cortisol

Cortisol is a hormone produced by the adrenal glands in response to stress. It helps the body cope with stress by increasing blood glucose levels, suppressing the immune system, and promoting protein and fat breakdown.

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Stereotype threat

Stereotype threat is a psychosocial phenomenon where individuals are at risk of confirming negative stereotypes about their social group. This awareness creates anxiety and stress, leading to impaired performance.

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What is hypersecretion?

Hypersecretion is the excessive production of hormones by endocrine glands. It can be caused by tumors or other factors, disrupting normal hormone balance.

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What are gametes?

Gametes are specialized reproductive cells (sperm and eggs) that carry half of the genetic information needed to create a new organism.

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Fertilization

The process of fertilization involves the union of a sperm cell and an egg cell, combining their genetic material to form a diploid zygote.

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What are sperm?

Sperm are male gametes produced in the seminiferous tubules of the testes. They contain a haploid set of chromosomes and travel through the reproductive tract to reach the egg.

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Intercalated Disks

These specialized connections between cardiac muscle cells allow for rapid and efficient electrical conduction throughout the heart.

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What is semen?

Semen is a fluid mixture that contains sperm and secretions from various glands, including the seminal vesicles, prostate gland, and bulbourethral gland. Its main function is to transport and nourish sperm during ejaculation.

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Desmosomes

Structures within intercalated disks that provide strong cell-to-cell adhesion, ensuring the heart muscle functions as a cohesive unit.

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Gap Junctions

Channels that allow for direct passage of ions between adjacent cardiac cells, enabling rapid electrical impulse propagation.

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SA Node

The main pacemaker of the heart, located in the right atrium, responsible for initiating each heartbeat.

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Pacemaker Cells

Specialized cells in the heart that generate their own electrical impulses without input from the nervous system, controlling the heartbeat rate.

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Funny Channels

Unique ion channels found in pacemaker cells that contribute to their spontaneous depolarization, setting the heart's rhythm.

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Atrioventricular (AV) Valves

One-way valves located between the atria and ventricles of the heart, preventing backflow of blood from the ventricles to the atria.

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Semilunar (SL) Valves

One-way valves located between the ventricles and arteries of the heart, preventing backflow of blood from the arteries to the ventricles.

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Equilibrium Potential

The electrical charge inside a cell when an ion has reached equilibrium across the cell membrane. It represents the theoretical point where there's no net movement of that specific ion.

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Depolarization

This occurs when the membrane potential of a neuron becomes more positive, moving closer to zero. It's the first step towards an action potential.

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Hyperpolarization

A cell becomes more negative inside, moving further away from zero. This can happen after an action potential to bring the membrane back to resting potential.

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Resting Membrane Potential

The negative charge that a neuron normally maintains at rest (-70mV). It's mostly determined by the permeability of potassium ions and the action of the sodium-potassium pump.

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Sodium-Potassium Pump

The process where sodium and potassium ions are transported across the cell membrane, with 3 sodium ions being pumped out and 2 potassium ions being pumped in. This helps maintain the resting membrane potential and the ion gradients.

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Voltage-gated Ion Channels

These specialized proteins embedded in the axon membrane open when the membrane potential crosses a certain threshold. They are essential for generating an action potential.

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Action Potential

A large, rapid depolarization that travels down the axon of a neuron. It's all-or-nothing, meaning it either occurs fully or not at all.

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Myelin Sheath

The fatty substance that wraps around the axon, increasing the speed of action potential conduction. It helps insulate the axon and prevents signal loss.

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Partial Pressure

The pressure exerted by a specific gas in a mixture of gases.

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Gas Diffusion

The movement of a gas from an area of high partial pressure to an area of low partial pressure.

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Gas Exchange in Lungs

The process of oxygen moving from the alveoli in the lungs into the blood, while carbon dioxide moves from the blood into the alveoli.

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Hemoglobin

The protein in red blood cells that binds and transports oxygen throughout the body.

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Hemoglobin Saturation

The percentage of oxygen binding sites on hemoglobin that are occupied by oxygen molecules.

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Hemoglobin Affinity Shift

A change in the affinity of hemoglobin for oxygen, influencing how much oxygen is unloaded to tissues. A left shift indicates higher affinity, while a right shift indicates lower affinity.

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Bicarbonate Formation

The conversion of carbon dioxide into bicarbonate in red blood cells, facilitated by the enzyme carbonic anhydrase.

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Bronchoconstriction

Smooth muscle surrounding the bronchioles contracts, increasing airway resistance and decreasing airflow.

