HUBS1416 –PASS Sessions

Questions and Answers

Which of the following neurotransmitters is classified as autonomic?

Dopamine

Acetylcholine (correct)

Serotonin

Glutamate

What function is associated with cholinergic receptors?

Regulate heart rate

Initiate the fight or flight response

Increase blood sugar levels

Facilitate muscle contraction (correct)

Which reflex is known as a primitive reflex that should be inhibited by the time a child is around 4-6 months old?

Babinski reflex

Moro reflex (correct)

Stepping reflex

Rooting reflex

What are nociceptors primarily responsible for?

Detecting pain signals Signup and view all the answers

Which of the following processes can be manipulated for therapeutic effects?

Synaptic transmission Signup and view all the answers

Which reflex is characterized by an infant's automatic response to turn their head towards a touch on the cheek?

Rooting reflex Signup and view all the answers

How can analgesia be achieved according to the discussed methods?

Blocking pain signals Signup and view all the answers

What is an important study tip for succeeding in HUBS courses?

Utilize online resources for clarity on difficult concepts Signup and view all the answers

What are the two main components of the central nervous system (CNS)?

Brain and spinal cord Signup and view all the answers

Which cells are found in the peripheral nervous system (PNS)?

Schwann cells and satellite cells Signup and view all the answers

What role does sodium play in membrane potential?

It contributes to depolarization Signup and view all the answers

Why do myelinated axons conduct action potentials faster than unmyelinated axons?

Myelination provides insulation and reduces ion leakage Signup and view all the answers

What is meant by afferent and efferent in the nervous system?

Afferent carries signals towards the CNS, while efferent carries signals away from it Signup and view all the answers

What describes the process of depolarization in a neuron?

The membrane potential shifts toward a more positive value Signup and view all the answers

What is synaptic transmission?

The transfer of signals between neurons at the synapse Signup and view all the answers

Which cells are responsible for the production of myelin in the central nervous system?

Oligodendrocytes Signup and view all the answers

What is the primary function of the gall bladder in the digestive system?

To stimulate the contraction of the bladder and release bile Signup and view all the answers

How are catabolic enzymes transported to the duodenum?

Via the common bile duct Signup and view all the answers

What triggers the release of bile salts from the gall bladder?

The contraction of the bladder musculature Signup and view all the answers

Once bile is released from the gall bladder, where does it primarily act?

In the duodenum for fat digestion Signup and view all the answers

Which process occurs when the gall bladder releases bile?

Contraction of the bladder to force bile into the duodenum Signup and view all the answers

What is the role of the chief gastric cells in the stomach?

They produce pepsinogen and gastric lipase. Signup and view all the answers

Which part of the stomach is primarily responsible for churning the chyme?

Body Signup and view all the answers

Why do the longitudinal, circular, and oblique muscles in the stomach not get damaged by gastric juice?

They are protected by the mucosal layer. Signup and view all the answers

What is the function of the pylorus in the stomach?

To funnel chyme toward the pyloric sphincter. Signup and view all the answers

What condition results from the leaking of stomach acid into the esophagus?

Reflux or heartburn Signup and view all the answers

Which of the following statements is true regarding the fundus of the stomach?

It is the top part of the stomach. Signup and view all the answers

What is a primary characteristic of gastric juice producing cells in the stomach?

They are most abundant in the body of the stomach. Signup and view all the answers

What is the result of dysfunction in the esophagus due to excess stomach acid?

Burning sensation or heartburn. Signup and view all the answers

What is the primary function of ghrelin in the body?

Stimulates hunger and the drive to eat. Signup and view all the answers

Where is leptin produced in the body?

Adipose (fat) cells. Signup and view all the answers

What role does leptin play in hunger regulation?

Stops feelings of hunger and increases feelings of satiety. Signup and view all the answers

What activates the release of ghrelin?

Empty stomach conditions when sensors are not activated. Signup and view all the answers

What center in the hypothalamus does ghrelin primarily interact with?

Appetite center. Signup and view all the answers

What physiological response occurs when leptin levels are high?

Inhibition of appetite and enhancement of satiety. Signup and view all the answers

Which statement correctly describes the effects of ghrelin?

Ghrelin stimulates hunger and the drive to eat when the stomach is empty. Signup and view all the answers

What happens to hunger signals when leptin levels are low?

Hunger signals are intensified, promoting food intake. Signup and view all the answers

What is the primary function of villi in the intestine?

Increasing surface area for nutrient absorption Signup and view all the answers

What do lacteals primarily transport?

Lipids directly into the bloodstream Signup and view all the answers

What is the role of Peyer's patches in the small intestine?

Filtering pathogens and gut flora Signup and view all the answers

Which of the following statements is accurate about the portal vein?

It delivers absorbed nutrients to the liver Signup and view all the answers

What is the main function of the large intestine?

Absorbing water and remaining nutrients Signup and view all the answers

What does the caecum primarily do?

