8. Animal Organogenesis And Circulation Flashcards
1
Q
What is a gastrula?
A
An animal embryo with three layers of cells (endoderm, ectoderm, mesoderm) surrounding a central cavity with a small opening (blastopore) to the exterior.
2
Q
What is invagination?
A
The process of being turned inside out or folded back on itself to form a cavity or pouch.
3
Q
What is morphogenesis?
A
The origin and development of morphological characteristics.
4
Q
What is embryogenesis?
A
The process of initiation and development of an embryo from a zygote.
5
Q
What is a gastrocoel?
A
The primitive gut formed during gastrulation.
6
Q
What do the germ layers develop into?
A
Every other type of tissue in the body.
7
Q
The gastrulation of embryos only occurs in…?
A
Animals.
8
Q
Why are diploblast body plans simpler than triploblast body plans?
A
Diploblasts lack certain structures and tissues derived from the mesoderm, such as muscles and most internal organs.
9
Q
What is the classification of an animal where the blastospore forms the anus?
A
A deuterostome.
10
Q
What is the classification of an animal where the blastospore forms the mouth?
A
A protostome.
11
Q
What is a protostome?
A
An animal where the blastospore eventually forms the mouth.
12
Q
What is a deuterostome?
A
An animal where the blastospore eventually forms the anus.
13
Q
Unlike most other animals’ eggs, human eggs are…?
A
- Small.
- Contain very little nutrition for the developing embryo.
14
Q
What are 4 steps of human embryonic development?
A
- The egg is released from the ovary into the oviduct, where it is fertilised.
- The zygote travels down the oviduct to the uterus over 6 days, undergoing cleavage to form a blastocyte (mammalian blastula).
- The outer layer of the blastocyte initiates the implementation of the embryo into the wall of the uterus on day 7.
- Extra embryonic layers start to form after about 10 days and gastrulation begins.
15
Q
What are the 3 ways mammals give birth?
A
- Laying eggs. monotremes
- Birthing at an early developmental stage. marsupials
- Birthing fully developed offspring. humans and whales
16
Q
What 2 things are considered adaptions for land animals to enable embryonic development in a fluid environment?
A
- Shells.
- The uterus.
17
Q
What are the 4 extraembryonic membranes?
A
- Amnion.
- Chorion.
- Yolk sac. Vitellus
- Allantois.
18
Q
What is the purpose of the amnion membrane?
A
Fiills with amniotic fluid, causing the ammion to expand and become the amniotic sac.
Provides a protective environment for the developing embryo.
19
Q
What is the purpose of the chorion membrane?
A
The outermost membrane.
Largely used for gas exchange of O2 and CO2.
20
Q
What is the purpose of the yolk sac membrane?
A
- Provides nutrition before the formation of the placenta.
- Produces RBCs.
- Gas exchange between mother and embryo in a mammal.
21
Q
What is the purpose of the allantois membrane?
A
- Associated with the formation of the placenta and umbilical chord in mammals.
- Disposes of waste in reptiles.
22
Q
What is the placenta?
A
An organ that develops in the uterus during pregnancy.
Provides oxygen and nutrients to a growing baby, as well as removing the baby’s waste products.
23
Q
What is neurulation?
A
The process of the neural plate bending and fusing to form the hollow tube that will differentiate into the brain and spinal cord of the CNS.
A type of organogenesis.
24
Q
What is the notochord?
A
A cartilaginous skeletal rod supporting the body in all embryonic and some adult chordate animals.
25
What is the neural tube?
The structure that forms the early brain and spinal cord.
26
What are somites?
Precursor cells that give rise to important structures associated with the vertebrate body plan.
*They eventually differentiate into skeletal muscle, cartilage, tendons, and vertebrae.*
27
What are neural crest cells?
Embryonic cells pinched off during the formation of the neural tube that migrate extensively to form sensory and autonomic neurons.
*They also produce parts of the teeth and skull bones.*
28
What is induction?
The process of a group of cells or tissues influencing another group through close-range interactions.
29
What are 3 steps of neurulation?
1. The neural plate forms the dorsal epidermis *(ectoderm)*.
2. The neural tube develops from the folding and pinching of the neural plate.
3. The neural crest cells form between the epidermis and the neural tube.
30
Which precursor cells determine the migration paths of neural crest cells?
Somites.
31
Which structure helps embryonic cells migrate? How?
The cytoskeleton.
It enables cells to 'crawl' through the extracellular matrix by extending and retracting fibres.
32
What is the cytoskeleton?
A structure that helps cells maintain their shape and internal organisation while providing mechanical support for functions like division and movement.
Capable of rearranging - enabling the cell to change shape.
33
What mechanism is used to help with organ sculpting?
Cell apoptosis - programed cell death that kills off unnecessary cells.
