EXAM 2 STUDY GUIDE

Endocrine Section:

What type of communication occurs in this system (fast or slow why)? How does nervous system play a role in the endocrine system?

• Type of Communication

  • Slow communication because hormones must travel through the bloodstream to reach distant target cells

• Nervous System’s Role

  • The nervous system sends signals to the hypothalamus to control the pituitary glands (master gland of endocrine system) to release hormones

Endocrine Section:

What role does the bloodstream have in the endocrine system

• Bloodstream

  • Acts as a transport highway for hormones

  • Hormones release from endocrine gland → enters bloodstream → travel to target cells

Endocrine Section:
What types of cells are endocrine gland made of?

= Secretory Epithelial Cells (secrete substhormones directly into the bloodstream)

Endocrine Section:

Compare the hormone pathway of anterior hormones versus posterior hormones starting from a signal in the hypothalamus to hormones entering the circulatory system.

Note: You can use the drawings and flow charts we made in class and in the assignment for this section!

• Anterior Hormones

  • 1. Hypothalamus

    • Command for hormones

    • Signals through MEN (median eminence neuron)

  • 2. Releases Hormones

    • Communicates hormone order

    • Travels through HPV (Hypophyseal portal vein)

  • 3. Anterior pituitary 

    • Synthesizes hormone & secretes into blood

  • 4. Enters bloodstream

  • 5. Target cell, organ, tissue or gland

  • 6. Action

• Posterior Hormones

  • 1. Hypothalamus

    • Command for hormones & synthesizes ADH (Antidiuretic Hormone) & Oxytocin

      • Paraventricular neuron stimulates oxytocin 

      • Supraoptic neuron stimulates ADH

  • 2. Posterior Pituitary

    • Storage of ADH & Oxytocin and dumps

  • 3. Hormones enter the bloodstream

  • 4. Target cell/organ/tissue/gland

  • 5. Action

Endocrine Section:

Name and describe all of the all of the hormones associated with the anterior pituitary. What do those hormones do? What tissues/glands/organs do they act on?

Hormone	Target	Function
ACTH (Adrenocorticotropic Hormone)	Adrenal Cortex	Stimulates cortisol release for stress response, immune/pain reduction, and blood pressure regulation
TSH (Thyroid-Stimulating Hormone)	Thyroid Gland	Stimulates T3 and T4 to control metabolism
GH  (Growth Hormone)	Liver, Bones, Muscle, Fat	Used for growth, fat breakdown, increasing muscle/bone mass, and signals the liver to release glucose
LH (Luteinizing Hormone)	Ovaries & Testes	Ovulation & Testosterone Production
FSH (Follicle-Stimulating Hormone)	Ovaries & Testes	Follicle Development, Female Maturation, and Sperm Production
PRL (Prolactin)	Mammary Glands	Milk Production

Endocrine Section:

Name and describe all of the all of the hormones associated with the posterior pituitary. What do those hormones do? What do those hormones do? What tissues/glands/organs do they act on?

Note: These hormones are produced by the hypothalamus but stored and released by the posterior pituitary.

Hormone	Target	Function
Oxytocin	Uterus & Mammary Glands	Uterine contractions & Milk Ejection
ADH  (Antidiuretic Hormone/Vasopressin)	Kidneys & Blood Vessels	Water reabsorption in the kidneys and constricts blood vessels to regulate blood pressure

Endocrine System:

What is a releasing factor (RF) or releasing hormone (RH), and what does it do or act on?

• Made by the hypothalamus

• Travels through the hypophyseal portal system to the anterior pituitary

• Role: stimulates synthesis & release of a specific hormone

Muscle Contraction Section:

Provide a step by step process for skeletal muscle contraction.

• 1. Action potential arrives to neuromuscular junction

• 2. ACH (acetylcholine) is releasing into neuromuscular junction

• 3. ACH binds to nicotinic receptors on muscle membrane

• 4. Action potential is made and moves down T-Tubules

• 5. Action potential activates DHP (Dihydropyridine) receptors in T-Tubules

• 6. Mechanical coupling if DHP is active, the RyRs (Ryanodine) receptor channels open

• 7. Calcium is released meaning calcium levels are up

• 8. THE DANCE

  • 1. Calcium binds to troponin, moving tropomyosin to expose binding sites on actin

  • 2. Myosin heads binds to actin

  • 3. Myosin makes power stroke, pulling actin filaments inward, causing contraction

  • 4. Myosin releases ADP (adenosine diphosphate) + P (phosphate)

  • 5. ATP binds to myosin, detaching from actin and resetting head

  • 6. Myosin hydrolyzes ATP into ADP + P to move back into cocked position

Relaxation

• 1. SERCA (sarcoplasmic endoplasmic reticulum calcium ATPase) pump moves calcium back into the sarcoplasmic reticulum

• 2. Low calcium levels allow tropomyosin to block actin → muscle relaxes

• 3. AChE (acetylcholinesterase) breaks down remaining ACH in the neuromuscular junction

Muscle Contraction Section:

What makes skeletal muscle unique?

