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Questions and Answers
What role do prostaglandins play in reproduction?
What role do prostaglandins play in reproduction?
Where does spermatogenesis occur?
Where does spermatogenesis occur?
What is the first stage of sperm cell development during spermatogenesis?
What is the first stage of sperm cell development during spermatogenesis?
What is the primary function of the seminiferous tubules?
What is the primary function of the seminiferous tubules?
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Which statement about sperm cell development is accurate?
Which statement about sperm cell development is accurate?
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Which neurotransmitter is primarily associated with the regulation of mood and emotional responses?
Which neurotransmitter is primarily associated with the regulation of mood and emotional responses?
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What is the primary function of GABA in the nervous system?
What is the primary function of GABA in the nervous system?
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Which neurotransmitter is primarily involved in the reward system and pleasure sensations?
Which neurotransmitter is primarily involved in the reward system and pleasure sensations?
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What occurs when a nerve signal reaches an axon terminal?
What occurs when a nerve signal reaches an axon terminal?
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Which neurotransmitter serves as the primary excitatory neurotransmitter in the brain?
Which neurotransmitter serves as the primary excitatory neurotransmitter in the brain?
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What happens to the secondary oocyte if it is fertilized?
What happens to the secondary oocyte if it is fertilized?
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What is the primary purpose of the polar body during oocyte development?
What is the primary purpose of the polar body during oocyte development?
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Where do males produce sperm?
Where do males produce sperm?
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What is produced within the ovaries in females?
What is produced within the ovaries in females?
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What is the correct description of parents' gametes in sexual reproduction?
What is the correct description of parents' gametes in sexual reproduction?
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What is one function of male sex hormones in relation to physical development?
What is one function of male sex hormones in relation to physical development?
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Which of the following describes a characteristic typically associated with males during puberty?
Which of the following describes a characteristic typically associated with males during puberty?
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How do male secondary sexual characteristics generally affect the physique?
How do male secondary sexual characteristics generally affect the physique?
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Which trait is associated with deeper voices in males?
Which trait is associated with deeper voices in males?
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Which of the following is NOT a male secondary sex characteristic?
Which of the following is NOT a male secondary sex characteristic?
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What role do actin filaments play during cell division?
What role do actin filaments play during cell division?
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What happens to the cleavage furrow as the contractile ring becomes smaller?
What happens to the cleavage furrow as the contractile ring becomes smaller?
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What is enclosed around each newly formed cell after the cleavage process?
What is enclosed around each newly formed cell after the cleavage process?
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Which process is primarily facilitated by the formation of a contractile ring in cells?
Which process is primarily facilitated by the formation of a contractile ring in cells?
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Which statement is true regarding the division of cells during the cleavage phase?
Which statement is true regarding the division of cells during the cleavage phase?
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What is the primary role of proteins in the signal transduction pathway?
What is the primary role of proteins in the signal transduction pathway?
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What happens after the last signal in the signal transduction pathway?
What happens after the last signal in the signal transduction pathway?
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Which of the following outcomes can gene expression in the nucleus lead to?
Which of the following outcomes can gene expression in the nucleus lead to?
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In the context of the signal transduction pathway, what is a potential effect of gene expression regulation?
In the context of the signal transduction pathway, what is a potential effect of gene expression regulation?
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Which statement reflects a potential misconception regarding the function of the signal transduction pathway?
Which statement reflects a potential misconception regarding the function of the signal transduction pathway?
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Study Notes
Human Biology 112
- The course is titled Human Biology 112, a course for health students.
- It's in its 17th updated edition.
- Instructor is Dr. Gamal Sharawy.
- Contact information is provided.
Chapter 14: Nervous System
- The nervous system is divided into two main parts: Central Nervous System (CNS) and Peripheral Nervous System (PNS)
- CNS consists of the brain and spinal cord.
- PNS consists of nerves that lie outside the CNS
- Sensory (afferent) nerves carry sensory information to the brain and spinal cord.
- Motor (efferent) nerves carry motor information from the CNS to effectors (muscles, glands etc.)
- Somatic sensory nerves carry signals from skin, muscles, joints, and special senses.
- Visceral sensory nerves carry signals from body organs.
