The Ultimate Heart Anatomy and Function Quiz

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168 Questions

Which of the following factors contributes to an increased stroke volume in a trained athlete's heart?

Increased preload

Which of the following hormones can increase the contractility of cardiac cells?

Epinephrine

Which division of the autonomic nervous system is responsible for decreasing heart rate?

Parasympathetic division

Which chamber of the heart receives blood from the superior and inferior vena cava?

Atria

What is the purpose of the longer action potential in cardiac contractile fibers?

To prevent summation and tetanus in the myocardium

What is the function of the electrocardiogram (ECG)?

To record the overall spread of electrical activity through the heart

What is the role of the medulla oblongata in autonomic innervation of the heart?

Receives input from higher centers and controls sympathetic and parasympathetic neurons

Which layer of the heart is responsible for pumping blood through the heart?

Myocardium

Which valves separate the chambers of the heart?

Atrioventricular (AV) valves

Where does the heart receive oxygen-poor blood from?

Superior and inferior vena cava

Which phase of ventricular systole includes isovolumic contraction and ventricular ejection?

Ventricular systole

Which of the following is responsible for generating its own rhythm in the heart?

Autorhythmicity

What is the purpose of the interventricular septum in the heart?

To separate the left and right sides of the heart

Which of the following is responsible for routing blood in the heart?

Heart

What is the function of the atria in the heart?

To receive blood

What is the function of the ventricles in the heart?

To pump blood

What is the purpose of the large number of mitochondria in cardiac cells?

To produce ATP for energy

What is the purpose of the plateau phase in the action potential of cardiac contractile fibers?

To prevent summation and tetanus in the myocardium

What is the purpose of the T-tubules in cardiac cells?

To create fast cell-cell signals

What is the purpose of the electrocardiogram (ECG)?

To record the overall spread of electrical activity through the heart

Which part of the brain is responsible for controlling the autonomic innervation of the heart?

Medulla Oblongata

Which of the following factors does NOT contribute to an increased stroke volume in a trained athlete's heart?

Increased afterload

Which of the following is responsible for maintaining normal heart function by regulating intra- and extracellular ion concentrations?

Intrinsic and extrinsic ion concentrations

Which of the following hormones is released by sympathetic stimulation and increases heart rate and force of contraction?

Epinephrine

Which division of the autonomic nervous system is responsible for decreasing heart rate?

Parasympathetic division

Which of the following is responsible for stretching the ventricles by contained blood?

Preload

Which phase of ventricular systole includes isovolumic contraction and ventricular ejection?

Isovolumic contraction phase

Which of the following is NOT a function of the electrocardiogram (ECG)?

Monitoring blood pressure

Which chamber of the heart receives blood from the superior and inferior vena cava?

Right atrium

Which layer of the heart is responsible for pumping blood through the heart?

Myocardium

Which of the following hormones can increase the contractility of cardiac cells?

Norepinephrine

Which layer of the heart is responsible for pumping blood through the heart?

Myocardium

Which valves separate the chambers of the heart?

Atrioventricular (AV) valves

Which chamber of the heart receives blood from the superior and inferior vena cava?

Right atrium

Which of the following is responsible for regulating the heartbeat?

All of the above

Which phase of ventricular systole includes isovolumic contraction and ventricular ejection?

Ventricular systole

Which of the following is a factor affecting cardiac output?

Venous return

Which of the following is NOT an abnormality of the heart mentioned in the text?

Aortic stenosis

What is the difference between cardiac output and cardiac reserve?

Cardiac output is the amount of blood pumped by each ventricle in one minute, while cardiac reserve is the difference between resting and maximal cardiac output.

Which of the following is responsible for pumping oxygen-rich blood to the systemic circuit?

Left ventricle

What is the purpose of the endocardium?

To line the inner surface of the heart chambers and valves

ECG MATCH UP appropriate parts

P wave = atrial depolarization PR segment = AV node delay QRS COMPLEX = Ventricular Depolarization ST segment = Time during Ventricle contract& empty

what does the T wave represent in a ECG?