• Voluntary control

• Striated

• Multinucleated Fibers

• Uses mechanical coupling between receptors (DHP receptor & RyRs receptor) to release calcium

Muscle Contraction Section:

Provide a step by step process for cardiac muscle contraction.

• 1. SA (sinoatrial) node generates action potential, specifically through gap junctions moving quickly

• 2. Action potential travel deep into muscle via T-Tububles

• 3. Action potential activates L-Type (DHP (dihydropyridine receptor)) Calcium channel meaning calcium enters cardiac muscle

• 4. CICR (Calcium-Induced Calcium Release): where extracellular calcium triggers calcium to release from sarcoplasmic reticulum via calcium channels

• 5. Increased calcium levels leads to THE DANCE

  • 1. Calcium binds to troponin, moving tropomyosin to expose binding sites on actin

  • 2. Myosin heads bind to actin

  • 3. Myosin performs power stroke, pulling actin filaments inward causing contraction

  • 4. Myosin releases ADP (adenosine diphosphate) + P (phosphate)

    during this movement

  • 5. ATP binds to myosin, detaching from actin and resetting head

  • 6. Myosin hydrolyzes ATP into ADP + P to move back into cocked position

Relaxation

• 1. SERCA pump returns to calcium into sarcoplasmic reticulum

• 2. Na+K+ATPase pump (primary active transport) powers the Na+Ca2+ exchanger (secondary active transport)

• 3. Calcium moves out of cell → calcium levels drop

Cardiac Muscle Section:

What makes cardiac muscle unique?

• Stimulus comes from SA node

• Autorhythmic (involuntary)

• Super independent (does not need direct control by central nervous system)

• Has gap junctions (intercalated discs)

• Calcium-Induced Calcium Release (CICR) (needs extracellular calcium to trigger sarcoplasmic reticulum calcium release)

Cardiac Muscle Section:

Provide a step by step process for smooth muscle contraction.

• 1. Diverse Stimuli (hormone, local factors, neurotransmitters)

  • Triggers start of contraction

• 2. Calcium channels on membrane open and calcium enters cell

  • Primary source

• 3. Calcium from outside triggers calcium channels to open on sarcoplasmic reticulum

• 4. If calcium levels are high, calcium binds to calmodulin

• 5. A calcium-calmodulin complex activates MLCK (myosin light chain kinase)

• 6. MLCK causes myosin and actin to contract

Relaxation

• 1. SERCA pump moves calcium back into sarcoplasmic reticulum

• 2. Na+K+ATPase pump powers a Na+CA2+ exchanger

  • Calcium moves out 

• 3. Ca2+ATPase pump

  • Calcium moves out as well

• 4. MLCP (Myosin light chain phosphate) cuts off phosphates towards myosin → myosin releases

Cardiac Muscle Section:

What makes smooth muscle unique?

• Non-striated, spindle-shaped cells

• Slow & sustained contractions

• Lacks troponin; regulated by calmodulin instead

• Primary source } extracellular calcium (NOT sarcoplasmic reticulum as it’s underdeveloped)

Circulatory System Section:

What is the purpose of the circulatory system?

• Transport oxygen, nutrients, hormones, and immune cells 

• Removing waste products 

• Body & pH regulation

• Maintain homeostasis

Circulatory System Section:

Describe the pressure and velocity (speed of blood flow) of arteries vs capillary beds vs veins

• Arteries

  • = carries blood away from heart

  • Walls are thick, strong, & elastic

  • High pressure

  • Blood moves fast

    • Helps get blood to body quickly

• Capillary Beds

  • Tiny blood vessels where exchange happens

  • Thin walls (only one cell-thick walls)

  • Low pressure 

  • Blood moves very slowly

    • Helps oxygen, nutrients, & wastes move in & out easily

• Veins/Venules

  • = carries blood back to heart

  • Has valves (prevents backflow)

  • Thinner walls than arteries (vessels are stretching like a balloon)

  • Low pressure

  • Blood moves slower than arteries

Easy Way To Remember:

• Arteries = high pressure, fast

• Capillaries = lowest/low pressure, slowest

• Veins = low pressure, slower flow back to heart

Circulatory System Section:

Where are capillary beds located? What are the purpose of capillary beds?

• Located throughout body tissues (everywhere).

• Purpose:

  • Where gases, hormones, nutrients enter/exit (diffusion exchange)

Circulatory System Section:

Describe vein vs artery anatomy, what do they look like? What does this have to do with their function.

• Vein

  • Anatomy

    • Thinner walls, larger lumen (inner tube opening), has valves

  • Relation to Function

    • Suited for low pressure to carry blood back to heart

• Artery

  • Anatomy

    • Thick walls, small lumen

  • Relation to Function

    • Can withstand/handle high pressure from the heart

Circulatory System Section:

What causes varicose veins?