Absorbs nutrients and water Signup and view all the answers

Which part of the large intestine is responsible for extracting remaining nutrients and water?

Colon Signup and view all the answers

What is the function of GI capillaries located in the villi?

Carrying blood and nutrients back to the liver Signup and view all the answers

What is the primary function of the pyloric sphincter?

To reduce the rate of stomach emptying Signup and view all the answers

Which cells are responsible for secreting secretin?

S-cells in the wall of the duodenum Signup and view all the answers

How does secretin influence pancreatic function?

It stimulates the release of sodium bicarbonate Signup and view all the answers

What triggers the release of secretin in the duodenum?

Detection of gastric acid Signup and view all the answers

What occurs when CCK levels are high in relation to the pyloric sphincter?

The pyloric sphincter remains closed to slow emptying Signup and view all the answers

What role does sodium bicarbonate play in digestion?

It neutralizes gastric acid in the chyme Signup and view all the answers

What is a result of the pyloric sphincter closing?

Slowed transit of stomach contents to the intestines Signup and view all the answers

What is the effect of high levels of gastric acid in the duodenum on secretin release?

It stimulates secretin release Signup and view all the answers

What is the primary role of dendrites in a neuron?

To receive neurochemical signals from sensors and other neurons Signup and view all the answers

What characteristic of myelinated axons contributes to their faster conduction of action potentials?

Saltatory conduction due to insulated areas Signup and view all the answers

What structure is produced by glial cells that provides insulation for the axon?

Myelin sheath Signup and view all the answers

Which part of the neuron is closest to the dendrites?

Soma Signup and view all the answers

Which of the following statements is true regarding the function of neurons?

Neurons receive and transmit information through specialized structures Signup and view all the answers

What is the primary function of sodium ions (Na^+^) in neurons?

To enter the neuron during depolarization Signup and view all the answers

Which ion is primarily responsible for causing leakage in the neuron when concentration gradients are present?

Potassium (K^+) Signup and view all the answers

What is a function of the Sodium/Potassium (Na/K) ATPase pump?

To establish resting membrane potential Signup and view all the answers

Which of the following statements about potassium (K^+) channels is correct?

Potassium channels are mostly open, contributing to K^+ movement Signup and view all the answers

What type of channels allow sodium ions (Na^+) to enter the neuron during the action potential?

Voltage-activated sodium channels Signup and view all the answers

What role do voltage-gated calcium channels play in neuron function?

They facilitate the release of neurotransmitters Signup and view all the answers

Which ion is the main extracellular cation involved in neuronal signaling?

Sodium (Na^+) Signup and view all the answers

How are neurotransmitters primarily contained in a neuron?

In vesicles within the axon terminals Signup and view all the answers

What happens when excitatory signals are received at the dendrites of a neuron?

They raise the membrane potential. Signup and view all the answers

What is the threshold membrane potential that must be reached for sodium channels to open?

-55 mEV Signup and view all the answers

How does depolarization propagate along the axon of a neuron?

By triggering additional sodium channel openings. Signup and view all the answers

What role do the Nodes of Ranvier play in the propagation of an action potential?

They act as sites for sodium channel clustering. Signup and view all the answers

What triggers the opening of calcium ion channels in the axon terminals?

The arrival of the depolarization wave. Signup and view all the answers

Which of the following best describes the process of depolarization in neurons?

An influx of sodium ions into the cell. Signup and view all the answers

What is the primary effect of inhibitory signals on neuronal membrane potential?

They decrease the membrane potential. Signup and view all the answers

In myelinated neurons, how does myelin affect action potential conduction?

It increases the speed by allowing saltatory conduction. Signup and view all the answers

What is the primary function of astrocytes in the central nervous system?

To provide physical protection and structural support for neurons Signup and view all the answers

Which of the following cell types is responsible for myelinating multiple neurons in the central nervous system?

Oligodendrocytes Signup and view all the answers

What is the primary difference between Schwann cells and oligodendrocytes?

Schwann cells wrap around individual axons Signup and view all the answers

Which glial cell type functions as a macrophage in the central nervous system?

Microglia Signup and view all the answers

What is the role of ependymal cells in the nervous system?

To produce cerebrospinal fluid Signup and view all the answers

Which type of glial cell provides similar functions to astrocytes in the peripheral nervous system?

Satellite Cells Signup and view all the answers

Which cell type is primarily responsible for the production of myelin in the peripheral nervous system?

Schwann Cells Signup and view all the answers

What characteristic distinguishes satellite cells from astrocytes?

Satellite cells surround neuron cell bodies Signup and view all the answers

What effect does an increase in intracellular organic anions have on membrane potential?

It makes the membrane potential more negative. Signup and view all the answers

Which ion is primarily responsible for triggering the release of neurotransmitters at the axon terminal?