34
How do phagocytes remove dead cells?
They recognise and engulf the dead cells before transferring them to lysosomes, where their cellular components are degraded for use.
35
What are pseudopodia?
Temporary projections of a cell.
Typically used for locomotion or phagocytosis.
36
What cells ingest foreign particles such as bacteria, carbon, dust, or dye?
Phagocytes.
37
What are lysosomes?
Membrane-bound organelles that contain digestive enzymes.
Used to break down excessive or worn-out cells, as well as invading viruses and bacteria.
38
What is interstitial fluid?
The fluid filling the spaces between cells in most animals.
39
What is circulatory fluid?
The fluid that moves around the internal structures of an organism.
40
What vessels slow down the movement of fluid and spread it over a large surface area to maximise gas exchange?
Capillaries.
41
What circuit moves blood from the heart to the lungs and back?
The pulmonary circuit.
42
What circuit moves blood from the heart to the rest of the body and back?
The systematic circuit.
43
How does the pulmonary circuit move blood?
1. From the right side of the heart.
2. To the lungs.
3. Back to the left side of the heart.
44
How does the systematic circuit move blood?
1. From the left side of the heart.
2. To the rest of the body.
3. Back to the right side of the heart.
45
Where does gas exchange occur?
From the cell's cytoplasm to the surrounding interstitial fluid via the cell membrane.
46
What type of cells need gas exchange?
All of them!
47
What 2 gases cross the cell membrane in gas diffusion?
1. Carbon Dioxide (CO2)
2. Oxygen (O2)
48
Why can an amoeba diffuse directly into the external environment?
It has a high surface area to volume ratio.
49
What is diffusion?
A process resulting from the random motion of molecules from an area of high concentration to an area of low concentration.
50
The time taken for a substance to diffuse is proportional to...?
The distance needing to be travelled.
51
What is the difference in the concentrations of the molecules of two areas called?
The concentration gradient.
52
What is a gastrovascular cavity?
A simple digestive structure possessing only one opening for both foods and waste products.
*Found in primitive invertebrates.*
53
Why can primitive invertebrates (including hydras and jellyfish) directly diffuse?
1. The outer and inner tissue layers of these organisms are bathed in water.
2. The body wall is only two cells thick.
*These creatures have no distinct circulatory system*
54
What are the 3 basic components of a circulatory system?
1. Circulatory fluid.
2. Interconnecting vessels.
3. A muscular pump *(heart)*.
55
What animals require a circulatory system?
Those with a complicated body system.
56
What is hydrostatic pressure?
The pressure exerted by a fluid at equilibrium at any point in time due to the force of gravity.
57
What is the fluid in an open circulatory system called?
Haemolymph.
*It acts as the interstitial fluid*.
58
What is the fluid in a closed circulatory system called?
Blood.
*It is separate from the interstitial fluid*
59
What is the circulatory system in vertebrates often called?
The cardiovascular system.
*It contains a heart as well as an extensive network of blood vessels and blood.*
60
Arteries carry blood...?
Away from the heart.
61
Veins carry blood...?
Towards the heart.
62
What do arteries branch into?
Arterioles.
These, in turn, connect to the capillaries.
63
What are capillary beds?
Networks of capillaries that infiltrate tissues, diffusing gases, and chemicals into the interstitial fluid around the cells.
64
What do veins branch into?
Venules.
*These occur where the capillaries converge to become venules, then veins*
65
What are capillary walls like?
Thin and porous.
66
What is plasma?
The liquid martix in which blood cells are suspended.
67
What is the scientific name for red blood cells?
Erythrocytes.
68
What is the scientific name for white blood cells?
Leukocytes.
69
What is the scientific name for platelets?
Thrombocytes.
70
What is the function of erythrocytes?
Carrying oxygen to the tissues of the body using a protein called haemoglobin.
71
What is the function of leukocytes?
Detecting and dealing with infections or foreign molecules through the production of antibodies.
Part of the immune system.
72
What are thrombocytes?
Small colourless disc-shaped cell fragments without a nucleus found in large numbers in the blood.
Involved in clotting.
73
What chambers of the heart receive blood?
The artia/atriums.
74
What chambers of the heart pump blood?
The ventricles.
75
What is single circulation?
The process of blood travelling through the body and returning to where it was first pumped in a single loop.
*This requires a 2 chamber heart with a single atrium and a single ventricle. Occurs in boney fish, rays, and sharks*
76
Where does O2 diffuse in fish?
In the gills.
77
What is double circulation?
The process of blood flow by 2 circuits.
*This requires 2 pumps combined into a single heart.*
*Occurs in mammals, reptiles and amphibians*
78
What is the pulmonary circuit called in amphibians?
The pulmocutaneous circuit.
79
What atrium of the heart contains oxygen-rich blood?
The left atrium.
