Type of Transport😊

Type of Transport

Identify the Transport Mechanisms

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Cat	Name	Type
A	Phagocytosis	cell engulfing a solid
B	Pinocytosis	cell taking up fluid
C	Receptor-mediated endocytosis	receptor-mediated engulfing

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Classification:

Based on energy use.

Active Transport:

Active Transport	• Against the concentration gradient	ㅤ
↳ Primary	• Uses ATP directly • "ATP pump"	ㅤ
ㅤ	↳ Na+/K+-ATPase pump	• Pumps 3 Na+ out, 2 K+ in.
ㅤ	↳ Calcium ATPase	• Pumps Ca2+ for muscle relaxation to inside SR
ㅤ	↳ K+/H+ ATPase	• Secretes H+ ions • takes in K+ in parietal cell
ㅤ	↳ P-glycoprotein pump transporter	• ATP-binding cassette
↳ Secondary	• Uses energy indirectly • Using gradient of other substance	ㅤ
ㅤ	↳ Symporter (same direction)	• Sodium Glucose cotransporter -1 • Sodium Iodide symporter • Sodium Amino acid cotransporter • Sodium Bicarbonate cotransporter
ㅤ	↳ Antiporter (opposite directions)	• Sodium calcium exchanger (NCX) • Sodium H' antiporter
Based on direction	ㅤ	ㅤ
Uniport	One substance is transported	ㅤ
Symport	Two substances → same direction	ㅤ
Antiport	Two substances → opposite directions	ㅤ

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Primary Active Transport — Primary Active Transport

Secondary Active Transport — Secondary Active Transport

Carrier Protein vs. Channel Protein:

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ㅤ	Carrier Protein	Channel Protein
Required for	• Facilitated diffusion • Active transport	• Simple diffusion
Action	• Binds & • Changes shape during transport	• Pore or opening • Transport substances
Saturation Property	• Present ↳ when all carriers are occupied	• Absent

Passive Transport:

1. Osmosis

2. Diffusion

Simple Diffusion vs Facilitated Diffusion

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ㅤ	Mechanism	Examples
Passive Transport	ㅤ	ㅤ
1. Simple diffusion	• Down concentration gradient	ㅤ
↳ Non Selective	• Without any protein	CO2, O2, urea, Lipid-soluble molecules
↳ Selective	• Ion channel proteins ↳ Inherent membrane properties • Channel protein → • already present in membranes	Sodium channel, Potassium channel
2. Facilitated Diffusion	• Down concentration gradient	ㅤ
ㅤ	• Requires a carrier protein • Not inherent property of membrane • Does not require energy Examples:	Protein in carried to membrane
ㅤ	↳ GLUT transporters	Insulin mediated
ㅤ	↳ ENaC	Mineralocorticoid
ㅤ	↳ Aquaporin 2 channels	Vasopressin
3. Non-ionic diffusion	• Transport of weak acids or weak bases	ㅤ

Non Selective Simple Diffusion — Non Selective Simple Diffusion

Selective Simple Diffusion — Selective Simple Diffusion

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Transport Process MCQ Example

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Context: Diagram showing three transporters (X, Y, Z).

Transporter X:

Action: Pumps Sodium out (against gradient), Potassium in (against gradient).
Identified as: Primary active transporter (specifically, Sodium potassium ATP pump).

Transporter Y:

Action: Moves Sodium along its gradient (high to low), Calcium against its gradient (low to high).
Identified as: Antiporter, Secondary active transporter. (Uses energy from sodium movement. Example: Sodium calcium exchanger (NCX)).

Transporter Z:

Structure: Has a pore/opening.
Action: Transports Chloride ions in both directions. No change in shape.
Identified as: Simple diffusion (via a channel).

Glucose Reabsorption Mechanism

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SGLTs and GLUTs

Glucose Transporters

Glucose Transporters	Apical side	Basolateral side	ㅤ
Intestine	SGLT 1	GLUT 2	ㅤ
Glucose Transporters	Luminal Membrane	Basolateral Membrane	Reabsorption % in kidney
PCT	SGLT 2	GLUT 2	90%
PST	SGLT 1	GLUT 1	10%
Fructose uptake	Apical side	Basolateral side	ㅤ
Intestine	GLUT 5	GLUT 2	ㅤ
Mechanism	SGLT • Secondary active transport • co-transports Na⁺ and glucose	GLUT • Facilitated diffusion	ㅤ

Note: 100% reabsorption occurs in proximal tubules.