Calcium ions (Ca^2+) Signup and view all the answers

What is the primary role of GABA in neurons?

To inhibit neuronal activity. Signup and view all the answers

What happens to a neuron when chloride channels are activated by GABA?

The neuron hyperpolarizes and is less likely to fire. Signup and view all the answers

What is the effect of having more cations than anions inside a neuron?

The resting membrane potential becomes positive. Signup and view all the answers

What are rods and cones responsible for in the eye?

Detection of light intensity and color Signup and view all the answers

Which structure of the eye is primarily responsible for focusing light?

Lens Signup and view all the answers

What is the primary function of the olfactory sense?

To perceive chemical compounds Signup and view all the answers

What role do hair cells play in hearing and balance?

They convert sound vibrations into neural signals Signup and view all the answers

Which part of the auditory system is primarily involved in sound perception?

Cochlea Signup and view all the answers

Proprioception refers to which of the following?

The sense of body position and movement Signup and view all the answers

What do specialized hair cells detect in the inner ear?

Sound vibrations and movement Signup and view all the answers

Which sense is considered a chemical sense, alongside olfaction?

Taste Signup and view all the answers

What is the primary function of the liver in relation to digestion?

To produce bile for fat digestion Signup and view all the answers

Which nutrient provides the most energy per gram?

Lipids Signup and view all the answers

What primarily regulates our intake of food?

Hormonal signals and satiety cues Signup and view all the answers

What are the two main types of metabolic reactions?

Catabolism and Anabolism Signup and view all the answers

How are amino acids utilized in the body?

They serve primarily for protein synthesis and energy if necessary Signup and view all the answers

What is the primary role of pepsinogen in gastric juice?

To convert into pepsin and aid protein digestion Signup and view all the answers

Which of the following accurately describes segmentation in the digestive system?

It mixes and churns food in the small intestine for better absorption Signup and view all the answers

Which component of gastric juice protects the stomach lining from acid?

Mucus Signup and view all the answers

What triggers the release of the hormones cholecystokinin (CCK) and secretin?

Fatty acids and amino acids in the duodenum Signup and view all the answers

What is the primary function of the intrinsic factor in gastric juice?

To aid in vitamin B12 absorption Signup and view all the answers

Which of the following is NOT a function of the small intestine?

Production of bile Signup and view all the answers

What is the bolus in the digestive process?

A mass of chewed food ready to swallow Signup and view all the answers

Which structure increases the surface area of the small intestine for nutrient absorption?

Villi Signup and view all the answers

What is the primary role of bile in the digestive system?

It helps to emulsify fats. Signup and view all the answers

Which section of the small intestine is responsible for the initial digestion and absorption of nutrients?

Duodenum Signup and view all the answers

What is the primary site for water absorption within the gastrointestinal tract?

Large intestine Signup and view all the answers

Which hormones are known to inhibit gastric activity?

Secretin and Somatostatin Signup and view all the answers

What is the primary function of Peyer's patches in the intestine?

To protect against pathogens. Signup and view all the answers

What role does the mouth play in digestion?

It initiates digestion through mechanical breakdown and saliva secretion. Signup and view all the answers

Which structure primarily regulates the passage of chyme from the stomach to the small intestine?

Pyloric sphincter Signup and view all the answers

What is the primary function of the large intestine?

Reabsorption of water and electrolytes, and formation of feces. Signup and view all the answers

What is the primary difference between the exocrine and endocrine functions of the pancreas?

Exocrine function aids in digestion through secretions like enzymes. Signup and view all the answers

Which hormone is primarily involved in regulating satiety and feeding?

Leptin Signup and view all the answers

What is a potential consequence of failure in the normal function of the gastrointestinal tract?

Decreased metabolic rate and energy levels. Signup and view all the answers

Where does most nutrient absorption occur within the gastrointestinal tract?

Small intestine Signup and view all the answers

What are the principal digestive enzymes produced by the pancreas activated by?

Secretions from the small intestine Signup and view all the answers

Which nervous system division primarily controls voluntary movements?

Somatic nervous system Signup and view all the answers

What is the correct sequence of components in a reflex arc?

Receptor, Sensory neuron, Integrator, Motor neuron, Effector Signup and view all the answers

Which of the following best describes the role of sensory (afferent) neurons?

They relay information from receptors to the central nervous system. Signup and view all the answers

How do simple reflexes provide insight into the health of the nervous system?

They demonstrate the interaction of both peripheral and central neurons. Signup and view all the answers

What typically happens to certain reflexes as humans mature?

Some reflexes present in infancy disappear, while others emerge. Signup and view all the answers

Which of the following accurately describes autonomic nervous system function?

It operates independently of conscious control, managing involuntary functions. Signup and view all the answers

What purpose does reflex testing serve in a clinical setting?

It assesses the functional integrity of the nervous system. Signup and view all the answers

Which of the following best characterizes the relationship between efferent neurons and their function?