80
What atrium of the heart contains oxygen-poor blood?
The right atrium.
81
On which of the 2 main circuits is the contraction of the heart stronger?
The systematic circuit.
82
What are endotherms?
'Warm blooded' animals.
Animals that maintain a constant temperature independent of the environment.
*Includes mammals and birds.*
83
What are ectoderms?
'Cold blooded' animals.
Animals whose body temperature regulation depends on external sources such as sunlight or a heated rock surface.
*Includes fish, amphibians, reptiles, and invertebrates*
84
What type of heart do amphibians have?
A 3 chambered heart.
Two atria *(left and right atrium)* and a single ventricle.
85
What is the difference in the ventricles between reptiles and mammals?
1. Reptiles have incomplete separation of the ventricles, resulting in some mixing of oxygenated and deoxygenated blood.
2. Mammals *(and birds)* have completed separating of the arterial and venus systems, with no mixing of blood.
86
What are external nares?
The openings that lead to the nasal cavity.
*Nostrils*
87
Why don't amphibians (and many reptiles) need to breathe through their facial orifices for long periods of time?
They can exchange gases with the environment through their skin.
*Shutting down bloodflow to the lungs and rerouting it to their skin*
88
What is a limitation of subcutaneous breathing?
The skin must be **moist**.
89
What type of animals require more energy for internal regulation?
Endotherms.
90
What process generates energy in a mammal?
Aerobic cellular respiration.
91
What is the *word* equation of aerobic respiration?
Glucose + Oxygen = Carbon Dioxide + Water + ATP
92
How quickly do brain cells begin to die when starved of oxygen?
Within minutes.
93
What technique is applied to manually squeeze a person's heart when they are in cardiac arrest?
CPR
*Cardiopulmonary Resuscitation*
94
What are the 3 circuits in the mammalian circulatory system?
1. Pulmonary.
2. Systematic.
3. Coronary.
95
Where does contraction of the right ventricle pump blood?
Through the pulmonary artery towards the capillary beds in the right and left lungs.
96
Where does the left ventricle pump blood?
Through the aorta to either the body tissues through the systematic circuit or to the heart muscle through the coronary circuit.
97
Where does oxygenated blood return to in the heart?
Through the pulmonary veins into the left atrium.
98
Where does deoxygenated blood return to in the heart?
To the right atrium via either the superior vena cava *(head and forearms)* or the inferior vena cava *(rest of the body)*.
99
In the systematic circuit, what does the aorta branch into?
1. The capillary beds of the head and arms.
2. The lower body capillary beds.
100
What is the coronary circuit?
The network of blood vessels that supply oxygen and nutrients to the heart muscle.
101
What prevents blood backflow?
Unidirectional valves.
102
What is stroke volume?
The volume of blood pumped by one contraction of the ventricle.
*Approximated 70ml in a human*
103
What is heart rate?
The number of times per minute that the heart muscle contracts.
*beats per minute*
104
What is systole?
Ventricular contraction.
*heart pumping out blood*
105
What is diastole?
Ventricular relaxation.
*heart filling with blood*
106
What are the atrioventricular valves (AV valves)?
Connective tissues that open when pushed from one side and close when pushed from the other side.
Located between the atrium and ventricle.
107
What are semilunar valves?
Heart valves located at the exits from the heart.
108
What are the 2 semilunar valves?
1. The aortic valve.
2. The pulmonary valve.
109
What are the 2 AV valves?
1. The tricuspid valve.
2. The mitral valve. Also known as the bicuspid valve.
110
Where is the aortic valve located?
Between the aorta and the left ventricle.
111
Where is the pulmonary valve located?
Between the pulmonary artery and the right ventricle.
112
Where is the tricuspid valve located?
Between the right atrium and the right ventricle.
113
Where is the mitral (bicuspid) valve located?
Between the left atrium and the left ventricle.
114
When does a heart murmur occur?
When blood squirts back through a defective valve.
115
What is cardiac output?
1. Stroke volume.
2. Heart rate.
116
What is the cardiac cycle?
One contraction (systole) and one relaxation (diastole).
117
When does coronary bypass occur?
When the coronary circuit is blocked, preventing the heart tissues from getting nutrients and oxygen.
118
What causes the two *'lub' 'dub'* sounds of the heart?
The closure of the AV valves and the closure of the semilunar valves, respectively.
119
What is the average cardiac output for a human at rest?
5L per minute.
120
Approximately how many litres of blood are in a humans body?
5 Litres
121
What is the thick muscle layer of the heart called?
Myocardium.
122
What node works as a heart 'pacemaker'?
The SA Node.
123
Where is the sinoatrial node (SA node) located?
In the right atrium, near the superior vena cava.
124
What does the sinoatrial node (SA node) do?
