The Circulatory System in Animals Flashcards
(24 cards)
1
Q
Describe the circulatory system in mammals.
A
- closed: blood remains within blood vessels
- double circulatory system (pulmonary + systemic circulatory systems): blood passes through heart twice in 1circuit
2
Q
Describe the general pattern of blood circulation in a mammal.
A
- right side of heart pumps deoxygenated blood, at a lower pressure, to lungs for gas exchange
- blood returns to left side of heart which pumps oxygenated blood at high pressure to rest of body, ensuring blood reaches all respiring cells
3
Q
What are the main blood vessels?
A
- pulmonary artery: carries deoxygenated blood from right ventricle in heart, to lungs
- pulmonary vein: carries oxygenated blood from lungs to left atrium in heart
- coronary arteries: supplies cardiac muscle w oxygenated blood
- aorta: carries oxygenated blood from left ventricle in heart, to rest of body
- vena cava: carries deoxygenated blood from body to right atrium of heart
- renal artery: supplied kidneys w oxygenated blood
- renal vein: carries deoxygenated blood away from kidneys, towards heart
4
Q
Describe the structure of the human heart.
A
- 4 chambers: 2 atria + 2 ventricles
- semi-lunar valves in aorta + pulmonary artery
- atrioventricular valves (bicuspid + tricuspid) between atria + ventricles
- septum separating deoxygenated + oxygenated blood
5
Q
Describe the atria.
A
- when atria contract, thin, muscular walls only generate pressure enough to force blood into ventricles through bicuspid (left) + tricuspid (right) valves
6
Q
Describe the ventricles.
A
- thick, muscular walls to enable bigger contractions that create a high blood pressure to pump blood to lungs + rest of body
- left ventricle: thicker muscular wall allows larger muscle contractions to create high pressure to pump blood to all cells in body for respiration
- right ventricle: thinner, muscular walls pump blood to lungs at a lower pressure to prevent damage to capillaries in alveoli + dec speed of blood flow allowing more time for gas exchange
7
Q
Describe the valves in the heart.
A
- open when pressure is higher behind valve
- close when pressure is higher in front of valve
- important in preventing backflow of blood
- pulmonary valve is between right ventricle + pulmonary artery (semi-luna valve)
- aortic valve is between left ventricle + aorta (semi-luna valve)
8
Q
Why is it important for the coronary arteries to remain clear?
A
- if they become blocked, cardiac muscle won’t receive O2 so won’t be able to respire + cells will die, resulting in myocardial infarction (heart attack)
9
Q
What stages is the cardiac cycle split into?
A
- diastole
- atrial systole
- ventricular systole
10
Q
What does diastole + systole mean?
A
- diastole: heart muscles are relaxed
- systole: heart muscles are contracted
11
Q
Describe atrial systole.
A
- muscular walls of atria contract which dec volume of atria + inc pressure, causing pressure in atria to be > pressure in ventricles
- this forces atrioventricular (bicuspid + tricuspid) valves to open + blood to flow into ventricles causing volume + pressure of ventricles to slightly inc
12
Q
Describe ventricular systole.
A
- muscular walls of ventricles contract which dec volume of ventricles + inc pressure, causing pressure in ventricles to be > pressure in atria
- this forces atrioventricular (bicuspid + tricuspid) valves to close, preventing backflow of blood, + semi- lunar valves to open, as pressure in ventricles is > in aorta + pulmonary artery, so blood is forced out of heart into arteries
13
Q
Describe diastole.
A
- atria + ventricles are both relaxed when blood enters atria via vena cava + pulmonary vein
- causes volume + pressure in atria to inc > in ventricles forcing atrioventricular valves to open + blood to passively flow into ventricles
- this slowly inc volume + pressure in ventricles as they start to fill w blood
14
Q
What are the diff types of blood vessels?
A
- arteries: transport blood away from heart + into arterioles
- arterioles: smaller than arteries + transport blood into capillaries
- veins: transport blood into heart
- capillaries: connect arterioles to veins
15
Q
What is the structure + function of arteries?
A
- have a thick muscle layer so constriction + dilation can occur to control volume of blood
- have a thick elastic layer, so walls can stretch + recoil in response to heart contracting + relaxing, + a narrow lumen, to help maintain high blood pressure
- have a thicker wall to prevent vessels bursting from high pressure produced from contracting heart
16
Q
What is the structure + function of veins?
A
- have a relatively thin muscle layer so can’t control blood flow
- have a relatively thin elastic layer due to lower pressure of blood
- have a thin wall + large lumen to allow blood to flow at low pressures into heart, so risk of bursting is low + vessels can be easily flattened
- have valves to prevent backflow of blood
17
Q
What is the structure + function of arterioles?
A
- have a thicker muscle layer than arteries to restrict blood flow into capillaries
- have a thinner elastic layer than arteries as pressure is lower
- have thinner walls as pressure is slightly lower
18
Q
What is the structure + function of capillaries?
A
- form networks called capillary beds that are important exchange surfaces
- have a v narrow lumen (diameter) to slow blood flow, as red blood cells can only just fit through + are squashed against wall, allowing more time for diffusion
- have v thin walls (no muscle or elastic layer), 1 cell thick, to create a short diffusion distance for exchanging substances between blood + cells
- have pores in cells of wall allowing blood plasma to leak out + form tissue fluid
19
Q
What is tissue fluid?
A
- fluid containing water, glucose, AAs, fatty acids, ions + O2 which bathes tissues
20
Q
Describe how tissue fluid is formed + reabsorbed back into the circulatory system.
A
- capillaries have small gaps in walls allowing liquid + small molecules to be forced out of blood
- as blood enters capillaries from arterioles, the smaller diameter results in a high hydrostatic pressure causing water, glucose, AAs, fatty acids, ions + water to be forced out arteriole end of capillaries by ultrafiltration
- large molecules (e.g. red blood cells, platelets + large proteins) are too big to be forced out so remain in capillaries
- towards venule end of capillaries, hydrostatic pressure is low due to loss of liquid + water potential is low causing water to re-enter capillaries by osmosis
21
Q
Describe how lymph is formed + how it is returned to circulatory system.
A
- not all tissue fluid is reabsorbed by osmosis bc equilibrium will be reached
- so rest of tissue fluid is absorbed as lymph into the lymphatic system + eventually drains back into bloodstream through veins near heart
22
Q
What are the key points to keep in mind when analysing the cardiac cycle?
A
- curves on graph represent pressure of left atria, aorta + left ventricle
- points where curves cross indicates when valves open + close: Bleft = AV valve closes, Tleft = semilunar valve opens, Tright = semilunar valve closes, Bright = AV valve opens
23
Q
What are the risk factors + incidence of cardiovascular disease?
A
Risk factors:
- genetic factors
- age + sex: risk inc w age + more likely to affect males
- high blood pressure: can causes arteries to develop thicker walls + lumen to narrow to less blood transported to heart
- smoking: can damage heart + lungs + negatively impact blood pressure
Incidence of cardiovascular disease:
- positive correlation between risk factor + incidence of cardiovascular disease, however, correlation doesn’t prove causation
24
Q
Describe a method for a dissection.
A
- wear a lab coat, gloves + eye protection to avoid contamination w biological material
- place specimen on dissecting board
- use tools to access desired structure (cut away from body when using scalpel)
- scissors can be used to cut larger sections of tissue + a scalpel enables finer, more precise cutting