They carry signals from the central nervous system to effector organs. Signup and view all the answers

What is the primary purpose of the nervous system?

To facilitate communication between different body parts Signup and view all the answers

Which regions of a generalized neuron are responsible for processing incoming signals?

Dendrites Signup and view all the answers

Which glial cells are primarily responsible for supporting and insulating neurons in the CNS?

Oligodendrocytes Signup and view all the answers

What is required for a membrane potential to exist in a neuron?

A difference in ion concentrations inside and outside the cell Signup and view all the answers

How is resting membrane potential maintained in a neuron?

Through active transport of potassium ions in and sodium ions out Signup and view all the answers

During which event does depolarization primarily occur in a neuron?

When sodium channels open and sodium enters Signup and view all the answers

What is the main role of myelin in relation to axons?

To increase the rate of conduction of action potentials Signup and view all the answers

Which process describes the key events of synaptic transmission?

Transfer of neurotransmitters from presynaptic to postsynaptic neurons Signup and view all the answers

What is a primary role of the cranial nerves in the peripheral nervous system?

Transmitting both sensory and motor information Signup and view all the answers

Which statement accurately reflects the nature of touch, pain, and proprioception sensations?

They involve different types of sensory receptors. Signup and view all the answers

What describes the significance of dermatome and myotome maps?

They indicate the regions affected by spinal nerve damage. Signup and view all the answers

What type of information do spinal nerves carry?

Mixed sensory and motor information Signup and view all the answers

Which of the following is true regarding the functions of cranial nerves?

They can have both sensory and motor roles. Signup and view all the answers

How can one predict areas affected by spinal nerve damage?

By using dermatome and myotome maps Signup and view all the answers

What role do special sensory organs play in the peripheral nervous system?

They facilitate the senses such as sight and hearing. Signup and view all the answers

What function does a PASS leader serve in the learning environment?

To help students learn content and key concepts Signup and view all the answers

What is the function of the Abducens Nerve (CN VI)?

Eye movements (Lateral rectus muscle) Signup and view all the answers

Which cranial nerve is responsible for hearing and balance?

Vestibulocochlear Nerve (CN VIII) Signup and view all the answers

Which cranial nerve is primarily responsible for taste from the anterior 2/3 of the tongue and movement of facial expression muscles?

Facial Nerve (CN VII) Signup and view all the answers

What type of functions does the Vagus Nerve (CN X) perform?

Both sensory and motor Signup and view all the answers

Which of the following nerves is responsible for taste from the posterior 1/3 of the tongue and swallowing?

Glossopharyngeal Nerve (CN IX) Signup and view all the answers

Which cranial nerve is involved in eye movements and pupil constriction?

Oculomotor Nerve (CN III) Signup and view all the answers

Which cranial nerve controls tongue movements?

Hypoglossal Nerve (CN XII) Signup and view all the answers

What is the main function of the Trigeminal Nerve (CN V)?

Sensory sensation to the head and face Signup and view all the answers

Study Notes

PASS Session Overview

Casual and relaxed study environment
1 hour of PASS equates to 3 hours of solo study
Emphasis on open communication; no silly questions
Sessions are voluntary; attendance is flexible
Sign-in sheet required each week

Autonomic Neurotransmitters

Acetylcholine and noradrenaline are key autonomic neurotransmitters

Cholinergic Receptors

Receptor Types:
- Nicotinic receptors: Mediate fast synaptic transmission
- Muscarinic receptors: Involved in slower, modulatory pathways
Function: Regulate various physiological responses such as heart rate and muscle contraction

Adrenoceptors

Types:
- Alpha and beta adrenoceptors: Play different roles in the response to noradrenaline
Function: Influence cardiovascular function, respiratory system, and metabolism

Primitive Reflexes

Moro Reflex: Startle response, should be inhibited after 4-6 months
Stepping Reflex: Indicates readiness for walking, inhibited later in infancy
Rooting Reflex: Assists in breastfeeding, should be inhibited around 4 months
Babinski Reflex: Foot response to stimuli, inhibited by 1 year
Grasping Reflex: Allows infant to grasp fingers, typically inhibited by 5-6 months

Synaptic Transmission Steps

Action potential triggers neurotransmitter release
Neurotransmitters bind to receptors on the postsynaptic neuron
Ion channels open, leading to depolarization/hyperpolarization
Can be targeted by drugs for therapeutic effects, such as pain relief or mood regulation

Nociceptors and Analgesia

Nociceptors: Specialized sensory receptors for pain detection
Analgesia can be achieved through:
- Medication (e.g., NSAIDs, opioids)
- Non-pharmacological methods (e.g., physical therapy, acupuncture)

Study Tips

Consistency is key; review concepts regularly
Utilize online resources such as YouTube or Khan Academy for diverse explanations

Introduction to the Nervous System

PASS sessions offer a supportive and casual study environment to enhance learning effectiveness.
A one-hour PASS session can be equivalent to three hours of individual study.
Participation is voluntary, and students can come as they are and whenever possible.