What is the TP interval?

First heart sound or “lubb”

AV valves close and surrounding fluid vibrations at systole

MATCHY MATCHY

the volume of blood pumped from one ventricle of the heart with each beat = Stroke Volume The amount of blood remaining in a ventricle after full ventricular ejection = End Systolic Volume (ESV) The amount of blood in a ventricle just before ventricular ejection = End Diastolic Volume (EDV) is the amount of blood pumped by each ventricle in one minute = Cardiac Output (CO)

your patients HR is 60bpm, his SV is 100ml, what is their Cardiac output?

so your patient has End diastolic volume (EDV) of 145 & an end systolic volume (ESV) of 70. what is the Stroke volume?

Homeostasis is the maintenance of a relatively stable ______ environment.

internal

Most cells are not in direct contact with the ______ environment.

external

The fluid environment in which the cells live is called ______ fluid.

extracellular

The fluid contained within all body cells is called ______ fluid.

intracellular

Na+ binding stimulates ______ by ATP.

phosphorylation

Extracellular K+ binds to the ______, triggering release of the Phosphate group.

protein

The initial carrier protein uses ATP to move substance 1 across the membrane against its concentration gradient, storing ______ energy.

potential

Lipophilic ligands – can diffuse through the phospholipid bilayer of the cell membrane and bind to cytosolic or nuclear ______ to generate a response within the cell.

receptors

____ functions as a second messenger in other pathways.

DAG

Signal molecule (first messenger) ______ activates a G protein.

Surface receptor

G protein activates the membrane-bound enzyme, ______.

phospholipase C

Phospholipase C catalyzes synthesis of inositol triphosphate (IP3), which stimulates release of ______ from ER.

Ca2+

Released Ca2+ initiates cellular ______.

change

IP3 quickly diffuses through the cytosol and binds to an IP3– gated ______ channel in the ER membrane, causing it to open.

calcium

Homeostasis is continually being disrupted by: External stimuli Heat, cold, lack of oxygen, pathogens, toxins Internal stimuli Body temperature Blood pressure Concentration of water, glucose, salts, oxygen, etc. Physical and psychological ______

distresses

Control systems are grouped into two classes: Intrinsic controls Local controls that are inherent within an organ Involves detecting deviations and making corrections within the organ, often called ______

autoregulation

Extrinsic controls Regulatory mechanisms initiated outside an organ Accomplished by nervous and endocrine systems Responses of an organ that are triggered by factors external to the organ or ______

systems

In order to maintain homeostasis, control system must be able to: Detect deviations from normal in the internal environment that need to be held within narrow limits Integrate this information with other relevant information Make appropriate adjustments in order to restore factor to its desired ______

value

Enzyme-linked receptors are embedded in the plasma membrane, with their catalytic site exposed ______ the cell

inside

The most common enzyme-linked receptor is the receptor tyrosine ______

kinase (RTK)

Phosphorylation is the process of activating a protein by the addition of a ______ (PO43) group

phosphate

Three stages of Signal Transduction: 1) Reception – an extracellular ligand binds to and activates a ______ receptor

membrane

______ uses membrane proteins to transport large, polar molecules that are not usually permeable to the phospholipid bilayer. Two types of transport proteins: 1) Channel proteins – provide a narrow channel for the substance to pass through. Mostly for water and ions 2) Carrier proteins – physically bind to the substance on one side of the membrane, and change conformation in order to release it on the other. Ideal for small organic molecules, such as glucose and amino acids, that are too large to pass through channels.

Facilitated diffusion

______ uses energy from ATP to move a substance against its concentration gradient. Requires the use of carrier proteins, not channel proteins. 2 types of Active Transport: Membrane pump (protein-mediated active transport) Coupled transport (co-transport)

Active transport

______ is the most important membrane pump in all animal cells. It transports 3 Na+ out of the cell and 2 K+ into the cell for each ATP consumed. Properly called “Na+/K+ ATPase”.

The Na+/K+ pump

______ – the diffusion of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. In some circumstances, the solvent may be something other than water. However, in living systems, the solvent is always water, so biologists generally define osmosis as the diffusion of water across a semipermeable membrane.