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Study Notes

Human Physiology Study Notes

  • Human physiology studies how the human body functions, with multiple organ systems working together.
  • Parts of the body connected to the external environment are called the external environment.
  • Materials from the external environment enter the internal environment via epithelial cells and blood vessels to be carried throughout the body.
  • Blood vessels transport materials and remove waste.
  • The human body comprises intracellular fluid (inside cells, roughly half the body's water content) and extracellular fluid (outside of cells, in the internal environment, including plasma and interstitial fluid).
  • Homeostasis is maintaining a stable internal environment. Negative feedback mechanisms regulate this, like temperature control—a sensor measures the temperature, comparing it to a set point in an integrating center. Effectors bring about a response (shivering, etc.).
  • Positive feedback amplifies a stimulus. Examples include ovulation and blood clotting.
  • Chemical elements/molecules called atoms are held together by covalent bonds.
  • Covalent bonds can be nonpolar (electrons shared equally) or polar (unequal electron sharing between atoms). Polar bonds are common between oxygen and nitrogen and hydrogen and carbon.
  • Polar molecules or those with many polar bonds are hydrophilic, interacting well with water.
  • Nonpolar molecules or those with many nonpolar bonds are hydrophobic, interacting better with fats.
  • Biomolecules (carbohydrates, lipids, proteins, nucleic acids) perform crucial functions in cells—carbohydrates provide energy, lipids store energy and aid in cell structure/function, proteins are structural and functional molecules, and nucleic acids (DNA/RNA) store genetic information.
  • Enzymes are protein catalysts, speeding up reactions by lowering the activation energy. They are not used up in reactions.
  • Enzymes can be regulated allosterically by molecules which bind to sites other than the active site, or covalently (like adding a phosphate group).
  • There are four basic tissue types in the body: epithelial, connective, muscle, and nervous tissue. Each tissue type has different roles and structures in the body.
  • Glands (exocrine and endocrine) release materials to do specific jobs.
  • The circulatory system transports molecules and cells in the blood throughout the body, with a two-loop system.
  • The heart pumps blood through arteries, arterioles, capillaries, venules, and veins.
  • The heart has four chambers (2 atria and 2 ventricles).
  • The heart has valves between the atria and ventricles and ventricles and arteries, to prevent backflow.
  • The heart's conduction system involves pacemaker cells in the heart (SA and AV nodes) which generate electrical signals to initiate and regulate the heartbeat.
  • Action potentials in pacemaker and contractile cells of the heart are different in that they are regulated differently.
  • The respiratory system exchanges gases—bringing in oxygen, removing carbon dioxide. The respiratory system uses tubes (trachea, bronchi, bronchioles), and air sacs (alveoli).
  • The rate of gas exchange is regulated by partial pressures (O2 and CO2).
  • There are peripheral and central chemoreceptors; they measure blood gas levels and pH, initiating changes in breathing rate as needed.
  • The autonomic nervous system consists of sympathetic and parasympathetic branches, which regulate essential functions, including heart rate and blood pressure. The autonomic nervous system has a critical role to play in maintaining homeostasis.
  • The autonomic nervous system includes the sympathetic nervous system for "fight or flight" responses, and the parasympathetic for "rest and digest" functions.
  • The two branches of nervous systems include the peripheral nervous system (PNS) which collects sensory info from nerves throughout the body (afferent division) and the central nervous system which processes this information (efferent division).
  • The central nervous system is contained in the skull and spine and includes the brain and spinal cord.
  • The somatosensory system incorporates sensory receptors for touch, temperature, pain, and proprioception (body position), gathering data and sending it to the brain for processing.
  • The nervous system communicates across synapses at chemical synapses with neurotransmitters.
  • The kidneys filter blood by regulating water balance and osmolarity, using a series of processes for filtration, reabsorption, and secretion.
  • Hormones regulate various cellular processes and help maintain homeostasis through glands. There are three main types: peptide, steroid, and amine hormones.
  • Hormones are important for cell-to-cell communication via chemical messengers.
  • The reproductive system is responsible for producing gametes and maintaining fertilization across the reproductive cycle.
  • Muscle tissue, whether skeletal, smooth, or cardiac, has the ability to contract.
  • Skeletal muscles contract using motor units and neurotransmitters (acetylcholine).
  • Metabolism is the process of converting food into usable energy and storing excess nutrients like glycogen and fat.
  • The body regulates blood glucose levels after meals through the release of insulin by the pancreas and glycogen as needed.
  • During periods of fasting, the body utilizes glycogen and fats for energy.
  • Exercise physiology involves the physiological adaptations to physical exertion.
  • Glucose, fats, and proteins are used to provide energy during exercise through various pathways including glucose breakdown to pyruvate, ATP production, and anaerobic and aerobic respiration.

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Test your knowledge on the role of hormones and enzymes in physiology with this quiz. Explore concepts like lipophobic and lipophilic messengers, enzyme regulation, and the hierarchical structure of the body. Perfect for students studying human physiology or related fields.

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