Central Nervous System (CNS)

Comprises the brain and spinal cord.

Peripheral Nervous System (PNS)

Made up of sensory (afferent) neurons and motor (efferent) neurons.

Neurons

Key parts to diagram: dendrites, cell body, axon, synaptic terminals.

Glial Cells of the CNS

Astrocytes: Support neurons, maintain blood-brain barrier, regulate nutrient release.
Oligodendrocytes: Myelinate CNS axons to facilitate faster signal transmission.
Ependymal cells: Line ventricles and produce cerebrospinal fluid.
Microglia: Act as immune cells in the CNS, removing debris and pathogens.

Glial Cells of the PNS

Schwann Cells: Myelinate PNS axons, aiding in signal conduction.
Satellite Cells: Support and protect neuronal cell bodies in ganglia.

Membrane Potential

Refers to the voltage difference across a neuron’s membrane, crucial for action potentials.
Sodium (Na+) influx causes depolarization; potassium (K+) efflux is key to repolarization.

Depolarization

Process initiated when stimuli cause Na+ channels to open, increasing the membrane's positive charge.

Repolarization

Occurs when Na+ channels close, and K+ channels open, allowing K+ to exit the cell and restoring the membrane's negative charge.

Action Potentials and Myelination

Myelinated axons conduct action potentials faster due to saltatory conduction, where signals jump between nodes of Ranvier.

Synaptic Transmission

Involves the release of neurotransmitters from the presynaptic neuron into the synaptic cleft, signaling the postsynaptic neuron.

Divisions of the Nervous System

Simple tree diagram to illustrate: Central Nervous System (CNS) and Peripheral Nervous System (PNS) further divided into somatic and autonomic nervous systems.

Afferent and Efferent Neurons

Afferent: Carry sensory information to the CNS.
Efferent: Transmit motor commands from the CNS to muscles and glands.

Effective Study Tips

Review learning outcomes regularly; ensure the ability to explain them clearly to others.
Use a "traffic light" system to assess understanding: green for confident, yellow for uncertain, red for needing further review.

Stomach Anatomy and Function

Fundus: The top part of the stomach, contributes to acid secretion.
Main body: Contains the majority of gastric juice-producing cells; responsible for churning food into chyme.
Pylorus: The lower part of the stomach; regulates chyme passage to the duodenum through the pyloric sphincter.
Muscle Layers: Composed of longitudinal, circular, and oblique muscles that churn food; protected by the mucosal layer.

Gastric Cells and Nutrient Absorption

Chief gastric cells: Produce pepsinogen and gastric lipase, essential for protein and fat digestion.
Villi: Microscopic projections in the intestinal wall that increase surface area for nutrient absorption; contain GI capillaries and lacteals.
GI Capillaries: Blood vessels in the villi that absorb nutrients and transport them to the liver via the portal vein.
Lacteals: Lymphatic capillaries within the villi that absorb lipids and transport them into the bloodstream.

Immune Function and Nutrient Transport

Peyer's Patches: Lymphoid tissue in the small intestine that helps manage gut flora and immune response, particularly numerous in the ileum.
Portal Vein: Transports absorbed nutrients from intestines directly to the liver for processing.

Large Intestine Components

Caecum: First part of the colon that absorbs water, nutrients, and electrolytes; secretes mucus to aid stool passage.
Colon: Divided into ascending, transverse, descending, and sigmoid sections; extracts final nutrients and water before waste is sent to the rectum.

Digestive Enzymes and Hormonal Regulation

Gall Bladder: Stimulates the release of bile salts into the duodenum, aiding fat digestion.
Pyloric Sphincter: Slows stomach emptying by contracting in response to high CCK levels.
Secretin: Released from S-cells in the duodenum; stimulates bicarbonate release from the pancreas to neutralize stomach acid in chyme.
Ghrelin: Produced by the stomach, signals hunger and stimulates the drive to eat when the stomach is empty.
Leptin: Hormone from adipose cells that reduces hunger and promotes the feeling of fullness in the hypothalamus.

Glossary of Key Terms

Anabolic: Processes that build larger molecules from smaller ones.
Antacid: A weak base that neutralizes stomach acid; used to alleviate heartburn and ulcers.
Bile: A mixture of bile salts, cholesterol, and enzymes; stored in the gall bladder and released as needed.
Catabolic: Processes that break down larger molecules into smaller ones.
Cholecystectomy: Surgical removal of the gall bladder.

Neuron Anatomy

Soma: Cell body housing the nucleus; integrates signals from dendrites.
Dendrites: Project from soma; receive neurotransmitter signals from sensors and other neurons.
Axon: Long projection transmitting signals away from the soma to other neurons or muscles.
Myelin Sheath: Lipid-based insulation produced by glial cells; enhances signal speed along the axon.
Nodes of Ranvier: Gaps in myelin sheath; facilitate rapid depolarization via saltatory conduction.
Synapse: Junction between neurons; site of neurotransmitter release and reception.
Neurotransmitters: Chemicals stored in vesicles at axon terminals; allow communication between neurons.