Osmosis

Negative feedback loops consist of: Stimulus – a change Receptor Receptor – structures that monitor a controlled condition and detect the change Control Center (Integration Center) – determines next action Efferent Pathway – the means to send a signal from the integration center to the effector organ Effector – the organ or tissue that receives directions from the control center and produces ______

Response

Positive feedback loops consist of: Stimulus – a change Receptor Receptor – structures that monitor a controlled condition and detect the change Control Center (Integration Center) - determines next action Efferent Pathway – the means to send a signal from the integration center to the effector organ Effector – the organ or tissue that receives directions from the control center and produces ______

Response

NFbL Stimulus: Low serum T3, T4 Receptors: T3, T4 binding sites on Hypothalamus Neural Integrating Center: Hypothalamus releases TRH ______ Efferent Pathway: Hypothalamic-Pituitary Portal Veins Endocrine Integrating Center: Anterior Pituitary releases TSH Efferent Pathway: Bloodstream Endocrine Integrating Center: Thyroid Gland (releasing T3, T4) Efferent Pathway: Bloodstream Effector: Various body tissues Response: Increased serum sT3, T4, relieves original stimulus

Negative Feedback

Stimulus: Amniotic sac breaks, fetus drops lower in uterus Receptors: Stretch receptors in walls of uterus Afferent Pathway: Vagus nerve (sensory) to Hypothalamus Efferent Pathway: Hypothalamo-neurohypophyseal nerve tract Integrating Center: Neurohypophysis releases oxytocin Efferent Pathway: Bloodstream to uterine smooth muscle Effector: Uterine contractions cause cervix to dilate & fetus to descend in birth canal Response: More stretch… more oxytocin release… more contractions…. repeat PFbL ends with birth of the baby & ↓ uterine stretch

Positive Feedback

Parathyroid hormones are regulators of ______ levels in healthy adults

calcium

Adrenal medulla – Nervous tissue that functions as part of the Sympathetic Nervous System Secretes ______

catecholamines

Adrenal cortex – Glandular tissue Secretes ______

corticosteroids

The most important mineralocorticoid is ______

aldosterone

The most important glucocorticoid is ______

cortisol

Most gonadocorticoids secreted are ______

androgens

Blood contains low concentration of Ca2+, which stimulates…

parathyroid glands

PTH causes [Ca2+] in blood to rise (Ca2+ is reabsorbed in kidneys and leached from bones) and the stimulus is removed

parathyroid glands

Neural Stimuli: Neural Stimulus Hormones are released in response to neural stimulation originating from the

CNS (brain, spinal cord)

Preganglionic sympathetic fibers stimulate

adrenal medulla cells

Hormonal Stimuli: Hormonal Stimulus Hormones are released in response to hormones produced by other

endocrine organs

The hypothalamus secrets hormones that stimulate the

anterior pituitary gland

ADH and oxytocin are made and packaged in ______

neuron soma

Hormones are released into the blood when stimulated by ______ from the hypothalamus

APs

The ______ is structurally part of the brain and contains axons of hypothalamic nerves where hormones are manufactured

posterior pituitary

Oxytocin is a strong stimulant of ______

uterine contraction

Antidiuretic Hormone (ADH) reduces urine formation in order to avoid ______

dehydration

The thyroid gland produces hormones such as thyroxine (T4) and triiodothyronine (T3) that regulate ______

metabolism

Endocrine system includes all cells and endocrine tissues that produce hormones or ______ factors.

paracrine

Endocrine system regulates long-term ongoing metabolic activity management, while the nervous system performs short-term ______ management.

crisis

Endocrine system functions include maintaining an optimal biochemical environment within the body, influencing metabolic activities, and controlling growth, development, and ______ reproduction.

sexual

Endocrine system consists of various glands, including the hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas, and ______.

gonads

Hormones are chemicals secreted by cells into the bloodstream for transport to distant target tissues, where they bind to specific receptors and induce ______ changes.

cellular

Hormones can have different cellular responses, such as altering plasma membrane permeability, stimulating gene activation and protein synthesis, activating or deactivating enzyme systems, inducing secretory activity, and stimulating ______ and cytokinesis.

mitosis

The hypothalamus controls the release of hormones from the pituitary gland by sending ______ stimuli.

chemical

The anterior pituitary synthesizes and releases six hormones: TSH, PRL, GH, ACTH, FSH, and ______.

