Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IB Biology HL > Option D4 The Heart > Flashcards

Option D4 The Heart Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Cardiac muscle cells

A

Heart cells that…

  • Are myogenic (contract without stimulation by the central nervous system)
  • Are branched, allowing for faster signal propagation and contraction in three dimensions
  • Are not fused together, but connected by intercalated disks
  • Have more mitochondria because they are more reliant on aerobic respiration than skeletal muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Structural features of cardiac tissue

A
  • Muscles have a longer period of contraction and refraction, which is needed to maintain a viable heart beat
  • Tissue does not become fatigued (unlike skeletal muscle), allowing for continuous, lifelong contractions
  • Interconnected network of cells is separated between atria and ventricles, allowing them to contract separately
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Result of intercalated discs

A

While electrical signals can pass between cells, each cell is capable of independent contraction.
- Coordinated contraction of cardiac muscle cells is controlled by specialized auto-rhythmic “pace-making” cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sinoatrial (SA) node

A

A cluster of cardiomyocytes within the wall of the right atrium that direct the contraction of the heart tissue.

  • Primary pacemaker that controls heart rate
  • Sends out electric signals that stimulate heart contractions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Atrioventricular (AV) node

A

A separate node that separates atrial and ventricular contractions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Atrial contraction (systole)

A
  • SA node signals for the heart to contract
  • Electric signal is transmitted via gap junctions to the atrial myocardium
  • Atria contract, forcing blood into the ventricles
  • SA node sends signals to the AV node simultaneously
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Time lag between atrial and ventricular systole

A

Optimizes blood flow between chambers, allowing blood to fill ventricles before AV valves close.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Bundle of His

A

A specialized bundle of cardiomyocytes that innervate the Purkinje fibers, causing cardiac muscle to contract.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Ventricular contraction (systole)

A
  • AV node is triggered by signals of the SA node
  • Signals are sent down the septum via the Bundle of His
  • Bundle of His triggers Purkinje fibers in the wall of ventricles
  • Ventricles contract, forcing blood into the arteries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Diastole

A

A relatively long recovery period that allows the heart to passively refill with blood between beats.
- Recovery period helps prevent heart tissue from becoming fatigued

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Structural features and its contribution to functional properties

A
  • Cardiac muscle has a longer period of contraction and refraction, which is needed to maintain a viable heart beat
  • The heart tissue does not become fatigued (unlike skeletal muscle), allowing for continuous, life long contractions
  • The interconnected network of cells is separated between atria and ventricles, allowing them to contract separately
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Specialized cluster of cardiomyocytes

A
  • This cluster of cells is collectively called the sinoatrial node (SA node or SAN)
  • The sinoatrial node acts as a primary pacemaker, controlling the rate at which the heart beats (i.e. pace ‘making’)
  • It sends out electrical signals which are propagated throughout the entire atria via gap junctions in the intercalated discs
  • In response, the cardiac muscle within the atrial walls contract simultaneously (atrial systole)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Fibrous cardiac skeleton composed of connective tissue

A
  • This connective tissue functions to anchor the heart valves in place and cannot conduct electrical signals
  • The signals from the sinoatrial node must instead be relayed through a second node located within this cardiac skeleton
  • This second node is called the atrioventricular node (or AV node) and separates atrial and ventricular contractions
  • The AV node propagates electrical signals more slowly than the SA node, creating a delay in the passing on of the signal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Two sets of valves located in the heart:

A
  • Atrioventricular valves (tricuspid and bicuspid) prevent blood in the ventricles from flowing back into the atria
  • Semilunar valves (pulmonary and aortic) prevent blood in the arteries from flowing back into the ventricles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Heart sounds

A
  • The first heart sound is caused by the closure of the atrioventricular valves at the start of ventricular systole
  • The second heart sound is caused by the closure of the semilunar valves at the start of ventricular diastole
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Normal heart beat

A
  1. The P wave represents depolarization of the atria in response to signalling from the sinoatrial node (i.e. atrial contraction)
  2. The QRS complex represents depolarization of the ventricles (i.e. ventricular contraction), triggered by signals from the AV node
  3. The T wave represents repolarization of the ventricles (i.e. ventricular relaxation) and the completion of a standard heart beat
  4. Between these periods of electrical activity are intervals allowing for blood flow (PR interval and ST segment)
17
Q