Important Electrolytes (Ions)

Sodium (Na^+): Main extracellular cation; enters neuron during depolarization through voltage-gated channels.
Potassium (K^+): Main intracellular cation; maintains resting membrane potential and helps repolarization.
Calcium (Ca^2+): Extracellular cation; triggers neurotransmitter release upon entering axon terminals.
Organic Anions (P^-): Main intracellular anions; contribute to resting membrane potential of -70 mV.
Chloride (Cl^-): Main extracellular anion; hyperpolarizes the neuron when entering, inhibited by GABA.

Action Potentials in Neurons: Key Events

Signal Reception: Excitatory and inhibitory signals at dendrites affect membrane potential.
Threshold Activation: If membrane potential reaches -55 mV, Na^+ channels open, leading to rapid depolarization.
Depolarization Wave: Propagates down the axon; triggers neighboring channels to open, amplified by Nodes of Ranvier in myelinated neurons.
Calcium Channel Activation: At axon terminals, depolarization opens Ca^2+ channels, facilitating neurotransmitter release.

Glial Cells of the Central Nervous System (CNS)

Astrocytes: Provide structural support, protect neurons, maintain blood-brain barrier, regulate external environment.
Oligodendrocytes: Produce myelin for CNS axons; can myelinate multiple axons simultaneously.
Microglia: Serve as immune defense; protect against pathogens and clear debris.
Ependymal Cells: Produce and circulate cerebrospinal fluid.

Glial Cells of the Peripheral Nervous System (PNS)

Satellite Cells: Similar to astrocytes; support peripheral neuron cell bodies.
Schwann Cells: Produce myelin for PNS axons; each wraps around a single segment of an axon, requiring multiple Schwann cells for one myelinated axon.

Peripheral Nervous System Overview

Relaxed and safe study environment known as PASS, encouraging casual attendance and inquiry.
One hour of PASS equates to three hours of individual study productivity.
Email for questions or support: [email protected].

Cranial Nerve Review

There are 12 cranial nerves, each with designated sensory or motor functions.
Utilize a mnemonic device to remember the order of the cranial nerves and their functions.
A music video available on the PASS canvas page aids in learning cranial nerves.

Special Senses Overview

Olfaction (Smell)

Smell is classified as a chemical sense, detecting airborne chemical molecules.
Other chemical sense: Taste.

Taste

Human tongue can detect five basic tastes: sweet, sour, salty, bitter, and umami.
Different tastes inform about food quality and safety.
Taste buds are structures on the tongue responsible for taste perception.

Vision

Key structures of the eye include:
- Cornea: Provides clarity and focus for incoming light.
- Retina: Houses photoreceptors (rods and cones) that convert light to neural signals.
- Iris: Regulates the size of the pupil, controlling light entry.
- Lens: Focuses light onto the retina.
Rods are responsible for low-light vision; cones detect color and function in bright light.

Hearing

Sound perception involves the movement of specialized hair cells in the inner ear.
Hair cells bend in response to sound vibrations, triggering electrical signals to the brain.
Specialized structures, such as the cochlea, play crucial roles in hearing and balance.

Proprioception

Proprioception is the sense of body position and movement, providing awareness of limb placement and coordination.

General Overview

PASS provides a casual study environment that enhances productivity, equating one hour of study with three hours of individual study.
Sessions are voluntary, and students are encouraged to ask questions without judgment.
Attendance is recorded through a sign-in sheet each week.

The Digestive System Tour

The Mouth, Oesophagus, and Swallowing

Mechanical digestion in the mouth involves chewing and mixing food with saliva; chemical digestion begins the breakdown of nutrients.
Key components of saliva include enzymes like amylase that initiate starch breakdown.
A bolus is a chewed ball of food ready for swallowing.
Peristalsis is a wave-like muscle contraction that moves food through the digestive tract, while segmentation refers to the rhythmic contraction of intestines to mix food.

The Stomach

Components of gastric juice:
- Hydrochloric acid: activates enzymes and provides an acidic environment.
- Mucus: protects stomach lining against acidity and enzymes.
- Pepsinogen: a precursor activated to pepsin for protein digestion.
- Gastric lipase: aids in the digestion of fats.
- Intrinsic Factor (IF): essential for vitamin B12 absorption.
The stomach is stimulated by the sight, smell, and taste of food and inhibited by factors like high acidity.