LH

The posterior pituitary stores and releases two hormones: ______ and vasopressin (ADH).

oxytocin

The hypothalamus releases hormones that stimulate the synthesis and release of hormones from the ______ pituitary.

anterior

Hypothalamic hormones include TRH, CRH, GnRH, GHRH, and ______, which regulate the release of TSH, ACTH, FSH, LH, and PRL, respectively.

PRH

The pituitary gland is attached to the hypothalamus by the ______.

infundibulum

Up-regulation of ______ receptors occurs after four weeks of exercise

GLUT

When low plasma glucose levels occur, the ______ are released to accelerate lypolysis

catecholamines

Triglycerides are reduced to free fatty acids (lipolysis) by ______ which is activated by:

lipase

Osmoreceptors in hypothalamus sense dehydration, Antidiuretic Hormone (ADH) is released from the posterior pituitary, and ______ is then reabsorbed by the kidneys.

water

Three Phases of ______ (General Adaptation Syndrome): Alarm Phase Resistance Phase Exhaustion

GAS

______ Phase: immediate, fight or flight, directed by the sympathetic nervous system, dominated by glucocorticoids

Alarm

Breakdown of homeostatic regulation and failure of one or more organ systems

Exhaustion

______ binding stimulates ______ by ATP.

Na+, ATPase

Adrenal medulla – Nervous tissue that functions as part of the Sympathetic Nervous System Secretes ______.

epinephrine

PRH stimulates the development of ______ glands and milk production in females.

mammary

PIH inhibits the development of ______ glands and milk production.

mammary

Oxytocin stimulates contraction cells in ______ glands and smooth muscle cells in the uterus.

mammary

The thyroid gland produces hormones T3 and T4, which regulate ______.

metabolism

Parathyroid glands produce ______, which regulates calcium levels in the body.

parathyroid hormone (PTH)

The adrenal glands consist of the adrenal medulla and ______.

adrenal cortex

The adrenal medulla secretes catecholamines, such as epinephrine and ______.

norepinephrine

The hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, adrenal glands, pancreas, and ______ are all key players in the endocrine system.

gonads

Hormones bind to their corresponding receptors and induce changes in the target cell's behavior, such as altering plasma membrane permeability, stimulating gene activation, and inducing ______ activity.

secretory

The nervous system can modify the stimulation of endocrine glands and their negative ______ mechanisms.

feedback

The hypothalamus regulates both the nervous and endocrine systems, secreting regulatory hormones that control the anterior pituitary gland and exerting direct neural control over the endocrine cells of the ______ medullae.

adrenal

The pituitary gland releases nine important peptide hormones, is divided into the anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis), and is attached to the hypothalamus by the ______.

infundibulum

Paracrine communication refers to chemical messengers between cells within one tissue, while hormones are chemicals secreted into the bloodstream for transport to distant ______.

target tissues

Tropic hormones stimulate the release of another hormone, while ______ hormones stimulate the growth and nourishment of a gland.

trophic

Rising blood levels of Thyrotropic hormone stimulates the normal development and secretory activity of ______ gland

thyroid

Adrenocorticotropic Hormone stimulates the release of ______ by the adrenal gland

glucocorticoids

FSH stimulates gamete (egg or sperm) production and ______ secretion in females

estrogen

LH causes ovulation and ______ production in females

progestin

LH stimulates testes to produce ______ in males

testosterone

GHRH stimulates cell growth and replication by promoting the release of ______

insulin-like growth factors (IGFs)

GHIH/ Somatost inhibits release of ______

Growth Hormone

Cardiac impulse originates at ______ node

SA

Action potential delayed at ______ node to ensure atrial contraction precedes ventricular contraction for complete ventricular filling

AV

Impulse travels rapidly down ______ septum by means of bundle of His

interventricular

Autorhythmic cells have “drifting” resting potentials called ______ potentials

pacemaker

Large T ______

tubules

A long refractory period + prolonged plateau phase prevents summation and tetanus in ______

myocardium

Action potential from autorhythmic cells is passed to contractile cells, propagating down ______

T-tubules

Gap junctions (instead of synapses) create fast cell-cell ______

signals

Intercalated discs allow branching of ______

myocardium

Pericardium, epicardium, myocardium, ______

endocardium

Sympathetic stimulation releases ______ and initiates a cAMP second-messenger system

norepinephrine

Preload – amount ventricles are stretched by contained blood ______

EDV

Afterload – back pressure exerted by blood in the large arteries leaving the heart ______

Contractility

Intra- and extracellular ion concentrations must be maintained for normal heart ______

function

Increased force of contraction is a result of increased ______

contractility

Blood loss and extremely rapid heartbeat cause ______ venous return

decreased

Heart rate is modified by the ______ nervous system

ANS

Epinephrine and ______ hormones increase heart rate and force of contraction

thyroxine

The SA node establishes the ______ heart rate

baseline

The hypothalamus releases hormones that stimulate the synthesis and release of hormones from the ______ pituitary

anterior

Cardiac muscle tissue forms the thick layer of ______ and is responsible for pumping blood through the heart.

myocardium

The chambers of the heart are separated by ______, including atrioventricular (AV) valves and semilunar valves.

heart valves

The heart receives oxygen-poor blood from the superior and inferior vena cava in the right atrium, and pumps it to the right ______.

ventricle

The right ventricle then pumps the blood to the pulmonary circuit through the pulmonary trunk and ______ valve.

semilunar

Oxygen-rich blood from the lungs enters the left ______, and is pumped to the left ventricle.

atrium

The left ventricle pumps the oxygen-rich blood to the systemic circuit through the aorta and ______ valve.

semilunar

The heart has a specialized conduction system, including the SA node, AV node, and Purkinje fibers, which regulate the ______.

heartbeat

Abnormalities of the heart can include extrasystole, ventricular fibrillation, complete heart block, myocardial infarction, and congestive ______.

heart failure

The phases of ventricular systole include ______ contraction and ventricular ejection.

isovolumic

Cardiac output is the amount of blood pumped by each ventricle in one minute and is determined by heart rate and ______ volume.

stroke

Study Notes

Anatomy and Function of the Heart

  • The heart is composed of three layers: epicardium, myocardium, and endocardium.
  • Cardiac muscle tissue forms the thick layer of myocardium and is responsible for pumping blood through the heart.
  • The heart is divided into four chambers: right atrium, right ventricle, left atrium, and left ventricle.
  • The chambers are separated by heart valves, including atrioventricular (AV) valves and semilunar valves.
  • The heart receives oxygen-poor blood from the superior and inferior vena cava in the right atrium, and pumps it to the right ventricle.
  • The right ventricle then pumps the blood to the pulmonary circuit through the pulmonary trunk and semilunar valve.
  • Oxygen-rich blood from the lungs enters the left atrium, and is pumped to the left ventricle.
  • The left ventricle pumps the oxygen-rich blood to the systemic circuit through the aorta and semilunar valve.
  • The heart has a specialized conduction system, including the SA node, AV node, and Purkinje fibers, which regulate the heartbeat.
  • Abnormalities of the heart can include extrasystole, ventricular fibrillation, complete heart block, myocardial infarction, and congestive heart failure.
  • The phases of ventricular systole include isovolumic contraction and ventricular ejection.
  • Cardiac output is the amount of blood pumped by each ventricle in one minute and is determined by heart rate and stroke volume. Cardiac reserve is the difference between resting and maximal cardiac output. Factors affecting cardiac output include heart rate, stroke volume, autonomous innervation, hormones, cardiac reflexes, and venous return.

Anatomy and Function of the Heart

  • The heart is composed of three layers: epicardium, myocardium, and endocardium.
  • Cardiac muscle tissue forms the thick layer of myocardium and is responsible for pumping blood through the heart.
  • The heart is divided into four chambers: right atrium, right ventricle, left atrium, and left ventricle.
  • The chambers are separated by heart valves, including atrioventricular (AV) valves and semilunar valves.
  • The heart receives oxygen-poor blood from the superior and inferior vena cava in the right atrium, and pumps it to the right ventricle.
  • The right ventricle then pumps the blood to the pulmonary circuit through the pulmonary trunk and semilunar valve.
  • Oxygen-rich blood from the lungs enters the left atrium, and is pumped to the left ventricle.
  • The left ventricle pumps the oxygen-rich blood to the systemic circuit through the aorta and semilunar valve.
  • The heart has a specialized conduction system, including the SA node, AV node, and Purkinje fibers, which regulate the heartbeat.
  • Abnormalities of the heart can include extrasystole, ventricular fibrillation, complete heart block, myocardial infarction, and congestive heart failure.
  • The phases of ventricular systole include isovolumic contraction and ventricular ejection.
  • Cardiac output is the amount of blood pumped by each ventricle in one minute and is determined by heart rate and stroke volume. Cardiac reserve is the difference between resting and maximal cardiac output. Factors affecting cardiac output include heart rate, stroke volume, autonomous innervation, hormones, cardiac reflexes, and venous return.

Overview of the Endocrine System and Hormones

  • The endocrine system includes all cells and endocrine tissues that produce hormones or paracrine factors.
  • The endocrine system regulates long-term ongoing metabolic activity management, while the nervous system performs short-term crisis management.
  • The endocrine system functions include maintaining an optimal biochemical environment within the body, influencing metabolic activities, and controlling growth, development, and sexual reproduction.
  • The endocrine system consists of various glands, including the hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas, and gonads.
  • Hormones are chemicals secreted by cells into the bloodstream for transport to distant target tissues, where they bind to specific receptors and induce cellular changes.
  • Hormones can be classified based on their chemical composition, such as amino acid derivatives, protein derivatives, and lipid derivatives.
  • Amino acid derivatives include tyrosine-based hormones like catecholamines and thyroid hormones, and tryptophan-based hormones like serotonin and melatonin.
  • Protein derivatives include glycoproteins and short polypeptides/small proteins, which have various functions in the body.
  • Lipid derivatives include steroids, such as androgens, estrogens, progestins, mineralocorticoids, glucocorticoids, and calcitriol, as well as eicosanoids.
  • Hormones can also be classified based on the location of their receptors, such as membrane receptors, second messenger systems, tyrosine kinase-linked receptors, hormone-gated ion channels, and intracellular and intranuclear receptors.
  • Hormones can have different cellular responses, such as altering plasma membrane permeability, stimulating gene activation and protein synthesis, activating or deactivating enzyme systems, inducing secretory activity, and stimulating mitosis and cytokinesis.
  • Hormone concentrations in the blood are controlled by negative feedback systems and vary within a narrow desirable range. Hormones are synthesized and released in response to humoral, hormonal, and neural stimuli. Humoral stimuli detect blood solutes, hormonal stimuli detect blood hormones, and neural stimuli are stimulated by action potentials from the central nervous system.