- Somatic motor nerves signal to skeletal muscles.
- Automatic motor nerves signal to smooth muscle, cardiac muscle, glands.
- The nervous system has two major divisions: sympathetic division ("fight or flight") and parasympathetic division ("rest and digest").
Three Functions of Nervous System
- Receives sensory input: Sensory receptors in skin and other organs respond to stimuli by generating nerve signals. These travel to the CNS
- CNS performs information processing and integration of sensory input.
- CNS generates motor output: Nerve signals travel from the CNS via the PNS to effectors (muscles, glands, & organs).
Nervous Tissue: Two Types of Cells
- Neurons: greatly outnumber neuroglia, but support and nourish neurons -Microglia: phagocytic cells -Astrocytes: structural support -Oligodendrocytes: form myelin sheath in CNS -Schwann cells: form myelin sheaths in PNS
Neurons Have Three Structures
A) Cell body: contains the nucleus and other organelles. B) Dendrites: short extensions that receive signals from sensory receptors or other neurons. C) Axon: transmits nerve signals away from the cell body; axons form axon terminals.
Myelin Sheath
- Covers only long axons, not short ones.
- Formed when Schwann cells (PNS) or oligodendrocytes (CNS) wrap around the axon many times.
- Gives nerve fibers their white appearance & acts as an insulator.
- Gray matter in CNS is gray because it lacks myelinated axons; white matter is white due to myelinated axons.
- Important in nerve regeneration if accidentally severed in PNS
Multiple Sclerosis (MS)
- When myelin breaks down, neurons can't transmit information.
Synapse
- The region of close proximity between axon terminals of one neuron and the dendrite/cell body of another.
- Synaptic cleft: a small gap that separates the sending neuron from the receiving neuron.
- Neurotransmitters: molecules that transmit signals across the synapse.
- Stored in synaptic vesicles in axon terminals.
Excitation & Inhibition
- Depending on the neurotransmitter, the response can be excitatory (sodium gates open) or inhibitory (potassium ions exit).
- Removal of the neurotransmitter: occurs via enzymes or reabsorption.
- The short existence prevents continuous stimulation.
Neurotransmitter Molecules
- Acetylcholine (ACh) and norepinephrine are active in the CNS and PNS, acting at neuromuscular junctions.
- Norepinephrine usually excites smooth muscle.
- Serotonin is involved in thermoregulation, sleep, emotions, and perception.
Resting Potential (Polarization)
- Exists because the plasma membrane is polarized (more positive outside, more negative inside), caused by potassium ions (K+) diffusing out and negatively charged proteins inside.
- Measured in millivolts (mV)
Action Potential (Depolarization)
- The process of nerve signal conduction.
- A stimulus activates the neuron, causing sodium gates to open, and sodium rushes into the cell.
- Inside of the axon becomes positive compared to the outside → charge changes from negative to positive.
- Threshold: minimum voltage required for an action potential to occur.
Repolarization
- Sodium channels close and potassium channels open. Potassium flows out of the cell. The inside of the cell becomes negative again.
- The sodium-potassium pump restores ions to their original positions.
Unmyelinated Axons
- Action potentials stimulate adjacent parts of the axon membrane to produce an action potential.
- Conduction is slow (1 m/s) because each section of the axon must be stimulated.
Myelinated Fibers
- Action potentials only occur at Nodes of Ranvier.
- This is called saltatory conduction, and it's much faster (100 m/s).
Refractory Period
- The period immediately after an action potential during which the axon cannot conduct another action potential and ensures one-way signal transmission.
Central Nervous System (CNS): Brain & Spinal Cord
- Both spinal cord and brain are protected by bone.
- Spinal cord is surrounded by vertebrae, while the brain is enclosed within the skull.
- Meninges: protective membranes that surround the spinal cord and brain.
- Cerebrospinal fluid: found between meninges; cushions and protects the CNS.
- Lumbar puncture: withdrawing cerebrospinal fluid for testing.
Brain (Cerebrum/Diencephalon/Cerebellum/Brainstem)
- Cerebrum (telencephalon): largest part, responsible for sensory integration and commands of voluntary motor responses.
- It's located between the skull and meninges.
- It communicates with & coordinates activities of other parts of the brain via corpus callosum (extensive bridge of nerve tracts).
- Diecenphalon → includes the hypothalamus/ thalamus/ pineal gland.
- Cerebellum, under the occipital lobe.
- Maintains posture and balance.
- Brain stem: midbrain/pons/medulla oblongata. Produces smooth, coordinated, voluntary movements.
Peripheral Nervous System (PNS):
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Contains nerves A) Cranial nerves (12 pairs) arise from brain. B) Spinal nerves (31 pairs) arise from spinal cord.
-
Ganglia: collections of nerve cell bodies outside the CNS.
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Nerves: collections of axons (nerve fibers) outside the CNS.
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Two divisions: A) Somatic PNS: nerves that serve the skin, skeletal muscles, and tendons. B) Autonomic PNS: regulates cardiac and smooth muscles, organs, and glands.
Autonomic Nervous System:
- Sympathetic division: Active in emergencies ("fight or flight"), increases heart rate and dilates airways, reduces digestive/urinary activity.
- Parasympathetic division: promotes processes associated with restfulness (“rest and digest”), slows heart rate, promotes digestion of food.
Chapter 16: Endocrine System
- Endocrine glands produce hormones, chemicals that regulate the functions of other organs.
- Hypothalamus and pituitary glands are located at the center of the brain.
- The pituitary glands have 2 parts- anterior and posterior.
- The thyroid gland is situated in the throat.
- The parathyroids are four small glands located close to the thyroid.
- The thymus gland is located near the heart.
- The adrenal glands are located on top of the kidneys.
- The pancreas has both endocrine and exocrine functions.
- The testes and ovaries are located in the groin.
Chapter 17 - Reproductive System
Chapter 19 - Patterns of Chromosome Inheritance
- Mitosis: chromosome number remains constant; cell division for growth and repair. Ensures each new cell has 46 chromosomes.
- Meiosis: chromosome number reduces from 46 to 23; cell division for reproduction. Introduces genetic variation, ensuring that each new individual inherits a unique combination of genetic material from both parents.
Male Reproductive System
- Testes (testis, singular): male gonads that produce sperm and sex hormones like testosterone.
- Lie outside the abdominal cavity within the scrotum.
- Necessary for development and spermatogenesis.
- Composed of lobules, each of which contains one to three tightly coiled seminiferous tubules. the site of spermatogenesis.
- Contains interstitial cells between the seminiferous tubules; produce male sex hormones (androgens).
- Most important androgen is testosterone.
Female Reproductive System
- Ovaries: female gonads that produce eggs and sex hormones, such as estrogen and progesterone.
- Lie in shallow depressions, one on each side of the upper pelvic cavity.
- Uterine tubes (oviducts or fallopian tubes) → conduct eggs from ovaries to the uterus; site of fertilization.
- Uterus → houses the developing fetus.
- Cervix which connects to the vagina → Contains opening to vagina → passage way for menstrual flow and childbirth.
- Vagina → receives the penis during sexual intercourse, and serves as the birth canal.
DNA Biology and Technology
- DNA structure: a double helix formed by two strands that spiral around each other. DNA backbone consists of phosphate and sugar molecules; bases are adenine (A), guanine (G), cytosine (C), and thymine (T). A pairs with T, and G pairs with C.
- DNA replication → semiconservative; each new double helix has one original strand and one new strand. Enzymes needed for replication: DNA helicase, DNA polymerase, and DNA ligase.
Transcription and Translation
- Transcription: DNA in the nucleus is copied into mRNA. Enzymes involved: RNA polymerase.
- Translation → mRNA is translated into an amino acid sequence, which assembles into a polypeptide (a protein). Role of Ribosomes.
Gene Expression.
- Gene expression describes how cells use DNA to make proteins in 2 main steps: Transcription & Translation; using a genetic code.
Cell Cycle Control
- Checkpoints in the cell cycle ensure that DNA is undamaged.
- External signals, such as hormones or growth factors, can influence a cell to divide. A damaged DNA can become a cancerous cell.
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Description
Test your knowledge on key concepts in human reproductive biology, including the roles of hormones, neurotransmitters, and the processes of spermatogenesis and oocyte development. This quiz covers essential functions and stages within the reproductive system.