Examples of heart conditions

A
  • Tachycardia (elevated resting heart rate = >120 bpm) and bradycardia (depressed resting heart rate = < 40 bpm)
  • Arrhythmias (irregular heart beats that are so common in young people that it is not technically considered a disease)
  • Fibrillations (unsynchronised contractions of either atria or ventricles leading to dangerously spasmodic heart activity)
18
Q

Cardiac output equation

A

Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV)

19
Q

Heart rate

A

Heart rate describes the speed at which the heart beats, measured by the number of contractions per minute (or bpm)

  • Each ventricular contraction forces a wave of blood through the arteries which can be detected as a pulse
  • The typical pulse rate for a healthy adult is between 60 – 100 beats per minute

Heart rate can be affected by a number of conditions – including exercise, age, disease, temperature and emotional state
- Additionally, the body will attempt to compensate for any changes to stroke volume with a corrective alteration to heart rate

An individual’s heart rate is controlled by both nervous and hormonal signals:

  • Heart rate is increased by the sympathetic nervous system and decreased by parasympathetic stimulation (vagus nerve)
  • Heart rate can also be increased hormonally via the action of adrenaline / epinephrine
20
Q

Blood pressure

A

Stroke volume is the amount of blood pumped to the body (from the left ventricle) with each beat of the heart
- It is affected by the volume of blood in the body, the contractility of the heart and the level of resistance from blood vessels

Changes in stroke volume will affect the blood pressure – more blood or more resistance will increase the overall pressure

  • Blood pressure measurements typically include two readings – representing systolic and diastolic blood pressures
  • Systolic blood pressure is higher, as it represents the pressure of the blood following the contraction of the heart
  • Diastolic blood pressure is lower, as it represents the pressure of the blood while the heart is relaxing between beats

Blood pressure readings will vary depending on the site of measurement (e.g. arteries have much higher pressure than veins)

  • A typical adult is expected to have an approximate blood pressure in their brachial artery of 120/80 mmHg to 140/90 mmHg
  • Blood pressure can be affected by posture, blood vessel diameter (e.g. vasodilation) and fluid retention or loss
21
Q

Hypertension

A
  • Hypertension is defined as an abnormally high blood pressure – either systolic, diastolic or both (e.g. > 140/90 mmHg)
  • Common causes of hypertension include a sedentary lifestyle, salt or fat-rich diets and excessive alcohol or tobacco use
  • High blood pressure can also be secondary to other conditions (e.g. kidney disease) or caused by some medications
  • Hypertension itself does not cause symptoms but in the long-term leads to consequences caused by narrowing blood vessels
22
Q

Thrombosis

A
  • Thrombosis is the formation of a clot within a blood vessel that forms part of the circulatory system
  • Thrombosis occurs in arteries when the vessels are damaged as a result of the deposition of cholesterol (atherosclerosis)
  • Atheromas (fat deposits) develop in the arteries and significantly reduce the diameter of the vessel (leading to hypertension)
  • The high blood pressure damages the arterial wall, forming lesions known as atherosclerotic plaques
  • If a plaque ruptures, blood clotting is triggered, forming a thrombus that restricts blood flow
  • If the thrombus becomes dislodged it becomes an embolus and can cause blockage at another site
  • Thrombosis in the coronary arteries leads to heart attacks, while thrombosis in the brain causes strokes
23
Q

Risk factors for coronary heart disease

A

A - Age – Blood vessels become less flexible with advancing age

G - Genetics – Having hypertension predispose individuals to developing CHD
O - Obesity – Being overweight places an additional strain on the heart
D - Diseases – Certain diseases increase the risk of CHD (e.g. diabetes)
D - Diet – Diets rich in saturated fats, salts and alcohol increases the risk
E - Exercise – Sedentary lifestyles increase the risk of developing CHD
S - Sex – Males are at a greater risk due to lower oestrogen levels
S - Smoking – Nicotine causes vasoconstriction, raising blood pressure

24
Q

Artificial pacemakers

A

a medical device that delivers electrical impulses to the heart in order to regulate heart rate

25
Q

Reason for artificial pacemakers

A
  • Abnormally slow heart rates (bradycardia)

- Arrhythmias arising from blockages within the heart’s electrical conduction system

26
Q

Fibrillation

A

the rapid, irregular and unsynchronized contraction of the heart muscle fibers

27
Q

Treatment of fibrillation

A
  • This functions to depolarize the heart tissue in an effort to terminate unsynchronized contractions
  • Once heart tissue is depolarized, normal sinus rhythm should hopefully be re-established by the sinoatrial node

IB Biology HL (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions