Lecture 25- Circulation Flashcards
True or False: The circulatory system of insects is an open system that bathes tissues directly with blood.
False; the circulatory system of insects is an open system that bathes tissues directly with HEMOLYMPH
A(n) _____ is a blood vessel that carries blood away from the heart.
Artery
The initiation of a heartbeat occurs at the _____.
Sinoatrial (SA) node
The top chamber(s) of the heart are called ____.
Atria
How can the endocrine system influence heart rate?
Secretion of epinephrine during acute stress accelerates heart rate
Also temperature
True or False: Amphibians have double circulation and a four-chambered heart.
False; amphibians have double circulation and a THREE-chambered heart
At the apex of the heart, the bundle branches diverge into the _____.
Purkinje fibers
The bottom chamber(s) of the heart are called _____.
Ventricles
What are the three layers of blood vessels from the lumen outward?
Endothelium → Smooth muscle → Connective tissue
The aortic and pulmonary valves are types of _____.
Semilunar valves
The _____ is a connective tissue sac that encloses the heart.
Pericardium
Why do arteries have a thicker layer of smooth muscle than veins?
Sustain higher pressures
How many chambers do fish hearts have?
Two
What is the connective tissue surrounding blood vessels composed of?
Collagen fibers
True or False: Amphibians withdraw oxygen through their skin.
TRUE
____ is the body fluid between blood vessels and cells.
Interstitial fluid
Impulses from the sinoatrial (SA) node travel directly to the _____.
Atrioventricular (AV) node
What are the primary functions of the lymphatic system?
Collect & return interstitial fluid / Absorb lipids (from digestion) / Immunity
What is lymph composed of?
Derived from interstitial fluid
What are baroreceptors and what is their primary function?
Nerves on blood vessels that sense blood pressure and communicate with the medulla
Oxygenated blood returns to the left atrium from the pulmonary circuit via the _____.
Pulmonary veins
What is the primary function of the atrioventricular (AV) node?
Delays impulses from reaching ventricles immediately (which allows the atria enough time to fill)
Where do cardiac impulses travel following the atrioventricular (AV) node?
Bundle branches
True or False: The sympathetic nervous system can accelerate heart rate and the parasympathetic nervous system can decelerate heart rate.
TRUE
True or False: Resting heart rate during a fever is generally slower than a healthy individual.
False; resting heart rate during a fever is generally FASTER than a healthy individual
Open Circulatory System
Fluid= hemolymph= interstitial fluid
Heart Contractions- hemolymph-> vessels-> interconnected sinuses
Heart Relaxations- Draw hemolymph back into heart
Low pressure, low efficiency, low E
Arthropods, most molluscs
Closed Circulatory System
Blood: Circulatory fluid confined to vessels
Heart(s) pump blood through branched vessels
Higher pressure- more efficient, requires more E
Annelids, cephalopods, vertebrates
Components of Vertebrate Circulation
Cardiovascular system
Involves:
- Heart: Pumps blood
- Vessels: Carry blood
Exchange at capillaries
What type of circulation do fish do?
Single circulation
Single Circulation in Fish Cycle
Heart: 2 chambers
1 atrium
1 ventricle
Not very efficient
Blood enters the heart through the atrium and goes to the ventricle. Then moves up into the gill capillaries and then into body capillaries. Deoxygenated blood then returns to heart.
What type of circulation do amphibians do?
Double Circulation
Double Circulation in Amphibians Cycle
Heart: 3 chambers
2 atria
1 ventricle
Blood flow: 2 circuit
Deoxygenated blood goes into the right atrium which empties the blood into the ventricle. The ventricle pumps the blood into the skin and lung capillaries in the pulmocutaneous circuit. It picks up oxygen and returns it through the left atrium to the ventricle, then enters the systemic capillaries in the systemic circuit and then returns through the right atrium back to the ventricle.