Caused by valve failure, leading to blood pooling and vein distention (vein gets stretched & widened).

Circulatory System Section:

(Fill in the Blank)

Arteries have ______ walls that allow them to ______ pressure.

Arteries have thick muscular walls that allow them to withstand pressure.

Circulatory System Section:

(Fill in the Blank)

Arterioles are known as ______ vessels because they ______

Arterioles are known as resistance vessels because they regulate blood flow through vasoconstriction/vasodilation.

Circulatory System Section:

(Fill in the Blank)

Veins are known act as a ______ because they ______

Veins are known act as a blood reservoir because they contain most of the body's blood at rest.

Circulatory System Section:

Describe what baroreceptors are, where they are located and what their function is

• = specialized mechanoreceptors (pressure sensors)  

• Location:

  • Aortic Arch & Carotid Sinus

• Function:

  • Help detect changes in blood pressure

    • Blood pressure rises → arterial walls stretch more → increases baroreceptors

    • Blood pressure drops → arterial walls stretch less → decreases baroreceptors

  • Has a homeostatic range that signals feedback loop when range is too low/high

Circulatory System Section:

(Fill in the Blank)

Increase stimulation DUE TO MORE PRESSURE would cause _____; a decrease would cause ________.

Increase stimulation DUE TO MORE PRESSURE would cause a decrease in heart rate and vasodilation (parasympathetic response); a decrease would cause an increase in heart rate and vasoconstriction (sympathetic response).

Circulatory System Pt. 2 Section

How does blood from veins make it back to the heart if they have low pressure and velocity?

• One-way valves in veins stop backflow 

• Skeletal muscle contractions push blood through the veins.

Circulatory System Pt. 2 Section

Describe how the heart beat (electrical activity of the heart) starting with the SA node and ending with Ventricular contraction

SA Node depolarizes →
action potentials are made and are spread over atria →
atrial contraction →
there’s a delay for ventricular filling →
AV Node depolarizes →
action potential travels to Bundle of His →
bundle branches →
Purkinje Fibers →
ventricular contraction

Circulatory System Pt. 2 Section

Electrical Conduction Pathway of the Heart described:

1. SA (Sinoatrial) Node

• Starts signal in right atrium

• Heart’s natural pacemaker

2. AV (Atrioventricular) Node 

• Delays signal so ventricles fill

3. Bundle of His

•  = pathway of specialized muscle fibers

• Carries signal down the interventricular septum (wall between ventricles)

4. Right & Left Bundle Branches

• Conducts an impulse to the ventricle’s apex

5. Purkinje Fibers

• Spread signal upward, causing contraction

Circulatory System Pt. 2 Section

Describe the electrical events of the PQRST complex. Which parts lead to atrial contraction? Ventricular contraction?

• P Wave

  • Atrial depolarization → atrial contraction

• QRS complex

  • Ventricular depolarization → ventricular contraction

• T wave 

  • Ventricular repolarization

Circulatory System Pt. 2 Section

Describe all of the mechanical events of the heart (plus: where do the heart sounds occur):

• 1. Ventricular Filling

  •  (Diastole)

  • Mechanical Events

    • Blood flows from atria into ventricles

    • Ventricles are relaxed & filling up

  • Valves

    • AV (Atrioventricular) Valves → open

    • SL (Semilunar) → closed

• 2. Atrial Contraction 

  • (End of Diastole)

  • Mechanical Events

    • Atria Contracts, pushing blood into ventricles

  • Valves

    • AV (Atrioventricular) Valves → open

    • SL (Semilunar) → closed

• 3. Isovolumetric Contraction

  • (Start of Systole)

  • Mechanical Events

    • S1 “Lub” sound occurs

    • Ventricles begin to contract

    • Valves are closed

  • Valves

    • AV (Atrioventricular) Valves → closed

    • SL (Semilunar) → closed

• 4. Ventricular Ejection

  • (Mid to Late Systole)

  • Mechanical Events

    • Blood ejected from ventricles into aorta & pulmonary artery

  • Valves

    • AV (Atrioventricular) Valves → closed

    • SL (Semilunar) → open

• 5. Isovolumetric Relaxation

  • (Start of Diastole)

  • Mechanical Events

    • S2 “Dub” sound occurs

    • Ventricles relax without filling

    • Semilunar valves close

  • Valves

    • AV (Atrioventricular) Valves → closed

    • SL (Semilunar) → closed

Circulatory System Pt. 3 Section:

How does sympathetic innervation and parasympathetic innervation affect the heart?

• Sympathetic 

  • Effect

    • Speeds up heart & contractility

  • How

    • Releases norepinephrine  

  • Why

    • “Fight or flight” response

• Parasympathetic

  • Effect

    • Slows heart rate

  • How

    • Vagus nerve releases acetylcholine

  • Why

    • “Rest and digest” response

Circulatory System Pt. 3 Section:

Provide a definition for diastole and systole

• Diastole = relaxation

• Systole = contraction