Functions and Hormones of the Hypothalamus and Pituitary Gland

  • The pituitary gland is divided into two parts: the anterior pituitary or adenohypophysis, and the posterior pituitary or neurohypophysis.
  • The hypothalamus controls the release of hormones from the pituitary gland by sending chemical stimuli.
  • The anterior pituitary synthesizes and releases six hormones: TSH, PRL, GH, ACTH, FSH, and LH.
  • The posterior pituitary stores and releases two hormones: oxytocin and vasopressin (ADH).
  • The hypothalamus releases hormones that stimulate the synthesis and release of hormones from the anterior pituitary.
  • Hypothalamic hormones include TRH, CRH, GnRH, GHRH, and PRH, which regulate the release of TSH, ACTH, FSH, LH, and PRL, respectively.
  • The hypothalamus also releases inhibiting hormones, such as dopamine, that inhibit the release of certain hormones from the anterior pituitary.
  • The pituitary gland is attached to the hypothalamus by the infundibulum.
  • The anterior pituitary, or adenohypophysis, contains five different types of endocrine cells that secrete hormones like GH, PRL, TSH, ACTH, FSH, and LH.
  • Tropic hormones released by the anterior pituitary, like TSH, ACTH, FSH, and LH, regulate the secretion of hormones by other endocrine glands.
  • The hypothalamus also synthesizes and releases two neurohormones, oxytocin and vasopressin, which are stored and released by the posterior pituitary.
  • Neurohormones are hormones released by neurons into the bloodstream to target distant cells.

The Endocrine System: Key Players and Functions

  • The endocrine system includes all cells and tissues that produce hormones or paracrine factors.
  • Its functions include maintaining an optimal biochemical environment, influencing metabolic activities, regulating growth and development, and controlling sexual reproduction.
  • Paracrine communication refers to chemical messengers between cells within one tissue, while hormones are chemicals secreted into the bloodstream for transport to distant target tissues.
  • Up-regulation is when target cells form more receptors in response to a hormone, while down-regulation is when target cells lose receptors in response to a hormone.
  • Tropic hormones stimulate the release of another hormone, while trophic hormones stimulate the growth and nourishment of a gland.
  • Stress refers to any condition that threatens homeostasis, and neurohormones are hormones released and secreted by neurons into the bloodstream to target distant cells.
  • The hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, adrenal glands, pancreas, and gonads are all key players in the endocrine system.
  • Hormones bind to their corresponding receptors and induce changes in the target cell's behavior, such as altering plasma membrane permeability, stimulating gene activation, and inducing secretory activity.
  • Hormone concentrations in the blood reflect the rate of release and the speed of inactivation and removal from the body.
  • The nervous system can modify the stimulation of endocrine glands and their negative feedback mechanisms.
  • The hypothalamus regulates both the nervous and endocrine systems, secreting regulatory hormones that control the anterior pituitary gland and exerting direct neural control over the endocrine cells of the adrenal medullae.
  • The pituitary gland releases nine important peptide hormones, is divided into the anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis), and is attached to the hypothalamus by the infundibulum.

Anatomy and Function of the Heart

  • The heart is composed of three layers: epicardium, myocardium, and endocardium.
  • Cardiac muscle tissue forms the thick layer of myocardium and is responsible for pumping blood through the heart.
  • The heart is divided into four chambers: right atrium, right ventricle, left atrium, and left ventricle.
  • The chambers are separated by heart valves, including atrioventricular (AV) valves and semilunar valves.
  • The heart receives oxygen-poor blood from the superior and inferior vena cava in the right atrium, and pumps it to the right ventricle.
  • The right ventricle then pumps the blood to the pulmonary circuit through the pulmonary trunk and semilunar valve.
  • Oxygen-rich blood from the lungs enters the left atrium, and is pumped to the left ventricle.
  • The left ventricle pumps the oxygen-rich blood to the systemic circuit through the aorta and semilunar valve.
  • The heart has a specialized conduction system, including the SA node, AV node, and Purkinje fibers, which regulate the heartbeat.
  • Abnormalities of the heart can include extrasystole, ventricular fibrillation, complete heart block, myocardial infarction, and congestive heart failure.
  • The phases of ventricular systole include isovolumic contraction and ventricular ejection.
  • Cardiac output is the amount of blood pumped by each ventricle in one minute and is determined by heart rate and stroke volume. Cardiac reserve is the difference between resting and maximal cardiac output. Factors affecting cardiac output include heart rate, stroke volume, autonomous innervation, hormones, cardiac reflexes, and venous return.

Test your knowledge of the anatomy and function of the heart with this informative quiz. Learn about the layers, chambers, valves, and conduction system of the heart, as well as common abnormalities and factors affecting cardiac output.

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