Double Circulation in Mammals & Birds
Heart: 4 chambers
2 atria
2 ventricles
Blood comes from body and goes into right atrium, goes through right atrioventricular valve into the right ventricle. It is pumped out of the right ventricle through the pulmonary valve into the pulmonary arteries which bring blood to the lungs which is the pulmonary circuit. Then the blood is brought back to the heart through the pulmonary veins. They dumps the blood into the left atrium and when the atria contract, the blood goes through the left atrioventricular value into the left ventricle and then when the ventricles contract the blood goes up through the aortic valve into the aorta which then goes to the systemic circuit which takes the blood through the rest of the body, dumps off the oxygen and the deoxygenated blood returns to the right atrium.
Atria
Receive blood from veins
Ventricles
Pump blood to arteries
Pericardium
Connective tissue sac, encloses heart
Atrioventricular valves
Flaps of connective tissue- prevent backflow
2 atrioventricular- right, left AV
Blood from tissues-> atria
Blood pressures in atria opens AV valves
Ventricular contractions closes AV valves
Semilunar valves
Ventricles-> arteries
Opened by ventricular contraction
Pulmonary valve- RV-> pulmonary artery
Aortic valve- LV-> aorta
Heart Contractions (Heartbeat)
Heartbeat starts by the SA node in the right atrium. Triggers the contraction of the right atrium. Intercalated discs allow the ions to directly diffuse from cell to cell which allows an action potential in one cell to directly depolarize the next cell. This allows the atria to contract in a coordinated way from top to bottom and then pause at the AV node between the right atrium and right ventricle. Pauses for 1/10th second to allow the blood to pump into the ventricle. The bundle branches transmit action potential to the apex of the heart and then radiate upwards through Purkinje fibers. The fibers contract the ventricles which push blood out through pulmonary arteries + aorta.
Regulation of Heart Rate by NS
Baroreceptors: Sensory receptors, wall of blood vessels, heart
Detect changes in blood pressure
-> cardiac centers in medulla-> autonomic nerves-> SA node
Sympathetic- increase heart rate, strength of contraction
Parasympathetic- decrease HR
Regulation of Heart Rate by Endocrine System
Stress
Adrenal medulla-> epinephrine-> increase heart rate
Temperature
Increase temp impresses heart rate (fever-> faster pulse)
Decrease temp decrease HR
3 components of blood vessel structure
3 layers
Endothelium- lines lumen- smooth
Smooth muscle- Thicker in arteries, thin in veins
Connective tissue- Many elastic, collagen fibers
Thick walls prevent diffusion
Arteries
Heart-> organs
Arteries-> arterioles in organs-> capillaries
Capillaries
Microscopic blood vessels in tissues
Capillary bed: Network of capillaries, infiltrate all tissues
Exchange between blood, tissues
Capillary Structure
2 layers- endothelium and basal lamina
At least 1 capillary near every cell in body
Only location of exchange between blood and interstitial fluid
Veins
Organs-> heart
Capillaries-> venues-> veins
Between skeletal muscle- squeezed by muscles
1-way valves prevent backflow
Veins vs. Arteries
Direction of blood flow-> veins bring blood to heart, arteries take blood from heart
Mechanism of Exchange
Thin capillary lining- single cell layer
Allows diffusion of nutrients, ions, gases, waste
Plasma under pressure
-> some forced into tissue-> interstitial fluid
Interstitial Fluid
No RBCs
25% of protein content of blood- hypotonic relative to blood
Leads to…
Fluid exchange between capillaries, tissues- in and out
Antagonistic forces- blood pressure, osmotic pressure
Arterial end of capillaries- fluid out
Venous end of capillaries- fluid in
Not all fluid returns
15% remains in interstitial fluid- intolerable over long term
Lymphatic System
Accessory circulatory system
Plasma of blood into the interstitial fluid into the lymphatic system and circulates back into the blood vessels
Absorbs lipids from SI
Defend against disease
Anatomy of lymphatic system
Contains lymph: watery fluid derived from interstitial fluid
Travels through lymph vessels
Lymph nodes- where vessels meet
Return to circulatory system via lymph ducts
Flows due to muscle contractions