Insulin dependent → GLUT4 → Skeletal muscle → SGLT3 is also seen

SGLT1 Transport Mechanism

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Location: Apical side of enterocytes

Na⁺-K⁺ ATPase pump (basolateral side):

pumps 3 Na⁺ out of enterocyte
maintains low intracellular Na⁺.

Due to this gradient:

Na⁺ enters cell from lumen
high → low concentration

Energy released from Na⁺ influx is utilized

to transport glucose into cell
against its gradient.

Transporter	Type
SGLT1	• Intestine > PST
SGLT2	• PCT mainly
SGLT3	• Skeletal muscle • Glucose sensor in Small Intestine
GLUT1	• PST • Endothelial cell in BBB • RBCs, Placentas Where glucose is primarily needed ↳ Brain, RBC, Placenta, PST
GLUT2	• Enterocytes • Hepatocytes • Beta cells of pancreas • PCT cells Absorption and regulation
GLUT3	• Neuronal membrane (CNS) • RBCs, Placentas • Maximum affinity for glucose uptake
GLUT4	Most important insulin responsive GLUT • Skeletal Muscles • Cardiac Muscles • Adipose Tissues
GLUT 5	• Astrocytes (CNS) • Fructose transporter ↳ Seminal vesicle.
GLUT 11	• Also transports fructose
GLUT 12	• Also insulin responsive

Fructose

GLUT → 5, 11
Basolateral → GLUT 1, 2

Brain

GLUT → 1 (BBB), 3 (Neuronal membrane), 5 (Astrocystes)

GLUT 4 → Insulin

Remember exercise → Heart muscle, skeletal muscle, surrounding adipose

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Revise Epilepsy

Epilepsy	Characteristic EEG
GTCS	DOC • Phenytoin, Valproate
Absence / Petit mal	• Spike & wave (dome) pattern • 3 Hz spikes DOC • Ethosuximide, Valproate • Absent? → Ethuvo ? (Ethosuximide)
Infantile spasms	• Hypsarrhythmia Age • < 1 years DOC • without tuberous sclerosis: ACTH, Prednisolone • with tuberous sclerosis: Vigabatrin
Juvenile myoclonic Epilepsy (Janz)	• 4–6 Hz polyspikes & slow wave discharge • JME → JANZ S → 4-5 letters → 4 - 6 Hz polyspikes, slow Age • 10 - 19 years DOC • Valproate
Lennox Gastaut syndrome	• Slow (<3 Hz) spike wave complex • LGS → < 3Hz spike complex DOC • Valproate, Lamotrigine
Hepatic encephalopathy	• Triphasic wave {- wave → +ve wave → - wave}
1. SSPE → 8 years age 2. HIE 3 3. Comatose → (drug/severe hypothermia)	• Burst suppression
Prion disease (Kuru)	• Periodic sharp wave complexes Age • 35 years
HSV encephalitis	• Periodic lateralized epileptiform discharge • Affects temporal lobes • DOC: IV Acylovir • HSV → His Wife → Like temples (Period late)

SSLC / SCENE Genes

SCN/SLC	Disease	Features
SLC6A19	Hartnup’s Disease (Chr 5) 6 days Hearty trip	• Defect of tryptophan transporter • Cutaneous photosensitivity (m/c symptom) • Obermeyer test → indoxyl in urine Accumulation of tryptophan in intestine → bacterial decomposition → indoxyl compounds → Indoles absorbed → excreted in urine as indoxyl sulfate→ bluish discoloration of diaper
SLC2A1	GLUT 1 defect SSLC → 2 times → bcz brain hypoglycemia	↓ CSF glucose → seizures ↳ Rx: Pure ketogenic diet
SCN1A	Dravet syndrome ↳ defective Nav1.1 Na channel ↳ ⛔ GABA	Seizures ↳ DOC: Valproate
SCN5A (Loss of function)	Brugada syndrome ↳ defective Cardiac Na channel 1 Dragon drank 5 Bru	Brutal (Brugada) scene (SCN5A) guy like me (pseudo RBB) → drinking soda (Na channelopathy) → sudden seizure and death () Broad P wave → Long PQ seg → raised J point → coved ST → T inversion
SCNN1B/G genes	Liddle Syndrome ↳ Defect: ENaC channel	• AD inheritance • Hypertension + Pseudoaldosteronism • Hypokalemic metabolic alkalosis
Anti GM1 Antibody	Guillain Barre Syndrome (AIDP)	• Albumino-cytological dissociation • Earliest sign: Distal areflexia. • Bladder and bowel spared. • Bilateral ascending symmetrical flaccid paralysis. • Brighton Criteria for GBS
Anti GQ1 Antibody.	Miller Fisher Fish vangan Que nikkanam	Triad • Ophthalmoplegia (3rd nerve palsy). • Areflexia. • Ataxia.
anti P/Q antibody	Lambert Eaton Syndrome Eat 3, 4 Amino acid (3,4 aminopyridine) → gain strength → ↑↑ response	• Pre-junctional ↓↓ release of Ach at NMJ • Oat cell cancer lung → Paraneoplastic • Repetitive nerve stimulation test: ↳ Incremental response Treatment: • DOC: 3,4 aminopyridine • Pyridostigmine