It coordinates the auto-rhythmic contractions of the heart to be in time with each other by producing electrical impulses.
These impulses spread through the walls of the aria, causing them to contract in unison.
125
What is used to detect the electrical impulses of the SA node?
An electrocardiogram (ECG).
The current generated can be measured when it reaches the skin via body fluids.
126
What does the atrioventricular node (AV node) do?
Delays impulses from the SA node for 0.1 seconds, allowing the atrium to empty completely before the signal is sent to the heart apex.
127
Where is the AV node located?
In the walls between the atria.
128
Does the mammalian heart need the nervous system to control its beating?
No and yes.
The auto-rhymic cardiac muscle cells will beat on their own.
But the nervous system regulates that heartbeat.
129
What does the parasympathetic nervous system do to the heart?
Slows down heart rate while at rest, conserving energy.
130
What does the sympathetic nervous system do to the heart?
Speeds up heart rate during movement and exercise, enabling more oxygen to reach the muscles.
131
Can hormones affect the heart rate?
Yes.
For example, adrenaline will increase heart rate.
132
Can a change in body temperature affect heart rate?
Yes.
For example, an increased body temperature will also increase heart rate.
133
What device checks the heart's rhythm and shocks it if the rhythm is abnormal?
An AED.
Automatic External Defibrillator.
134
All blood vessels contain a central cavity lined with...?
Endothelium.
135
What is endothelium?
A thin and smooth membrane that lines the inside of the heart and blood vessels.
136
What blood vessels have the smallest diameter?
The capillaries.
Their diameter is only slightly bigger than a red blood cell.
137
What 2 tissue types surround the endothelium in blood vessels (excluding capillaries)?
1. Smooth muscle.
2. Connective tissue.
138
What membranes do capillaries have?
Only a single basal lamina membrane.
139
What are artery walls like?
Thick, strong, and flexible.
Able to accommodate high blood pressure by buldging.
140
What blood vessels contain valves?
Veins.
141
What are the 3 layers of blood vessels?
1. The outer tunica externa.
2. The middle tunica media.
3. The inner tunica intima (endothelium).
142
What are the 2 main structural differences between arteries and veins.
1. Thickness of the different layers.
2. The presence of valves in veins.
143
What epithelial layers do capillaries have?
Only the tunica intima (endothelium).
144
What are precapillary sphincters?
Rings of smooth muscle that regulate blood flow through capillaries - controlling the location of blood flow to where it is needed.
145
How much slower is blood flow in the capillaries compared to the aorta?
500 times slower.
146
How do arterioles and capillaries maintain blood pressure from the arteries?
By having increasingly narrower and narrower diameters.
147
What is the order of blood vessels that blood travels through after leaving the heart?
1. Artery.
2. Arterioles.
3. Capillaries.
4. Venules.
5. Veins.
148
What pressure can be felt in the walls of the arteries as your pulse?
Systolic pressure.
149
How do arterioles ensure the circulatory system is stable?
They have the capacity to contract and increase pressure in the arteries or to dilate and reduce pressure in the arteries.
150
Where is blood pressure typically measured?
On an artery in the bicep, as it is the same height as the heart.
151
How is blood pressure recorded?
Systolic pressure / diastolic pressure
152
What is a normal blood pressure (based on a 20 year old)?
120 / 70
*(millimetres of mercury - mm Hg)*
153
Blood only flows in what percentage of the human body's capillaries at any given time?
10%
154
As well as gas exchange, capillary beds also exchange substances including...?
1. Dissolved sugars.
2. Salts.
3. Urea.
155
What 2 things control the diversion of blood from capillary beds?
1. Constriction or dilation of the arterioles.
2. Opening and closing of precapillary sphincters.
156
What is the lymphatic system?
A network of delicate tubes all throughout the body that drain fluids *(lymph)* that have leaked from blood vessels into tissues.
157
What is the main roles of the lymphatic system?
Management of fluid levels of the body.
158
Where is lymph emptied back into the bloodstream?
At lymph nodes.
159
What is the lymphatic system intermingled with, and why?
1. The blood capillaries.
2. Because the average body loses 4-8L of blood from the capillaries daily, and the lymphatic system mitigates this.
160
How does fluid from the capillaries move into the interstitial space and the lymph capillaries?
Through diffusion down a pressure gradient and through osmosis.
161
What percentage of blood is made of plasma?
55%
162
What is plasma?
The clear, yellowing fluid that carries blood cells and clotting proteins.
163
What are erythrocytes?
Biconcave discs that carry the pigment haemoglobin and do not contain a nucleus.
164
Where are blood cells made?
Bone marrow.
165
What is bone marrow?
Sponge-like tissue, present in bones, that contains stem cells that develop into RBCs, WBCs, and platelets.
166
What are lymph nodes?
Glands present throughout the body that filter lymphatic fluid.