The Small Intestines

Regions of the small intestine: duodenum, jejunum, ileum; they function in digestion and nutrient absorption.
Accessory organs: pancreas (produces enzymes and bicarbonate), liver (produces bile), gallbladder (stores bile).
Pancreatic juice contains enzymes and bicarbonate, and bile aids in fat digestion.
CCK and secretin are hormones triggered by food presence; CCK stimulates bile release while secretin regulates bicarbonate secretion.

Structural Adaptation of the Small Intestines

The small intestines have folds, villi, and microvilli that increase surface area for efficient nutrient absorption.
Absorbed nutrients are transported directly to the liver via the hepatic portal vein.

The Liver

Key functions: processing and storing nutrients, detoxification, bile production, and metabolism regulation.

The Large Intestines

Primary function is water absorption and the formation of feces.

Metabolism and Nutrient Utilization

Metabolism is the sum of all chemical reactions in the body; consists of catabolic (breakdown) and anabolic (building) reactions.
Lipids provide the most energy per gram compared to amino acids and glucose.
Nutrient utilization:
- Amino acids: used for protein synthesis and energy.
- Lipids: broken down for energy or stored.
- Glucose: primary energy source for cells.
Food intake regulation involves hormones like insulin, glucagon, and leptin.

Study Tips

Refer to learning objectives to guide study.
Engage in teaching concepts to enhance understanding.
Utilize practice questions on canvas and analyze mistakes for improvement.
Attend all lectures and participate actively in lectorials to solidify knowledge.

Expectations of PASS Sessions

Relaxed environment; participants encouraged to bring coffee and lunch.
PASS leaders support learning but are not tutors.
Judgement-free atmosphere; all questions are welcome.
Worksheets serve as guides to identify knowledge gaps.

Learning Objectives

Understand the body's nutritional needs sourced from food.
Identify major organs of the gastrointestinal tract (GIT) and their functions.
Describe structure and functions of accessory organs in digestion and metabolism.
Explain the role of smooth muscle in GIT, including types of motility.
Detail the function of the mouth and saliva in digestion.
Outline the swallowing process and the oesophagus's role.
Characterize the stomach's structure and digestive functions.
Understand regulation of GIT actions by hormones and the nervous system.
Discuss small intestine's digestive functions and its secretions.
Explain nutrient absorption processes in the small intestine.
Describe the large intestine's structure and functions.
Differentiate between exocrine and endocrine pancreas functions and exocrine actions.
List principal digestive enzymes, their action sites, activation, substrates, and products.
Outline absorption sites for primary nutrient groups.
Discuss principles of metabolism: anabolism, catabolism, metabolic rate.
Compare metabolic fates of carbohydrates, proteins, and fats.
Recognize how GIT or accessory organ dysfunctions impact digestion and metabolism.
Define obesity, associated health risks, contributing factors, and hormone roles in satiety.
Apply knowledge to clinical scenarios and treatment understandings.

Energy Expenditure

Energy expenditure refers to the total amount of energy used by the body, influenced by factors such as age, sex, physical activity level, and body composition.

Gastrointestinal Tract (GIT) Organs

Comprises organs like the mouth, oesophagus, stomach, small intestine, and large intestine, each with specific digestive roles.

Accessory Organs in Digestion

Includes organs like the liver, pancreas, and gallbladder, contributing enzymes, bile, and hormones for digestion.

Gut Motility

Mixing and moving of gut contents primarily involve:
- Peristalsis: wave-like muscle contractions that move food through the digestive tract.
- Segmentation: rhythmic contractions that mix and break down food in the small intestine.

Role of Bile

Bile is essential for the emulsification of fats, aiding in fat digestion and absorption.

Bile Production and Storage

Bile is produced in the liver and stored in the gallbladder until needed for digestion.

Gastric Juice and Vitamin B12

Intrinsic factor, found in gastric juice, is crucial for the absorption of vitamin B12.

Small Intestine Anatomy

The first section of the small intestine is called the duodenum.

Water Absorption in the GIT

The primary site for water absorption is the large intestine.

Importance of GIT Areas and Accessory Organs

Different areas of the GIT, along with accessory organs, are crucial for the digestion and absorption process.

Hormones Inhibiting Stomach Activity

The two hormones that inhibit stomach activity are somatostatin and secretin.

Intestinal Mucosa Defense

Peyer's patches are nodules of lymphatic tissue within the intestinal mucosa that protect the GI tract from pathogens.

Metabolic Reactions

The two main types of metabolic reactions are:
- Anabolic reactions: build complex molecules from simpler ones, requiring energy.
- Catabolic reactions: break down complex molecules into simpler ones, releasing energy.

Introduction to the Nervous System

The nervous system serves as the body's communication network, regulating and coordinating functions throughout the body.
It comprises two main divisions: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Neuron Structure

Neurons have distinct regions: input, output, and integration areas.
Key components of a neuron: dendrites (input), cell body (integration), and axon (output).