Insulin independent glucose transporter is present in all of the following except?

Brain

Adipose tissue

RBC

Pancreas

ANS

Adipose tissue

Important Information:

Heart prefers FA in adults

due to continuous energy demands.

Fetal heart and failing heart

Rely on glucose (via GLUT-4).

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Identify the Transporter and Transport Mechanism Involved

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Sodium Potassium ATPase.

Primary active transport.

Epithelial cell junctions

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TAD GH

CADherins (A → Adherans, D → Desmosomes)

Cholera toxin (zonula occludens) receptor - GM1 Gangliosidosis

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Junctions	Notes	ㅤ
Tight junction - Zona occludens	• Apical margin • Paracellular movements • Prevents leakage between cells • Maintains cell polarity • Components: Claudins, occludins • Mnemonic: Tight clouds	ㅤ
ㅤ	↳ Watery diarrhea / Rice gruel diarrhea	ㅤ
ㅤ	↳ Claudin-16 mutation	Familial hypomagnesemia hypercalciuria
Zona adherens	• Attached to actin • Contain Cadherin • Loss of E-cadherin promotes metastasis	ㅤ
Desmosome (Macula Adherens / Spot Desmosome)	• “Spot weld” • Attached to intermediate filaments to neighboring cells	ㅤ
ㅤ	↳ Ab to Desmoglein 3 +/- Desmoglein 1	Pemphigus vulgaris
ㅤ	↳ Ab to Desmoglein 1	Pemphigus Foliaceus
ㅤ	↳ DEFECT IN DESMOSOMES • NAXOS syndrome • PLAKOGLOBIN gene mutation	Arrythmogenic Right Ventricular Cardiomyopathy
Gap junction	• Contain Connexons • Enable electrical coupling • Responsible for functional syncytium • Gapil keri kona (connexin) adikkuka	ㅤ
Hemidesmosome	• Basal surface of epithelial cells • Attached to intermediate filaments to basal lamina • Contain Integrins	ㅤ
ㅤ	↳ Abs	Bullous pemphigoid

Connexin mutations

Connexin mutations	Conditions
Connexin-32	Charcot Marie Tooth disease
Connexin-40	Idiopathic atrial fibrillation

CDH gene (E-cadherin):

Chromosome 16

"Glue" for cell-to-cell connection.

Loss/mutation

Mnemonic: Kadich (CDH) → Breastlum Vyarilum

"Golu" tumors/Kadicha tumors

Diffuse Gastric Cancer

Lauren's Classification	Intestinal Lauren's Classification	Diffuse Lauren's Classification
Epidemiological	Environmental	Familial
Pathology	Gastric atrophy, intestinal metaplasia	Blood Group A
Sex	m > F	F > M
Age	↑ Incidence with ↑Age	Younger age
Morphology	Gland formation Round glands	Poorly differentiated
Cell Type	ㅤ	• Gross: Linitis plastica ("leather bottle appearance"). • Microscopy: Signet ring cells.
Genetics	APC gene mutations, Microsatellite instability p53, p16 inactivation	Loss of E-cadherin (↓ E-cadherin) p53, p16 inactivation
Invasion	Hematogenous spread	Transmural/Lymphatic spread

Lobular Carcinoma Breast

Indian File/Single File Pattern

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Mnemonic: File (Indian file) of Breast Ca patients

Claudin low → EMT positive breast cancer

Krukenberg tumor

Stomach > Breast/ Colon
Signet Ring Cells
Retrograde lymphatic spread

NOTE: Miscellaneous one liners

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Intercalated Discs – Cardiac Muscle — Intercalated Discs – Cardiac Muscle

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