Glial Cells in the CNS

Four types of CNS neuroglia include:
- Astrocytes: Support and maintain the blood-brain barrier.
- Oligodendrocytes: Produce myelin sheaths around axons.
- Ependymal cells: Line the ventricles and produce cerebrospinal fluid.
- Microglia: Act as immune defense for the CNS.

Glial Cells in the PNS

Two types of PNS neuroglia include:
- Schwann cells: Form myelin sheaths around peripheral nerves.
- Satellite cells: Support and protect neuron cell bodies in ganglia.

Membrane Potential

Membrane potential refers to the voltage difference across a neuron's membrane, crucial for signal transmission.
It is dependent on the distribution of ions (primarily sodium and potassium) inside and outside the neuron.

Resting Membrane Potential

The resting membrane potential is maintained through the sodium-potassium pump, which actively transports sodium out and potassium into the cell.

Action Potential Dynamics

Depolarization occurs when sodium channels open, allowing Na+ to enter the neuron.
Repolarization follows as potassium channels open, allowing K+ to exit the neuron.
An action potential is a rapid rise and fall in voltage that travels along the axon.

Role of Myelin

Myelin sheaths insulate axons, increasing the speed of electrical conduction through saltatory conduction (jumping between nodes of Ranvier).

Synaptic Transmission

Synaptic transmission involves three key processes: neurotransmitter release from the presynaptic neuron, binding to receptors on the postsynaptic neuron, and subsequent response.
Modulation of synaptic transmission can alter nervous system signaling.

Divisions of the Nervous System

The nervous system is divided into:
- CNS: Comprises the brain and spinal cord, responsible for processing information.
- PNS: Comprises all nerves outside the CNS, responsible for transmitting messages to and from the CNS.
Somatic Nervous System: Controls voluntary movements and sensory information.
Autonomic Nervous System: Regulates involuntary bodily functions, further divided into sympathetic and parasympathetic.

Reflex Arc

A reflex arc involves sensory input, integration in the CNS, and motor output.
It enables quick reactions to stimuli, bypassing the brain for faster response.

Diagnostic Uses of Reflex Testing

Reflex testing can provide insights into the functioning of peripheral and central neurons.
Certain reflexes are present in infants and disappear as they grow, while others appear later in development.

Clinical Application

Understanding the nervous system's structure and function is crucial for diagnosing and treating neurological disorders.

PASS Session Overview

PASS provides a relaxed study environment, encouraging participants to bring snacks or drinks.
Leaders serve as facilitators rather than tutors to enhance understanding of content and core concepts.
It operates without judgment, fostering an atmosphere where all questions are valid.
The provided worksheet serves as a guide and may not cover all topics; it aims to help identify knowledge gaps.

Contact Information

Students are encouraged to reach out for additional help via email.
Contact email: [email protected]

Learning Objectives

Understand the names, numbers, and primary functions of the 12 cranial nerves, identifying if each is sensory, motor, or mixed.
Be able to interpret results from cranial nerve tests and predict outcomes of specific nerve damage based on known functions.
Outline structures of each special sensory organ and their functional relevance.
Recognize the roles of touch, pain, and proprioception sensations, including their associated receptors.
Comprehend the significance of dermatome and myotome maps, including spinal nerve distribution relative to vertebral levels.
Predict body areas affected by spinal nerve damage using knowledge from dermatome/myotome maps.
Describe sensory information carried by spinal nerves.
Use knowledge of the peripheral nervous system to analyze clinical symptoms related to nervous system damage or diseases.

Cranial Nerves and Their Functions

Olfactory Nerve (CN I): Sensory - Smell
Optic Nerve (CN II): Sensory - Vision
Oculomotor Nerve (CN III): Motor - Eye movements, pupil constriction, raising eyelids
Trochlear Nerve (CN IV): Motor - Eye movements (superior oblique muscle)
Abducens Nerve (CN VI): Motor - Eye movements (lateral rectus muscle)
Trigeminal Nerve (CN V): Both - Sensation to head/face, movement of muscles for mastication
Facial Nerve (CN VII): Both - Taste from anterior 2/3 of tongue, facial expression muscles
Vestibulocochlear Nerve (CN VIII): Sensory - Hearing and balance
Glossopharyngeal Nerve (CN IX): Both - Taste from posterior 1/3 of tongue, swallowing, salivation
Vagus Nerve (CN X): Both - Sensory and motor/autonomic supply to organs
Accessory Nerve (CN XI): Motor - Movement of neck muscles, swallowing, vocal cords
Hypoglossal Nerve (CN XII): Motor - Tongue movements

Sensory Information in Spinal Nerves

Spinal nerves relay diverse sensory signals, essential for an individual’s perception of the environment.
Understanding dermatome and myotome distributions is critical for localizing clinical symptoms and injuries.

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Description

Join our PASS session focused on Neurotransmitters, Receptors, and the Integration of Electrical Signals. This relaxed and friendly environment encourages collaboration and questions, making your study experience more productive. Bring your snacks and come ready to learn!